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© International Telecommunication UnionINTERNATIONAL RADIO CONSULTATIVE COMMITTEE

C.C.I.R.
DOCUMENTS OF THE

Xth PLENARY ASSEMBLY
GENEVA, 1963

VOLUME III
FIXED AND MOBILE SERVICESSTANDARD-FREQUENCIES AND TIME-SIGNALSMONITORING OF EMISSIONS

Published by the

IN T E R N A T IO N A L T E L E C O M M U N IC A T IO N U N IO N
GENEVA, 1963

INTERNATIONAL RADIO CONSULTATIVE COMMITTEE

C.C.I.R.
DOCUMENTS OF THE

Xth PLENARY ASSEMBLY
GENEVA, 1963

VOLUME III
FIXED AND MOBILE SERVICESSTANDARD-FREQUENCIES AND TIME-SIGNALSMONITORING OF EMISSIONS

Published by the

IN T E R N A T IO N A L T E L E C O M M U N IC A T IO N U N IO N
GENEVA, 1963

PAGE INTENTIONALLY LEFT BLANKPAGE LAISSEE EN BLANC INTENTIONNELLEMENT

Recommendations of Section C (Fixed services)

FIXED SERVICES

Reports of Section C (Fixed services)
Questions and Study Programmes assigned to Study
Group III (Fixed service systems); Opinions and Resolutionsof interest to this Study Group; List of documents of theXth Plenary Assembly concerning Study Group III

Recommendations of Section D (Mobile services)

MOBILESERVICES

Reports of Section D (Mobile services)
Questions and Study Programmes assigned to Study
Group X m (Mobile services); Opinions and Resolutionsof interest to this Study Group; List of documents of theXth Plenary Assembly concerning Study Group XHI
Recommendations of Section H (Standard-frequencies. andtime-signals)

STANDARD-FRE­QUENCIES AND
TIME-SIGNALS

Reports of Section H (Standard-frequencies and time-signals)
Questions and Study Programmes assigned to Study
Group VD (Standard-frequencies and time-signals); Opinions
and Resolutions of interest to this Study Group; List of docu­
ments of the Xth Plenary Assembly concerning Study Group VII

Recommendations of Section J (Monitoring of emissions)

MONITORING
OF EMISSIONS. Reports of Section J (Monitoring of emissions)
Questions and Study Programmes assigned to Study
Group VHI (Monitoring of emissions); Opinions andResolutions of interest to this Study Group; List of docu­
ments of the Xth Plenary Assembly concerning Study Group VUI

— 4 —

DISTRIBUTION OF THE TEXTS OF THE Xth PLENARY ASSEMBLY
OF THE C.C.I.R. AMONG VOLUMES I-VI

1. Recommendations

N u m b er

V olum e

N u m b er

V olum e

N u m b er

V olum e

45
48,49
75-77
80
100
106
136
139,140
162
166
168
182
205
212
214-216

III
V
III
V
III
III
V
V
III
III
II
III
V
V
V

218,219
224
237
239
240
246
257,258259
261,262264-266268
270-271275,276279
281-283

III
III
I
I
III
III
III
IV
V
V
IV
IV
IV
IV
IV

289,290297-300302
304-306
310,311313
314
325-334
335-349
350-367368-373374-379
380-406
407-421422-429
430,431

IV
IV
IV
IV
II
II
IV
I
III
IV
II
III
IV
V
III
I

N u m b er

V olum e

N u m b er

V olum e

N u m b er

V olum e

19
32
42
43
46
77
79
93
106

III
V
III
II
II
V
V
III
III

107
109
111
112
122
130
134
137
151
175-194

III
III
III
III
V
IV
IV
IV
II
I

195-203204-226227-266267-282283-290291-316317-320
321
322

III
IV
II
III
IV
V
III
I
*

N u m b er

V olum e

N u m b er

V olum e

N u m b er

V olum e

1
2-13

III
II

14-16
17,18

III
IV

19,20
21,22
23-29

III
I
VI

2. Reports

3. Resolutions* P ublished separately.

— 5 —
4.

5.

6.

Opinions
N u m b er

V olum e

N u m b er

V olum e

N u m b er

V olum e

1,2
3

I
IV

4-10
11

II
III

12-14
15-19
20,21

IV
V
III

N u m b er

V olum e

N u m b er

V olum e

N u m b er

V olum e

3
23
43
66
74
81
95
102
118
120,121132,133140
152-154
156,157

III
V
III
V
III
III
III
V
V
V
III
III
V
V

163
166
175-177
180-183
185
188
191
192-195
197
199,200
205
206
207
219, 220

III
V
I
III
II
III
III
IV
IV
V
V
III
I
I

221
222
225
226
227-231232,233234-245
246-248249-259
260,261262-270271-275276-279
280-282

IV
V
I
III
I
III
IV
II
III
IV
V
III
IV
III

N u m b er

V olum e

N um ber

V olum e

N u m b er

V olum e

36
57
102
110
119

V
II
III
V
V

127
139
148
153
161,162
170

I
II
II
II
V
V

176
177
180-185
186,187
188-206
207

II
V
I
III
II
III

QuestionsjStudy Programmes *1* T h is list includes only th o se S tudy P ro g ram m es w hich do n o t derive fro m Q uestions. A S tudy P ro g ram m e d erived fro ma Q u estion carries th e sam e serial n u m b e r as th is Q uestion, follow ed by a le tte r (e.g. S.P. 102A (X II)). I t is in serted in th e b o o k
im m ed iately after th e text of th e Q u estio n fro m w hich it is derived.

ARRANGEMENT OF VOLUMES I TO VII OF THE DOCUMENTS
OF THE Xth PLENARY ASSEMBLY OF THE C.C.I.R.
(Geneva, 1963)

V olum e I

Emission. Reception.
and XTV).

Vocabulary (Sections A, B, K and Study Groups I, II

Volume II

Propagation (Section G and Study Groups V and VI).

V o l u m e III

Fixed and mobile services. Standard-frequencies and time-signals. International
monitoring (Sections C, D, H and J and Study Groups III, XIII,VII and VIII).

Volume IV

Radio-relay systems. Space systems and Radioastronomy (Sections F and L andStudy Groups IX and IV).

V olum e V

Sound broadcasting and Television (Section E, Study Groups X, XI and XII and
the C.M.T.T.).

V olume VI

Resolutions of a general nature.

Reports to the Plenary Assembly.
List of participants.
List of documents in numerical order.
V o l u m e VII

Minutes o f the Plenary Meetings.

Note 1. - To facilitate references, the pagination in the English and French texts is the same

N ote 2. - At the beginning of Volume VI will be found information concerning the Xth Plenary

Assembly of the C.C.I.R. and the participation at this meeting, on the presentation of texts(Definitions, origins, numbering, complete lists, etc.), together with general information on
the organization of the C.C.I.R.

TABLE OF CONTENTS OF VOLUME HI

Distribution of the texts of the Xth Plenary Assembly of the C.C.I.R. among Volumes I to VI . .
Arrangement of Volumes I to VII of the Xth Plenary Assembly of the C.C.I.R..................................
Table of contents of Volume I II ............................................................................................................ .

RECOMMENDATIONS OF SECTION C (FIXED SERVICES)
Rec. 75
Rec. 100
Rec. 106Rec. 162
Rec. 166
Rec. 240
Rec. 246
Rec. 335
Rec. 336
Rec. 337
Rec. 338
Rec. 339
Rec. 340
Rec. 341
Rec. 342
Rec. 343
Rec. 344
Rec. 345
Rec. 346
Rec. 347
Rec. 348
Rec. 349

Classification and essential characteristics of feed-back suppressors . . . .
Reduction of occupied bandwidth and transmitter power in radiotelephony
Voice-frequency telegraphy on radio circuits.......................................
Use of directional antennae................... ... .............................................. ...
Unit of quantity of information ......................................................................
Signal-to-interference protection ra tio s...............................................................
Frequency-shift k e y i n g ........................................................................................
Intercontinental radiotelephone systems and the use of radio links in inter­national telephone c irc u its....
Principles of the devices used to achieve privacy in radiotelephone conversa­
tions .....................................................................................................................
Channel se p a ra tio n ..............................................................................................
Bandwidth required at the output of a telegraph or telephone receiver . . .
Bandwidths and signal-to-noise ratios in complete sy ste m s.................... ... .
Fading allowances for the various classes of e m is s io n ...................................
The concept of transmission loss in studies of radio s y s te m s ........................
Automatic error correcting system for telegraph signals transmitted over radio
lin k s....................... ....................................................................................
Facsimile transmission of meteorological charts over radio circuits................
Standardization of phototelegraph systems for use on combined radio andmetallic circuits.....................................................................................................
Telegraph distortion ........................... ' . ..........................................................
Four-frequency diplex s y s t e m s ...........................................................................
Classification of multi-channel radiotelegraph systems for long-range circuits
operating at frequencies below about 30 Mc/s and the designation of thechannels in these systems .............................................................. ...................
Arrangement of channels in multi-channel single-sideband and independentsideband transmitters for long-range circuits operating at frequencies below
about 30 M c / s .....................................................................................................
Frequency stability required for single-sideband, independent-sideband andtelegraph systems to make the use of automatic frequency control superfluous

REPORTS OF SECTION C (FIXED SERVICES)
Report 19
Report 42
Report 106
Report 107

Voice-frequency telegraphy on radio circuits . . .
....................................
Use of radio circuits in association with 5-unit start-stop telegraph apparatus
Improvement obtainable from the use of directional a n t e n n a e ....................
Directivity of antennae at great d is t a n c e s .......................................................

—

8
Page

Report 109
Report 111
Report 112
Report 195
Report 196
Report 197
Report 198
Report 199
Report 200
Report 201
Report 202
Report 203

Radio systems employing ionospheric-scatter p ro p a g a tio n .............................
Influence on long-distance high-frequency communications using frequencyshift keying of frequency deviations associated with passage through theionosphere.............................................................................................................
Transmission loss in studies of radio sy stem s...................................................
Bandwidths and signal-to-noise ratios in complete systems - Prediction o f
the performance o f telegraph systems in terms o f bandwidth and signal-to-noiser a t i o ....................................................................................................................
Some aspects of the application of communication t h e o r y .............................
Factors affecting the quality of performance of complete systems in fixeds e rv ic e s ...............................
Voice-frequency (carrier) telegraphy on radio c i r c u i t s ..................................... t
Arrangement of voice-frequency frequency-shift telegraph channels on radioc i r c u i t s .................................................................................................................
Telegraph distortion, erro r-rate•. . .
Remote control signals for facsimile transmissions ........................................
Identification of the carrier frequency relative to the assigned frequency of an
em ission.................................................................................................................
Multipath propagation on high-frequency radio circuits - Measurements o fpath-time delay differences and their incidence on typical radio links................

63
79
84
90
98
100
101
101
103
103
104
105

QUESTIONS AND STUDY PROGRAMMES ASSIGNED TO STUDY GROUP III(FIXED SERVICES); RESOLUTION OF INTEREST TO THIS STUDY GROUP

Introduction by the Chairman, Study Group I II ......................................................................................
Resolution 1
Optimum use of the radio-frequency s p e c tr u m ...............................................
Question 3(111)
Revision of Atlantic City Recommendation No. 4 ............................................
Study Programme 3A(III)Factors affecting the quality of performance of complete
systems of the fixed services - Signal-to-noise and signal-tointerference protection ratios for fading signals, bandwidth andadjacent channel sp a cin g ..............................................................
Study Programme 3B(III)Radiotelegraph circuits used in automatic switched-networks .
Question 43(111)Voice-frequency telegraphy on radio c i r c u its .....................................
117
Study Programme 43A(1II)
Voice-frequency (carrier) telegraphy on radio circuits . . . .
Question 74(111)
Arrangement of channels in multi-channel telegraph systems for long-range
radio circuits operating on frequencies below about 30 Mc/s .
................
Question 81(111)
Directivity of antennae at great distances .......................................................
Study Programme 81A(III) Improvement obtainable from the use of directional antennae
Study Programme 81B(III) Directivity of antennae for fixed services using ionosphericscatter p ro p ag a tio n ........................................................
120
Question 95(111)Transmission of half-tone pictures over radio c i r c u its .....................
121
Question 132(111)Radio-relay systems employing ionospheric-scatter propagation......
121
Question 133(111)Communication theory...................................................................................
Study Programme 133A(III) Communication t h e o r y ................................................................
Question 180(111)
Use of intermittent communication in radiotelegraphy.....................
124
Question 181(111)Influence on long-distance high-frequency communication using frequencyshift keying of frequency deviations associated with passage through theionosphere...............................................................................................
124
Question 182(111)Frequency stability required for single-sideband, independent-sideband andtelegraph systems to make the use of automatic frequency control superfluous

109
Ill
112

113
116
117
118
118
119

122
122

125

— 9 —
Page

Question 183(111)Frequency-shift k e y i n g .......................................................................................
Study Programme 183A(III) Frequency-shift keying . . . . .................................................
Study Programme 183B(III) Four-frequency diplex s y s te m s ...................................................
Question 232(111)
Facsimile transmission of documentary matter over combined radio andmetallic circuits.....................................................................................................
Question 233(111)
Use of common-frequency systems on international radiotelephone circuits.
Question 280(111)
Use of directional antennae in the band 4 to 27-5 Mc/s - Limitation o f radiation
outside the direction necessary for the s e r v ic e ...................................................
Question 281(111)
Automatic control of the output power of HF transmitters . .
.................
Study Programme 186(111)
Efficiency f a c to r ...................
Study Programme 187(111)
Identification of the carrierfrequency relative to the assigned fre­quency of an e m is s io n

125
126
127

List of documents of the Xth Plenary Assembly of the C.C.I.R. concerning Study Group HI . . . .

132

127
128
128
129
130
131

The following texts, which are not contained in this Volume, also concern fixed services:

Text
Subject
Rec. 168Presentation of antennaradiation diagrams
The majority of theaRn 7 mRmeep o t ti0S
Section F
Rep. 178
Rep. 260.....................................................

VolumeII^ dio-relay s y ste m s.....................................................................................

IV

Reduction of interference and measurement of sp e ctra....................................
Ionospheric s c a t t e r ..............................................................................................

IIIRECOMMENDATIONS OF SECTION D (MOBILE SERVICES)
Rec. 45
Rec. 76
Rec. 77
Rec. 218
Rec. 219
Rec. 224
Rec. 257
Rec. 258
Rec. 422
Rec. 423
Rec. 424
Rec. 425

Avoidance of interference from ships’ radar to other radiocommunication
apparatus on b o a r d ..............................................................................................
137
Voice-operated devices for ship stations and carrier-operated devices forshore s t a t i o n s .....................................................................................................
138
Conditions necessary for interconnection of mobile radiotelephone stations(for instance, automobiles, aircraft and ships) and international telephoneline s .....................................................................................................................
139
Prevention of interference to radio reception on s h i p s .....................................
140
Alarm signal for use on the maritime radiotelephony distress frequency of2182 kc/s.................................................................................................................
141
Testing of 500 kc/s radiotelegraph auto-alarm receiving equipment on boards h i p s .....................................................................................................................
143
Selective calling devices for use in the international VHF (metric) maritime
mobile radiotelephone s e r v i c e ...............................
144
Single-sideband aeronautical and maritime mobile radiotelephone equipments
145
Pulse transmission for radio direction finding....................................................
148
Use of 8364 kc/s for radio direction f i n d i n g ....................................................
149
Bearing and position classification for direction finding.....................................
151
Technical characteristics of frequency-modulation VHF (metric) maritime
mobile e q u ip m e n ts.................................................................................................. '152

— 10 —
Page

Rec. 426
Rec. 427
Rec. 428
Rec. 429

Spurious emissions from frequency-modulated VHF (metric) maritime
mobile equipm ent.................................................................................................
Interference due to intermodulation products in the VHF (metric) maritime
mobile radiotelephone s e r v i c e ..........................................................................
Direction finding by ships in the 2 Mc/s b a n d ................................................
Interference level on the radiotelegraph distress fre q u e n c y ............................

154
155
156
158

REPORTS OF SECTION D (MOBILE SERVICES)
Report 93
Report 317
Report 318 Report 319
Report 320

HF (decametric) and VHF (metric) direction finding ....................................
Publication of service codes in use in the international telegraph service . .
Marine identification d ev ices...............................................................................
Characteristics of equipment and principles governing the allocation of
frequency channels in the VHF (metric) and UHF (decimetric) land mobiles e r v ic e s .................................................................................................................
Selective calling devices for the international maritime mobile radiotelephones e r v ic e s ................................................................................................................

161
165
167
171
174

QUESTIONS AND STUDY PROGRAMMES ASSIGNED TO STUDY GROUP XIII (MOBILESERVICES); OPINIONS AND RESOLUTIONS OF INTEREST TO THIS STUDY GROUP
Introduction by the Chairman, Study Group X I I I ..................................................................................
Opinion 20
Publication of the “ codes and abbreviations for the international tele­communication services ” published by the International Telecommunication
U n io n .............................................................................................
Resolution 19
Selective calling devices for use in the international maritime mobile radio­
telephone service ......................................................
Question 271 (XIII) Selective calling devices for use in the international maritime mobile radio­
telephone s e rv ic e .................................................................................................
Study Programme 271 A(XIII)
Selective calling devices for use in the international maritime
mobile radiotelephone se rv ic e s...............................................
Question 163(XIII) Characteristics of equipments and principles governing the allocation ofchannels in the VHF (metric) and UHF (decimetric) land mobile services .
Resolution 20
Characteristics of equipments and principles governing the allocation ofchannels in the VHF (metric) and UHF (decimetric) land mobile services .
Question 206(XIII) Direction finding by ships in the 2 Mc/s b a n d ................................................
Opinion 21
Emergency position-indicating rad io b e ac o n s....................................................
Question 272(XIII) Signal-to-interference protection ratios and minimum field strengths requiredin the mobile se rv ic e s..........................................................................................
Question 273(XIII) Use of classes of emission A2H and A3H on the distress frequencies 500 kc/s
and 2182 kc/s respectively..................................................................................
Question 274(XIII) Facsimile transmission of meteorological charts for reception by ships . . .
Question 282(XIII) Use of a control tone for automatic gain control of receivers in single-sideband
radiotelephone systems operating in the HF maritime mobile bands . . . .
List of documents of the Xth Plenary Assembly of the C.C.I.R. concerning Study Group XIII

. . .

177
180
180
181
182
183
184
185
185
186
187
188
189
190

RECOMMENDATIONS OF SECTION H (STANDARD-FREQUENCIES AND TIME-SIGNALS)
Rec. 374
Rec. 375

Standard-frequency and time-signal e m is s io n s ................................................
Standard-frequency and time-signal emissions in additional frequency bands

193
194

— 11 —
Page

Rec. 376

Avoidance of external interference with emissions of the standard-frequency
service in the bands allocated to that s e rv ic e ...................................................

195

REPORTS OF SECTION H (STANDARD-FREQUENCIES AND TIME-SIGNALS)
Report 267
Report 268
Report 269
Report 270
Report 271

Standard-frequencies and tim e-signals...............................; ............................
Stabilized frequency emissions and monitoring facilities in bands 4 and 5 . .
Reduction of mutual interference between standard-frequency and time-signale m is s io n s ........................................... ..................................................................
Frequency spectrum conservation for high precision tim e-sig n a ls.................
. A cause of reduced stability and accuracy in standard-frequency and timesignals as received ..............................................................................................

197
206
210
211.
212

QUESTIONS AND STUDY PROGRAMMES ASSIGNED TO STUDY GROUP VII (STANDARDFREQUENCIES AND TIME-SIGNALS); RESOLUTION OF INTEREST TO THIS STUDY GROUP
Introduction by the Chairman, Study Group V I I ..................................................................................
Resolution 14
Standard-frequency and time-signal emissions ................................................
Question 140(VII)Standard-frequency and time-signal e m is s io n s ................................................
Study Programme 140A(VII)Standard-frequency and time-signal e m is s io n s ....................
Study Programme 140B(VII)Single-sideband operation for the standard-frequency andtime-signal s e r v i c e ..................................................................
Question 249(VII)Standard-frequency and time-signal emissions in additional frequency bands
Study Programme 249A(VII)Standard-frequency and time-signal emissions from artificial
earth s a te llite s ..........................................................................
Question 250(VII)Stability of standard-frequency and time-signal emissions as received . . .
Study Programme 250A(VII)
Frequency spectrum conservation for high precision timesignals ......................................................................................
Study Programme 250B(VII)Instability of standard-frequency g e n e r a to r s ........................
Question 251 (VII) Standardization of timing c o d e s ................................................................
.

215
216
216
217,

220
220
221

List of documents of the Xth Plenary Assembly of the C.C.I.R,. concerning Study Group VII . . . .

222

218
218
219
219

RECOMMENDATIONS OF SECTION J (MONITORING OF EMISSIONS)
Rec. 182
Rec. 377
Rec. 378
Rec. 379

Automatic monitoring of occupancy of the radio-frequency spectrum . . .
Accuracy of frequency measurements at monitoring s ta tio n s .........................
Accuracy of field-strength measurements by monitoring stations . . . . .
Identification of radio s t a tio n s ...........................................................................

225
226
227
228

REPORTS OF SECTION J (MONITORING OF EMISSIONS)
Report 272
Report 273
Report 274
Report 275
Report 276

Frequency measurements at monitoring s t a t i o n s ............................................
Field-strength measurements at monitoring s ta tio n s ........................................
Measurement of S-values at monitoring s t a t i o n s ............................................
Bandwidth measurement by monitoring s t a t i o n s ............................................
Monitoring of radio transmissions from spacecraft at fixed monitoring stations

231
235
240
241
243

12
Page

Report 277
Report 278
Report 279
Report 280
Report 281
Report 282

Measurements at mobile monitoring sta tio n s.............................................
248
Automatic monitoring of occupancy of the radio-frequency spectrum . . . 253
Visual monitoring of the radio-frequency s p e c tr u m .................................
260
Identification of radio s ta tio n s ....................................................................
262
Identification of sources of interference to radio re c e p tio n ......................
263
International monitoring facilities - Reply to Recommendation No. 5 o f the
Administrative Radio Conference, Geneva, 1959 ...............................................
266

QUESTIONS AND STUDY PROGRAMMES ASSIGNED TO STUDY GROUP VIII (MONITORING
OF EMISSIONS); OPINION AND RESOLUTIONS OF INTEREST TO THIS STUDY GROUP
Introduction by the Chairman, Study Group V II I ..................................................................................
269
Resolution 15
Extension of the international monitoring system to a world-wide scale. . . 271
Resolution 16
Identification of sources of interference to radio r e c e p tio n .....................
272
Opinion 11
List of stations using special means of identification.................................
272
Question 188(VIII) Monitoring at fixed monitoring stations of radio emissions from spacecraft .
273
Question 191 (VIII) Visual monitoring of the radio-frequency s p e c tr u m .................................
274
Question 226(VIII) Monitoring of sweeping-type pulse em issions.............................................
275
Question 252(VIII) Frequency measurements at monitoring stations........................................
275
Question 253(VIII) Expeditious method of determining field-strength in the international
monitoring system............................4 .................................................................
276
Question 254(VIII) Direction finding at monitoring s ta tio n s .......................................
276
Question 255(VIII) Automatic monitoring of occupancy of the radio-frequency spectrum . . . 277
Question 256(VIII) Identification of radio s t a tio n s ....................................................................
278
Question 257(VIII) Identification of sources of interference to radio r e c e p tio n .....................
278
Question 258(VIII) Antennae for monitoring s ta tio n s................................................................
279
Question 259(VIII) Types and methods of assistance by monitoring stations to the operationof various radio services................................................................................
280
Study Programme 102(VI1I) Field-strength measurements at monitoring s ta tio n s .......................
280
Study Programme 207(VIII) Bandwidth measurements by monitoring s ta tio n s ...........................
281
Question 275(VIII) Monitoring in new and developing c o u n trie s .............................................
282
List of documents of the Xth Plenary Assembly of the C.C.I.R. concerning Study Group VHI

283

— 13 —

Rec. 75, 100

RECOMMENDATIONS OF SECTION C: FIXED SERVICESRECOMMENDATION 75
CLASSIFICATION AND ESSENTIAL CHARACTERISTICS
OF FEED-BACK SUPPRESSORS(Question 31)
The C.C.I.R.,(Geneva, 1951)

C O N S ID E R IN G

that the feedback suppressors now generally used are of a type, the operation of which is
sufficiently independent of the characteristics of those at the opposite end of the circuit;
U N A N IM O U S L Y RECO M M E N D S

that no classification of types nor terminology should be adopted.
Essential characteristics(§ (b) of Question 31)
The essential characteristics of the feedback suppressors, used on radiotelephone circuitsin the United Kingdom and in the United States of America for fixed services, are described
respectively in Docs. 49 and 51 of Geneva, 1951. These are in substantial accord with thecharacteristics described in C.C.I.F., 1950-1951, 5th Study Group, Doc. 7, Question 2.

RECOMMENDATION 100
REDUCTION OF OCCUPIED BANDWIDTHAND TRANSMITTER POWER IN RADIOTELEPHONY(Question 3(111))
The C.C.I.R.,(London, 1953)

C O N S ID E R IN G(a) the urgent need for improved use of the radio-frequency spectrum, particularly in the range

below 30 M c/s;(b) that a very great improvement in the use of the spectrum will arise from the replacementof double-sideband by single-sideband technique (see Recommendation 335, §§ 2.1 and 2.2);(c) that improvements can be obtained by the use of noise reducers and devices enabling the

average percentage of modulation to be maintained at a high level, e. g. peak-clipping devices(see Recommendation 339);

— 14 —

Rec. 100,106
R EC O M M E N D S

1.

that Administrations should, whenever possible, make use of single-sideband systems in
preference to double-sideband systems *;2.

that noise reducers should be employed at the receiving terminal of all circuits, where an
improvement in signal-to-noise ratio can be obtained * *;3.

that devices should be employed at the transmitting terminal of all circuits, to enable theaverage percentage of modulation to be maintained at a high level (for example, peak-clipping
devices). With the use of these devices, adequate precautions must be taken to prevent
radiation outside the necessary bandwidth (for example, by the use of an adequate low-passfilter after the device) ***.

RECOMMENDATION 106
VOICE-FREQUENCY TELEGRAPHY ON RADIO CIRCUITS(Question 43(111))
The C.C.I.R.,(London, 1953)

C O N S ID E R IN G(a) that diversity reception is not a common practice on radiotelegraph circuits;(b) that, when voice-frequency equipment is used on radio circuits at frequencies lower than about

30 Mc/s, the quality of these circuits will, in general, be insufficient if no means of diversity
reception is provided;(c) that, in the presence of fading, space- or frequency-diversity gives comparable improve­ments in the quality of reception of telegraph signals transmitted over radio channels;( d) that, for adequate frequency diversity, it appears necessary that the frequencies which areused in combination to obtain this diversity should differ by at least 400 c/s;
( e) that space diversity needs only half the bandwidth and less power for each telegraph channel,
as compared with frequency diversity, but usually requires more equipment;
U N A N IM O U SL Y R EC O M M EN D S

1.

that, when voice-frequency telegraph systems are used on radio circuits at frequencies lower
than about 30 Mc/s, diversity reception should be used on the individual voice-frequency
channels;

2.

that, whenever practicable, space diversity should be used in preference to frequency diversity;

3.

that, for frequency diversity, the channel frequencies used in combination should have aseparation of at least 400 c/s so that adequate diversity effects may be obtained.

* Im p ro v em en t of signal-to-noise ra tio , o r a red u ctio n in p o w er o f a t least 9 d b , is o b ta in ed b y th e use of single-sideband
system s in ste ad of d o uble-sideband system s.
** T h e im provem ent, w hich m ay b e o b ta in ed in practice , b y th e use of a n o ise red u cer is d e p e n d en t u p o n th e sig n al-to -n o ise
ra tio a t th e in p u t to th e noise red u cer (for exam ple, a n im p ro v em en t o f th e o rd e r o f 10 d b m ay b e o b ta in ed o n rad io telep h o n ecircuits o f go o d com m ercial quality).
*** T he im provem ent, w hich m ay be o b ta in ed in p ractice, is d ep e n d en t u p o n th e o rig in al average p ercentage m o d u la tio n ofth e tra n sm itter. Im p ro v e m en t up to 6 d b m ay be o b ta in ed in practice.

Rec. 162

— 15 —R E C O M M E N D A T IO N 162 *USE OF DIRECTIONAL ANTENNAE(Question 3(111) - Study Programme 45)
The C.C.I.R.,(London, 1953 - Warsaw, 1956)

C O N S ID E R IN G(a) the urgent need to determine the minimum separation between frequencies of stations operating

on adjacent channels, below 30 Mc/s;(b) that the improvement in the signal-to-noise ratio and signal-to-interference ratio to be obtainedby the use of directional receiving antennae is an important means of reducing to a minimum
the necessary channel spacing;(c) that the use of directional transmitting antennae considerably reduces the level of interferenceby- providing the necessary field-strength at the receiver with reduced transmitted power,- reducing the received field-strength at stations situated outside the principal lobe of thetransmitting antennae;(d) that, in addition, the use of a directional antenna can contribute an improvement by reducing
echo and multipath effects;(e) that, highly directional antennae can be constructed, using known techniques;(f) that, despite the non-homogeneous nature of the transmission medium, it is possible toemploy transmitting and receiving antennae with appreciably greater directivity than that ofantennae in general use;(g) that it is not yet possible to give full and precise answers to the questions posed in Study
Programme 45, §§ 1.1.9 and 1.2.9.

F ig u r e 1* This Recommendation replaces Recommendation 103.

Rec. 162

— 16 —U N A N IM O U SL Y R EC O M M E N D S

1.

that the characteristics, which might reasonably be expected in practice for rhombic antennae
in use at present for point-to-point circuits, should be considered in three main arcs as shownin Fig. 1, i. e .:(M ) the main arc, including only the main lobe,(A) two arcs A x and A 2, on either side of the main arc,
( B ) the remaining arc, from the limits of the arcs A x and A 2, including the whole of the back­ward arc.

2.

that the gains in the correct azimuthal direction and the gains for the arcs A and B, as shownin the Annex, should be adopted for distances of 3000 to 10 000 km.

ANNEX
M edian value of gain relativ e
to o p tim u m gain fo r half-w ave d ip o lea t th e sam e height

A zim u th al ran g e (degrees)(db)

F requency
range(M c/s)I n th e correct
azim uthal
dire ctio n

In a rc A

In a rc B

H a lf ofm ain arc

A rc
Ax = A2

H alf ofa rc B

4

6

0

-3

30

35

115

6

8

0

-3

25

30

125

8

10

0

-4

20

25

135

11

12

1

-5

15

22

143

15

14

2

-6

10

20

150

22

15

3

-6

8

18

154

— 17 —

Rec. 166, 240

R E C O M M E N D A T IO N 166

UNIT OF QUANTITY OF INFORMATIONThe C.C.I.R.,(Warsaw, 1956)

U N A N IM O U SL Y RECO M M E N D S

the following definition of the unit of quantity of information:“ the unit of quantity of information corresponds to a ‘ message unit ’ consisting of a random
choice between two equally probable signals ” (Xth General Assembly of U.R.S.I., Sydney,
1952). This unit may be designated by the word “ bit ”.
Note. - The U.R.S.I. (The Hague, 1954), has drawn attention to the fact that the quantity of
information in a message cannot be measured by a simple instrument. In most cases only astatistical estimate of an upper limit for the received quantity of information can be computed.
It is doubtful whether the construction of a computer for this purpose would serve a
useful end, since such statistical estimates can also be made indirectly.

R E C O M M E N D A T IO N 240 *SIGNAL-TO-INTERFERENCE PROTECTION RATIOS(Q uestion 3(111) - Study Program m e 3A(III))The C.C.I.R.,(London, 1953 - Warsaw, 1956 - Los Angeles, 1959)

C O N S ID E R IN G

that a knowledge of the signal-to-interference protection ratios for various types of serviceis needed;
RECO M M E N D S

1.

that the values of signal-to-interference ratios for stable conditions, below which harmfulinterference occurs, can be used in conjunction with the fading allowances in the Annex toRecommendation 340;

2.

that the values shown in the Table are appropriate to emissions indicated.

* T h is R ec o m m e n d atio n replaces R ec o m m e n d atio n 163. T h e R .P . of B ulgaria, th e U k rain ian S .S .R ., th e C zechoslovak
S .R . an d th e U .S.S .R . reserved th eir o p in io n on th is R ecom m endation.

T ableMinimum protection ratios and frequency separations required under stable conditions
W a n ted signal

In te rfe rin g signal
A1
50 b au d sf1)

T ype of service

1

2

FI 50 b au d s
2 D = 280 c/s(1)A1100 b au d s

3

4

1

2

3

4

1

2

3

FI 100 b au d s
2 D = 400 c/s
4

1

2

3

(db)

(kc/s)(db)(kc/s)(db), (kc/s)(db)(kc/s)

A 1-50 baud teleprinterB = 500 c/s

110-36 0-44 114

(2)
12

(2)
(2)
0-25 0-35

13

0-46 0-54 1-24

(2)
3

(2)
(2)
0-40 0-55

F I-50 baud teleprinter
2D = 280 c/s, B = 500 c/s

1

0-2

7

0-32 0-39 0-67

0-28 0-6

Fl-50 baud teleprinter
2D = 280 c/s, B = 3000 c/s

4

1

(2)
3

(2)
(2)
0-35 0-50

(2)
2

(2)
(2)
0-45 0-60

F 1-171 baud ARQ system
2D = 400 c/s, B = 500 c/s(4)4(4) ' (4)0-40 0-55

(4)
4

(4)
(4)
0-50 0-70

15

100 1-20

15

110 1-20

'

2

(db)

(3)
18

F l-50 baud teleprinter
2D = 400 c/s, B = 500 c/s

F4-phototelegraphy, 60 r.p.m.
B = 1000 c/s

B ro ad c ast^ )3 1 4(kc/s)

(3)
3

(3)
4-5

(3)
7-5

In the co lu m n “ T ype of service ” , B represents th e receiver b an d w id th an d 2 D rep resen ts th e to ta l frequency sh ift. C olum ns n u m b e red 1 give th e lim itin g values of signal-to-interference
ra tio (db) w hen th e occupied b a n d of th e in terferin g em ission eith er falls en tirely w ithin th e p ass-b an d of th e receiver, o r covers it com pletely. C o lu m ns n u m b e red 2, 3 an d 4 in d icate th e fre­quency sep aratio n necessary betw een a w anted an d an interfering sig n al, w hen th e level of th e la tte r is 0, 6 o r 30 d b h ig h er th a n th e w an ted signal.
p ) B an d w id th of interfering signals lim ited to 500 c/s;
(2) F o r a ch a ra cte r e rro r ra te of 1/10 000;
(3) F o r a ch a ra cte r e rro r ra te of 1/1000;(4) F o r a traffic efficiency of 9 0 % ;(6) A verage m o d u latio n degree of 4 0 % ; for this te st th e sideb an d com p o n en ts extended to ± 9 kc/s.

-

— 19 —

Rec. 246I

R E C O M M E N D A T IO N 246 *FREQUENCY-SHIFT KEYING(Q u estio n 183(111))
The C .C .I.R.,(Geneva, 1951 - London, 1953 - Warsaw, 1956 - Los Angeles, 1959)

C O N S ID E R IN G(a) that frequency-shift keying is employed in radiotelegraphy in the fixed service and th at its
use has also been extended to the mobile service;(b) th at it is desirable to adapt the frequency shift used to the telegraph speed;(c) that traffic interruptions should be reduced to a m inim um by avoiding frequent changes ofthe shift employed;(d) th at it is often necessary to employ the same radio transm itter to work with m ore than one
receiving station;(e) th at it is desirable to standardize the m ain operating characteristics of systems employing
frequency-shift keying;(f) th at various technical factors influence the choice of operating characteristics in such systems
in particular:- economy of bandw idth and the consequent need to control the shape o f the transm itted
signals;- signal distortion due to propagation conditions;- instability of the characteristics of certain transm itter and receiver elements (such as oscilla­
tors, filters or discrim inators); this instability being one of the reasons for the relatively
large shift employed in m any existing equipm ents;(g) th at difficulties can arise from the use of term s “ m ark ” and “ space ” on teletype circuits andalso th at the C.C.I.T., at its V llth Plenary Assembly, issued Recom m endation 1.4 introducing
new term s; these term s have been published by the I.T .U . in the “ List of Definitions of Essen­tial Telecom munication Terms ”, P art I, June 1957;
U N A N IM O U S L Y REC O M M E N D S

1. th at it is too early to standardize actual values of frequency shift, but that every effort should
be m ade to achieve this as quickly as possible for emissions using only two frequencies; andto assist in this, the characteristics shown below should be used as far as possible;2.

th at the value of the frequency shift employed should be the lowest com patible w ith the
maximum telegraph speed regularly used, the propagation conditions and the equipm ent
stability;3.

th at for frequency-shift systems working on two conditions only (i. e. single-channel and tim e - .
division multiplex systems) and operating between about 3 Mc/s and 30 M c/s, the preferredvalues of frequency shift are 200 c/s, 400 c/s and 500 c/s **;4.

th at the values 140 c/s, 280 c/s and 560 c/s may be used provisionally, but 560 c/s should not
be adopted for new system s;

5.

th at the value of the frequency shift should, if possible, be maintained w ithin
nom inal value and, in any case, within ± 1 0 % ;± 3 % of its

6. th at for circuits using the M orse code, the higher frequency should correspond to the M ark
signal, and the lower frequency should correspond to the Space signal;* T h is R eco m m en d atio n replaces R ec o m m e n d atio n 150.
** F o r long-distance co m m u n icatio n , see Q uestion 181 (III),Rec. 246, 335— 20 —

7.* that for circuits using the International Alphabet No. 2 code with start-stop apparatus, thehigher frequency should correspond to the start signal (position A) and the lower frequency
to the stop signal (position Z );.
8.* that, for telex circuits using the International Alphabet No. 2 code directly on the radio
circuit, the higher frequency should correspond to the C.C.I.T.T. “ free circuit condition ”(position A) and the lower frequency to the C.C.I.T.T. “ idle-circuit condition ” (position Z);
9.* that for channels of a 7-unit automatic repetition system, which are referred to in the Annex
to Recommendation 342 as directly keyed channels (e. g., channel A of a two-channel system),. the higher frequency should correspond to the code elements shown as letter A and the lower
frequency to the code elements shown as letter Z. For the channels which are to have reversed
keying (e. g. channel B of a two-channel system), the higher frequency should correspond tothe code elements shown as letter Z and the lower frequency to the code elements shown as
letter A.

RECOMMENDATION 335 **INTERCONTINENTAL RADIOTELEPHONE SYSTEMS AND THE USE
OF RADIO LINKS IN INTERNATIONAL TELEPHONE CIRCUITSThe C.C.I.R.,(Geneva, 1951 - Geneva, 1963)

C O N S ID E R IN G(a) that, at the present time, radiotelephone systems connecting the various continents usuallyemploy carrier frequencies below about 30 Mc/s * * *;(b) that the use of such a radio link, in a long-distance telephone circuit, implies certain special

conditions, which introduce particular difficulties not encountered when purely metallic con­nections are used;(c) that such a radiotelephone circuit differs from a metallic circuit in the following ways:
c.a such a radiotelephone circuit is subject to attenuation variation with the special difficultyof fading;c.b such a radiotelephone circuit suffers from noise caused by atmospherics, the intensity ofwhich may reach, or even exceed, a value comparable with that of the signal which it is desired
to receive;c.c special precautions are necessary in the setting up and maintenance of such a radiotelephone

circuit, to avoid disturbance of the radio receiver by any radio transmitter and especially by its
own radio transmitter;
c.d to maintain the radiotelephone link in the best condition from a point of view of transmission

performance, it is necessary to take special measures to ensure that the radio transmitter
always operates, as far as possible, under conditions of full loading, whatever may be the natureand the attenuation of the telephone system connected to the radiotelephone circuit;c.e it is necessary to take measures to avoid or correct conditions of abnormal oscillation or

crosstalk;c . f although the recommended frequency band, to be effectively transmitted by international

landline circuits, has been determined by a study of the requirements of the human ear, thisband (for a radiotelephone circuit operating at a frequency below 30 Mc/s), may be limited by
the necessity of obtaining the maximum number of telephone channels in this part of the radio­* W hen m odification of eq u ip m en t is necessary, it is recognized th a t it m ay tak e som e tim e before th e reco m m en d a tio n s
o f these p arag ra p h s can be im plem ented on circu its betw een different A d m in istratio n s.
** T h is R ecom m endation replaces R ec o m m e n d atio n 40.
*** F u rth e r reference t o “ 30 M c/s ” in th is R ec o m m e n d atio n m eans “ a b o u t 30 M c/s ” .

— 21 —

Rec. 335

frequency spectrum and so th a t each telephone channel does n ot occupy a radio-frequency
band larger than necessary;c.g in general, such a radiotelephone circuit is a long distance intercontinental circuit giving
telephone service between two extended networks, and this fact is of great im portance fromtwo points of view:c.g.a on the one hand, intercontinental conversations, in general, are of great im portance tothe subscribers and, on the other hand, they are made in languages which are notalways their m other tongue, so that high quality reception is particularly im portant;c.g.b the public should not be deprived of a very useful service, under the pretext th at it does
not always satisfy the degree of excellence desirable for long distance com m unication,from the point of view of transm ission quality;
U N A N IM O U SL Y R EC O M M E N D S

1.

Circuits above 30 Mc/s
that between fixed points, telephone com munications should be effected wherever possible
by means of metallic conductors or radio links, using frequencies above 30 Mc/s, to m ake theallocation of radio frequencies less difficult; where this can be realized, the objective should
be to attain the transm ission perform ance recom m ended by the C.C.I.T.T. for international
telephone circuits on metallic conductors.

2.

Circuits below 30 Mc/s

2.1 that, since it becomes necessary to economize in the use of the frequency spectrum, when
considering intercontinental circuits which consist mainly of single long-distance radio links
operating on frequencies less than 30 Mc/s, it is desirable to use single-sideband transm ission
to the maximum extent possible, to employ a transm itted band less than the 300 to 3400 c/s
recommended by the C.C.I.T.T. for land-line circuits and, preferably, to reduce the upper
frequency to less than 3000 c/s, but not below 2600 c/s, except in special circumstances;
2.2 that, although it will be necessary to tolerate large variations in noise level on such a rad io ­telephone circuit, every possible effort should be made to obtain m inimum disturbance to thecircuit from noise and fading, by the use of such techniques as full transm itter m odulation,
directional antennae and single-sideband operation;
2.3 that, during the time that such a radiotelephone circuit is connected to an extension circuit,equipped with echo suppressors, the intensity of disturbing currents should not be sufficientto operate the echo suppressor frequently;
2.4 th at such a radiotelephone circuit should be provided with a reaction suppressor (voiceoperated switching device), to avoid singing or echo disturbance on the complete circuit;
2.5 th at such a radiotelephone circuit should be equipped with autom atic gain control to com ­pensate automatically, as far as possible, for the phenom enon of fading;
2.6 th at the term inal equipments of such a radiotelephone circuit should be such, th a t it may beconnected, in the same way as any other circuit, with any other type of circuit;
2.7 that, where privacy equipment is used, this equipment should n ot appreciably affect the qualityof telephone transm ission;
2.8 that, when suitable autom atic devices are not provided, the circuit controls should be adjusted,
as often as necessary, by an operator to ensure optim um adjustm ent of transm itter loading,received volume and the operating conditions of the reaction suppressor.
Note. - A lthough the requirem ents contained in § 2 of this Recom m endation are m uch less severe
than those imposed on international land-line circuits, the objective remains to attain the same
standards of telephone transm ission in all cases. In view of this, it is desirable th at the
telephone systems connected to a radiotelephone circuit should conform to C.C.I.T.T.
Recom mendations, referring to the general conditions to be met by international circuits used
for land-line telephony, especially in respect of equivalent, distortion, noise, echoes and transientphenom ena.

— 22 —'

Rec. 335,336

Bearing in m ind the recommendations contained in §§ 1 and 2, it is desirable th at in eachparticular case, A dm inistrations and private companies concerned should first reach agree­m ent on how far the standards usually employed for international land-line circuits may beattained in the case considered. If the technique of § 1 of the Recom m endation can be used,
the objective should be to obtain, as far as possible, the characteristics recommended by the
C.C.I.T.T. for international land-line circuits. Otherwise, the Adm inistrations and privatecompanies concerned should study the best solution from the point of view of both techniqueand economy.

R E C O M M E N D A T IO N 336 *P R IN C IP L E S O F T H E D E V IC ES U SED T O A CH IEV E
PRIV A CY IN R A D IO T E L E P H O N E CO N V ER SA T IO N S(Q uestion 30)
The C.C.I.R.,(Geneva, 1951 - Geneva, 1963)

C O N S ID E R IN G(a) that the devices referred to are intended to achieve privacy rather than secrecy in radiotelephone
conversations;(b) that, in the interest of maximum privacy, the details of the systems employed and of theirperform ance, should be agreed upon between the A dm inistrations and private enterprises
concerned;
U N A N IM O U SL Y RECO M M E N D S

1.

that the following statem ent of principles and characteristics of the devices concludes the studyof Question 30, for radio circuits operating at frequencies less than about 30 M c/s;

1.1 Principles o f the devices
Two general types of system are used, to achieve privacy in radiotelephone circuits
operating at frequencies less than about 30 M c/s:
1.1.1 For double-sideband systems
inverter systems, with or without wobbling of the carrier (i. e. rapid cyclic variation of
the carrier frequency over a few hundred c/s), the speech band being inverted about afixed frequency;
1.1.2 For single-sideband and independent-sideband systems
band-splitting systems, in which the speech band is subdivided into equal frequency
bands, the speech com ponents in the sub-bands being interchanged, with or without
frequency inversion, and, according to a prearranged repetitive sequence, to give“ scrambled ” speech. The process is reversed at the receiving term inal to reform the
speech signals. A ccurate synchronization of the switching processes at the two term inals
is required;
1.2 Characteristics o f the devices
1.2.1 the band-splitting system provides privacy superior to th at obtained with the inverter
system, but for satisfactory operation it can tolerate less radio distortion;
1.2.2 the apparatus is designed to reduce attenuation distortion and the levels o f unw anted
products of m odulation and of carrier signals to a minimum. The extent of thepermissible distortion due to the presence of the privacy devices is, in general, dependent
on the type of privacy and is usually agreed between the A dm inistrations or private
enterprises concerned;* This Recommendation replaces Recommendation 74.

— 23 —

Rec. 336, 337, 338

1.3 Location o f the devices
to facilitate control and maintenance and on the grounds of economy, the privacy apparatus
is normally located at the point where the transmitting and receiving channels of a radiotele­phone circuit are combined;
2. that, for frequencies above about 30 Mc/s, the details of the systems to be employed and of theirperformance should be agreed upon between the Administrations or private enterprises
concerned.

R E C O M M E N D A T IO N 337 *CHANNEL SEPARATIONThe C.C.I.R.,(Stockholm, 1948 - Geneva, 1951 - London, 1953 - Geneva, 1963)

C O N S ID E R IN G(a) that, in the more usual cases, the prim ary factors which determine frequency separation
between channels include:- the signal power required by the receiver;- the interference power intercepted by the receiver, including th at from interfering signals
and from noise;(b) th at transm itters, in general, emit radiations outside the frequency bandw idth necessarily
occupied by the emission;(c) th at many factors are involved, am ong which are the properties of the transm ission medium(which are variable in character and difficult to determine), the characteristics of the receiver
and, for aural reception, the discriminating properties of the hum an ear;U N A N IM O U SL Y REC O M M E N D S

1. th at the required separation between channels should be calculated by the following m eth o d :- determine the signal power intercepted by the receiver;- determine the interfering power intercepted, including both noise and interfering signal;- determine, from these data, the degree of frequency separation th at produces acceptableratios of signal power to interfering power, for an acceptable percentage of the time.
A ccount should be taken of the fluctuating nature both of the signal and of the interference,
and, whenever appropriate, the discriminating properties of the hum an ear ;2.

that, at every stage of the calculation, com parison should be made, as far as possible, withdata obtained under controlled representative operating conditions, especially in connection
with the final figure arrived at for the channel separation,

RECOMMENDATION 338 **BANDWIDTH REQUIRED AT THE OUTPUT OF A TELEGRAPH
OR TELEPHONE RECEIVER(Question 3(111))
The C.C.I.R.,(London, 1953 - Geneva, 1963)

C O N S ID E R IN G(a) the urgent need to determine the minimum separation between frequency assignments ofstations operating on adjacent channels, in the range 10 kc/s to 30 000 kc/s;* T h is R ecom m endation replaces R ec o m m e n d atio n 97.
** T h is R ec om m endation replaces R eco m m en d atio n 101.

Rec. 338, 339— 24 —(b) th at the width of the frequency band, which is necessary at the output of the receiver, is one of
the factors which determine the band of frequencies required for the overall system;(c) that, for telegraphy, the permissible degree of distortion is n o t yet defined;( d) that, for telephony, the bandw idth may depend, am ong other factors, upon the type o f privacy
equipm ent in u se;
U N A N IM O U SL Y REC O M M E N D S

Lthat, for telegraphy, a provisional value for the bandw idth necessary at the output of thereceiver, under average practical conditions, should be as follows:
1.1 for A1 emissions, the bandw idth in cycles per second, after the final detector stage, should beequal to 2-5 times the signalling speed in bauds;
1.2 for F I emissions, the bandw idth (c/s) after the discriminator, should be equal to 1*4 times
the signalling speed in bauds.
The extent to which these values can be applied, to perm it closer spacing o f adjacentchannels, depends upon the degree and speed of am plitude variations due to fading and upon
the differential fading of the m ark and space frequencies;

2. that, for telephony, as a com prom ise between intelligibility and economy of bandwidth, thebandw idth necessary, for each speech channel at the output o f the receiver, should be as follow s:
2.1 in accordance with Recom m endation 335, the upper limit frequency should be reduced to3000 c/s or less but not lower than 2600 c/s;
2.2 the lower frequency limit of speech channels should be 250 c/s, and th at o f broadcast relay
channels should be 150 c/s;
2.3 for systems employing privacy equipment, the necessary bandw idth for satisfactory service
may require the use of an upper limit frequency greater than 2600 c/s (e. g. in five-band privacy
equipm ent the necessary bandw idth is 2750 c/s, the upper limit being 3000 c/s).

R E C O M M E N D A T IO N 339 *BAND W ID T H S AND SIG N A L -T O -N O ISE R A T IO S
IN C O M P L E T E SY STEM S(Q uestion 3(111))
The C.C.I.R.,(Geneva, 1951 - London, 1953 - W arsaw, 1956 - Geneva, 1963)

C O N S ID E R IN G

that it is n o t yet possible to give a full and accurate answer to Question 3(111), b ut to assist
in giving such an answer, it is desirable to classify the im portant points with which future
study will have to deal;U N A N IM O U SL Y REC O M M E N D S

1.

that meanwhile, the values given in Table I should be adopted as provisional values for thesignal-to-noise ratio required for the classes of emission concerned;

2.

that, in further study relating to the minimum separation between frequencies of stations
operating on adjacent channels, the factors detailed in Annex I should be taken into considera­tion.
* This Recommendation replaces Recommendation 161.

Rec. 339

— 25 —
T a b leI

Signal-to-noise ratios required(Stable conditions (Note 6))
R a tioof p ea k R F
signal-noise
in a 6 kc/sband
(N o te 1)(db)

A ud iob an d w id thof receiver(kc/s)A u d iosignal-to-noise
ra tio(db)

B an d w id thof receiver(kc/s)

A1 telegraphy
8 baud, low g r a d e ...................................................
24 baud......................................................................
120 baud, reco rd er........................... .......................
50 baud, p r in te r .......................................

1-5
1-5
0-6
0-25

- 4
11
10
16

3
3
0-6
0-25

A2 telegraphy
8 baud, low g r a d e ..................................................

1-5

- 4

3

24 baud......................................................................

1-5

11

3

- 3
(Note 2)
12(Note 2)

FI frequency-shift telegraphy
120 baud, reco rd er..................................................
50 baud, p r in te r ......................................................

0-25
0-10

4
10

1-5
1-5

2
- 2

Class of em ission

F3 telephony(3) ..........................................................
D is the frequency deviation (k c /s ).......................
M is the audio bandwidth (k c /s ) ...........................
K is normally 1, but sometimes a higher value isnecessary(The ratio of peak RF signal-to-noise in a 6 kc/s band,is lower by (4-77+20 log DjM) db than that
required for A3 double-sideband telephony)

3

-

7
8

0
2

%

2M +2D K

Phototelegraphy F4Sub-carrier frequency-modulation single-sideband
emission.....................................................................

3

15

3

12

Hellschreiber
F requency-shift......................................................

1-5

6

3

3

Telephony
Double-sideband, just usable quality, operator tooperator (Note 4)......................................................
Double-sideband, marginally commercial (Note 5)
Double-sideband, good commercial quality (Note 5)
Single-sideband and independent-sideband,
1 channel ..................................................
2 ch a n n els..................................................
3 ch a n n els..................................................
4 ch a n n els..................................................

(Note 3)
3
3
3

6
15
33

6
6
6

18
27
350

3
3
3
3

33
33
33
33

3
3(2)
3(2)
3(2)

260
280
290
300

(0 A ssum ing 10 db im provem ent due to th e use of noise reducers.
(2) P e r channel.
(3) N o . 466 of th e R ad io R egulations, G eneva 1959, p ro h ib its F3 em issions fo r th e fixed services in th e b an d s b elow 30 M c/s.

Rec. 339, 340— 26 —

Note 1. - M easured as the ratio of the r.m.s. signal corresponding to peak output of the transm itterand the r.m.s. noise in a 6 kc/s band, assuming stable conditions.
Note 2. - Carrier keyed. Beat-frequency oscillator used.
Note 3. - F or telephony, the figures in this column represent the ratio of the audio signal, as
measured on a standard VU-meter, to the r.m.s. noise, for a bandwidth of 3 kc/s. (Thecorresponding peak signal power,- i.e ., when the transm itter is 100% tone-m odulated, isassumed to be 6 db higher.)
Note 4. - F or 90% intelligibility of unrelated words.
Note 5. - W hen connected to the public service network.
Note 6. - These values are based on Doc. 138 of W ashington, 1950, Doc. 112 of Geneva, 1951,
and Doc. 11 of The Hague, 1952.

ANNEX IF actors

to

be

taken

in t oaccount

fo r

v a r io u s

s e r v ic e s

ind e t e r m in in gthem in im u m

S E P A R A T IO N B ET W EE N T H E FR EQ U E N C IE S O F STA TIO N S O P E R A T IN G O N A D JA C E N T C H A N N E L S
01.

Required signal-to-interference ratios.

2.

Necessary bandwidth for required intelligence.

3.

Transmitters:- out-of-band radiation;- frequency instability.

4.

Propagation:- allowances for fluctuations due to absorption and fading.

5.

Receivers:- necessary bandwidth;- attenuation slope;- frequency instability.

6.

Effect of:- inequalities of received field-strength on wanted and adjacent channels;- antenna directivity at transmitter and receiver.

RECOMMENDATION 340 *FADING ALLOWANCES FOR THE VARIOUS CLASSESOF EMISSION(Question 3(111) - Study Programme 3A(III))The C.C.I.R.,(Geneva, 1951 - London, 1953 - W arsaw, 1956 - Geneva, 1963)

C O N S ID E R IN G

(a)that Annex I to Recom m endation 339 is a provisional and partial reply to Question 3(111),
applying to stable conditions;* This Recommendation replaces Recommendation 164.

— 27 —

Rec. 340(b) th at there is a need for figures which take into account fading and fluctuations in field intensity;(c) th at it is not yet possible to give a full answer to Study Program m e 3A (III);(d) that, however, the inform ation contained in Reports 248 and 266 give some results fromwhich provisional data on fading allowances can be derived;
U N A N IM O U SL Y RECO M M E N D S

1.

that the studies in connection with Recom m endation 339 and Study Program m e 3A (III)should be continued, in conjunction with those of Study Program m e 148 (VI), for the purposeof determining whether the provisional values given in the Annex may be accepted or should
be modified;2.

th at meanwhile, the values given in the Annex may be regarded as provisional total fading
allowances (combined fading safety-factors and intensity fluctuation-factors);3.

th at meanwhile, these values may be used as a guide, in conjunction with the values for signalto-noise ratios required for stable conditions given in Recom m endation 339, Annex I, toestimate monthly-m edian values of hourly-hiedian field intensity, necessary for the various
types and grade of service: similarly, the fading allowances may be used as a guide, in conjunc­tion with the values for signal-to-interference ratios (for stable conditions), appropriate to thevarious services.

ANNEX

Note 1. - The allowance for day-to-day fluctuation (intensity fluctuation factor) for the signal,
against steady noise, is 10 db, estimated to give protection for 90% of the days. The fluctua­
tions in intensity o f atm ospheric noise are also taken to be 10 db for 90 % of the days. Assum ­ing that there is no correlation between the fluctuations in intensity of the noise and thoseof the signal (the worst condition likely to exist), a good estimate o f the com bined signal andnoise factor is :VlO2 + 102 = 14 db
The combined fading allowance in Colum n 1 is obtained by adding 14 db to the fading
safety factor applied to each type of service. Subtraction of 4 db reduces the intensity
fluctuation allowance to 10 db, which is the value for the signal alone; the net allowance
would then be appropriate for the protection of a fading signal against steady (non-fluctuating)noise or a steady (non-fading or fluctuating) interfering signal.
Note 2. - The probability distribution of the ratio of two signals fading independently has been
applied in accordance with Doc. 443 (U.S.A.) of London, 1953. The com bined intensity
fluctuation allowance for two signals has been taken as 7 db, which represents a com prom ise' between the 0 db allowance, appropriate to perfectly correlated intensity fluctuations of thetwo signals, and the 14 db allowance, appropriate to uncorrelated intensity fluctuations of
the two signals (see N ote 1).
General Note. - Use of the recommended values only permits an estimate to be obtained, which
may have to be adjusted for radio circuits of different lengths, depending on the quality oftransm ission required. In calculating the fading safety factor for rapid or short periodfading a log-normal am plitude distribution of the received fading signal has been used (using
7 db for the ratio of median level to level exceeded for 10% or 90% of the time) except forRec. 340

— 28 —
Provisional total fading allowancesi1)

F o r th e p ro te ctio n of a fading sig n al against:

atm o sp h eric noise
subject to d ay-to-day
in ten sity flu ctu atio n(su b tract 4 db for
p ro te ctio n ag ain st
steady n o ise o r steadyinterferin g signal)(see N o te 1)

C lass of em issio n /2)

interferin g signal
subject to fadingan d d ay-to-day
in ten sity fluctuation(see N o te 2)

d b relative to ra tio s of m o n th ly m edianvalues of h o u rly -m ed ian field-strength

A1 telegraphy
8 baud, low g r a d e ...........................................
24 baud. .
120 baud r e c o r d e r ...........................................
50 baud printer..................................................

(Note 3)(Note 4)(Note 6)(Notes 5, 6)

21
25
25
32

17
20
20
27

(Notes 3, 7)(Notes 4, 7)

17
20

13
17

(Note 6)(Notes 5, 6)(Notes 6, 8)

25
32
17

20
27
12

sub-carrier frequency-modulation single-sideband emission. .

23

20(Note 9)23

20

DSB just usable quality, operator to operator (Note 10)
DSB marginally com mercial........................... (Note 11)
DSB good commercial q u a lity ....................... (Note 12)
1 channel...................................
2 channels...................................
SSB and ISB• (Note 12)
3 channels...................................
4 channels...................................

17
19
21

11
14
17

21

17

A2 telegraphy
8 baud, low g r a d e ..........................................
24 baud

FI telegraphy
120 baud r e c o rd e r ...........................................
50 baud printer..................................................
automatic repetition printer (ARQ)................

Phototelegraphy F4Hellschreiber frequency-shift ...............................

A3 telephony( 0 C om bined fading safety facto r and intensity fluctuatio n allow ances.
(2) F ro m R ec o m m e n d atio n 339, A nnex I.

— 29 —

Rec. 340, 341

high-speed autom atic telegraphy services, where the protection has been calculated on theassum ption of a Rayleigh distribution. The following notes refer to protection against rapid
or short-period fading.
Note 3. - F or protection 90% of the time.
Note 4. - F or protection 98 % of the time.
Note 5. - F or protection 99-99% of the time.
Note 6. - M inimum of 2-element diversity assumed.
Note 7. - Total sideband power, combined with keyed carrier, is assumed to give partial (twoelement) diversity effect. A n allowance of 4 db is m ade for 90 % protection (8 baud), and 6 db
for 98% protection.
Note 8. - Based on 90% traffic efficiency.
Note 9. - Based on 95 % protection.
Note 10. - Based on 70 % protection.
Note 11. - Based on 80% protection.
Note 12. - Based on 90% protection.

R E C O M M E N D A T IO N 341 *THE CONCEPT OF TRANSMISSION LOSS IN STUDIES OF RADIO SYSTEMS(Q uestion 3(111) and Study Program m e 3A(III))The C.C.I.R.,(Los Angeles, 1959)

C O N S ID E R IN G

fa ) th at the radio-frequency signal power, pa, available ** at the terminals of a receiving antenna
for a given power input, p t, to the term inals of a transm itting antenna, provides a m easure
which is useful in determining, at the term inals of the receiving antenna, the service from , or
the interference produced by, a radio system involving a transm itting antenna, a receiving
antenna, and the intervening propagation m edium;(b) th at the ratio, p t[pa, which will be called the system loss, is a convenient dimensionless form
for expressing this measure of the com bined radio propagation and circuit loss characteristics
o f such a system;(c) th at the available power, at the terminals of the receiving antenna, is sometimes a simpler andm ore directly useful concept than th at of the effective field-strength, especially where theeffective field is the resultant of a large num ber of received field components, corresponding
to several modes of propagation, arriving at the receiving antenna at different angles andpossibly with different polarizations;(d) th at the relationship between the system loss and the conditions in the neighbourhood o f thereceiving antenna, does not depend solely on the received field-strength, because the impedanceof the antenna depends itself upon the conditions,in its neighbourhood;* T h is R ec o m m e n d atio n replaces R ec om m endation 241.
** T h e available pow er, p a, is th e pow er which w ould go to th e lo a d if it w ere m atch ed to th e an ten n a im pedance.

— 30 —

Rec. 341(e) that the power, P /, radiated from the transm itting antenna, required for satisfactory reception
in the presence of noise, is precisely determined for a system with transmission loss, L, by thesimple relation: P / = L + P; P is the minimum signal power that is required to provide
satisfactory reception (as defined in R eport 322), available from an equivalent lossless receiving
antenna;(f) that it is desirable to standardize term inology and notation for describing system loss andits various com ponents;
U N A N IM O U SL Y RECO M M E N D S

that the terminology and notation given in the Annex should be adopted for use by the C .C .I.R.,
in accordance with the further discussion of the use of these term s given in R eport 112.

ANNEX
1.

System loss (Ls)
The system loss of a radio circuit, consisting of a transm itting antenna, a receiving antenna
and the intervening propagation medium, is defined as the ratio, p tlpa, where p t is the radiofrequency power input to the term inals of the transm itting antenna and p ais the resultant radio­frequency signal-power available at the term inals of the receiving antenna. Both p t and pa
are expressed in watts. The system loss is usually expressed in decibels: *L s — 10 log10 {ptlp a) = P t - P a
N ote that the system loss, as defined above, excludes any transm itting or receiving antennatransm ission line losses, since it is considered th at such losses are readily measurable. On
the other hand, the system loss includes all of the losses in the transm itting and receiving
antenna circuits, including, not only, the transm ission loss due to radiation from the trans­mitting antenna and re-radiation from the receiving antenna, but also any ground losses,
dielectric losses, antenna loading coil losses, term inating resistor losses in rhom bic antennae,
etc. The inclusion of all of the antenna circuit losses in the definition of system loss provides
a quantity which can always be accurately m easured and which is directly applicable to thesolution of radio system problems.

2.

Transmission loss (L )The transm ission loss of a radio circuit, consisting of a transm itting antenna, a receiving
antenna, and the intervening propagation medium, is defined as the dimensionless ratio,
PtlPai where p t' is the radio-frequency pow er radiated from the transm itting antenna, andPa is the resultant radio-frequency signal power which would be available from the receiving
antenna, if there were no circuit losses other than those associated with its radiation resistance.
The transm ission loss is usually expressed in decibels:
L ■= 10 log10 (Pi’/Pa') = L S — L tc - L rc
where L tc and L rc are the losses, expressed in decibels, in the transm itting and receiving
antennae circuits respectively, excluding the losses associated with the antennae radiation
resistances; i. e., the definitions of L tc and L rc are 10 log10 (r'/r), where r is the resistive com po­
nent of the antenna circuit and r is the radiation resistance.

3.

Basic transmission loss (Lb)
The basic transmission loss (sometimes called path loss), of a radio circuit, is the trans­mission loss expected between ideal, loss-free, isotropic, transm itting and receiving antennae
at the same locations as the actual transm itting and receiving antennae.

* T h ro u g h o u t th is R ecom m endation, ca p ital letters are used to d en o te th e ratio s, expressed in decibels, of th e co rresp o n d in g
q u an tities designated w ith low er-case type; e.g., .Pt = 10 lo g 10p t. Pt is th e in p u t p o w er to th e tra n sm ittin g a n ten n a, expressed indecibels above 1 W.

Rec. 341

— 31 —
4.

Path antenna gain (Gp)
The path antenna gain is equal to the change in the transm ission loss when lossless,isotropic, antennae are used at the same locations as the actual antennae:
Gp = L b — L

5.

Path antenna power gain ( Gpp)
The path antenna power gain is equal to the increase in the system loss when lossless,isotropic, antennae are used at the same locations as the actual antennae:
Gpp ~ Lb

L s = Gp

,Ltc

L rc

Note that Gpp will be negative when the antenna circuit losses exceed the path antenna gain.
In some idealized situations, the path antenna power gain, Gpp, is simply the sum(Gtp + Grp) of the free space power gains, Gtp and Grp, of the transm itting and receiving
antennae relative to lossless, isotropic, antennae. However, in m ost practical situations, Gpp
is less than (Gtp + Grp), because of the complex nature of the received field. The pathantenna power gain may be measured, by determining the increase in the system loss whenboth the transm itting and receiving antennae are replaced simultaneously, by simple standard
antennae such as short electric or magnetic dipoles, and then adding the calculated pathantenna power gain corresponding to the use of the standard antennae. F o r ionospheric or
tropospheric scatter propagation, the path antenna power gain is sometimes substantiallysmaller than the sum of the free space power gains (Gtp + Grp) ; in such cases, the p ath antenna
power gain cannot be defined by the sum of the effective power gains of the transm itting andreceiving antennae (as determined by replacing first one antenna and then the other successively
by a standard antenna), since such effective power gains depend upon the gain of the antennaused at the other terminal.
F or ionospheric or tropospheric propagation, the transm ission loss L , the basic trans­mission loss L b, and the path antenna gain Gp, are all random variables with respect to time,
and tend to be normally distributed about their expected values. Typically, L and Gp are
negatively correlated with each other, and thus the variance of L b is usually substantially lessthan the sum of the variances of L and of Gp ; for this reason, it will often be m ore practical
simply to measure the system loss with the particular antennae intended for use, rather thanattem pt to calculate the expected system loss and its variance with time, in term s o f the measured
or calculated values of the basic transm ission loss, the path antenna gain, and the losses L tc
and L rc.
N ote also that the path antenna gain may actually be negative. F o r example, the pathantenna gain will usually be negative for ground wave or tropospheric wave propagation
between a vertically polarized and a horizontally polarized antenna, and the concept o f pathantenna gain should prove to be useful for expressing the results of such cross-polarization
measurements.
6.

Propagation loss (Lp)
The propagation loss is the system loss expected if the antennae gains and circuit
resistances were the same as if the antennae were located in free space:
Lp ~ L s

Lt

Lr

L t and L r are defined by 10 log10 (r'/r/) where r is the actual antenna resistance and /y is theresistance the antenna would have if it were in free space and there were no losses other thanradiation losses.

Rec. 342

— 32 —R E C O M M E N D A T IO N 342 *AUTOMATIC ERROR CORRECTING SYSTEM FOR TELEGRAPH
SIGNALS TRANSMITTED OVER RADIO LINKS(Study Program m e 3A(III))The C.C.I.R.,(Geneva, 1951 - London, 1953 - W arsaw, 1956 Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) that it is essential to be able to interconnect term inal start-stop apparatus employing theInternational Telegraph A lphabet N o. 2 by means of radiotelegraph circuits;(b) that radiotelegraph circuits are required to operate under varying conditions of radio propaga­tion, atm ospheric noise and interference, which introduce varying degrees of distortion which
may at times exceed the m argin of the receiving apparatus;( c) that, in consequence, the transm ission of 5-unit code signals over radio circuits is liable toerrors and that such errors are not autom atically detectable by the receiving apparatus;( d) that an effective means of reducing the num ber of wrongly printed characters is the use ofcodes, perm itting the correction of errors by detecting the errors and autom atically causing
repetition;( e) that the m ethod using synchronous transm ission and autom atic repetition (ARQ), is now
well proven;(f) that it is desirable to perm it correct phase to be established autom atically on setting up acircuit;(g) that certain circumstances can occur which may result in a loss of the correct phase relationshipbetween a received signal and the receiving apparatus;(h) that it is desirable to perm it the correct phase relationship to be re-established autom aticallyafter such a loss, w ithout causing errors;(i) that, to avoid m is-routing traffic, it is essential to prevent phasing to a signal which has been
unintentionally inverted;(j) that there is sometimes a need to subdivide one or m ore channels, to provide a num ber ofservices at a proportionately reduced character rate;(k ) that the m ethod of automatically achieving the correct phase relationship between the received
signal and the sub-channelling apparatus should be an integral p art o f the phasing process;(I) that compatibility with existing equipm ent, designed in accordance with R ecom m endation 242(Los Angeles, 1959), is a requirem ent;
U N A N IM O U SL Y REC O M M E N D S

1. that, when the direct use of a 5-unit code on a radio circuit gives an intolerable error rate andthere is a return circuit, a 7-unit A RQ system be em ployed;

2. when autom atic phasing of such a system is required, the 7-unit system, described in the
Annex, should be adopted as a preferred system;
3.

that equipment, designed in accordance with § 2, should be provided with switching, to perm it
operation with equipm ent designed in accordance with Recom m endation 242 (Los Angeles,
1959).

Note. - M ethods, in accordance with this Recom m endation, are described in Doc. I l l / 17 o f Geneva,
1962.
* This Recommendation replaces Recommendation 242.

Rec. 342

— 33 —
ANNEX I
1.

Table of conversion
T a b leI

Table o f code conversion

A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
Q
R
S
T
U
V
W
X
Y
Z
Carriage return
Line feed
Figures
LettersSpace
Unperforated tape
Signal repetition
Signal a
Signal [32.

In te rn a tio n a l code N o . 2

7 -u n it code

ZZA A AZ A AZZAZZZ AZAAZAZAAAA
Z AZZ AAZ AZZA A ZAZAZZ A AZZAZAZZZZ AAZAAZ
A AZZZAAZZ AA A AZZA Z Z AZZ Z Z AZAZ AZ AZAZ A AAAA AZ
ZZZAA
AZZZZ
ZZAAZ
ZAZZZ
ZAZAZ
ZA A AZA A AZ A
AZ A A A
ZZ A ZZ
ZZZZZ
AAZAA
AAAAA

AAZZAZAAAZZAAZZAAZZAA
AAZZZAAAZZZAAAAAZAAZZZZAAAAZZAZAAZAZZZAAAAAZAAAZZAAAZAZZZZAAAZAZAZAAAZZAZAZAAZAAAZZAZAAZAZAAAAZZAZZZAAZAAAZAZAZAZAAAZAZAZZAAZAZAAZAAZAZAAZAZ
AAZAZZAAAZAZAZAZZAAAZZAAAAZZZAZZAAAAZAAZZAAAAZZZAZZAZAAA
AAAAZZZAZZAZAAAZAZAAZAZAZZAA

Repetition cycles

2.1 F our characters for norm al circuits, which are not subject to excessive propagation time.
2.2

The cycle should comprise one “ signal repetition ” and three stored characters.
Eight characters on circuits for which the four-character repetition cycle is inadequate. The
cycle should comprise one “ signal repetition ”, three signals [3 and four stored characters, or
one “ signal repetition ” and seven stored characters.

3.

Channel arrangement

3.1

Channel A

3.1.1 F or equipm ent employing a 4-character repetition cycle: one character inverted followedby three characters erect.

(See Fig. la.)3.1.2 F or equipments employing an 8-character repetition cycle: one character inverted
followed by seven characters erect.

(See Fig. 2a.)Rec. 342

— 34 —

3.2 Channel B
3.2.1 For equipments employing a 4-character repetition cycle: one character erect followedby three characters inverted. (See Fig. lb.)
3.2.2 For equipments employing an 8-character repetition cycle: one character erect followed
by seven characters inverted. (See Fig. 2b.)
3.3 Channel C
As for Channel B (See Figs. lc and 2c).
3.4 Channel D
As for Channel A (See Figs. Id and 2d).
3.5 Order o f transmission
3.5.1 Characters of Channels A and B are transmitted consecutively. (See Figs. lc and 2c).
3.5.2 Elements of Channel C are interleaved with those of Channel A. (See Figs. 1g and 2g).
3.5.3 Elements of Channel D are interleaved with those of Channel B. (See Figs. Ig and 2g).
3.5.4 In the aggregate signal, A elements precede those of C, and B elements precede those ofD. (See Figs. 1^ and 2g.)
3.5.5 The first erect character on A, transmitted after the inverted character on A, is followedby the erect character on B. (See Figs. lc and 2c.)3.5.6 The erect character on C is followed by the inverted character on D. (See Figs. 1/
and 2/.)
3.5.7 The inverted character on A is element-interleaved with the erect character op C.
(See Figs. 1g and 2gl)
4.

Sub-channel arrangement

4.1 The character transmission rate of the fundamental sub-channel should be a quarter of thestandard character rate.
4.2 Sub-channels should be numbered 1, 2, 3 and 4 consecutively.
4.3 Where a 4-character repetition cycle is used, sub-channel 1 should be that sub-channel which
has opposite keying polarity to the other three sub-channels of the same main channel.
(See Fig. 3a-d.)
Where an 8-character repetition cycle is used, sub-channel 1 should be that sub-channel
which has alternately erect and inverted keying'polarity. (See Fig. 3e-h.)
4.4 When sub-channels of half-character rate, or three-quarter-character rate are required,combinations of the fundamental sub-channels should be arranged as shown in Table II.
T a b leP ro p o rtio nof full-channel ch a ra cte r rate

5.

II
C o m b in atio nof fu n d am en tal su b-channels(1) quarter(2) quarter(3) half

No. 1
No. 3
Nos. 2 and 4(1) half(2) half

Nos. 1 and 3
Nos. 2 and 4(1). quarter(2) three-quarters

No. 1
Nos. 2, 3 and 4

Diagrams
As a result of the characteristics specified in §§ 2, 3 and 4 of this Annex, the transm issionof characters will be as shown in Figs. 1, 2 and 3.

Rec. 342

— 35 —
6.

C.C.I.T.T. Recom m endation S. 12 recommends, th at the interval between the beginning o f
successive start elements of the signals transm itted into the land line netw ork be 145 5/6 ms.
Therefore, the duration o f the transm ission cycle on the radio circuit and also the m odulation
rate m ust be chosen correspondingly, if interconnection to the netw ork is required.
Practical values for the m odulation rate in bauds and the duration o f the transm ission
cycle, which enable synchronization to be effected by using a single oscillator for three cases,
are shown in Table III.

T a b leIII
M o d u la tio n ra te (bauds)

T ran sm issio n
cycle
(m s)

145 5/6

2 -ch an n e lo p e ra tio n

96

4 -c h a n n e lo p e ra tio n|

192

This is the preferred standard. See C.C.I.T.T. Recommendations S. 12
and S,13i

163 1/3

85 5/7171 3/7

140

100

200

The transmission cycle of 145 5/6 ms is the preferred standard for connection to 50-baud
networks.
The transm ission cycle of 163 1/3 ms is suitable for connecting to 45-baud networks.
The transm ission cycle of 140 ms is suitable for radio links w ithout direct connection to ,alandline network.
The tolerance on the stability of the master oscillator, controlling the tim ing of eachterm inal equipment, should be ± 1 x 10~6.
7.

C.C.I.T.T. Recom m endation U.20 gives the signalling conditions to be used when telex
com m unication is to be established by means of such radio circuits.

7.1 F o r circuits on switched telegraph networks, the conditions of C.C.I.T.T. Recom m endation
U.20 should apply.
7.2 F o r point-to-point circuits, signal (3 should be transm itted to indicate the “ idle circuit ”
condition.

Rec. 342

— 36 —

Ref. in Annex /Characters

(a)

3.1.1

Channel A

(b)

3.2.1

Channel B

(c)

3.3

Channel C

(d)

3.4

Channel D

4

r 1____ iFour-character repetition cycle

Combination of charactersof channels A and B(B1 follows A2)

(e)

3.5.1
3.5.5

(f)

3.5.6

Combination of charactersof channels C and D(D1 follows Cl)

(g)

3.5.2
3.5.3
3.5.4
3.5.7

Expanded view of
4 channels A, B, C and D

are element-interleaved

F ig u r e

1

Channel arrangement for a four-character repetition cycle

B and D

Rec. 342

— 37 —

Ref. in Annex I
Characters

2

(a)

3.1.2

Channel A

(b)

3.2.2

Channel B

1

2

(c)

3.3

Channel C

i

2

(d)

3.4

Channel D

1

2- 1

1----------- 1-----------1-----------1

3

i

i

3

3

3

4

i

i

4

4

l_ 4

5

i

I
'

5

5

5- 1

'

I

i

6

6

6

6

z

7

i

'

7

i

"

8

i

1 1

I___

8

1 1

8

I

8

1 1

____ 17

1------ 1------ 1
'

7

‘

1

I__

Eight-character repetition cycle

( e)

3.5.1
3.5.5

Combination of charactersof channels A and B(B1 follows A2)

(f)

3.5.6

Combination of charactersof channels C and D(D1 follows C l)

(g)

3.5.2
3.5.3
3.5.4
3.5.7

Expanded view of
4 channels A, B, C and D

The characters of channels A and C
are element-interleaved.

F ig u r e 2

Channel arrangement for an eight-character repetition cycle

Channels
B and D

Rec. 342

38 —R e f in Annex I
Four-character repetition cycle

(a)

3.1.1
4.2
4.3

(b)

3.2.1
4.2
4.3

(c)

3.3
4.2
4.3

(d)

3.4
4.2
4.3

Eight-character repetition cycle

(e)

3.1.2
4.2
4.3

(f)

3.2.2
4.2
4.3

( g)

3.3
4.2
4.3

(h)

3.4
4.2
4.3

—A

—C

2

1_

3

I___

2

I

3

I

3

D

4

4

5

I___
2

4

I--4

1

3

1--- 1----5

6

F igure 3

Sub-channelling arrangements for a four and an eight-character repetition cycle

— 39 —

Rec. 342

ANNEX IIT erm srelatedto

A R Q -S ystem sPart 1

1. Signal repetition
RQ-signal
Signal Roman one- the seven unit combination (AZZAZAA) which is used torequest a repetition (RQ-signal) or to precede a re-transmission
BQ-signal);

2. Repetition cycle- the sequence of characters, the number of which is determinedby the loop time-delay o f the system, to provide automatic
repetition of information;

3. RQ-cycle
Request cycle- the repetition cycle transmitted by ARQ-apparatus at thedetection of a mutilation;

4. BQ-cycle
Response cycle- the repetition cycle transmitted by ARQ-apparatus at a request
for repetition;

5. Non-print cycle- the interval at the ARQ-receiver, initiated by the detection ofa mutilation or a signal repetition, that has the same duration
as a repetition cycle and during which all signals received areprevented from being printed;

6. Gated RQ- a procedure in which a check is made for the presence of asignal repetition during a non-print cycle;

7. Tested RQ- a procedure in which a check is made for the presence of asignal repetition and a check is made for the ratio A/Z on all
characters received after the signal repetition within the non­print cycle ;8. Tested repetition cycle- a non-print cycle in which a check is made for the presence of asignal repetition and for the correct ratio A/Z of all the characters
received;

9. Cycling- the condition that a repetition procedure is in progress;

10. Marking pattern- a specific pattern of polarity inversions applied to characters inan aggregate signal;

11. Marked cycle
System cycle- a cycle consisting of a specific character marking pattern, that iscontinuously repeated and has the duration of a repetition cycle;

12. System phase
Marked cycle phase- the condition in which the marking pattern of the local timing
coincides with the m arked cycle of the received signal;

13. Phasing
Phase hunting- the condition in which a station is hunting for character phaseor system phase-,* T h e tw en ty -th ree term s an d definitions in p a rt 1 o f this list have been stu d ied by a jo in t W ork in g P a rty o f S tu d y G ro u p s II I
a n d X IV d u rin g th e X th P len a ry A ssem bly of th e C .C .I.R ., G eneva, 1963, as a p ro v isio n al co n trib u tio n (see § 2.1 of A n n ex toR e so lu tio n 21) fo r th e “ L ist of D efinitions of E ssential T elecom m unicatio n T erm s ” (V olum e I I to be p u b lish e d later).
T h e o th e r term s an d definitions co n tain ed in p a rt 2 of th is list, w hich are of m o re general ap p licatio n , are given as in fo rm atio n
p en d in g ex am in atio n b y th e C .C .I.T .T .

Rec. 342

— 40 —

14. M anual phasingphasing by m anual action only;

15. Semi-automatic phasingphasing com pleted autom atically after m anual in itiation;

h6. A utom atic phasingphasing, initiated and com pleted autom atically after automatic
detection of “ out-of-phase ” ;17. M aster station

the station, the transm itting equipm ent of which is directly
driven by a master oscillator but the receiver timing of which
is normally synchronized to the incoming signal;

18. Slave station

the station, the receiver and transm itter tim ing o f which areboth synchronized to the received signal;

19. End-to-end tim e delay

the delay between the output term inals of an A RQ -transm itterand the input term inals of the ARQ-receiver at the other end(this is the sum of radio and line circuit delays in one directionof a route);

20. Loop time-delay of a routethe sum of the end-to-end time delays in the send and return
directions o f a route;

21. M aster station delay

the period between the beginning o f reception of a signal
repetition at the A R Q -input term inals at the master station andthe beginning of transm ission o f the replying signal repetitionat th at station.
Note. - This comprises the “ scanning ” and equipm ent delays
and a further delay which, when added to the loop time delayo f the system, produces an integral multiple o f the character
cycle duration;

22. Slave station delay

the period between the beginning of reception of a signal
repetition at the A R Q -input term inals at the slave station andthe beginning of transm ission o f the replying signal repetitionat that station.
Note. - This comprises “ scanning ” and equipm ent delays anda “ preset ” delay between the receiver and the tran sm itter;

23. Loop tim e delay o f a sys­tem (as seen from the m as­
ter station)

the sum of the loop time delay o f the route and the slave station
delay, measured under working conditions;

Part 2(a) Aggregate signal

the synchronous signal produced by com bining the channel
signals;(b) Balanced aggregate signal

an aggregate signal containing equal num bers of elements ofeach polarity;(c) C haracter cycle

the period in which each channel o f a time-division multiplex
transm ission has com pleted one character in the synchronouspath;

— 41 —

Rec. 342, 343(d) Element synchronism- in synchronous systems :the condition in which an element of the local tim ing coincides
completely with an element of the received signal;(e) Synchronizing- the action of adjustm ent of element synchronism;(f) Phase relationship- in synchronous systems:
the relative phase of receiving apparatus and incom ing signals,
or receiving and sending apparatus;(g) C haracter phase- the condition in which a character cycle of the local timing
coincides completely with a character cycle of the received
signal.
Note. - U nder these conditions, a character of the aggregate
signal transm itted on a particular channel is received on thecorrect channel.

Sub-channel- a teleprinter channel which is allocated a quarter rate of anorm al channel, or multiples thereof;(j) Sub-channel phase- the condition in which a character transm itted on a particular
sub-channel is received on the correct sub-channel;( k ) Transposition- A dd to definition 33.25 o f the I.T.U . “ List of definitions... ”( P a rti):•“ Transpositions may be regarded as of first or higher orderaccording to the num ber of interchanges occurring within acharacter.”(h)

R E C O M M E N D A T IO N 343 *F A C SIM IL E T R A N SM ISS IO N O F M E T E O R O L O G IC A L C H A R T S
O V ER R A D IO C IR C U IT S
(Q uestion 232 (III))The C .C.I.R.,(Warsaw, 1956 - Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) th at increasing use is being m ade of facsimile telegraphy for the transm ission o f meteorologicalcharts for reception on direct-recording apparatus;(b) th at it is desirable to standardize certain characteristics of the radio circuits for this purpose;U N A N IM O U SL Y REC O M M E N D S

1.

that, when frequency m odulation of the sub-carrier is employed for the facsimile transm issionof meteorological charts over radio circuits, the following characteristics should be u se d :centre frequency
frequency corresponding to black
frequency corresponding to white* This Recommendation replaces Recommendation 243.

1900 c/s,
1500 c/s,
2300 c /s ;Rec. 343, 344
2.

— 42 —

that, when direct frequency modulation is employed on radio circuits, the following charac­
teristics should be used:

2.1 H F (decametric) circuits
centre frequency(corresponding to the assigned frequency) f 0,
frequency corresponding to blackf 0 —400 c/s,
frequency corresponding to whitef 0 + 400 c/s;
2.2 L F (kilometric) circuits
centre frequency(corresponding to the assigned frequency) f 0,
frequency corresponding to blackf 0 —150 c/s,
frequency corresponding to whitef 0 + 150 c/s;
3.

that this Recommendation should be considered as an answer to Question 130, the study ofwhich is hereby terminated.

Note. - It is to be observed that, whereas with the drum speed of 60 r.p.m. satisfactory reception

on H F can usually be expected, the quality of the recording may be impaired at higher drum
speeds, depending upon the composition of the circuit and the presentation of the original
document.

R E C O M M E N D A T IO N 344 *STANDARDIZATION OF PHOTOTELEGRAPH SYSTEMS FOR USE
ON COMBINED RADIO AND METALLIC CIRCUITSiThe C .C.I.R.,(Stockholm, 1948 - London, 1953 - W arsaw, 1956 Los Angeles, 1959 - Geneva, 1963)/

C O N S ID E R IN G(a) that, to facilitate interworking, it is desirable to standardize the characteristics of systems
employed for phototelegraph transm ission over long-distance H F (decametric) circuits;(b) that it is desirable to standardize certain characteristics of the systems in such a way as tom ake them equally suitable for transm ission over metallic circuits;(c) that the transm ission system using direct am plitude-m odulation is generally unsatisfactory
over H F (decametric) radio circuits, because o f the intolerable fading ratio usually encountered;(d) that the tim e-m odulation system gives insufficiently good definition;(e) that the system of sub-carrier frequency-m odulation has proved satisfactory, b u t requires
standardization in respect of the centre frequency and shift frequencies, taking into account thevalues of the picture-m odulation frequencies to be transm itted;(f) that, when a direct frequency-m odulation system is employed, the terminal equipm ent
norm ally used for a sub-carrier m odulation system, should be usable w ithout serious modifi­
cations;(g) that, taking into account the degree of distortion th at is tolerable, the effect o f m ultipath
echoes on long-distance H F (decametric) radio circuits norm ally limits the m axim um adm is­sible picture-m odulation frequency to approxim ately 500 c/s;
* This Recommendation replaces Recommendation 244.

Rec. 344

— 43
U N A N IM O U SL Y R EC O M M E N D S

I

1.

that over the radio path,

1.1

when a sub-carrier frequency-m odulation system is used, the following characteristics should
be observed:
centre frequency
1900 c/s,
frequency corresponding to white
1500 c/s,
frequency corresponding to black
2300 c/s;(The 1500 c/s frequency is also used for the phase-synchronizing frequency)

1.2 when a direct frequency m odulation system is employed, the following characteristics should
be observed:
centre frequency(corresponding to the assigned frequency) f 0,
frequency corresponding to whitef 0 — 400 c/s,
frequency corresponding to blackf 0 + 400 c/s;
1.3 in both systems, it is as yet too early to state definite frequency tolerances *, b u t pending adecision on this m atter, the frequency stability should, in allcases, be at least:
8 c/s in any period of 30 s;
16 c/s in any period of 15 m in;2.

that, for the present, the following alternative characteristics should be used:
index of cooperation
speed o f rotation o f drum in r.p.m .

3.
'

a
b
352 264
60 90/45 (The lower speed is for use when
the radio propagation conditions
dem and it); ,th at frequency-m odulation or am plitude-m odulation may be used in the metallic portions of
the com bined circuit. W hen conversion from am plitude m odulation to frequency m odulation(or vice versa) is required, the conversion should be such th at the deviation o f the frequencym odulated carrier varies linearly with the am plitude of the am plitude-m odulated carrier.
The standards for both am plitude-m odulated and frequency-modulated transm issions
will be found in C.C.I.T.T. Recom m endations T .l, T .l l and T.15.
Each A dm inistration will decide, when the question arises, on the location of m odulation
converters. They will be placed either at the term inal phototelegraph station or a t the control
station associated with the radio station, to facilitate speech on the circuit used for ph o to ­telegraphy, if the radio channel will carry speech.

Note. - The provisions o f § 2 above do not imply the im position o f such standards on private
users who use their own equipm ent for the transm ission of pictures over private circuits.

* See D o c. 111/66 (R ev.) of G eneva, 1962.

— 44 —

Rec. 345

RECOMMENDATION 345 *TELEGRAPH DISTORTION(Question 18)
The C.C.I.R.,(London, 1953 - W arsaw, 1956 - Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G

th at the definitions applying to telegraph distortion and to the m utilation of telegraphic
signals, which appear in Section 33, P art I, of the “ List of Definitions of Essential Telecom­
munication Terms ”, published by the International Telecommunication U nion, give an answer
to Question 18, which required a general definition of telegraph distortion capable of being
usefully applied to the cause of radiotelegraphy;
U N A N IM O U S L Y RECO M M E N D S

that the following definitions, contained in Section 33 of the above-mentioned “ List of Defi­
nitions of Essential Telecommunication Terms ”, should be applied to radiotelegraphy:
Perfect modulation (or restitution) (Definition 33.01 of the List)
M odulation (or restitution) such, th at all the significant intervals are associated withcorrect significant conditions and conform accurately to their theoretical durations.
Incorrect modulation (or restitution) 1 ' „ . .
. Al T . .
Defective modulation (or restitution) } (Definition 33.03 of the List)
M odulation (or restitution) containing one or m ore elements, the significant conditionof which differs from th at corresponding to the kind prescribed by the code.
Telegraph distortion ( o f a modulation or a restitution) (Definition 33.04 of the List)(a) A m odulation (or restitution) suffers from telegraph distortion, when the significant inter­vals have not all exactly their theoretical durations.
(b) A m odulation (or restitution) is affected by telegraph distortion, when significant instants
do not coincide with the corresponding theoretical instants.
Transmitter distortion (Definition 33.059 of the 1st Supplement to the List)
A signal transm itted by an apparatus (or a signal at the output of a local line with its
term ination), is affected by telegraph distortion, when the significant intervals of this signal
have not exactly their theoretical durations.
Degree o f individual distortion o f a particular significant instant ( o f a modulation or o f a restitu­tion) (Definition 33.06 of the List)
R atio to the unit interval of the displacement, expressed algebraically, of this significant
instant from an ideal instant.
This displacement is considered positive when the significant instant occurs after the ideal
instant.
The degree of individual distortion is usually expressed as a percentage.
Degree o f isochronous distortion (Definition 33.07 of the 1st Supplement to the List)(a) R atio to the unit interval of the maximum measured difference, irrespective of sign,
between the actual and the theoretical intervals separating any two significant instantsof m odulation (or of restitution), these instants being not necessarily consecutive.
(b) Algebraical difference between the highest and lowest value of individual distortion
affecting the significant instants of an isochronous m odulation. (The difference isindependent of the choice of the reference ideal instant.)
The degree of distortion (of an isochronous m odulation or restitution), is usually expressed
as a percentage.
* This Recommendation replaces Recommendation 245.

— 45 —

Rec. 345

Note. - The result of the m easurem ent should be completed by an indication of the period, usuallylimited, of the observation.
F or a prolonged m odulation (or restitution), it will be appropriate to consider the p ro ­bability that an assigned value of the degree of distortion will be exceeded.
Degree o f start-stop distortion (Definition 33.08 of the 1st Supplement to the List)(a) R atio to the unit interval of the maximum measured difference, irrespective o f sign,
between the actual and theoretical intervals separating any significant instant of m odula­tion (or of restitution) from the significant instant of the start element immediately pre­ceding it.
(b) The highest absolute value of individual distortion affecting the significant instants of astart-stop m odulation.
The degree of distortion of a start-stop m odulation (or restitution) is usually expressed asa percentage.
Note 1. - Same as the note to Definition 33.07.
Note 2. - D istinction can be m ade between the degree of late (or positive) distortion and thedegree of early (or negative) distortion.
Degree o f gross start-stop distortion (Definition 33.09 of the List)
Degree of distortion determined when the Unit interval and the theoretical intervals
assumed are exactly those appropriate to the standardized m odulation rate.
Note. - As for Definition 33.07.
Degree o f synchronous start-stop distortion ( i. e. at the actual mean modulation rate) (Definition
33.10 of the List)
Degree of distortion determined when the unit interval and the theoretical intervals
assumed are those appropriate to the actual m ean rate of m odulation (or of restitution).
Note 1. - As for Definition 33.07.
Note 2. - F or the determ ination of the actual mean m odulation rate, account is only taken of thosesignificant instants of m odulation (or of restitution), which correspond to a change of conditionin the same sense as th a t occurring at the beginning of the start element.
Characteristic distortion (Definition 33.15 of the List)
D istortion caused by transients which, as a result of the modulation, are present in thetransm ission channel and depend on its transm ission qualities.
Fortuitous distortion (Definition 33.16 of the List;
D istortion resulting from causes generally subject to random laws (accidental irregu­
larities in the operation of the apparatus and of the moving parts, distubances affecting thetransm ission channel, etc.).
Bias distortion, Asymmetrical distortion (Definition 33.17 of the List)
D istortion affecting a two-condition (or binary) m odulation (or restitution), in which all
the significant intervals corresponding to one of the two significant conditions have longer or
shorter durations than the corresponding theoretical durations.
Character error rate o f a telegraph communication (Definition 33.19 of the 1st Supplement to
the List)
Ratio of the num ber of alphabetic signals of a message incorrectly received (after au to ­matic translation, where applicable), to the num ber of alphabetic signals of the message, thekeying being correct.
Note 1. - A telegraph com m unication may have a different error rate for the two directions oftransmission.
Note 2. - The notion of character error rate could be applied to any operation taking place in atelegraph com m unication (e. g. keying, translation, etc.).
Note 3. - The statem ent of the error rate will be accom panied by th at of the time interval, generally
limited, during which the observation was made. F or a com m unication established for a
sufficiently long time, the probability of exceeding an assigned value of error rate could beconsidered.

Rec. 345, 346— 46 —

Note 4. - Faulty translation, resulting from a previous error in functional control (such as shift, line
feed, synchronism, etc.), is not counted in calculating a character error rate; in such a case,the error in the functional control signal is alone counted and is counted only once.
Element error rate (Doc. 203 of Geneva, 1963)
The ratio of the num ber of unit elements incorrectly received to the total num ber of unit
elements sent.
Efficiency factor in time (of a telegraph com munication with autom atic repetition for thecorrection o f errors) (Definition 33.23 of the List)
Ratio o f the time necessary to transm it a text automatically without repetition, at a
specified m odulation rate, to the time actually taken to receive the same text with a given
error rate.
Note 1. - The whole of the apparatus comprising the com munication is assumed to be in the norm alconditions o f adjustm ent and operation.
Note 2. - A telegraph com m unication may have a different efficiency factor in time for the two
directions o f transmission.
Note 3. - The actual conditions in which the measurem ent is m ade should be specified, in particular
the duration of the measurement.
M utilation (Definition 33.24 of the List)
A transm ission defect in which a signal element becomes changed from one significant
condition to another.
Transposition * (Definition 33.25 of the List)
A transm ission defect in which, during one character period, one or m ore signal elements
are changed from one significant condition to the other, and an equal num ber o f elements
are changed in the opposite sense.

RECOMMENDATION 346 **FOUR-FREQUENCY DIPLEX SYSTEMS(Question 183(111))
The C .C.I.R.,(Warsaw, 1956 - Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) that there are in use, in the fixed radiotelegraph services operating between 2 Mc/s and 27 Mc/s,
four-frequency diplex (or twinplex) systems, in which each o f four frequencies is used to tran s­m it one of the four possible com binations of signals corresponding to two telegraph channels;
it being understood that either one, or both of the two telegraph channels may be sub-channelled
by time-division methods and that the use of such systems m ay be extended;(b) that it is desirable to standardize the m ain characteristics of four-frequency diplex systems;(c) th at it may sometimes be necessary to employ the same radio transm itter to w ork with m ore
than one receiving station;(d) th at circuit interruptions should be reduced to a minimum, by avoiding frequent changes ofthe spacing between adjacent frequencies and of the correspondence between the frequencies
and the significant conditions o f the channels;* See also A nnex II, P a rt 2, definition k of R eco m m en d atio n 342.
** T h is R ec o m m e n d atio n replaces R ec o m m e n d atio n 247.

Rec. 346

— 47 —(e) th at various technical factors influence the choice of operating characteristics in such systems,
in particular:- the economy of bandw idth and the consequent need to control the shape of the transm itted
signals;- th at a relatively wide spacing between adjacent frequencies may be necessary for hightelegraph speeds;- the signal distortion due to propagation conditions;- the instability of the characteristics of certain receiver and transm itter elements such as
oscillators, filters or discrim inators;(f) th at many existing four-frequency diplex systems each use one of four values of spacing
between adjacent frequencies with corresponding telegraph speeds;(g) th at it is desirable to use only one coding system, the simpler the better;U N A N IM O U S L Y R EC O M M E N D S

1.

2.

th at the following preferred values should be adopted for the spacing between adjacentfrequencies:

Spacing
betw een ad jacen t frequencies(c/s)

N o m in a l teleg rap h speedo f each ch an n el(bauds)

1000
500*
400*
200*

over 300
200 to 300
100 to 200
200**

th at the following coding system should be adopted: ***C h an n e l 1

C h an n e l 2

F req u en cy of em ission

f . (highest frequency)kkf x (lowest frequency)

T e lep rin ter

M o rseT elep rin ter

M o rse

A
A
Z
Z

Mark
Mark
Space
Space

A
Z
A
Z

Mark
Space
Mark
Space

where /j, / 2, / 3, / 4 designate the frequencies of the emissions; the spacings between adjacentfrequencies ( / 4 - / a) ( / 3 - / 2) ( / 2 - / x), being equal,
A represents the start signal of the teleprinter,Z represents the stop signal of the teleprinter;3.

th a t the value of the frequency separation between adjacent frequencies em ployed should be
the lowest of the preferred values com patible with the maximum telegraph speeds regularly
used, the propagation conditions and the equipm ent stability;

4.

that, when the two channels are not synchronized, it is desirable to limit the m axim um rateof change of frequency to minimize the bandw idth of the emission.

* L o w er teleg rap h speeds m ay be used w ith these spacings a t present.
** S y nchronous o p eratio n w ith phase-locked channels.
*** W h ere m odification of equipm ent is required, it is recognized th a t it m ay ta k e som e tim e before the co d in g system s in d icatedin ,th is p ara g ra p h can be im plem ented on circuits betw een different A d m inistratio n s.

48 —Rec. 347R E C O M M E N D A T IO N 347 *CLASSIFICATION OF MULTI-CHANNEL RADIOTELEGRAPH SYSTEMSFOR LONG-RANGE CIRCUITS OPERATING AT FREQUENCIESBELOW ABOUT 30 Mc/s AND THE DESIGNATION OF THE CHANNELS
IN THESE SYSTEMSThe C.C.I.R.,(Warsaw, 1956 - Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) that there exists a large num ber of long-range multi-channel radiotelegraph systems using
frequencies below about 30 Mc/s and that it is desirable to classify them in categories;(b) that the lack of uniform ity in the arrangem ent and designation o f the channels in these systems,
may give rise to certain difficulties when one transm itting station has to work with several
receiving stations;( c) that the increasing use of multi-channel telegraph systems makes it desirable to adopt a uni­
form designation of channels in such systems;
U N A N IM O U SL Y RECO M M E N D S

1.

that the systems should be classified and the different categories designated by letters, as
follow s:

1.1 Time-division multiplex system s: capital letter T (for example, synchronous systems, such as
Baudot, R C A and T O R multiplex and double-current cable code);
1.2 Frequency-division multiplex systems
1.2.1 Systems with constant frequency arrangem ents o f significant conditions: capital letter U(for exam ple: voice-frequency multiplex with frequency shift);1.2.2 Systems with variable frequency arrangem ents o f significant conditions: capital letter V(for example: four-frequency diplex);
1.3 Multi-channel systems using a combination o f these processes
1.3.1 Frequency-division systems, with constantfrequency arrangem ent, combined with acom bination of the above-mentioned
time-division m ultiplex;
letters (always beginning w ith the
1.3.2 Four-frequency diplex system, combined
frequency division letters U or V)
with a time-division multiplex system.
2. when a multi-channel telegraph signal is applied to a multi-channel telephone transm itter, thedesignation of the telephone channel should come first in the sequence and should be inaccordance with Recom m endation 348;
3. when a multi-channel telegraph signal is applied to an independent-sideband transm itter usedsolely for telegraphy, the designation of the sideband should come first in the sequence. The
letter H should denote the upper sideband, and the letter L the lower sideband;4. that in time-division systems, the telegraph channels should be designated by capital letters
A, B, C, D, etc.; for sub-division, the sub-channels should be designated by A l, A2, A3, A4,
B l, B2, B3, B4, etc.;
5.

that in frequency-division systems, the telegraph channels should be designated by figures;* This Recommendation replaces Recommendation 248.

— 49 —
6.

Rec. 347

th at in a com bination of multi-channel processes, the telegraph channels should be designatedby a letter and figure sequence.
For exam ple:when using a frequency-division system with constant frequency arrangem ent of significant
conditions (letter U), and m odulating the 3rd channel of this latter system with a time-divisionmultiplex (letter T), channel B of this latter system would be indicated by “ U3TB ” ;where channel B of the time-division system is sub-divided and sub-channel 2 is in use, thedesignation would be “ U3TB2
if the above-mentioned system is applied to channel B o f an independent-sideband telephonetransm itter, the corresponding designation would be “ BU3TB ” or “ BU3TB2
if the above-mentioned system is applied to the upper sideband of an independent-sideband
multi-channel transm itter used solely for telegraphy, the corresponding designation would be“ H U3TB ” or “ HU3TB2
where additional inform ation is required, the multiplex system may be identified by a num ber
inserted between the letters T and B, and where two sub-channels (quarter-channels) arelinked together to form a half-speed sub-channel (half-channel), each quarter-speed sub­channel com ponent may be designated by the use of num bers separated by an oblique stroke.
The full designation “ HU3T4B2/4 ” would be applicable to the arrangem ent show n diagrammatically by the arrows on the right of the figure below;
in established com m unication networks, where the sub-carrier, multiplex system, channels
and sub-channels arrangements are m utually know n to the station m anagem ent a t each endof the circuit, it shall be permissible to shorten the full designation “ HU3T4B2/4 ” above,
beginning at the first letter or num ber which is of m ajor significance for identification purposes.
F o r example, in the given instance “ 4B2/4 ” will identify the specific area illustrated by thearrows to the right of the figure below.

Lower
sideband “ L ”

Carrier F

Upper
sideband “ H

Sub-carriers

Multiplex systems

Time-division channels

1 2

3

4

Time-divisionsub-channels

Multi-channel independent-sideband radiotelegraph transmitter
Note. - Sub-carriers are numbered sequentially in both upper and lower sidebands, starting with the num­ber 1, adjacent to the carrier (radiated or suppressed).

Rec. 348

— 50 —R E C O M M E N D A T IO N 348 *ARRANGEMENT OF CHANNELS IN MULTI-CHANNEL SINGLE-SIDEBAND
AND INDEPENDENT-SIDEBAND TRANSMITTERS FOR LONG-RANGECIRCUITS OPERATING AT FREQUENCIES BELOW ABOUT 30 Mc/s
(Q uestion 74(111))
The C .C.I.R.,(London, 1953 - Warsaw, 1956 - Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) that the lack of uniformity, in the arrangem ent and designation of the channels in m ulti­
channel transm itters for long-range circuits operating on frequencies below about 30 Mc/s,
may give rise to certain difficulties when one transm itting station has to work with several
receiving stations;(b) that, since it is necessary to economize in the use of the radio-frequency spectrum, when
considering inter-continental circuits consisting mainly of single long-distance radio links,
operating on frequencies below 30 Mc/s, it is desirable:- to use independent-sideband transm issions to the maximum extent possible;- to transm it a band less than the 300 to 3400 c/s recommended by the C.C.I.T.T. for landline circuits;- to reduce the upper frequency to 3000 c/s or less but not below 2600 c/s, except in special
circumstances;(c) th at there are already in operation international m ulti-channel radiotelephone circuits, inwhich the bandw idth allocated to each channel is 3000 c/s, but are actually transm itting aspeech band of 250 to 3000 c/s;(d) that, in general, the outer channels are liable to cause and receive m ore interference to andfrom stations operating on adjacent assigned frequencies, the outer channels being thoselocated furthest from the assigned frequency;( e) th at there are num erous transm itters in service which, when operated on a twin-channel basis,give rise to excessive cross-talk, unless one of the channels is placed away from the carrier;(f) th a t there are transm itters in service which perm it the addition of a third channel when it isdesired to provide additional traffic capacity;(g) th at there are advantages in adopting channel arrangem ents which are the same in all parts ofthe H F (decametric) range;
U N A N IM O U SL Y RECO M M E N D S

1.

that standard channel arrangem ents should be adopted for multi-channel radiotelephonesystems;2.

th a t the effective speech channel allocation should be 3000 c/s;

3.

th at the transm itted band in each speech channel should be from 250 to 3000 c/s;

4.

th at in four-channel systems, the channel arrangem ent should be as shown in Fig. la;5.

that, when less than four channels are used, the channels nearest to the carrier should be- selected according to the arrangements shown in Figs. lb, c, d, e, or / ;* This Recommendation replaces Recommendation 249.

Rec. 348

Audio frequency (c/s)— 51 —

Radio frequency (kc/s)

F igure 1

Relationship between audio-frequencies and radio-frequencies for the various channel arrangements

— 52 —

Rec. 348, 349

Note. - It is necessary that the subdivision of channel C into two parts, Ca and Cb, as well as the arrange­ments of these parts, should be agreed upon by the operating organizations.

6.

that with some transm itters in service, which do n ot give satisfactory operation with thearrangem ent shown in Fig. Id, a channelling arrangement, such as th at shown in Fig. 2 may
be used to minimize cross-talk;7.

that with some transm itters in service, which do not give satisfactory operation with thearrangem ent shown in Figs. lb or lc, a third channel may be provided as shown in Fig. 3;

8.

th at the effective date of these arrangements be fixed by the next Administrative R adio
Conference.

R E C O M M E N D A T IO N 349
l

FREQUENCY STABILITY REQUIRED FOR SINGLE-SIDEBAND,
INDEPENDENT-SIDEBAND AND TELEGRAPH SYSTEMS TO MAKE
THE USE OF AUTOMATIC FREQUENCY CONTROL SUPERFLUOUS(Q uestion 182(111))
The C .C.I.R.,(Geneva, 1963)

C O N S ID E R IN G

( a) th a t it is the practice with single-sideband (SSB) and independent-sideband (ISB) telephonesystems, and with m any telegraph systems, to em ploy autom atic frequency control (a.f.c.) toadjust the receiver oscillator frequency in sympathy with frequency variations o f the transm itted
signal;— 53 —

Rec. 349(b) th at such a.f.c. systems may give rise to difficulty under unfavourable conditions o f propaga­tion;(c) th at the frequency stability, which can now be achieved, is m uch higher than th a t laid downin Appendix 3 to the R adio Regulations, Geneva, 1959, and is approaching a value which
could provide sufficient inherent stability to enable a.f.c. to be dispensed with. However, incertain cases when narrow-shift telegraph systems are employed, reasons other th an stability
require the use of a.f.c.;
U N A N IM O U SL Y RECO M M E N D S

1. th at the values of permissible frequency deviations, given in the Table below, should beconsidered as suitable for use on systems dispensing w ith autom atic frequency control;
2. th at in view of § d) of Question 182(111), the study of this Question should be continued fornarrow-shift systems.

System1.

SSB and ISB telephony

2.

Radiotelegraphy:

M axim um
perm issible
overalle rro r(c/s)

F requen cy dev iatio n(c/s)

M o d u lato r D em o d u lato r
stagesstagesP erm issib le freq u en cy e rro rs
due to th e rad io -freq u en cy
tra n sla tin g stages a t b o th ends
an d to th e p ro p a g a tio n p a th(c/s)(3)

20

5

5

10

2.1 Two-tone multichannel VF (e.g.
100 baud, channel spacing 340 c/s)

120

3

3

6

2.2 Phototelegraphy(2)

16

4

4

8

2.3 FI or F6 systems using narrow
band filters at the receiving end

12

3

3

6

2.4 Reception by limiter/discriminator; mod. index on. 2; 196
baud, 400 c/s shift

20

3

3

, 14

(U See D o c. 111/27 of G eneva, 1962.
(2) F o r sh o rt-term frequency stab ility , see R eco m m en d atio n 344. T he figures u n d e r § 2.2 sh o u ld be co n sid ered as pro v isio n alpending a reply by th e C .C .I.T .T . to th e questions p u t to it by th e C .C .I.R . (see D o c. 111/66 (R ev.) of G eneva, 1962).
(3) T h is is the m axim um e rro r a t th e d em o d u lato r in the frequency of th e ca rrier, if tran sm itted .

PAGE INTENTIONALLY LEFT BLANKPAGE LAISSEE EN BLANC INTENTIONNELLEMENT

— 55 —

Rep. 19REPO RTS O F SECTIO N C: FIX E D SERVICESR E P O R T 19 *V O IC E -FR E Q U E N C Y T E L E G R A PH Y O N R A D IO C IR C U IT S
(Q uestion 43(111))(London, 1953)
The C.C.I.R. has carried out certain studies, in answer to Question 43(111), concerning
voice-frequency telegraphy on radio circuits.
These studies have shown th at it is not yet possible to give a complete answer to theQuestion. However, as regards radio circuits using frequencies below 30 M c/s, a Recom ­m endation has been made dealing with diversity reception. M oreover, the C .C .I.R . would
draw the attention of the C.C.I.T.T. to the following points in respect of reception below
30 Mc/s:1.

the voice-frequency system, which radiates one frequency for one signalling condition andsuppresses the radiation for the other signalling condition, does not give satisfactory results
when applied to radio circuits;2.

systems, which radiate one frequency for one signalling condition and a different frequency
for the other signalling condition (using two oscillators or one frequency-shift oscillator), havein general to be modified for this special use. F or instance:' - the range of linear amplification of the audio-frequency amplifier, com m on to all channels
in the receiving equipment, has to be m uch greater than is necessary on land-line circuits
because of the large changes in am plitude of the received signals due to fading;- for the same reason, the limiter preceding each channel discrim inator should operate overa large range of input signal am plitudes;- many filters used in equipm ent designed for land-line circuits do n o t have suitable charac­
teristics ;- to obtain good diversity results it is not sufficient merely to connect the outputs o f separate
channels of standard voice-frequency equipm ent in series or in parallel, b ut special provi­sions have to be m ade;3.

notw ithstanding all precautions taken, it should be realized th at the use o f voice-frequency
equipm ent on radio circuits may become impossible when reception conditions are poor.

* T h is R e p o rt w as a d o p te d u n anim ously.

Rep. 42

— 56 —R E P O R T 42 *USE OF RADIO CIRCUITS IN ASSOCIATION WITH 5-UNIT
START-STOP TELEGRAPH APPARATUS(Study Program m e 3A(III))(London, 1953 - W arsaw, 1956)
The principal factors determining the error rate in a radiotelegraphy transm ission arise
from the fact that:- radio propagation is essentially variable,- unw anted signals caused by noise or interference appear at the receiving end.
1. As a result of variations in propagation a complex signal is supplied to the receiver, consistingof superimposed signals from several transm ission paths, with, in certain cases, widely different
delays, the paths providing attenuation and phase characteristics varying with frequency.
As a result, the telegraph signal appearing at the output of the dem odulator suffers random
distortion, which becomes m ore pronounced as the telegraph speed increases, the rounding of
the signal em itted possibly being also a contributory factor.

2. W hen this complex signal is further disturbed by noise or interference o f any sort, two pheno­
m ena occur sim ultaneously: modification of the distortion of the dem odulated signal and theappearance of telegraph signals alien to those of the original m odulation.
Whereas, at least for relatively low speeds (50 bauds), the distortion due to propagation
phenom ena (§ 1) has a limited am plitude and rarely, in itself, gives rise to errors in translation,
the attenuation of the signals received emphasizes the effect of the unw anted signals. Thiseffect can be reduced by increasing the transm itter power.
Consequently, the signals received seem in general to undergo a natural random distortion,
which cannot be reduced below a certain threshold by increasing the transm itter power,
whereas such a measure does in general m ake it possible to lower the error rate.
A n element to be considered in assessing the expected quality of a given code is thecorrelation existing between the instants of appearance of incorrect signals, which depends
firstly on the type of noise or interference in question and secondly on the variable charac­
teristics of propagation.
A further factor to be considered is the im provem ent resulting from diversity reception,
taking into account the com bination m ethod thereof.
F or relatively high telegraph speeds (200 bauds), when the appearance of errors may
correspond with an increase in the distortion of the signal received, synchronized systems arem ore reliable because of the wider margin they provide.
For lower speeds, the chief disadvantage of start-stop systems lies in the risk of a transient
loss of synchronizm during the m utilation of a start or a stop signal.

* This Report, which replaces R eport 30, was adopted unanimously.

Rep. 106

— 57 —R E P O R T 106 *IMPROVEMENT OBTAINABLE FROM THE USE
OF DIRECTIONAL ANTENNAE(Q uestion 81(111))(London, 1953 - Warsaw, 1956 - Los Angeles, 1959)

1.

Introduction
Contributions by A dm inistrations to the V IH th Plenary Assembly, W arsaw, 1956, and to
the interim meeting of Study G roup III, Geneva, 1958, provide a basis for a prelim inary reporton the question of signal power gain, and signal-to-interference discrimination, afforded inpractice by rhom bic antennae. The experimental observations given by Docs. III/4 and111/31 of Geneva, 1958, are summarized, as well as the pertinent Docs. 19, 139, 265, 320 and
532 of W arsaw, 1956. The relation of these preliminary results to the m edian gain, given by
Recom m endation 162, is indicated.
In the text below:/ = length of leg (m).
<p = half the obtuse angle (deg).
h = height above ground (m).

2.

Summary and discussion of reported results
Doc. III/4 (Federal Republic of Germany) o f Geneva, 1958, contains a sum m ary (Table I
below) of m edian values of measurements made, using a rhom bic of a type in general service
in the Post Administration, having / = 115 m, h = 20 m, «p = 75°. This first set of m easure­ments was m ade relative to a vertical antenna; the results are otherwise expressed in the formof the Annex to Recom m endation 162:
T able I

A zim u th al ran g es
(degrees)

M edian value of gain relativ e to m a in lobe
(d irectio n of o p tim u m gain) (db)
F req u en cy(M c/s)In A rc B
m a in lobe

10
15
20

0
0
0

In A rc A-8

U n id ire ctio n ala n te n n a

R eversible
an ten n a

-2 1

-12
-1 7
-1 5

- 6

-8

-2 3

H alf
o f m ain arc

A rc
A i = A%H a lfof a rc B

23
18
13

22
29
24

135
133
143

In Doc. 111/31 of Geneva, 1958, there are also reported the results of observations of
the gain of the rhom bic antenna in the m ain lobe, relative to a half-wave horizontal antenna.
These observations were, ih the main, m ade at 15 Mc/s receiving WWV which transm its w ith anom nidirectional antenna, but there is also one set of observations made at 18 M c/s receiving* T h is R e p o rt w as ad o p ted by correspondence w ith o u t reservations.

— 58

Rep. 106

PPZ which transm its with a directional antenna. The data show the realized gain to be lessthan the plain-wave gain in direction of maximum response, and to have a striking variability
with time of day and/or signal strength. The data are not adequate to establish a systematic
diurnal variation, but the 15 Mc/s data suggest that the greatest values of gain are realized attimes of high signal intensity. This result is contradicted by the observations at 18 Mc/sof transm issions from a distant directional antenna, which emphasizes the need for additional
observations and draws attention to the virtually certain dependence of all such observations
on the directivity o f antennae at both ends o f the path. Table II below gives the decile andm edian values of the gain realized in these tests.

T ableII
G a in 10%(db)

G a in 50 %(db)

G a in 90 %(db)

Receiving W W V 15 Mc/s
11-22 June 1956
130]
28 July-6 August 1956 117
29 Sep.-ll Oct. 1956 217 ■ observations
28 Feb.-23 Mar. 1957 405
15-25 January 1958
162

12-9
15-2
12-9
10-8
111

91
11-7
10-7
7-1
8-5

6-7
7-7
6-8
00
3-2

Receiving PPZ 18 Mc/s
29 Sep.-lO Oct. 1956

130

7-8

4-4

P erio dDoc. 139 (United Kingdom) of Warsaw, 1956, gives results of the power gain and dis­
crim ination of rhom bic receiving antennae, th at is, off-azimuth response relative to maximum
response. The measurements were m ade receiving distant transm issions at 13 and 20 Mc/s,
using a ring of 30 antennae having I = 81 m, h — 23 m, <p = 70°. The results are given in
Table III for the m ain lobe and the forw ard arc (180°) excluding the m ain lobe, and for the
backward arc.

T ableIII

G a in relative to half-w ave h o riz o n ta l d ip o le(1) (db)

F requency

M ain lobe
gain
(db)

F o rw a rd arc (180°)
excluding m a in lobe

B ack w ard a rc (180°)

G ain 10%

G ain 50 %G ain 9 0 %G a in 10%

G a in 5 0%

G a in 9 0 %

—11

—19-5

-8 -3

-12-7

-1 7

13-4 Mc/s (New York)

11

-2 -5

20-4 Mc/s (Pretoria)

15

3-5

-

5-0

-13-5

-4-3

-

8-7

-1 3

20-4 Mc/s (Pretoria)

15

2-5

-

6-0

-14-5

-9 -2

-13-6

-1 8

(') M edian an d decile values, are relative to th e a rc except fo r th e m ain lobe.

M ore detailed data are given in the same docum ent; an exam ination of the data for allobserved azimuths has been made, and m edian values of gain obtained for the arcs specified
in Recom m endation 162, as follows:Rep. 106

— 59 —
T ableIlia

M edian value (!) of gain relative
to half-w ave d ip o le (db)

A zim u th al ran g e (degrees)(R ec. 162)

F requency
A rc
Ax = A2

H alf
of a rc B

M ainazim u th

A rc AA rc BH alf
of m ain arc

13-4 Mc/s (New York)

11

-5

-1 3

12

21

147

20-4 Mc/s (Pretoria)

15

2

-1 0

81/2

18i/2

153

( ') M edian values, are relative to the a rc except for th e m ain azim uth.

It is w orth noting that values given in Table Ilia , with respect to discrim ination against
off-azimuth signals, are somewhat better than the values shown in Recom m endation 162; itseems unlikely that values as favourable as those given in Tables III and I lia are generally
realized in practice. The value for arc A at 13 Mc/s is in fact better than might, at first sight,
be expected; but, especially in arc A, the available data were not adequate to establish a m edianvalue with much confidence.
Doc. 265 (Netherlands) of Warsaw, 1956, summarized experimental observations o f thepower gain in the m ain azimuth, and for certain discrete directions off the m ain azim uth are
given. The values of gain are for receiving rhom bic antennae, expressed relative to a hori­zontal half-wave antenna at the same height. D irectional antennae were also used at thetransm itters for the measurements. The design data for the receiving antennae used at
Amsterdam, for which observations are summarized in this docum ent, are as follows:

A n ten n aAB

Length I (m).......................................
Height h (m).......................................
Angle cp (deg) ...................................
Design frequency ( M c /s ) ...............

120
33
71
14-5

174-5
29-5
70
7-5

The gain measurements for the m ain lobe were m ade on a long propagation path
(7500 km), whereas some of the observations of gain off-azimuth were for a m edium range
p ath (3000 km). The results gave values of realized gain which are less th an expected
theoretically. The data showed m arked variability of gain and/or discrim ination with timeof day and somewhat with season, though the data did n ot establish a systematic seasonal
dependence, there was an apparent tendency for the highest values of gain in the m ain azimuth
to be observed during periods corresponding to maximum daylight on the p ath ; a depressionof gain appeared systematically in the m orning hours on the path. These data were reported
for 13 Mc/s which was n o t worked throughout the night hours. Values of gain in directions off
the main azimuth also showed m arked variability with time of day and season, b u t the data
were not conclusive as to any systematic pattern. Table IV below summarizes the observa­
tions.

Rep. 106

— 60 —
T ableauIV

G ain relative to half-w ave h o riz o n ta l an ten n a (db)

F re ­
quency(M c/s)A n­
te n n aA.
B

M ain lobe

H o u rsof obs.

G ain
10%

G ain
50%

G ain
90 %

7-7
13-7
13-7
13-7
13-7
17-6

83
158

9.4
13-4

8-3
11-4

6-7
8-8

46

14-2

13 3

121

7-7
13-7
17-6

30
50
34

150
13-7
9.9

11-4
110
7-8

7-6
9-2
60

D istance
(km )

2000
3200
9300
2000
5800

O ff-azim uth

A zim u th
relativeto m ainlobe(degrees)

H o u rsof obs.

G ain
10%

G ain
50%

G ain
90%

317
236.
143
14
37

17
49
56
14
42

8-5
-7-3
-2 -9
1-8
61

5-6
- 8-7
—10-7
0-5
4-5

2-4
—10-3
-13-5
- 1-4
0-2

Doc. 320 (Japan) of Warsaw, 1956, concludes th at discrimination o f greater than 15 to
20 decibels cannot be relied u p o n ; a num ber of observations are cited for values of discrim ina­tion (response outside the m ain lobe, relative to response in the m ain lobe), for a rhom bic
antenna having values of I = 120 m and 9 = 70° (height unspecified). These are shown in
Table V below; there were not enough data available to perm it statistical analysis in term s of
the arcs of Recom m endation 162.
Doc. 19 of W arsaw, 1956, draws attention to azim uthal variations of signals propagatedover great distances via the ionosphere, in relation to realized directivity of antennae at great
distances. M easured azimuths show only slight differences am ong the values of deviation
for propagation paths of various lengths. 80% of the measurements showed less than ± 2°
average deviation; 98 % showed average deviation less than ± 4 °. The shortest link observed(2000 km), showed the greatest deviation and the longst p ath the least deviation.

3.

Conclusions
The present data do not offer an adequate basis for revision o f Recom m endation 162.
The results show striking variability of gain and/or discrim ination with time, especially timeof day and, to some extent, season of the year. There are undoubtedly im portant effects neartimes of sunrise and sunset, at times of signal failure on operating frequencies near th e M U F,
and at times of ionospheric disturbance when great azim uth deviations can be observed.
Statistical correlation of values of gain with values o f transm ission loss would be of interestand the data expected from Study Programm e 81A (III) may be expected to show whether,and under which circumstances, such a correlation exists. The data given above suggest theextent of azimuth deviation encountered during norm al propagation conditions. It m ust be
noted that, because of the influence of irregularities in the ionosphere, such as give rise toazimuth-deviations, the directivity gain realized at the receiving term inal depends in a funda­
mental way on the directivity of the transm itting a n ten n a—and vice versa. It is, therefore,
im portant in carrying out observations (such as those outlined in Study Program m e 81 A (III)),
to specify the directivity of antennae at both terminals.

— 61 —
T ableV

Median values o f discrimination in decibels(Off-azimuth response relative to main lobe)

Rep. 106

Rep. 10762

REPORT 107 *DIRECTIVITY OF ANTENNAE AT GREAT DISTANCES(Question 81(111)(Los Angeles, 1959)
M ethods of testing the directivity of antennae at great distances have been:(a) the “ Statistical m ethod ”, a com parison of num erous observations of the same signal on
different fixed antennae at the same location but at different orientations. [1, 2 and 3.](b) M echanical rotation of antenna structures with various approaches to data statistics.
[4 and 5.]( c) the “ Back-scatter ” method, a com parison of back-scatter signals in a m ethod similar tothat of (a) above. [6.]M ost of the studies have been made at high frequencies, although at least one was perform edin the standard M F broadcast band [7].
References [4] and [5] indicate that, at m oderately long distances the m ain lobes are on the
average preserved, even under conditions of severe ionospheric disturbance. A m ore serious
m atter, which merits further study, is the question of preservation o f nulls and front-to-backratios. Reference [7] indicates that these are n o t preserved at medium frequencies. M easure­m ents of these effects are very difficult because of noise and interference. Besides, electricalbalance, at b oth polarizations in antennae, feeders, and equipm ent antenna circuits, is a very criticalm atter in the realization of nulls and m inima with rhom bic antennae in ionospheric propagation [8].
References [9] and [10] deal with non-great-circle effects. These effects were noted in the
1930’s [11].
The effect of the propagation medium on transm ission loss at different antenna orientations
is dealt with in [12].
The directivity of antennae at great distances is dealt with in the following docum ents:- Question 81(111) - Directivity of antennae at great distances.
- Study Program m e 81A(III) - Im provem ent obtainable from the use of directional antennae.
- Recom m endation 162 - The use of directional antennae.
- R eport 106, - R eport on Study Program m e 85, outlining the results of experiments in
the Federal Republic of Germ any (Docs. III/4 and 111/31 of Geneva, 1958), U nited K ingdom(Doc. 139 of W arsaw, 1956), N etherlands (Doc. 265 of W arsaw, 1956) and Japan (Doc. 320
o f W arsaw, 1956), in which the “ statistical m ethod ” was used for the determ ination ofgain in the 3 azimuthal arcs M , A , and B, specified in Recom m endation 162. It wasrecognized that these gains were in some way dependent upon ionospheric conditions.
It was also noted that the directivity gains were to some extent a function of the directivityof both antennae.
Note. - It is noteworthy that in the IR E Standards on transm itters, m odulation systems andantennae, 1948, the definition of “ directivity ” is: “ the value of the directive gain in the direc­
tion of the maximum value ”, thus differing from the usage of this Report.
* T h is R e p o rt was ad o p ted by correspondence w ithout reserv atio n s.

63

Rep. 107, 109

B ib l io g r a p h y

1. Doc: 23 of Geneva, 1951.
2. Doc. 206 of London, 1953.
3. Report 106.
4.

P e s s i o n , Admiral G. Papers appearing in Rassegna delle P.T.T., September 1935 and Alta Frequenza,
August 1936. Work abstracted in C.C.I.R. Stockholm, 1948 book: (Proposals submitted to the C.C.I.R),
Study Group II (Radio Propagation), 288.

5.

S i l b e r s t e i n , R. The long-distance horizontal radiation pattern of a high-frequency antenna. National
Bureau o f Standards Report No. 3538. Abstract given in Transactions o f the Institute o f Radio En­
gineers, Vol. AP-5 (Antennas and Propagation), 4, 397 (October 1957).

6. B e c k m a n n , B. and V o g t , K. Beobachtung der Riickstreuung im Kurzwellengebiet an kommerziellen
Telegraphiesignalen (Observations on backscattering of commercial telegraph signals in the highfrequency band). Fernmeldtechnische Zeitschrift, Vol. VIII 473-481 (1955). Doc. VI/45 of Geneva,
1958, contains some of this material.
7.

F i n e , H. and D a m e l i n , J. Suppressional performance of directional antenna systems in the standard

broadcast band. Federal Communications Commission Report, TRR-1.2.7.
8.

B r u e c k m a n n , H. Suppression of undesired radiation of directional HF antennas and associated feedlines. Proc. IRE, 46, 1510-1516 (August 1958).

9.

M i y a , K., I s h i k a w a , M. and K a n a y a , S. On the bearing of ionospheric radio waves. Rep. Ionos­
phere Res. Japan, 9, No. 3, 130-144 (1957).

10.

M i y a , K. and K a w a i , M. On the propagation of long-distance HF signals above the classical MUF- Pulse and dot transmission tests between England and Japan, Electronic and Radio Engineer(United Kingdom).

11.

K e e n , R.

12.

K.A. System loss in radio
wave propagation (See Sec. 9 of Report).National Bureau o fStandards Journal o f Research, 63 D, 1, 53-74 (July-August 1959).

Wireless Direction Finding,

4th ed. 1947, Iliffe and Co., London.

N orton,R E PO R T 109 *RADIO SYSTEMS EMPLOYING IONOSPHERIC-SCATTER PROPAGATION(Question 132(111))(Los Angeles, 1959)
A contribution, relating to Question 132(111), has been received from the U .S.A. (Doc.
111/29 of Geneva, 1958); references are cited in which inform ation on ionospheric-scatter
propagation relevant to exploitation of systems has been published [1, 6].
1.

Variation with frequency of propagation characteristics relevant to the use of systems
F or estim ation of the perform ance of fixed systems, it is im portant to know the variation
w ith frequency, of the m ean signal intensity, the fading characteristics, such as short termam plitude distribution and fading rate, and the background galactic noise level. F o r practical* T h is R e p o rt w as ad o p ted by correspondence.

T he U n ite d K in g d o m reserved its o p in io n o n th is R e p o rt.

Rep. 109

— 64 —

purposes, received power may be considered inversely proportional to approximately the 7th
power of the frequency, using scaled antennae. The background galactic noise is inversely
proportional to the 7/3 power of the frequency. The resulting signal-to-noise ratio, using scaled
antennae, is proportional approxim ately to / ~ 5. Studies have shown th at the frequency
dependence during hours of weakest signal intensity is n ot significantly different from thatobserved for the mean signal intensity. The short-term am plitude distribution of signal
intensity approxim ates a Rayleigh distribution at frequencies observed in the range of 30 to74 Mc/s. The typical m easured fading rate (median crossings), at 50 Mc/s, is approximately
1 c/s; the fading rate is proportional to operating frequency raised to a power of 0-7 to 1-2,
depending on conditions.
A nother im portant propagation characteristic which varies with frequency is the occur­
rence of long distance F2 propagation giving rise to m utual interference and back-scatter,
which represents a source of self-interference to a scatter system used for high-speed telegraphservices. The occurrence of this type of propagation is dealt with in the following paragraphs,
along with consideration of m utual interference.

2.

The extent to which systems employing this mode of propagation and operating on the same orneighbouring frequencies are liable to interfere with each other and with other services
The propagation modes, most significant in long distance interference between scatter
services and other services, are sporadic-E and F2. A dequate world-wide m easurem ents ofsporadic-E are not yet available to perm it a complete evaluation of the percentage of time th atinterference is likely to occur. A comprehensive study of world-wide occurrence of Es observedat H F by ionosphere recorders has been published [7,8]. F o r practical purposes, ionosphericscatter circuits, to avoid sporadic-E interference, should have their transm itting and receiving
terminals geographically separated from other circuits or services by at least 3000 km. Figs. 1-12
represent contours of F 2 —4000 km M U F exceeded 1% and 10% of the hours during threeseasons of the year at times of sunspot m aximum and minimum. These are derived fromstandard C.R.P.L. F2 prediction data, using m easured distributions of day-to-day values of
F2 M U F about the median. A circle of 2000 km radius centred on the station gives the locus
of frequencies at which propagation over 4000 km paths occurs 1 % or 10% of the time during
the season indicated. The percentage of th e tim e is less for paths longer or shorter th an
4000 km. Figs. 1-12 inclusive may be regarded as provisional and subject to revision atsuch time as the C.C.I.R. may adopt appropriate data regarding F2 M U F values.*

3.

Radio frequency and baseband characteristics of ionospheric-scatter systems
Ionospheric-scatter systems of high reliability are currently in operation and the num berof such systems may be expected to increase. These systems employ highly directional
antennae and transm itter output powers of the order of 40 kW.
In view of rapid technical advances, standardization is not practical at this time. T here­
fore, the m odulation characteristics of typical systems in use or under consideration arepresented for illustration:(a) a single voice channel of response from 300 to 3100 c/s using SSB, or narrow -band
frequency m odulation with a peak deviation of 3 k c/s;
* R evised versions of F igs. 1, 3 an d 5 have been issued as F ig . 1, 2 an d 3 in R e p o rt 260 (V ol. II, S ection G ).

— 65 —

Rep. 109(b) four to sixteen channel, time-division multiplex, at a rate of 150 to 600 bauds w ith fre­quency-shift keying; a separation of 6 kc/s is commonly used between m ark and spacefrequencies, to minimize errors due to D oppler com ponents;(c) com binations of the above, using linear transm itters, such as a voice channel and an
FSK system or two independent FSK system s; as an alternative, two transm itters may be
used, with one carrying voice intelligence and the other teleprinter;(d) a system has been proposed with a single voice channel and four channels of teleprinter,using error correction and detection techniques at 177 bauds. A typical assignment for
20 kc/s spectrum occupancy is shown in Fig. 13.

M odulation characteristics of the propagation m edium m ust be considered in systemapplication. Some pertinent characteristics are:(a) diversity reception is beneficial for voice or teleprinter operation.
is commonly used;

D ual or triple diversity(b) the coherence bandwidth, as determined by m ultipath considerations o f the transm ission
medium, is limited to approxim ately 3 k c/s;(c) meteoric m ultipath will, in general, limit the m axim um baud rate;(d) during periods where the M U F may be above the operating frequency, F2 propagation
may be expected. The above conditions are frequently accom panied by long-delay
m ultipath echoes, ranging up to 50 ms or more. The echo pulses may have am plitudes
com parable to or even greater than the desired signal, thus resulting in a very high error
rate. Long-delay m ultipath problem s may find solution by the use o f antennae havingm ore desirable directivity characteristics, the use of a frequency above M U F, or by theuse of special m odulation techniques;(e) ionospheric-scatter systems characteristically employ high power and highly directional
antennae; during periods of sporadic-E or high M U F, they m ust be considered as
potential sources of interference to other services sharing the same frequency b and;(f) current four-channel teleprinter systems, using dual-space diversity, typically require asignal-to-noise ratio of 24 db (noise m easured in a 250 c/s band), for a binary error rateo f l x l O - 4;(g) voice systems currently in use will provide usable operator-to-operator quality over a
single link with a radio-frequency signal-to-noise ratio of approxim ately 14 db, as m ea­
sured in a 3 kc/s noise bandwidth.
The frequencies used for this m ode of propagation are generally between 30 and 40 Mc/s.
A few circuits currently being installed will use dual-frequency operation. H igher frequencies,
perhaps as high as 60 Mc/s, will be useful as a means to avoid distance propagation during
periods of high F2 M U F ’s at time of maximum solar activity.
The distances over which these circuits operate generally range from 1000 to 2000 km,
and several of these circuits are now in operation in arctic regions.

Rep. 109

— 66 —B (S p e ed in b a u d s )SSB V o ice

B (S p e e d in b a u d s)

N a r r o w - b a n d v o ice

F igure 13

Typical 20 kc/s spectrum assignment s for ionospheric-scatter transmission(B is the frequency in c/s corresponding to the telegraph speed in bauds)

B ib l io g r a p h y

1. B a i l e y , D.K., B a t e m a n , R. and K i r b y , R.C. Radio transmission at VHF by scattering and otherprocesses in the lower ionosphere. Proc. IRE, 43, 1181-1230 (1955).
2.

A b e l , W.G., d e B e t t e n c o u r t , J.T., C h i s h o l m , J.H. and R o c h e , J.F. Investigations of scattering andmultipath properties of ionospheric propagation at radio frequencies‘exceeding the MUF. Proc. IRE,
43, 1255-1268 (1955).

3.

B r a y , W.J., S a x t o n , J.A., W h i t e , R.W. and L u s c g m b e , G.W. VHF propagation by ionospheric scatter­ing and its application to long-distance communication. Proc. I.E.E., 103, Part B, 236-260 (1956).
In addition to the above, attention is drawn to entire issues of journals as follows:
4. Proc. IRE, 43, 10 (October 1955).
5. IR E Transactions on Communications Systems, Vol. CS-4, 1 (March, 1956).
6. I.E.E. Symposium on long-distance propagation above 30 Mc/s. London (January 28, 1958). Journal
o f the I.E.E., 105, Part B.
7.

S m i t h , E.K. Worldwide occurrence of sporadic-E. National Bureau o f Standards Circular 582 (March 15,1957).
8. S m i t h , E.K. and D a v i s , Jr., R.M. The effect of sporadic-E on VHF transmission in the U.S.

Rep. 109

Values o f the F2 4000 MUF exceeded for l % o f hours; December solstice, sunspot maximum

F ig u r e 2

Values o f the F2 4000 M UF exceeded for 10% o f hours; December solstice, sunspot maximum

Values o f the F2 4000 M UF exceeded for JO % o f hours; Equinox, sunspot maximum

(io®

80®

100“

120®

140”

160® E100® w

160®

140”

120®

100”

80“

60”

40®

20®

w

0“ E

20®

40®

60®

80®

100”

120®

140®

160“ E

I80”w

160”

140®

120®

100“

80®

60”

40®

20® w

0” E

20“

40“

60”

F ig u r e 6

Values o f the F2 4000 M U F exceeded fo r 10 % o f hours; June solstice, sunspot maximum

Values o f the F2 4000 M UF exceeded fo r 1% o f hours; December solstice, sunspot minimum

Rep. 109

F ig u r e 7

F ig u r e 8

Values o f the F2 4000 M U F exceeded fo r 10% o f hours; December solstice, sun'spot minimumRep. 109

F ig u r e 9

Values o f the F2 4000 M U F exceeded fo r 1% o f hours; Equinox, sunspot minimumF ig u r e 10

Values o f the F2 4000 M UF exceeded fo r 10% o f hours; Equinox, sunspot minimumF ig u r e 11

Values o f the F2 4000 M U F exceeded fo r 1 / o f hours; June solstice, sunspot minimum

60°

80"

100°

180°

140"

160° E,180° w

160°

140°

120°

100°

80°

60°

40°

20°

w

0° E

20°

40°

80°

100°

120°

140°

160° E

I60°w

160°

140°

120°

100°

80°

60°

40°

20° w

0° E

20°

40'

F ig u r e 12

Values o f the F2 4000 M U F exceeded fo r 10% o f hours; June solstice, sunspot minimum

— 79 —REPO RT

Rep. I ll

111 *INFLUENCE ON LONG-DISTANCE HF COMMUNICATIONSUSING FREQUENCY-SHIFT KEYING OF FREQUENCY DEVIATIONSASSOCIATED WITH PASSAGE THROUGH THE IONOSPHERE(Question 181(111))(Los Angeles, 1959)
1.

Introduction
This Report, based mainly on Doc. 111/34 (U.S.A.) of Geneva, 1958, deals with three
aspects of the question. Firstly, the magnitude and time duration o f the frequency changes
to be expected are considered. Secondly, upper bounds of error rates for frequency-shiftsystems are calculated. Thirdly, experimental element-to-element phase changes are shown,
relevant to phase modulation techniques.
The present R eport gives only partial inform ation on the subject and a m ore com plete
study may be expected, to provide definitive inform ation on the minimum frequency shift
which is feasible in practical systems.

2.

Characteristics of frequency changes over HF circuits
It is well known that the rapid fading observed on H F circuits is the result of interference
between a num ber of different waves that have been reflected from different portions of theionosphere. The ionosphere may be thought of as an irregular reflecting surface th at isdrifting across the sky. Because of this drift, waves th at arrive at the receiving site are beingreflected from elemental surfaces that are in m otion; consequently, each reflected wave will
have a small D oppler frequency change. The interference of these frequency-shifted waves
gives rise to rapid fading. (This R eport will be concerned only with rapid fading and n o t slow
variations resulting from changes in absorption.) This being the case, a reasonable model
describing the fading signal is to assume it has the character of very narrow band Gaussian
noise. This approach was probably first described by J. A. Ratcliffe [1].
W hen the narrow -band noise representation is used, it is then possible to use the exten­
sive w ork done by S. O. Rice [2], in determining the nature of a fading H F signal.
N ow the relationship between the fading rate “ N g ” (defined as the m ean num ber oftimes per second the signal envelope passes through the median signal level w ith positive
slope), and the corresponding “ equivalent noise bandw idth ” of the fading signal is
N g = 1-48 a
where o is the standard deviation o f an assumed G aussian shaped band pass filter. (Thisequivalent noise bandw idth refers to the received signal only and n o t the noise th at may
accompany it.) It is equivalent to the 2-17 db half-bandwidth o f the filter. If a rectangularfilter is assumed then the fading rate N r is
N r

— B/2-32

where B is the bandw idth of the filter. The G aussian shaped filter seems to be a close approxi­
m ation to the true fading bandw idth of an H F signal [3]; however, for convenience only a* T h is R e p o rt w as ad o p ted by correspondence w ith o u t reservation.

Rep. I ll

— 80 —

rectangular filter will be considered. Once we have a measure of the bandw idth of the fading
signal, we may proceed to find the probability distribution of the instantaneous frequency
along with several other statistics.
Fig. 1 shows the cumulative probability distribution of the instantaneous frequency.
This curve has been normalized to the fading rate. F o r a fading rate of one cycle per second,
the instantaneous frequency will be within about 20 cycles of the carrier frequency 99-96%of the time.
Taking into account the fading rate indicated in R eport 266, the values of excursion of
instantaneous frequency are not inconsistent with the deviations o f 3 parts in 106 for a few
milliseconds duration reported in Doc. III/3 (U nited Kingdom) of Geneva, 1958.
The m ean duration of the instantaneous frequency deviation may also be found with theaid of results worked out by Rice. He derives the expression for the m ean num ber of times
per second that the instantaneous frequency exceeds or crosses a given instantaneous frequency,
when the bandw idth of the filter is known. Taking the reciprocal of these crossings-per-second
gives the m ean tim e interval between them. A nd since we also know the percentage of thetime the instantaneous frequency spends beyond the given crossings, we may com pute them ean time duration it spends there. This is simply the product of the probability th at it will
be beyond the crossing and the mean time interval between the crossing. This m ean timeinterval, At, versus frequency change from the centre frequency, is shown in Fig. 2. Fading
rate is the param eter. If the fading rate is known, the m ean duration o f exceeding a given
frequency change may be found. It is interesting to note that At, is practically independentof the fading rate.
It should be noted that a m ore complete study is required, to provide the cumulative
distribution of the time durations for various specified frequency changes. This is beyond
the scope of the present R eport.

3.

The effects on FSK of frequency changes due to passage through the ionosphere
To determine the effect of frequency changes associated with passage through theionosphere, we shall assume that no noise is present and that our detector is a frequency
discriminator. O ur system will m ake an error, if the transm itted frequency is changed far
enough to cross over into the wrong side of the discrim inator and remains there for a period
com parable to half the element length. We shall choose 20 ms as the element length.
If we assume a fading rate of one per second and a frequency shift of 40 c/s, we find,referring to Fig. 1, that the frequency of either the m ark or space channel will change by 20 c/s
and cross over into the wrong side of the discrim inator for only 0-04 % of the time. The
0-04 % represents the upper limit of the binary error rate to be expected in the no noise case.
If reference is m ade to Fig. 2, we find that A t is only 6-2 m s; consequently, even when the
instantaneous frequency does lie on the wrong side o f the discriminator, its duration is so shortthat only rarely will an error be made.
Fig. 3 shows the maximum binary error rate to be expected versus the frequency shift ofthe system with the fading rate as a param eter. It is assumed th at errors occur with theprobability that the instantaneous frequency has been displaced to the wrong side of thediscriminator. This over-estimates the true error rate due to frequency changes, when themean length of time of the change is small com pared with the signal pulse length, since thediscriminator (or post detection filter) time constant has been ignored. As an aid in estimating
the region where this time constant becomes effective, points on the curves, corresponding toA t of 10 ms, have been located from the curves of Fig. 2.

4.

Experimental data relevant to phase modulation
Several experimental studies have been conducted, to determine the perform ance of the
FSK systems and a phase-shift (synchronous) system over sky-wave transm ission in the H F

— 81 —

Rep. I llband. The phase-shift m odulation system requires reasonable phase stability over anapproxim ate 44 ms period. Results of these studies are pertinent to this study of D oppler
frequency changes.
A short study has been m ade of the phase stability of signals from WWV as received in
Burbank, California [4]. M easurements were made at frequencies o f 5, 10 and 15 Mc/s.
A sequence of discrete phase com parisons were made at a 50-cycle rate. Each m easurem ent
com pared the phase of the incoming signals during a 20 ms period with th at during the fol­lowing such period.
Stability of receiving equipm ent for such measurements is of prim ary im portance. F orthis test, all receiving gear was frequency controlled by a single high stability local standard
oscillator (1 p art in 108), thus ensuring th at apparent phase shifts due to frequency error were
insignificant com pared to phase changes due to the propagation.
In general terms, the m easuring technique consists of driving an extremely high Q resonatorcircuit with the received signal for 20 ms. The resonator was then allowed to ring, while thesecond resonator was driven by the signal for another 20 ms. The relative phase between
the two resonators was then m easured in a phase detector. This resultant m easurem ent was
the phase difference between two integration-phase samples taken 20 ms apart. By a suitableconnection between two quadrature phase detectors, a polar display of relative phase andam plitude was presented on an oscilloscope face. The oscilloscope intensity level was blanked
except at the end of each 20 ms integration period. The resulting display is a series of dots
representing the tips of vectors, whose lengths from the origin are proportional to the am plitudeof the applied signal, and having angles equal to the signal phase changes between samples.
Photographs of these dot displays were m ade with exposure times of from 15 s to 5 min. Them ajor results of the study were polar displays of signal phase shift and am plitude. Fig. 4
shows approxim ate probability contours drawn from these displays. These indicate a decreasein phase stability at higher frequencies, as expected, and give an indication of the degree ofphase uncertainty, which cannot be attributed to additive noise.
5.

Conclusions
To the degree that the theoretical model describes the behaviour of an H F fading signal,
it appears that frequency changes imposed by the propagation are small for typical fading
rates. This conclusion is supported by some experimental evidence on phase uncertainty
obtained over H F paths. F urther studies, especially of the distribution of the duration of
frequency changes are needed to improve the estimates o f errors imposed in FSK systems.

B ibliography

1. R atcliffe, J.A. Diffraction from the ionosphere and the fading of radio waves. Nature, 162, 9 (1948).
2. R ice, S.O. Properties of a sine wave plus random noise. Bell System Technical Journal, 21, 109-157(1948).
3. P rice, R. The autocorrelogram of a complete carrier-wave received over the ionosphere at oblique

incidence. Proc. IRE, 45, 879 (1957).
4. D oelz, M.L., H eald , E.T. and M artin , D.L. Binary data transmission techniques for linear systems.
Proc. IRE, 45, 656-662 (May, 1957).

Rep. I ll

— 82 —

F' = Instantaneous departure from centre frequency (c/s)
N r = Fading rate (fades per second)
F ig u r e 1

Cumulative probability distribution o f instantaneous frequency-change

Curve A: 0-2 fades/second

F' = departure from centre frequency (c/s)
Curve B: 1 fade/second

Curve C : 5 fades/second

F igure 2

Average duration that instantaneous frequency change due to the ionosphere exceeds F ', with fading rates
o f 0-2, 10, and 5 0 fades per second (assuming a model o f narrow-band Gaussian noise)-Rep. I ll

83 -%Frequency shift of the system
F igure 3

Relation between binary error-rate and. frequency-shift o f the system for fading rates, N, o f 0-2, 1 and 5 fades
per second. Element length = 20 ms (50 bauds)
A) 5 MHzB) 10 M H z

C ) 15 M H z

F igure 4

Polar probability contours o f phase change and amplitude o f WWV
The numbers shown represent the probability that a measurement will fall outside the contours.

Rep. 112

— 84 —R E P O R T 112 *T R A N S M IS SIO N L O S S IN ST U D IE S O F R A D IO SY STEM S(Question 3(111))(Los Angeles, 1959)

1.

Definitions of system loss, transmission loss, basic transmission loss, path antenna directivity
gain and path antenna power gain
Definitions and standard notations ** have been given in Recom m endation 341 for thesystem loss L s, the transm ission loss L, the propagation loss Lp, the basic transm ission loss L b,
the path antenna directivity gain Gp and the path antenna power gain Gpp. It is the purposeof this R eport to illustrate the use of these terms and the concepts involved, and to show theirrelationship to other parameters.

2.

Transmission loss in free space
As an example of the simplicity of transm ission loss calculations in some cases, we may
consider the transm ission loss between two isotropic antennae in free space. A t a distance,d, very m uch greater than the wavelength, X, the power flux density (field intensity), expressedin watts per square metre, is simply /j//(4 ra /2), since the power is radiated uniformly in all
directions. Since the effective absorbing area of the receiving antenna is X2/(4tt), the available
power at the term inals of the loss-free isotropic receiving antenna is given by:Consequently, the basic transm ission loss in free space may be expressed by:
L bf = 10 log10 (4 tu d /X f(d > X)(2)

Since the free-space gain of a short lossless electric dipole is gt — g r = 1-5, the path antenna
gain for two optimally oriented short electric lossless dipoles in free space is :Gp = Gt + G, = 3-52 db
Consequently, the transm ission loss between two optim ally oriented
dipoles in free space is:(3)
short lossless

electric

L = 10 loglc (4 tc d / l f - 3-52 db

3.

(4)

The concept of propagation loss and the influence of the environment of the antenna
To illustrate the influence of changes in the impedances of the antennae, caused byenvironm ental factors which are independent o f the antennae circuit losses, we will consider* T h is R e p o rt was ad o p ted by correspondence w ith o u t reserv atio n .
** T h ro u g h o u t th is R ep o rt, ca p ital letters a re used to deno te th e ratio s, expressed in decibels, of th e c o rresp o n d in g q u an tities
designated w ith low er-case ty p e; e.g., Pt —10 lo g 10p(. Pi is th e in p u t p o w er to th e tra n sm ittin g a n te n n a expressed in decibels
relative to 1 w att.

— 85 —

Rep. 112

the transm ission loss between two short vertical lossless electric dipoles at heights ht and hr,
respectively, above a plane perfectly conducting surface and separated by a distance, d, large
with respect to the wavelength, along the surface. In free space, the field strength e (V/m),
at a distance d (m) in the equatorial plane of a short lossless electric dipole rad iatin g p r (W),is given by:
e2K = I''5Prl(A 71 d2)(5)

where 7j0 = 4rcc x 1CK7 is the impedance of free space (fl), and c = 2-997925 x 108 (m/s),
is the velocity of light in free space. The factor (1-5) can be identified as the free space gainof the transm itting dipole antenna. The radiation resistance of a short vertical electric
dipole of effective length I at a height ht, above a perfectly conducting plane, is given by:r —2x°2 ~ 0+— r/ ( l + ^ i)

A , - (2 k 3htf

(6)

»]

In the above, k = 2tt/X = 2tt//c, i. e., X is the wavelength in free space. N ote th at A,
approaches zero a t large heights above the surface and r approaches its free-space value, ty.
On the other hand, A, = 1 for ht = 0, and the radiation resistance is then just twice its freespace value. The field intensity expressed in W /m 2 at a height hr for a short vertical lossless
electric dipole at a height ht over a perfectly conducting plane surface, may be expressed b y :e*

1-5 p r [ 2 cos2
cos (k h t sin <J0 f
4 tc <72 (1 + A,)

In the above expression, tan ^ = hrjd and the distance, d, along the surface m ust be large withrespect to both X and h\ in this case, the distance between the antennae is approxim ately
djcos
Since A, = 1 for ht = 0, the field intensity is 3 db greater, when <p = Oand the dipole
is on the surface of a perfectly conducting plane (i. e., e2jr\0 = 3pr/(4nd2)), th an when it is in
free space; note th a t in free space we m ust use (5) and not (8), since the ground reflection
influences the radiation for all values of ht. In m ore fam iliar units, when ht = h r = 0, (8)may be expressed by:
e = 2-998962 x 105 ( V ^ / d )
where

(9)

e is in y.V/m; p r is in kW ; and d is in km

The effective absorbing area of a short vertical lossless electric dipole receiving antenna, at aheight h, above a perfectly conducting plane, may be expressed b y :1-5 X2 cos2 ^Q* _ 4tu(1 + A ^(10)

where Ar is defined by (7), with ht replaced by hr. Since p a = e2 a jt\0, we find by com bining(8) and ( 10) that the transm ission loss between two short vertical lossless electric dipoles, atheights ht and hr above a plane perfectly conducting surface, may be expressed by:mi| [4 71 d/(X COS 4Q]2 (1 + &t) (1 + Ar) ,W'ogjo^(1>5)2 [2 cos2 cos (kht sin ^)]2 ‘* These relatio n s are derived by S. A . S c h e l k u n o f f in C h ap ters V I an d IX o f th e b o o k E lectrom agnetic W aves, D . V an
N o stra n d C o., 1943.

Rep. 112

— 86 —or L = L bf + A + L t + L r - G p - 6-02 (db) = Lp + L t + L r (db)

(12)

where
L, = 10 log10 [1 + AJ, L r = 10 log10 [1 + ArJ Gp « 20 log10 [(3/2) cos2 <\>]and A « -2 0 1 o g 10[cos (k ht sin <\>)]. It is of interest to note th at the transm ission loss between the dipoles on
the plane perfectly conducting surface, ht
hr — 0, is the same as if the dipoles were separated
by the same distance in free space, although the field intensity is 3 db greater for the same
power radiated. O n the other hand, when the dipoles are several wavelengths above theperfectly reflecting surface (ht = hr ^> X), and are separated by a large distance (<|> « 0), thetransm ission loss is 6-02 db less than for dipoles separated by the same distance in free space.
The above is no t the only logically consistent m ethod of describing the gains and losses
in the presence of a perfectly conducting ground. Thus, Schelkunoff, in the reference cited,considered the perfectly reflecting surface to be an integral p art of the transm itting andreceiving antennae, and set Gls = 10 log10 [3/(1 + A*)] and Grs= 10 log10 [3/(1 + Ar)].
In other words, he referred his maximum gains to those expected for isotropic antennae withthe earth rem oved; this leads to a path antenna gain, referred to th at expected between iso­tropic antennae with the earth removed, given by Gps = (Gp + 6-02 — L t — I — A), and thistransm ission loss is simply L = (Lbf — Gps). However, this m ethod o f approach is not.recommended since:- it is impracticable to remove the E arth to measure Gpsl
- it w ould lead to antenna gams 3 db larger than their free-space values, even when they
are m any wavelengths above a perfectly reflecting plane surface, and this is inconsistent
with the present usage of the concept of antenna gain in the higher frequency ranges.
A lthough it appears to be desirable to separate the effects of earth reflections from thegains of the antennae, by means of the propagation loss concept described earlier, there will
be other situations in which such a separation of environm ental effects is undesirable. F o r
example, the power gain o f an antenna, m ounted on an aircraft, satellite, or spacecraft
should be considered as the gain which would be determ ined by integrating the cymomotive
force over all directions as the vehicle is rotated in free space. E quation (12) illustrates thedefinition of Lp, the propagation loss, i. e., the transm ission loss expected if the antennae had
the same impedances they would have had if they were in free space. L t and L r are defined
above for antennae over a perfectly conducting ground plane; m ore generally, L t and L r are
defined as 10 log10 (r'/ry), where r is the actual resistance of the antenna and /y is the radiation
resistance it would have had if it were in free space. We note th at L t and L r contain the loss
com ponents L tc and L rc and may also vary substantially from one antenna site to the next,
depending upon polarization and ground conditions. They are also a function of the sizeo f the ground screen used, and depend on other environm ental factors, such as the presenceof trees or over-head wires. It is thus clear why it is desirable to separate these com ponents
from the system loss and to have a propagation loss, Lp, independent of these antenna environ­m ental conditions.

4.

Simplification possible at higher frequencies
A t higher frequencies, the antennae are usually located several wavelengths away fromthe ground and other environm ental disturbing elements and, in such cases, L t, L r, L ic andL rc will all be sufficiently small so that the propagation loss, the transm ission loss, and thesystem loss will all have essentially the same magnitude, and it will then be unnecessary to
distinguish between Lp, L and L s.

5.

Relation to current C.C.I.R. terminology
It is desirable to relate the above transm ission loss term inology to the term inology usedin other C.C.I.R. docum entation. We may express the free space cymomotive forceRep. 112

— 87 —

C = 20 log10 (e.d) in db rel. 1 V (e. g., relative to 1 V/m at a distance of 1 m) as in Recom m en­dation 168. In free space, we find by (5), when we note th at P{ = P t — L lc and L t = L tc:
C = 10 log10 (p, c. g t x 10-7) = P t - L t + Gt + 14-77 (db)(13)

The relation between the available power, p a, from the receiving antenna and the field strength,e, may be expressed in decibels as follow s:
E = 10 log10 [4 tt r)0 p a (r'/rf ) x 1012/(X2^ ) ] = Pa + 20 lo g / - G r + L r + 107-22 db (14)where / i s in Mc/s.
If (13) is solved for P t and (14) for Pa and we combine the results, the following expression for
L s is obtained:
L s = P , - P a = C - E c - G p + 20 log10/ + 92-45 + L t + L r
w h e r e /is in Mc/s.

(15)

In Recom m endation, 370, the curves of tropospheric field strength E, expressed in db relative
to 1 jj.V/m, were referred to a free-space cymomotive force C = P t — L t + Gt + 14-77 =46-92 db relative to 1 V (i. e., 222 V), since they correspond to 1 kW radiated (Pt — L t = 30)
from a half-wave dipole (Gt = 2-15); thus, the propagation loss corresponding to the valueso f E in those docum ents is given by:
Lp = L i - L t\ - L r = 139-37 - Gp + 20 log10/ — E
where / is in Mc/s.

(C = 46-92)(16)

The inverse distance field I (expressed in db relative to 1 V/m at 1 m), may be determinedover a perfectly conducting ground plane from (8):/ = P / ~ L t + Gt + 20-79 (db)(17)

N oting that P{ — P t over a perfectly conducting ground plane and then solving (17) for P t
and (14) for Pa and combining the results, the following expression for L s is obtained:
L s = P t - P a = I - E i - G p + 20 log10/ + 86-43 + L t + L r
where / is in Mc/s.

(18)

In Recom m endation 368, the curves of E = f (d) were referred to a value of / = 20 log10
300 = 49-54 db relative to 1 V, i. e., by (17) the inverse distance field corresponding to 1 kW
radiated (P r — 30) from a short vertical electric dipole (Gt = 1-76) over a perfectly conducting
ground (L t = 3-01) and thus the propagation loss corresponding to the values of E in Recom ­m endation 368 is given by:
Lp = L s - L t - L r = 135-97 — Gp + 20 log10/ — E
where / is in Mc/s.

(I = 49-54)(19)

It is seen from the above discussion that the propagation loss, L p, may be calculatedby (16), from the values of E given in Recom m endation 370, or by (19) from the values of F in
Recom m endation 368. The fact that there are different relations between Lp and the values of
E in these documents, illustrates the complexity of the conventions used in past studies of radio
wave propagation. There may be some advantage to the C .C.I.R. in adopting the propagation
loss, Lp, between short electric dipoles, as a standard m ethod of presenting the results o f radio
propagation studies such as those in the above documents. This would m ake possible the useof a single convention throughout the spectrum and would result in a presentation which is
directly useful to those engaged in radio systems studies. Short electric dipoles are suggested
as reference standards for the uniform presentation of propagation data throughout the spec­
trum , in preference to either isotropic antennae or half-wave dipoles, for the following reaso n s:
- short electric dipoles are physically realizable throughout the spectrum;- short electric dipoles have polarization characteristics, as do all real antennae;- short vertical electric dipoles have some directivity in the vertical plane and thus simulate
typical real antennae somewhat better, as regards ionospheric wave propagation in thelower frequency ranges.

Rep. 112

— 88 —

It is recognized, th a t it will often be m ore convenient, at the higher frequencies, to makepropagation measurements using half-wave dipoles, but such measurements can readily be
adjusted to the results expected with a short electric dipole, since the maximum gain of ahalf-wave dipole is ju st 0-39 db larger than th at of a short electric dipole.
If the propagation loss, Lp, between short electric dipoles were used as a standard by the
C.C.I.R., then Gp = 3-52 db and the field E ( C = 46-92) o f Recom m endation 370 could, by(16), be determined from :E = 135-85 + 20 logj0/ — L p(C = 46-92)(20)

and the field E ( I = 49-54) of Recom m endation 368 could, by (19), be determined from :E = 132-45 = 20 log 10f - Lp

( / = 49-54)(21)

where / is in Mc/s in both cases.

6.

Comparison between the measurement of field strength and the measurement of the available
power from the receiving antenna
The essential advantage of measuring or calculating propagation characteristics, in termsof system loss rather than in terms of field strength, is the fact that the former requires the deter­m ination of the available power from the receiving antenna for a given input power to thetransm itting antenna, and thus autom atically allows for both the directivity and the circuit
losses of the transm itting and receiving antennae. The available power p a = v2/4r', where r'
is the resistive com ponent of the receiving antenna output impedance, including both its
radiation resistance, r, and loss resistance com ponent, rc, while v is the open circuit voltage.
W hen the antenna is loaded by the complex conjugate of its output impedance, the voltage
appearing across its term inals is v/2 ; thus the available power is simply the power delivered by
the receiving antenna to a m atched load. The accurate determ ination of the available power
requires the measurements of both r' and v, whereas the field strength is independent of r'and, to this extent, does not provide a direct measure of the expected perform ance of a radio
system, at least in those cases where the receiver noise is com parable to, or larger than, the noise
picked up by the receiving antenna.

7.

Simplicity of systems problems solved in terms of system losses
Finally, it should be noted that the concept of system loss provides a simple solution to
the problem of allowing for the effects of interfering transmissions. Consider, as one example,
the determ ination of the interference to the reception at a particular receiving location of awanted transm ission caused by an unw anted transm ission on the same channel. The ratioof the w anted-to-unwanted signal power, available at the term inals of the receiving antenna
may be expressed b y :R = PtdP»

L sd + L su

(22)where Ptd and Plu denote the antenna input powers to the w anted and unw anted transm issions,while L si and L m denote the system losses for the w anted and unw anted transm ission paths.
W hen it is noted that the com ponent L rc is the same in L sd and L su, (22) becom es:
R = P J - P tu' - L d + L u(23)

where P J and P tu' are the radiated powers from w anted and unw anted transm itters, while
L d and L u are the transm ission losses for the wanted and unw anted transm ission paths. Both
L d and L u will vary with time, and these variations will, over long periods of tim e, be positively
correlated, so that the variance of R with time will be somewhat less than the sum o f thevariances of L d and L u. If R exceeds a prescribed minimum acceptable level, R m, for a

— 89 —

Rep. 112

sufficiently large percentage of time, then this particular receiving location may be considered
to be free of interference. N ote that the effect of the directivity of the receiving antenna isappropriately allowed for in determining R, since L d will be m easured (or calculated), with theantenna directed towards the desired station, while L u is the transm ission loss corresponding
to the effective receiving antenna gain in the direction of the unw anted transm itter. F o r abroadcasting service, one may choose a large num ber of receiving locations within the service
area of the w anted station in some systematic way * and at each of these locations determine,in the m anner described above, whether it is satisfactorily free of interference. This constitutes
a useful solution of the problem of assessing the im portance of the interference between stations
on the same channel; the same m ethod can also be used for interference between stations on
adjacent channels, simply by changing the value of R m. It is im portant to notice th at thetransm ission losses, L d and L u, will be very much influenced by the irregularities in the terrain
profiles to the wanted and unw anted stations respectively. Furtherm ore, there will be atendency for L d and L u to be correlated as one moves from one receiving location to the next,
since unfavourable locations for the reception of the wanted station will also tend to be
unfavourable for the reception of the unw anted station.
The above discussion represents one of a num ber of possible examples of the utility of theconcept of transm ission loss in systems studies. There are many circumstances, however, as,for example, in assessing the interference potential of Industrial Scientific and M edical equip­
ment, where it is m ore convenient to specify the interference in term s of field strengths, rather
than attem pt to specify the param eters involved in system loss calculations, and it is n ot theintention of this R eport to suggest that the concept of system loss should necessarily replaceth at of field strength. R ather it has been the intention in this R eport merely to discuss thepossible advantages of this concept and to show its relation to other terms in use by the C .C .I.R .

8.

Relationship to other C.C.I.R. Questions and Study Programmes
N ote that this m ethod of presenting the results of propagation studies has a direct bearing
on the following w ork of the C.C.I.R.
Questions : 81(111), 132(111), and 246(V).
Study Programmes: 3A(III), 57(V), 81A(III), 139(V), 148(VI), 188(V), 198(VI), 202(VI)and 227A (I).

* I t is convenient to choose these V H F -rec eiv in g lo c atio n s a t th e in tersectio n s of a reg u lar lattice w ith s e p a ra tio n s of, say,
2 k m , since it is kn o w n th a t th e re is very little c o rre la tio n betw een th e tra n sm issio n losses a t V H F fo r receiving p o in ts sep arated
by such d istances, an d th is w ill p erm it a m a xim um o f in fo rm atio n to be derived w ith a relativ ely sm all sam ple.

Rep. 195

— 90 —R E P O R T 195 *BANDWIDTH AND SIGNAL-TO-NOISE RATIOS IN COMPLETE SYSTEMS
Prediction of the performance of telegraph systems in terms of bandwidthand signal-to-noise ratio(Study Program m e 3A(III))(Los Angeles, 1959 - Geneva, 1963)
1.

Study Program m e 3A(III) sets out some questions, the answer to which would form a basis
for the evaluation of the perform ance of complete systems. The questions include terms like“ excellent service ”, the interpretation of which depends greatly on the type of traffic thesystem is intended to carry and the grade of service. This R eport will n o t discuss such ques­
tions in detail, but rather attem pt to give a basis for a m ore objective m ethod of performance
specification in the light of recent w ork on com m unication systems.
Theoretical studies of the mechanisms o f detection of telegraph signals in the presence ofnoise, having a G aussian distribution [1, 2], have m ade it possible to define the perform ance of asystem, in terms of element error-rate, as a function of the signal-to-noise ratio ju st prior to
the detector. The w ord “ detector ” is used here in a very general sense and the detector might
be a lim iter-discriminator. It is convenient to use a quantity called the “ norm alized signalto-noise ratio ”, R, which is defined as the quotient o f the average of the specific energies of them ark and the space signals, and the noise power per unit bandwidth. F o r systems which use
two equally probable signals o f equal energy, this ratio is equal to the signal-to-noise power
ratio per baud per unit bandw idth, or the ratio of the signal power to the noise power per unit
bandw idth, divided by the num ber of bauds. D irect com parison between receivers, evenwhen working at different speeds is, therefore, possible.
In these studies, it was also found possible to specify the perform ance of a telegraphreceiver by a single param eter. This param eter has been called the “ dem odulation factor ”
and it is the am ount (in db), by which the signal-to-noise ratio (normalized), applied to thereceiver under test, exceeds that applied to an idealized receiver of the same type for the same ele­ment error-rate. F or the purpose of this work, we have to distinguish between coherent andnon-coherent receivers. The coherent receiver has a priori knowledge of the phase of theelementary waveform. The m ark- and space-elements are assumed to be equally probable.

1.1 Coherent reception.

No fading

Assume that x 1 (t) and x 2 (t) are the two signal waveforms, th at t is the unit interval(duration of one element), and that N is the noise power per c/s. Then if:

4 Y j0the element error-rate Pe is given by:pe =/ exp { ^ dz = 2 erfc(y) = | - £ e rfi» .

This R eport, which replaces R eport 105, was adopted unanimously.

Rep. 195

91

In terms of the “ normalized signal-to-noise ratio ” , R, this error-rate can be expressed in thefo rm :
P e = | erfc (ccR)i;- for phase-reversal m odulation ax = 1;
- for frequency-shift keying with two orthogonal signals a2 =- for am plitude keying (on-off signals) too, a3 = §.
F o r large values of R, the com plem entary error function can be well approxim ated by an
exponential c u rv e:

1.2

Non-coherent reception.

No fadingF or non-coherent reception o f a steady signal, the error-rate is o f the form :P e = | e x p { - ccR}
A gain:- for differentially coherent reception [3] of phase-reversal m odulation ax = 1;
- for m atched filter reception and envelope detection [4] of frequency shift keying
a2 = ^ (for narrow -band FSK with shifts of the order (0-8/t), the effect o f correlation
leads to better results);- for am plitude keying, we get approxim ately [4] a3 = i .
1.3

Coherent diversity reception.

Flat fading

It is assumed th at the fading is of Rayleigh type, th at the fadings in different branches areuncorrelated (but th at they are the same for m ark and space signals), that the m ean signal-onenergies o f all branches are equal, and that the fading is so slow, relative to the speed of signalling,th at the signal power may be regarded as constant during any one signal element. The outputsof the diversity branches are assumed to be weighted, according to the signal energy and com ­bined (maximal ratio combination).
F or Rayleigh fading and one receiver, we get the following error-rate:

Pei = f ~ W a R / ( a R + 1)
F or dual diversity:

F o r triple diversity:(a* * » ■ + ! « *+Rep. 195

92

F or quadruple diversity:a R («8 R3 + 7 a27?2 + 7 . 5 ^+ 7_ 5 _ 3 >| _ y (ajR + ])7

F or large values of i?, these results are closely approxim ated by:
P el = l/4 a R ; P c2 = 3Pel2 = 3/(4a/?)2; Pf3 = 1 0 P el8 = 10/(4oc7?)3; Pei = 35

- 35/(4aR)4respectively.
In the definition of the norm alized signal-to-noise ratio R , the average signal energy
and signal power per branch should now be substituted for signal energy and signal power
respectively.
The basic curves, for idealized coherent reception of frequency shift signals in fading(a = i) , are given in Fig. 1 for single, double, triple and quadruple diversity systems.
1.4 Non-coherent reception.

Flat fading

The equations for the error-rate for non-coherent reception, under the circumstances
otherwise specified in § 1.3 (maximum ratio combining), are:Pel = 1/2(1 + a R), Rayleigh fading, one receiver;Pe2 = 1/2(1 + a R )2, D ual diversity;
Pe3 = 1/2(1 + ai?)3, Triple diversity;
Pei = 1/2(1 + a R f , Q uadruple diversity.
The basic curves for this case are given in Fig. 2, again for the reception of frequency
shift signals in fading (a = i).
1.5 Coherent reception.

Independent fading

1.6 Non-coherent reception. Independent fading
If it may be assumed that the m ark and space frequencies are sufficiently widely separated
for the fading in the two branches to be independent, then independent reception in the m ark
and space branches is possible.
If, furtherm ore, the same assumptions are m ade as in §§ 1.3 and 1.4, the resulting error
rates may be derived directly from the above. Then, going from flat fading to independent
fading is equivalent to doubling the order of diversity, while having the pow er in each diversity
branch [6].

2.

Demodulation factor
If the perform ance curve of an actual receiver for coherent reception is of the com ple­m entary error function type, then a constant factor indicates the extent by which a practicalreceiver falls short of the ideal, and it is the same for all types of diversity.
Also, if the perform ance curve of an actual receiver for non-coherent reception is of the
exponential type, the dem odulation factor will be a constant.
Equipm ent for measuring the dem odulation factor of a receiver in the laboratory, undersimulated fading conditions, has been described elsewhere [5]. Alternatively, a m easure of
the dem odulation factor may be obtained by calculation from the perform ance of the receiverunder non-fading conditions, as in the Annex.

93

Rep. 195

In this R eport we have only discussed maxim um -ratio combining. In the literature [7],one can find a com parison o f this type o f diversity with equal-gain, and selection diversity.
The loss for equal-gain combining is apparently of the order of 1 db.
The perform ance of a circuit is usually expressed in term s of character error-rates.
Calculations from the probability functions involved give a simple conversion from an element
error-rate to a character error-rate for various types of telegraph code, thus providing a simple
relationship between the signal-to-noise ratio and the num ber of errors on the printed copy.
The particular case for random arrival of element errors represents a useful limiting condition
which is approached closely when the error rate is low.
Relationships between element and character error-rates are shown in Figs. 3 and 4.
In Fig. 3, curve (1) represents the upper limit of the character error-rate for a synchronous
seven-unit code, when the element errors are m utually independent. It should be noted here,
th at the character error-rate is defined as being the num ber of characters subject to error at
the output of the detector and thus an error in “ letter shift ” or “ figure shift ” is counted
only once and similarly for other errors, such as those occurring in “ carriage return ” or “ line
feed ”. However, if the fading characteristics give rise to groups of errors, then the curveshowing the relationship between element and character error-rates becomes asym ptotic tocurve (2) which was calculated on the assum ption th at the signal level rem ains constantduring a character. F or element error-rates lower than 10-3, the curve (1) is appropriate.
In Fig. 4, the upper limits are shown as follows:- Curve (1): for a five-unit synchronous code: Pc x 5Pc;
- Curve (2): for a seven-unit code: Pc x lP e;- Curve (3): for a five-unit start-stop system with tape printing and allowing for errors due
to loss of synchronism in addition to the simple character-errors P c x YlPe\- Curve (4): for a five-unit start-stop system with page printing, i. e., including an additional
allowance for multiple errors due to carriage return and line-feed failures. Again, as forthe previous curves, errors in “ letter shift ” or “ figure shift ” are only counted once
Pc = 34P e.
A n example is given below to dem onstrate the way in which the curves m ay be used.
It is stressed that this example shows the m ethod employed in m aking one o f the steps in thecalculations necessary to plan circuits for a specified grade o f service, but that the dem odulation
factor of the receiver m ust be know n as a result of measurement.
First, we take the general case for reception of a steady signal.
Let R 0 = the pre-detection signal-to-noise ratio (db);
Rn = the normalized signal-to-noise ratio, corresponding to R (d b );— 10 log10 R ;S= the signalling speed in bauds (elements/sec.);

B = the pre-detection bandw idth (c/s) of the receiver in question;
D — the dem odulation factor of the receiver for the signalling speed specified, in db;
then

R0 = Rn + 10 log10 (SIB) + D(1)

ExampleA coherent receiver, having a pre-detection bandwidth of 1000 c/s, is used for 50 bauds,
5-unit synchronous working, using triple diversity. The m easured dem odulation factor of thereceiver, for this signalling speed and bandw idth, is 10 db. A character error-rate of 10-4 ispermissible; what m ust be the pre-detector signal-to-noise ratio?

Rep. 195

94

F rom Fig. 4, the corresponding element error-rate is 2 x 10~5. From Fig. 1, an ideal
receiver using triple diversity produces an element error-rate of 2 x 10~5 for R n = 16 db.
Using equation (1), we find:
R 0 = R n + 10 log10 (SIB) + D
and inserting the know n values we have
R 0 = 16 - 13 + 10 = 13 db.
This is the required signal-to-noise ratio per branch.
com bining will be 3 R 0 or 18 db.

3.

The signal-to-noise ratio after

Conclusion
Extension of this work, to cover noise other than therm al noise, may result in the need formore param eters to describe fully system perform ance, but it seems clear that:- the perform ance of telegraph circuits should be related to stated character error-rates, andfor the engineering planning of circuits and design of equipm ent it. is preferable to havethese expressed in corresponding element error-rates;- the approach indicated in this R eport form s a useful starting point in the development ofan objective m ethod determining the perform ance o f telegraph systems.

B ib l io g r a p h y

1.
2.

V.A. Theory of optimum noise-immunity. Thesis, Moscow, U.S.S.R. (January, 1947).
H.B. The detectability of fading radiotelegraph signals in noise. Proc. I.E.E., 104B, 130-140(March, 1957).
3. L a w t o n , J.G. Theoretical error-rates of “ differentially coherent ” binary and “ Kineplex ” data trans­mission systems. Proc. IRE, 4i , 333-334 (February, 1959).
4. R e i g e r , S. Error probabilities of binary data transmission systems in the presence of random noise.
Convention Record of the IRE, Point 9, 72-79 (1953).
5. L a w , H.B., L e e , F.J., L o o s e r , R.C. and L e v e t t , F.A.W. An improved fading machine. Proc. I.E.E.,
104B, 117-123 (March, 1957).
6. B a r r o w , B.B. Error probabilities for data transmission over fading radio paths. Thesis Delft, Nether­lands (March, 1962).
7. B r e n n a n , D.G. Linear diversity combining techniques. Proc. IRE, 47, 1075-1102 (June, 1959)
K o t e l n ik o v ,L aw ,ANNEX
In the absence of a fading sim ulator, it is possible to derive an approxim ate value o f theelement error-rate under fading conditions from the results o f tests under steady conditions.
These steady-state tests will give the error-rate as a distribution function g (R), of the norm alized
signal-to-noise ratio R.
If, for coherent reception, g (R) can be expressed in the following form :g ( R ) = ±erf c( bR/ 2) ithen the dem odulation factor is constant, 10 log10 b, independent of the order o f diversity employed.
In practice, this will not generally be the case and then the dem odulation factor will be afunction of both R, and q (the order of diversity). However, by an extension of the w ork in [2], it
can be shown that, in general, the element error-rate with q diversity branches will b e :— 95

Pcg = [ ( q — 1)1 N«]

Rep. 195- l f 00
yQ-1 exp { - y / R } g (y) dy.
JO

F o r large signal-to-noise ratios, or small error-rates, the following approxim ation for thedem odulation factor D q, with q diversity branches, and flat fading, can be found:(Dq)9 = [ 2<? •I*CO/ (2^ — 1)!] J y q~1 g ( y ) d y

M easured distribution functions under steady-state conditions can be expressed in the following
form :g ( R ) = ' Z ak . exp { - bk R}
Then for large values o f R :{DqY = [ 2 ^ . q \ ( q ~ l ) \ l ( 2 q ~ ] ) l ] Z (ak/bk«)
F o r other forms of the function g (R), similar calculations can be performed.
F o r non-coherent reception, the reasoning is completely analogous. Again, the answer is, simple, if the error-rate under steady conditions can be expressed as a single exponential form.
F o r the m ore com plicated error perform ance given by a sum o f exponentials, as above, thedem odulation factor is given in this case by:(D q)q = X (akJ2) (2 b t f

n=A 3\

Rep. 195

Coherent reception

Non-coherent reception

2\

vo
o\

[ \
\ \
\ \
\ \

y\ y\
\
\
\

\
\
\

\
■

-5

0

10

20

30

40

db

0

10

20

30

40

50

60.db

Normalized signal-to-noise ratio per diversity branch (db)R„ = 10 log R(n = number of diversity branches)

Normalized signal-to-noise ratio per diversity branch (db)R„ = 10 log R(n — number of diversity branches)

F igure 1

F igure 2

Character error-rate,

Character error-rate,

F igure 3

F igure 4

Curve 1: 5-unit synchronous code,

Rep. 195

2: 7-unit synchronous code,
3: 5-unit start-stop, tape printing,
4: 5-unit start-stop, page printing.

Rep. 196

— 98 —REPORT 196 *SOME ASPECTS OF THE APPLICATION OF COMMUNICATIONTHEORY(Question 133(111))(Los Angeles, 1959 - Geneva, 1963)
Question 133(111), § 1, has as its subject the relation between permissible delay and residual
uncertainty and its dependence on bandw idth utilization.
The permissible delay is related to the length of the code (we will suppose that all codecharacters have an equal num ber o f elements). If the length of the code character is n elements,
the delay is at least the time taken by 2n code elements. We shall characterize the behaviour ofa channel by its error probability instead of by the residual uncertainty. The bandw idth utilization
will be determined by the ratio between the num ber of check digits and the num ber of inform ation
digits, or by the difference between the inform ation rate and the capacity of a channel. (Theminimum ratio of check digits to inform ation digits, required for efficient use of a com munication
channel, is determined as a function of the capacity.)
F or any noisy channel w ithout memory having only a finite num ber of received signals, theerror in transm itting inform ation at a rate H < C and using uniform ly good codes of length n is•bounded by an expression F. exp { — Bn (C — H ) 2}, where F and B are constants depending
upon the channel parameters, but n o t upon H or n. This has been shown by Feinstein (1955).
H is the inform ation rate and C is the channel capacity. The relation therefore is logarithmic
and the coefficient depends on the square of the difference between the rate at. which inform ationis sent over a channel and the maximum possible rate.
Shannon (1957), has given m ore specific results expressed in the distribution function o f thetransinform ation p (x). He derives the following theorem : there exists a block code with M
messages and a decoding system such, that if these messages are used with equal probability, theprobability of error is bounded by:Pe ^ p ( R + 0) + exp { — n 0}
where 0 may be any given positive constant and R = (l/n) log M. M oreover, the optim al detec­tion system gives a probability of error Pt, satisfying the inequalities:y (R -

log 2) < P , < p (R -log 2)In 1959, the same author gave m ore accurate error bounds for channels with additive G aussian
noise, and so did Zetterberg (1961).
In older studies of Rice (1950), curves relating the probability of error to the num ber of digits
in a code were already given for some types of random codes, n ot necessarily uniform ly good.
Siforov (1956), has calculated the minimum distance of the code characters (the num ber o f elements
in which the code characters m ust differ), as a function of the element error-rate and the desired
probability of error.
F urther results for channels with memory have been obtained by Feinstein, W olfowitz andBlackwell.
From a practical point of view, all these studies have in com m on th at they give proofs o fexistence for certain codes. The construction of these codes, however, still seems to be out o f thereach of even m odern calculating machines. A fter this first problem has been solved, the maintechnical difficulty will concern decoding. W ozencraft (1957), has found m ore efficient decoding
procedures, whereby the complexity of this operation goes up slower th an the square of the length* 'This Report, which replaces Report 110, was adopted unanimously.

— 99 —

Rep. 195of the code, instead of growing exponentially with it. (H e and Reiffer have developed the “ seco ”
procedure further, and treated it in a book). Even so, the application o f these theoretical m ethods
will be an economic problem, where the position may change as the cost of channel capacity goesup, the interest in data transm ission increases and the cost of electronic equipm ent goes down
(Fano, 1958).
Block codes of different lengths have been studied extensively. A survey is given in P eterson’sbook. Though it is not possible to reach inform ation rates near channel capacity in this way,some systems, based on these codes, have been developed to a stage where their use should beseriously considered for digital data transm ission systems. It is n ot yet clear which com binationof error-detection or correction, use of null-zone thresholds, and A R Q will prove to be the bestcompromise. The development should be followed to see w hether a substantial gain w ith respect
to methods in use at present and their requirem ents, can be reached.
F rom a theoretical point of view, the presence of a return channel does n ot dim inish the p ro ­bability of error, unless the noise in the go and the return channel are correlated. The retu rn
channel, however, simplifies the coding considerably. Theoretical results for decision-feedback
systems so far cover only the simplest m athem atically tractable models, with additive G aussian
noise and possibly Rayleigh fading.
Time-varying channels, with delay spread, have been studied by Price, G reen, Siforov, K ailath,and Turin. The R ake system, adapted to small values of the product of m ultipath duration andfading rate, has been described in detail.

B ibliography

1. Shannon , C.E. Certain results in coding theory for noisy channels. Information and Control, 1, 6-25
(1957).
2. F einstein , A. Error bounds in noisy channels without memory. IR E Transactions, Professional Groupon Information Theory (September, 1955).
3. R ice, S.O. Communication in the presence of noise. B.S.T.J., 29, 60-93 (1950).
4. Siforov, V.I. Theory of ideal coding for binary transmission. Radiotechnika i Electronika, Moscow,
1, 407-417 (1956).
5. F einstein, A. Foundation o f Information Theory, McGraw-Hill, 137 (1958).
6. W olfowitz, D. The coding of messages subject to chance errors. Illinois Journal o f Mathematics, 1,
591-606 (1957), 2, 137-141, 454-458 (1958).
7. Wozencraft, D. Sequential decoding for reliable communications. IR E National Convention Record,
5, part 2 (1957).
8. F ano , R.M. The challenge of digital communication. IR E Transactions, Professional Group on Infor­
mation Theory, 4, 63-64 (1958).
9. S lepian, D.A. Class of binary signalling alphabets. B.S.T.J. (January, 1956).
10. Wozencraft, J.M. and R eiffen, B. Sequential decoding. Technology Press M.I.T.-Wiley (1961).
11. P eterson, W.W. Error-correcting codes. Technology Press M.I.T.-Wiley (1961).
12. P rice, R. and G reen, P.E. A communication technique for multipath channels. Proc. IRE, 46, 555570 (1958).
13. E lias, P., Swerling , P., G ill , A., P rice, R. and Z adeh , L.A. U.S. Nat. Comm. Report to U.R.S.I.,
Subcomm. VI-1. Jour, o f Res., N.B.S., 64D (November-December, 1960).
14. Siforov, V.I. U.R.S.I. Monograph o f Comm. VI (London, 1960).

— 100 —Rep. 197

REPORT 197 *FACTORS AFFECTING THE QUALITY OF PERFORMANCE
OF COMPLETE SYSTEMS ON THE FIXED SERVICES(Study Programme 3A(III)(Geneva, 1963)
1.

Urgent need for information
The attention o f A dm inistrations is draw n to the urgent need for the inform ation requested
in Study Program m e 3A(III), for several classes of emission. As requested in the Annex toStudy Program m e 3A(III), the establishment of minimum protection ratios for additionalclasses of emission under stable conditions should be given priority. It is realized that noA dm inistration will be able to give all the answers, but partial answers are very welcome.
This inform ation will perm it an improvement in the calculation of the probability of harmfulinterference between assignments and the consideration of the possibility of sharing.
The Study G roup also needs the inform ation to complete Recom m endations 240, 339 and
340 and to bring them up to date **.
The docum ents received allow only a very partial answer to some of the questions pro­
posed.

2.

Number of transposition errors in ARQ systems
In a study of the efficiency factor of a T O R circuit under varying signal-to-noise conditions,a relation was derived between the probability, v, of a correct character being printed and theattendant probability, p , of a transposition being printed [1]. One gets different theoreticallimits for flat fading, uncorrelated fading and selective fading.
. It has now been shown experimentally, that, under norm al traffic conditions the results
are nearly those expected for flat fading, or between those expected for flat fading and uncor­
related fading. U nder unfavourable conditions, the results are m ore characteristic of those
expected for uncorrelated fading.

B ib l io g r a p h y1.

V a n D u u r e n , H.C.A. Error probability and transmission speed on circuits using error detection andautomatic repetition of signals. IR E Transactions on Communication Systems, SC 9, 1, 44 to 48 (1961).

* T h is R e p o rt w as ad o p ted unanim ously.
** T h e I.F .R .B . has given a list of th e classes of em ission in w hich it is m o st d irectly in terested in D o c. 111/63, o f G en ev a, 1962.

— 101 —Rep. 198, 199

REPORT 198 *VOICE-FREQUENCY (CARRIER) TELEGRAPHY ON RADIO CIRCUITS(Study Programme 43A(III))(Geneva, 1963)
Theoretical w ork in Japan (Doc. III/23 of Geneva, 1962), indicates an optim um frequencyshift of 0-8 B (c/s), where B is the num ber of bauds. This would lead to a required minim um
bandw idth (at — 3 db points) of B cycles/sec. L aboratory experiments and m easurem ents on thesynchronous A RQ circuit Frankfurt-O saka, support these conclusions.
It is to be noted, th at this shift is preferably to be used on circuits near M U F and th a t otherwisea larger shift may be beneficial. F o r asynchronous circuits, some theoretical results indicate B to
2 B as best shift [Akima, Voss]. F urther experiments, on circuits of different lengths, in different
directions and in different seasons, are desirable before a definite conclusion can be reached.

REPORT 199 *ARRANGEMENT OF VOICE-FREQUENCY FREQUENCY-SHIFTTELEGRAPH CHANNELS ON RADIO CIRCUITS(Study Programme 43A(III))(Geneva, 1963)
1.

Introduction
Various types o f voice-frequency frequency-shift telegraphy have been tested and put
into service by different A dm inistrations during the past few years.** It seems desirable togive particular attention to those systems which appear to occupy a narrow er bandw idth,
account being taken of propagation conditions and of the type of telegraph m odulation usedover the circuit.
W ith this in view, the attention of A dm inistrations is drawn to systems corresponding to
the following characteristics.

2.

Synchronous telegraphy at 100 bauds with automatic error correction
Various docum ents and oral contributions were presented at the Interim M eeting ofStudy G roup III, Geneva, 1962, showing the possibilities given by the use of this type ofm odulation on systems with a channel spacing of 170 c/s. The central frequencies o f thechannels are given in Table I.
* T h is R e p o rt was a d o p te d unanim ously.
** See D o c. I I I /l and 111/16 of G eneva, 1962.

— 102 —Rep. 199

T ableI

Central frequencies o f voice-frequency frequency-shift telegraph channels
with a channel separation o f 170 c/s and a modulation index o f about 0-8(Frequency deviation: ± 42-5 c/s or ± 40 c/s)

3.

C h an n e l N o.

C en tral frequency
(c/s)

1
2
3
4
5
6
7

425
595
765
935
1105
1275
1445

C h an n el N o.

C en tral frequency
(c/s)

8
9
10
11
12
13
14
15

1615
1785
1955
2125
2295
2465
2635
2805

Start-stop telegraphy at 50 bauds
For several years, various Administrations have had in service, on certain selected circuits,
equipment with a channel spacing of 120 c/s, and central frequencies and frequency deviations
which are in agreement with C.C.I.T.T. Recommendation R.35. The central frequencies ofthese systems are given in. Table II.

T ableII

Central frequencies o f voice-frequency frequency-shift telegraph channels
with a channel separation o f 120 c/s and a modulation index o f about 1-4(Frequency deviation: ± 35 c/s or ± 30 c/s)
C h an n e l N o.

C en tral frequency(c/s)

C h an n e l N o.

C en tral frequency
(c/s)

1
2
3
4
5
6
7
8
9
10

420
540
660
780
900
1020
1140
1260
1380
1500

11
12
13
14
15
16
17
18
19
20

1620
1740
1860
1980
2100
2220
2340
2460
2580
2700

•

B ib l io g r a p h y

1. C.C.I.R. Doc. 111/23 (Japan) of Geneva, 1962.
2. D e V e r d i e r e , S o a v i and B r y a n t : Cables et Transmissions (April, 1951).

— 103 —Rep. 200, 201

REPORT 200 *TELEGRAPH DISTORTION, ERROR-RATE(Geneva, 1963)
1.

The study of the relationship between telegraph distortion and error rate received further
attention, but the results so far achieved are not usable under the conditions of radio propaga­tion. Nevertheless, the statistical distribution o f the distortion could be of value for assessing
the quality of a radiotelegraph circuit w ithout knowing the exact message, e. g., for purposesof investigation.

2.

Statistical measurements of the error-rate, on the connection W arsaw-New Y ork, did n o t
indicate any direct relationship between the error-rate and the received level o f the signal.

REPORT 201 *REMOTE CONTROL SIGNALS FOR FACSIMILE TRANSMISSIONS(Question 232(111))(Geneva, 1963)
W ith the rapidly increasing use of facsimile transm issions for various purposes, using con­tinuous web (chart type) recorders, it has become desirable for the C.C.I.T.T. to set up standards
for the rem ote control signals to be employed for the connection, starting, phasing, speed control,
stopping, etc. of a facsimile transmission.
The W orld M eteorological O rganization has been actively interested in this problem , and, in
collaboration with the C.C.I.T.T., have established a set of control signals for use over the leased
w eather netw ork (see Doc. 111/53 of Geneva, 1962).
The C.C.I.T.T. have also examined the problem , arid have established a Q uestion N o. 7/XIV(Vol. VII, p. 210), in which A dm inistrations have been requested to give their opinion as to theutility of certain types of rem ote control signal for the transm ission o f business docum ents.
The W .M .O . and the C.C.I.T.T. will m ake know n to the C .C.I.R. their proposal for standard­
ization of rem ote control signals, so th at the C .C .I.R . m ight determine if the proposed standards
are acceptable and applicable on radio circuits.

*

This R eport was adopted unanimously.

Rep. 202

— 104 —REPORT 202 *IDENTIFICATION OF THE CARRIER FREQUENCY RELATIVE
TO THE ASSIGNED FREQUENCY OF AN EMISSION(Study Programme 187(111))(Geneva, 1963)
1.

Introduction
The following m ethod of carrier-frequency identification form ed the subject of Doc. 111/60(U.S.A.) of Geneva, 1962, and appears to provide a simple and precise m ethod o f identifying
the carrier frequency of those classes of emission in which the carrier frequency and thecentre o f the assigned frequency band do n ot coincide. Examples of the application of thism ethod are given in the Annex to this Report.

2.

Description of method

2.1 Represent the assigned frequency o f the emission by X.
b e / ,;

Let the carrier frequency o f the emission

2.2 determine the value of the difference ( / — X ), let this value be n c/s;
2.3 divide the value of n by 100 to obtain the code num ber;
2.4 if the value of n is negative (i. e. the carrier frequency lies below the assigned frequency),
follow the value nj 100 by the indicator X ;2.5 if the value o f n is positive (i. e. the carrier frequency lies above the assigned frequency),
precede the value n/100 by the indicator X ;nn \2.6 the results obtained |X or X jqq I give the location of the carrier frequency relative tothe assigned frequency.
ANNEX
E xa m plesE xisting statio nd esignation

WEO86 A3 6840-5 kc/s
WEO86 A 6844-1 kc/s
WEO86 B6845-9 kc/s
WEP266851-8 kc/s
WER33 A 13448 kc/s
WES38 B 18942 kc/s
WMF27 B2 7717-7 kc/s
WMH30 A2 10387-3 kc/s

of

the

a p p l ic a t io n

of

the

m ethod

A ssigned
frequency(kc/s)

C arrie r
frequency(kc/s)

F req u en cy
difference(c/s)

V aluen100

C o d edin d ic a to r

C o d ed statio nd esig n a tio n ^ )

6845
6845
6845
6852-5
13450
18940
7715
10390

6840-56844-16845-96851-813448
18942
7717-710387-3

-4500
- 900
+ 900
- 700
-2000
+2000
+2700
-2700

-4 5
- 9
+ 9
- 7
-2 0
+20
+27
-2 7

45X
9X
X9
IX
2QX
X20
X21
21X

WEO86 45X
WEO86 9X
WEO86 ' X9
IX
WEP26
WER33 20X
WES38 X20
WMF27 X27
WMH30 21X(*) F o r use in th e exchange of o p eratin g in fo rm atio n betw een th e te rm in a ls of a ra d io circu it.

* This Report was adopted unanimously.

— 105 i -Rep. 202, 203

Assigned frequency band

I
Ic

X
//
Assigned frequencynf c is a carrier frequency designated Jqq Xn'f c' is a carrier frequency designated X ^qq

REPORT 203 *MULTIPATH PROPAGATION ON HIGH FREQUENCY RADIO CIRCUITS
Measurements of path-time delay differences and their incidence on typicalradio links(Study Programme 3A(III))(Geneva, 1963)
1.

Measurements on high-frequency radio circuits of the fixed service

1.1 Summary
Some 4000 facsimile pictures, received over a num ber of im portant radiotelegraph circuits
term inating in London, during the period from sunspot minimum to sunspot maximum(1953 to 1957), have been examined, to ascertain the incidence of m ultipath propagation andto measure the dispersion of path-tim e delays. M ultipath conditions were found to obtainfor a considerable proportion of the time throughout the whole period and path-tim e dif­ferences were observed up to 2-5 ms. The measurements were made on pictures received fromNew Y ork (1420 pictures), M elbourne (1600 pictures) and Moscow (350 pictures), together
with a few less-frequently used circuits. The technique of measurem ent is outlined below
and is similar to th at given by Japan in a contribution to the V llth Plenary Assembly.
1.2 M ethod o f measurement
The facsimile transm issions use frequency-modulation so that, in general, the received
picture will be derived from the predom inating path. If, due to fading, signals from different
paths o f unequal length predom inate at different times, a sharp, straight line in the transm itted
picture, at right angles to the line of scan, will appear as a jagged line in the received picture.
* This Report was adopted unanimously.

Rep. 203

— 106 —

By m easuring the width of the ripple of the received line, it is thus possible to determine thedifference in propagation time over the shortest and longest paths th at predom inate from time
to time during the transm ission of the picture.
The spread in path-tim e delay, as seen on the facsimile pictures, was obtained by measuring
the ripple on a line, at right angles to the direction of scan, which could be safely assumed to
be sharp and straight when transm itted. A low-power microscope, having a graticule divided
into squares, was used to measure the ripple. The magnification was adjusted so that one
square represented a tim e difference of 2 ms for the machines m ost generally used. Displace­ments were estimated to the nearest 0-5 ms and, when a num ber of different delays were observ­
ed, only the maximum delay difference was recorded. In some cases, this maximum delay
was not typical of the distortion throughout the picture as a whole.
A check was m ade under controlled conditions, using a fading machine which was adjusted
to produce random fading with known differences in path-tim e delay and with various mediansignal levels on the two paths. The incidence of m ultipath observed in these tests was almost
identical with that obtained by m athem atical analysis.
1.3 Measurement on facsimile pictures
Each picture was examined to determine the m aximum path-tim e delay difference. Since
the values o f delay were approxim ated to the nearest 0-5 ms, the probable distribution of dif­ferences in path-tim e delay between 0 and 2-5 ms was obtained by the usual m ethod ofapportioning the num ber of pictures at each value of delay, other than zero, equally between
the adjacent delay ranges.
The incidence of m ultipath distortion on each picture was assessed according to four
categories, viz: none, rare, frequent, continuous.
F or each m onth, the percentages of pictures received for each range of delay difference
and for each category of incidence were obtained. F or simplicity, these monthly percentages
have been averaged over a complete year, and the results are shown in Fig. 1.
1.4 Discussion o f results
The results show that, for each of the four years 1953 to 1957, frequent or continuous
m ultipath was in evidence on between 40 and 50 % of the pictures analyzed. Approximately
half the pictures affected by m ultipath showed path-tim e delay difference of 1 ms or more, andnearly 30% had delay differences of 1-5 ms or more.
M ultipath effects such as these are not particularly troublesom e in facsimile transmission.
Facsimile pictures have been used merely as a convenient means of obtaining data o n incidence
and delay difference over a long period on typical high-frequency fixed-service radio links.
The effect o f such m ultipath propagation could be m ore serious on telegraphy and data
circuits, particularly where the path-tim e delay difference is appreciable in relation to theduration of the telegraph element. F o r example, a path-tim e delay difference of 2 ms would
have an adverse effect on the perform ance of a telegraih circuit w orking at 200 bauds, since thedelay difference is equal to 40 % of the duration of the signalling element. Circuits w orking
at lower m odulation rates would be less affected by m ultipath propagation, since the path-tim edelay difference would be smaller in relation to the duration o f the telegraph element. F or
example, a 2 ms delay difference would equal only 20% of the element duration at 100 bauds.

2.

Measurement on meteorological broadcast services
Section 1 of this R eport shows the incidence of m ultipath propagation and path-tim e delaydifferences observed on typical point-to-point high-frequency radio circuits. M ore severem ultipath effects may, however, be experienced when frequencies below optim um have to be
used. Such circumstances often arise, for example, in high-frequency m eteorological bro ad ­cast services, and an analysis has been made of meteorological charts received in th e U nited
Kingdom by facsimile transm issions from W ashington, D .C ., and from Japan.

Rep. 203

— 107 —

Some 1600 charts received during the period June to September, 1961, have been analyzed.
O f these, 1000 were received from W ashington and 600 from Japan. The m ethod o f neasuring
the path-tim e delay differences was similar to that described in § 1 o f this Report. The results
are tabulated below and are shown graphically in Fig. 2.

Percentage of charts for each circuit 'Multipath time delay difference(ms)0

Washington, D.C. to United Kingdom(6000 km)Japan to United Kingdom(9600 km)

10
20
28
21
10
6
2
2
1

0
5
9
10
30
26
11
6
2

- /2
l/2- l1 -ll/2
1 /2 -2
2 -2 i/2
2i/2-3
3 -31/2
3 /2 -4
4 - 41/2

<5
o E
3
CU
.2
-!3 w
<D
O3

o

A B C DA B C D

A

B C

D

A B C

D

Oct. 53 - Oct. 54 Oct. 54 - Oct. 55 Oct. 55 - Oct. 56 Oct. 56 - Oct. 57
560 pictures
800 pictures
1080 pictures
1500 pictures(a)

Incidence o f multipath
A - noneB - rare,C - frequent,
D - continuous.

R
F71 rn
2*
2 3a

0

1

2

3

R
*
2 2 F30 1 2 3

n
*
0

rn
/

rr\

r?

f
* f f 7\ ■
1

2

F FI
FF F
F FF F

3

0

1

2

3

Oct. 53 - Oct. 54 Oct. 54 - Oct. 55 Oct. 55 - Oct. 56 Oct. 56 - Oct. 57(b)Range o f multipath delay-differences (ms)F igure 1

Multipath propagation on HF radio circuits o f the fixed serviceRep. 203

— 108 —

30

25

20

15

10

0,5

1

1, 5

2

2, 5

3

3, 5

4, 5

Multipath time delay-difference (m s)F ig u r e 2

M ultipath propagation on circuits o f the m eteorological broadcast service

Path, Washington, D.C. to United Kingdom,
Path, Japan to United Kingdom.

— 109 —STUDY GROUP III(Fixed service systems)
Terms o f reference:1.

To study questions relating to complete systems for the fixed and allied services and term inal
equipm ent associated therewith (excluding radio-relay systems). Systems using the so-called
ionospheric-scatter mode of propagation, even when working on frequencies above 30 Mc/s,
are included.

2.

To study the practical application o f com m unication theory.
Chairman :Vice-Chairman :D r. H. C. A. v a n D u u r e n (Netherlands)
D r. S. N a m b a (Japan)

IN T R O D U C T IO N BY T H E C H A IR M A N , S T U D Y G R O U P III

1.

The scope o f the w ork of Study G roup III covers the study of world-wide radiocom m unicationsin the fixed services, for which the H F (decametric) band is mainly used. The study aims at
recommending m ethods of two-way radiocom m unication by means of telephony, telegraphy
and facsimile. T he application of such methods will enable A dm inistrations to interconnect
their land line netw ork via radio to the world-wide com m unication network. The Recom ­m endations of the Study G roup contain the best solutions agreed upon internationally for
obtaining commercial quality.

2.

Recom m endations 100, 335, 336, 338, 348 and 349 contain inform ation to carry telephonyover radio by the application of single-sideband and independent-sideband systems (inform a­tion concerning: system bandw idth and frequency tolerances, channel arrangem ents, privacy
equipm ent and echo suppression).

3.

Recom mendations 106, 248, 338, 342, 345 346, 347, and 349 deal with com m unication bymeans of telegraphy (inform ation concerning: system bandw idth and frequency tolerances,
operation on F SK and twinplex channel and on ARQ-systems, classification of channels anddefinitions on the telegraphic distortion).

4.

Recom m endations 343 and 344 deal with facsimile transm issions of meteorological charts andthe transm ission of phototelegraphy on radio links, connected to the landline network.

5.

O peration on radio links is ham pered by fading and noise under unfavourable conditions ofradio propagation, or by interference from unw anted emissions. The study of the difficulties
encountered and o f measures to increase the time of operational quality for the several systems,
is covered mainly by Question 3(111) and Study Program m e 3A(III). This study continues,
and the fixing of protection ratios against unw anted interfering emissions, is in progress incooperation with the I.F.R.B. (R eport 197). Some inform ation is available in Recom ­m endations 240, 339 and 340. A n international W orking Party has been set up to w ork bycorrespondence, which will advise the C.C.I.R. on definitions and procedures to obtain abetter use of the radio-frequency spectrum (Resolution 1). Research work on propagation
effects has been recorded in Reports 109, 111, 198 and 203.

— 110 —6. The use of the radio path will be im proved by the application of directional antennae.
Recom m endation 341 gives definitions .on transmission gain and loss, and R eport 112 shows
the application of those concepts. The study on the directivity o f antennae at great distances
has not yet been finished. Some data are available in R ecom m endation 162 and R eport 106.
7.

Com m unication theory gives the basis for a better understanding of system performance.
Therefore developments in com m unication theory may lead to the im provem ent of systems.
Study Program m e 133A(III) deals with com m unication theory. R eport 196 shows some
applications. A practical application discussed by the Study G roup, is the ARQ-system,
described in Recom m endation 342. The Study G roup uses the binary inform ation unit (bit)as a standard for com paring the perform ance o f telegraph systems (Recom m endation 166),and the normalized signal-to-noise ratio for com paring radiotelegraph channels (R eport 195).

8.

Cooperation with the C.C.I.T.T. resulted in Recom m endation 335 (telephony), Recom­
mendations 342 and 345 (telegraphy) and Recom m endation 344 (phototelegraphy). This
cooperation is continued by studies laid down in Study Program m es 186(111) (efficiency
factor) and 3B(III) (autom atic phasing).

— I ll —Res. 1R E SO L U T IO N 1 *OPTIMUM USE THE RADIO-FREQUENCY SPECTRUM
The C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) that the available inform ation on the w anted-to-unwanted signal protection ratios and theoperating sensitivities of receiving systems needs further refinement for each of the services,to perm it the m ost efficient planning of the use of the radio-frequency spectrum ;(b) th at a larger num ber of simultaneous users of the spectrum m ust be accom m odated in the
future;(c) th at the accom m odation of these additional users, w ithout serious deterioration o f thoseservices in use at present, will require careful consideration of all the many technical factors
involved in the sim ultaneous operation of potentially interfering systems;
U N A N IM O U SL Y D EC ID ES

1.

th at an International G roup of Experts of the C .C.I.R.**, which would be representative of
the Study G roups interested in this problem , shall be established, to prepare a report on defini­tions and procedures which would, when m ade available to the various Study G roups o f the
C.C.I.R., be expected to lead to improved inform ation on:- the required signal-to-interference protection ratios;- the minimum field strengths required for various classes of emission;
which would perm it the optim um use of the radio-frequency spectrum by the,m axim um
num ber of sim ultaneous users;2.

th at the co-ordination of the w ork of the G roup should be undertaken by Study G roup III;

3.

that, as far as possible, the w ork of the G roup should be conducted by correspondence.

Note. - The D irector, C.C.I.R. is invited to bring this Resolution to the attention o f the U .R .S.I.
for inform ation.

* T h is R esolution relates to R ecom m endations 2 an d 3 of the A dm inistrativ e R a d io C onference, G en ev a, 1959.
** T h e follow ing A d m in istratio n s: U .S .A ., (D r. K .A . N o r t o n , C h airm an ), F ran ce, Ja p a n , N eth erlan d s, F .R . of G erm an y ,U n ited K in g dom , th e U .S .S .R . an d th e l.F .R .B . have already indicated th e ir w illingness to form p a rt of th is G ro u p .

— 112 —Q .3

Q U E S T IO N 3(111)

REVISION OF ATLANTIC CITY RECOMMENDATION No. 4
The C.C.I.R.,(Stockholm, 1948)

C O N S ID E R IN G

that to give maximum effectiveness to the studies requested by the International Radio
Conference of A tlantic City (1947), in its Recom m endation N o. 4 to the C.C.I.R., it is expedient,
to rearrange this Recom m endation and incorporate the relevant Bucharest questions;U N A N IM O U S L Y D E C ID E S !

A.

that the text of Atlantic City Recom m endation No. 4 can be rearranged and extended asfollow s:(a) consideration of the desirable conditions to be fulfilled by the com plete systems employedby the different services to determine the required technical perform ance of the equipm ent(including the station term inal apparatus and the antennae) and of the measuring appa­
ratus used, to ascertain whether the equipm ent satisfies the Recom m endations of the
C .C .I.R .;(b) consideration of the field-strength intensity, necessary for the reception of different classesof emission in the different services;(c) consideration of the effect of frequency stability of transm itters on the minimum practic­
able spacing between stations;(d) consideration of the minimum practicable spacing between the frequencies of stations
operating in adjacent channels, for different classes of emission in the different services;B. that the above questions * be studied simultaneously and with the same urgency;
C. that Questions 1, 4, 11, 14, 16 and 17 of the C.C.I.R. o f Bucharest be removed from the listof questions to be studied by the C .C .I.R .;A N D U N A N IM O U SL Y D E C ID E S !

to carry on permanently, the study of the above-mentioned questions and to publish its Recom ­m endations and possible revisions as soon as practicable.

* Q uestions 1, 2 an d 3(111).

S.P. 3A

— 113 —S T U D Y P R O G R A M M E 3A (III) *FACTORS AFFECTING THE QUALITY OF PERFORMANCE OF COMPLETE
SYSTEMS OF THE FIXED SERVICES
Signal-to-noise and signal-to-interference protection ratios
for fading signals, bandwidth and adjacent channel spacing
The C .C.I.R.,(Los Angeles, 1959)

C O N S ID E R IN G

fa ) that Question 3(111) establishes a perm anent study o f questions relating to the desired condi­
tions of perform ance to be fulfilled by the fixed services;(b) th at the conditions for satisfactory perform ance of a system m ust take account of the needto receive signals propagated via the ionosphere, which are subject to fading and m ultipath
effects and are accom panied by radio noise and interference;(c) th at studies requiring signal-to-noise and signal-to-interference protection ratios are closely
related, and th a t determ ination of necessary adjacent channel spacings requires, in addition,
consideration o f frequency stability and bandw idth o f the systems;(d) th at there are a num ber of different techniques and systems in use in the radiotelegraph andradiotelephone services and, while it is essential to consider the m ost advanced state o f theradio art, it is also necessary to give special study to conventional systems, either affecting
integration of land-line and radio services, or of concern to the I.F .R .B .;unanimously decides to carry out the following studies:

1.

Classes of service
The studies concern the following classes of service in regular use in the fixed services,
but should also give due regard to new techniques and systems, including those under develop­
ment, for application to the fixed services:

1.1 Radiotelephony
1.1.1 Types of emission: A3, A3 A, A3B, F3 **;1.2 Radiotelegraphy
1.2.1 Types of emission: A l, A2, A7, F I ;1.2.2 Telegraph speeds:- A l, A2, hand speed 8 and 24 bauds, machine speed 50 and 120 bauds;- A7, multichannel V F telegraphy, 50 to 200 bauds per channel;- F I, 50 to 600 bauds;
1.2.3 Codes:- 5-unit start-stop;- 5-unit synchronous;- synchronous error-detecting and correcting systems using two-condition signalling
codes other than the International A lphabet N o. 2;- other systems using m ore than two signalling conditions;
1.3 Facsimile, phototelegraphy; Hellschreiber
1.3.1 Types of emission: A4, F4.
* T h is S tudy P rogram m e, w hich replaces S tudy P rogram m es 44, 45, 49 an d 50 an d Q u estio n s 82, 129 a n d 131, was" p rev io u sly
d esig n ated S tudy P ro g ram m e 128(111).
** F3 above 30 M c/s only, w ith reference to io nospheric-scatter applicatio n s.

S.P. 3A
2.

— 114 —

Minimum conditions required for satisfactory service

2.1 Acceptable criteria and values for:2.1.1 intelligibility over radiotelephone circuits *;2.1.2 error rate for characters and elements over radiotelegraph circuits {efficiency factor for
A RQ circuits);
2.1.3 legibility of copy over facsimile (phototelegraphy) and Hellschreiber circuits;- w hat is the maximum duration and percentage o f the time during which perform ance
inferior to the standard values can be tolerated;
2.2 Performance o f the system as a function of:- signal-to-noise and signal-to-interference (co-channel) ratios;- required signal-to-noise and signal-to-interference (co-channel) protection ratios for theacceptable standard values of intelligibility, error rate (efficiency factor on A RQ circuits),or legibility, for the various services **, considering:
2.2.1 Signal fading, taking account not only of the am plitude distribution, but also of the
autocorrelation function and the distribution of duration o f the fades;
2.2.2 Diversity (space, frequency, or time) techniques:- noise reducers,- coding including the use of error-correcting; codes or A RQ ***,
- use of m ore than two signalling conditions, and- optim um m odulation and detection techniques ****,
2.2.3 M ultipath effects;
2.2.4 Interference effects of radio noise of various types, such as atmospheric, impulsive, orG aussian noise, as described by the wave form and am plitude distribution of theinstantaneous values of the noise,- the resulting interference effects on actual reception, taking account of the m ethodof detection, and of filtering prior to and following detection;
2.2.5 Interference effects of co-channel signals representing the various classes of emission,
taking account of the spectral and statistical (fading) characteristics of the interfering
signal;2.2.6 M onthly m ean signal-to-noise ratios and signal-to-interference ratios, required for cir­
cuits of various lengths and directions, for the acceptable standard values of circuit
perform ance (§2.1), to be m et during the specified percentage of the time, taking into
account,- the distribution within an hour of the mean values o f the short-term (fading) distri­butions of signals and noise,- the distribution, within a m onth or season, for a given hour of the hourly m ean valuesof the signal strengths and atmospheric noise levels (R eport 322) *****,* F o r the various grades - ju st usable, o p erato r to o p erato r (o rd er w ire);- m arginally com m ercial;—good com m ercial.
** F o r rad io telep h o n e services, th e signal-to-noise ratio req u ired in th e a u d io b a n d m u st be specified, an d from th is th e signalto-noise ra tio req u ired in the radio-frequency b a n d is established.
*** It w ould b e useful to com pare the system s using th e v ario u s teleg rap h codes, in c lu d in g th o se of § 1.2.3, in te rm s of u n d e ­tected o r uncorrected e rro r rate fo r a given pow er an d signallin g speed, in w ords p er m in u te, an d o p e ra tin g u n d e r th e sam e co n ­ditio n s. A 5-un it start-sto p system m ay also be used as th e reference system b y reg ard in g each m u tila te d ch a ra cte r as an e rro r
only. I t is p rovisionally suggested th a t th e ra tio of erro r rates sh o u ld be expressed fo r tw o c ircu it co n d itio n s only, n am ely , w hen th esystem u n d er te st is subjected to a n average of one undetected o r u n co rrec ted e rro r p er 1000 ch a ra cte rs, an d p er 10 000 ch a ra cte rs.
**** A special study is needed com p arin g th e different system s u sed fo r voice-frequency te leg rap h y o n ra d io circu its; th is is d ea lt
w ith in S tudy P ro g ram m e 43A (III).
***** T he m o nthly m ean values of atm o sp h eric noise for various tim e blocks, an d in fo rm atio n o n th e d istrib u tio n o f values w ithinth e m o n th , is given in R e p o rt 322; w ith regard to m o nthly m ean values of sig n al stren g th , an d d is trib u tio n of h o u rly values w ithinth e m o n th , u n til such tim e as C .C .I.R . ad o p ts in form ation on th is subject, o th e r sta n d a rd references m ay be used, su ch as U .S.
N a tio n a l B ureau of S tan d a rd s C irc u lar N o. 462.

A N NEX
M in im u m

p r o t e c t io n

r a t io s

andfrequ en cys e p a r a t io n

sta blec o n d it io n s

In te rfe rin g signal

W anted signal
Al
100 bau d s
T ype of service

under

1
db

2

3
kc/s

FI
2 D = 400 c/s

4

1
db

2

3
kc/s

4

1
db

2

A3

A 3A

F4
3
kc/s

4

1
db

2

3
kc/s

4

1
db

2

B ro ad c ast
3

kc/s

4

1
db

2

3

4

kc/s

24 bauds auralAl

1

50 bauds(printer)

50 bauds(printer)
FI

'

115 —

120 bauds(recorder)

120 bauds(recorder)
200 bauds(printer ARQ)

-F4phototelegraphy

A3A

SSB

A3

DSB
(commercial)
S.P. 3A

N ote. - C olum n 1 gives th e lim iting values in db of signal-to-interference ra tio , w hen th e o ccupied b an d of th e interfering em ission eith er falls entirely w ithin th e p assb an d of th e receiver,o r covers it com pletely. C olum ns nu m b ered 2, 3 an d 4 indicate th e frequency sep aratio n necessary betw een a w anted an d an in terferin g sig n al w hen th e la tte r is 0, 6 o r 30 d b hig h er thanth e w anted signal.

S.P. 3A, 3B— 116 —

this study is intended to lead to revisions or replacement of Recom mendations 240,
339 and 340.
2.3 M inimum bandw idth required for satisfactory transm ission and reception of the intelligence,in a complete system (this is not the question of “ bandw idth necessarily occupied ”, involving
the capability of the transm itting system to avoid radiation outside the band needed for com­m unication, which is included in Study Program m e 181(1)).
3.

Determination of adjacent channel signal-to-interference protection ratios, and frequency
separations between various classes of service, considering

3.1 the use of effective receiving band-pass filters no wider than necessary for satisfactory reception(§ 2.3 above, and Recom m endations 237, 330 and 332);
3.2 the bandw idth occupied by the interfering transm ission;
3.3 the frequency tolerance and stability of the w anted and unw anted signals;
3.4 the studies of § 2.2 above relating to co-channel signal-to-interference protection ratios.
Note. - The results of this study should be presented in the form indicated in the Annex.
results are intended to lead to revision of Recom m endation 240.

TheS T U D Y P R O G R A M M E 3B(III)RADIOTELEGRAPH CIRCUITS USED IN AUTOMATIC
SWITCHED-NETWORKS
The C .C .I.R.,(Geneva, 1963)

C O N S ID E R IN G

( a) that a high value of the efficiency factor is required for radiotelegraph circuits used in autom aticsw itched-networks;(b) that, on such circuits, the duration of possible interruptions should be kept to a m inim um ;( c) that it is desirable, when A RQ is used on such circuits, to use a phasing procedure th at restores
correct phase as soon as possible;
u n a n im o u s l yd e c id e sthat the following studies should be carried out:1.

the determ ination o f useful out-of-phase criteria;

2.

rearrangem ent of the ARQ -procedure to give m ore rapid phasing;3.

the establishment of a procedure for phasing, in which the sequence of phasing is fixed forboth the m aster and slave stations;4.

the development of a suitable indicator for the efficiency factor * of a radiotelegraph circuit.

See S tudy P ro g ram m e 186(111).

— 117 —Q. 43, S.P. 43A

QUESTION 43(111)

VOICE-FREQUENCY TELEGRAPHY ON RADIO CIRCUITS(Geneva, 1951)
The V lth Plenary Assembly of the C.C.I.T., Brussels (M ay, 1948),s u b m i t t e d the following question for study by the C .C .I.R .:w hat are the conditions which should be imposed on V F telegraph plant, employing double­
current technique used on m odulated radio transm ission channels?

Note. - To be studied in collaboration with C.C.I.T.T. Study G roup IX.

ST U D Y P R O G R A M M E 43A(III) *VOICE-FREQUENCY (CARRIER) TELEGRAPHY ON RADIO CIRCUITSThe C.C.I.R.,(Geneva, 1951 - London, 1953 - Los Angeles, 1959)

C O N S ID E R IN G(a) th at different m ethods are now in use for voice-frequency telegraphy on radio circuits operating
below 30 Mc/s subject to fading, noise and interference,- either using equipm ent normally designed for land-line working and suitably adapted for
ra d io ;- or using equipm ent especially designed for radio w orking (see for example Docs. 29 and195 of Geneva, 1951; Docs. 5, 205 and 273 of London, 1953; and Doc. 422 o f W arsaw,
1956, M A D FA S system);(b) th at studies carried out so far show, that it is impossible to com pare transm ission systems inwhich marking and spacing are obtained by the two-tone m ethod and by the m ethod of
frequency-shift keying of a single voice-frequency oscillator, w ithout taking into account all
the factors of the equipm ent (see m ore particularly Doc. 273 of London, 1953);(c) th at the study of Question 43(111) is to be continued, in conjunction with the C.C.I.T.T., toobtain, if possible, unification of at least some of the com ponent elements of voice-frequency
equipm ent used on wire and radio;(d) th at experience in reception of voice-frequency telegraphy over radio circuits has shown theim portance of correct design of the limiters, the filters and the diversity com bining circuits;
and that, from these considerations and the special conditions for com bined voice-frequency
telegraphy channels employing diversity operation, it appears th at frequency-m odulated voicefrequency telegraphy equipments for use on radio circuits, may differ substantially from voicefrequency land-line equipm ent; they may, therefore, have to be designed and constructedwith their special purpose in m ind;u n a n im o u s l yd e c id e sthat the following studies should be carried out:

com parisons of the different systems used to transm it and receive voice-frequency telegraphy
on radio circuits subject to the effects of fading, noise and interference, with a view tostandardizing their characteristics, taking into account the following techniques and factors:* This Study Programme, which replaces Study Programme 46, was previously designated Study Programme 129(111).

S.P. 43A, Q. 74, 81— 118 —- frequency-shift keying of one voice-frequency oscillator;- transm itting m ark and space by the two-tone m eth o d ;- other m odulation systems, e. g. phase m odulation;- reception by discriminator or separate filters;
frequency shift (c/s)- influence of m odulation index = —j------- ;telegraph speed (bauds)
on the error rate, and channel spacing.

Q U E S T IO N 74(111) *ARRANGEMENT OF CHANNELS IN MULTI-CHANNELTELEGRAPH SYSTEMS FOR LONG-RANGE RADIO CIRCUITSOPERATING ON FREQUENCIES BELOW ABOUT 30 Mc/s
The C.C.I.R.,(London, 1953)

C O N S ID E R IN G

( a) th at lack of uniform ity in the arrangem ent and designation o f the -channels in multi-channel
telegraph systems, for long-range radio circuits operating a t frequencies below about 30 Mc/s,
may give rise to certain difficulties when one transm itting station has to work with m ore than
one receiving station;(b) that m any such systems are in use, besides the multi-channel voice-frequency telegraph systems
referred to in Question 43(111);
u n a n im o u s l yd e c id e sthat the following question should be studied:what is the best way of arranging and designating the channels in multi-channel telegraphsystems-for long-range radio circuits, operating a t frequencies below about 30 M c/s?

Q U E ST IO N 81 (III) **DIRECTIVITY OF ANTENNAE AT GREAT DISTANCESThe C .C .I.R.,
d e c id e s(Stockholm, 1948 - Geneva, 1951 - L ondon, 1953)
to study the following question:

experimental study, by A dm inistrations and various organizations, of the directivity ofantennae realized at great distances (taking full advantage o f existing transmissions), by any
suitable m ethod, for example, by use of mechanically or electrically steered antennae.

* This Question replaces Question 46.
** This Question replaces Question 48.

— 119 —S.P. 81A

ST U D Y P R O G R A M M E 81A(III) *IMPROVEMENT OBTAINABLE FROM THE USE OF DIRECTIONAL ANTENNAE
The C .C.I.R.,(London, 1953 - Warsaw, 1956 - Los Angeles, 1959)

C O N S ID E R IN G(a) th at Study Program m e 3A(III) requires knowledge of the improvement in the signal-tointerference ratio that can be obtained by the use of directional antennae on long-distancecircuits;(b) th at the Annex to Recom m endation 162 shows median value of discrimination in the formof gains in various arcs, relative to the optim um gain for a half-wave dipole * * at the sameheight and on the correct azimuth, when the wanted and unw anted emissions are in therange 3000-10 000 km ;(c) th at it is also im portant to know the discrimination given by the antenna, when the w anted
station or the interfering station, or both, are at much shorter range;(d) th at it appears practicable to obtain some reduction of interference by using a null m ethod
at the receiver;1.

unanimously decides that the following studies should be carried out:
determ ination of the signal power gain in the m ain lobe provided by practical directional
antennae used under actual propagation conditions, relative to a half-wave horizontal dipole * *at the height of the centre of the directional antenna; the m edian value and cumulative
distribution with time of the values of gain during short periods (as, for example, less thanan hour), should be observed; observing periods should be suitably distributed and the data
studied on a statistical basis, so as to show dependence of results on time of day and season
for norm al propagation conditions, and the effect of especially critical propagation conditions
such as encountered near time of sunrise and sunset, and at times of failure of the operating
frequency near the M U F, and at times of ionospheric disturbances;2.

determ ination of the signal power gain in directions outside the main lobe and/or values of
discrimination provided by the antenna between the wanted and interfering signals. The data
should include the variations with time, referred to in § 1 above, and should specify directionsor the appropriate arcs shown in Fig. 1 of Recom m endation 162;

3.

the effects of the antenna height in increasing the num ber of hours of useful transm ission andin the reduction of interference;4.

the usefulness of a null method of minimizing the interference. The data required to evaluate
the usefulness might consist of:
4.1 logs of commercial receiving stations, showing outages due solely to interference and therelative azim uth bearing of interfering stations,
4.2 experimental data on the use of directional antenna systems and antennae with adjustabledirections of null, under conditions where interference is experienced.

* T h is S tudy P rogram m e, w hich replaces Study P rogram m e 85, w as prev io u sly designated Study P ro g ram m e 130(111).
** T h e m ed ian values of th e gain can also be expressed relative to the iso tro p ic an ten n a.

— 120 —S.P. 81B

S T U D Y P R O G R A M M E 81B(III) *DIRECTIVITY OF ANTENNAE FOR FIXED SERVICES USINGIONOSPHERIC-SCATTER PROPAGATIONThe C .C .I.R.,(Los Angeles, 1959)

C O N S ID E R IN G(a) th at systems are at present in service using ionospheric-scatter propagation, at frequencies
above 30 M c/s and that extension of use of this m ode of propagation may be expected in theinternational fixed services;t(b) th at it is desirable to establish the preferred characteristics of such systems needed to facilitate
their international connection, and that it is particularly im portant to have similar or matcheddirectivity of the antennae at opposite term inals of the circuit;(c) th a t antenna directivity, including the characteristics of radiation pattern, gain, beamwidthand direction of the m ain lobe or lobes, significantly affects transm ission loss, and the possi­
bility o f occurrence of m ultipath propagation and interference to and from other services;u n a n im o u s l yd e c id e sthat the following studies should be carried out:

studies of the desirable characteristics of the directivity of transm itting and receiving antennae
for international fixed services, using ionospheric-scatter propagation above 30 Mc/s, including
gain, beamwidth and direction of the m ain lobe or lobes, and tolerances for the radiation
pattern outside the m ain lobe, taking into account:- dependence on propagation characteristics of the scattering medium, including dependence
on scattering angle, size and inhomogeneity of the scattering region;- effects of meteoric ionization, and the techniques of beam slewing and beam splitting, andhow these may depend on season and time of day;- operating frequency;- diversity;- polarization;- m ultipath propagation, in relation to the m odulation technique used;- interference to and from other services.

* This Study Programme was previsouly designated Study Programme 131(111).

Q. 95, 132— 121 —QUESTION 95(111)

TRANSMISSION OF HALF-TONE PICTURES OVER RADIO CIRCUITSThe C.C.I.R.,(London, 1953)

C O N S ID E R IN G

that, in the transm ission of half-tone pictures over radio circuits, direct frequency-m odulationo f the radio carrier by the picture m odulation frequencies would result in a greater signalto-noise ratio than if the m ethod of sub-carrier frequency-m odulation were u se d ;u n a n i m o u s l y d e c i d e s that the following question should be studied:w hat are the desirable characteristics for a system transm itting half-tone pictures over radio
circuits, in which direct frequency-m odulation of the radio-frequency carrier is used ?

Q U E ST IO N 132(111)RADIO-RELAY SYSTEMS EMPLOYING IONOSPHERIC-SCATTERPROPAGATIONThe C.C.I.R.,(W arsaw, 1956)

C O N S ID E R IN G(a) th at experiments have already shown the possibility of utilizing frequencies above 27-5 M c/s
for transm ission by ionospheric-scatter propagation to distances well beyond the horizon;(b) th at systems using this m ode of propagation are already in service;(c) th at it is desirable to determine the preferred characteristics of such systems needed to facilitate
their international connection;(d) th at the frequency bands, which m ight be used for such systems, are already intensively used byother services;u n a n im o u s l yd e c id e s

th at the following question should be studied:1.

how do the propagation characteristics, relevant to the exploitation of systems employing
ionospheric-scatter propagation, vary with frequency;

2.

to w hat extent are systems employing this m ode of propagation liable to interfere with eachother and with other services operating on the same or neighbouring frequencies;3.

w hat are the radio-frequency and baseband characteristics o f such systems, which it is essential
to specify for the transm ission of telephony or telegraphy to enable two systems to be inter­
connected, and w hat values should be specified?

Q. 133, S.P. 133A

— 122 —QUESTION 133(111) *COMMUNICATION THEORYThe C.C.I.R.,(Geneva, 1951 - Warsaw, 1956)CONSIDERING(a) that for the transm ission of a given volume of inform ation through a given telecommunication
channel with a given power, either in a given time using a minimum bandwidth, or with agiven bandw idth in a m inim um time, the theoretical formulae suggest the use of pulse-code
m odulation;(b) that the theoretical coding m ethod for improving on this involves a long delay;(c) that the theoretical coding m ethods usually do n ot take into account the presence of a returnchannel, which in practice has led to efficient transm ission systems with a low error rate;(d) that the U.R.S.I. has suggested further study in Doc. 14 of Warsaw, 1956;
unanimously recommends that the following question should be studied:• 1.

the relation between permissible delay and residual uncertainty and its dependence on band­
width utilization;2.

the improvement practicably possible in existing systems, with regard to the transm ission of
inform ation, in particular for those systems where a go and a return channel are available.

ST U D Y P R O G R A M M E 133A(III) **COMMUNICATION THEORYThe C.C.I.R.,(Geneva, 1951 - London, 1953 - W arsaw, 1956 - Geneva, 1963)CONSIDERING(a) that, ip view of the increasing congestion of the radio spectrum and telecom m unication
circuits, it would be advantageous to discover technical methods of decreasing the bandw idth,
the transm ission time of a given quantity of inform ation, or the transm itted pow er;(b) that present studies seek mainly to perfect established systems, whereas recent theories seem
to show that these systems occupy several times the bandwidths strictly necessary for the trans­mission of the required inform ation at the required speed;(c) that, even with existing systems, it is not possible to reduce the bandw idth to th at strictly
necessary because of unpredictable noise, natural and m an-m ade interference, and complex
propagation conditions; a margin of bandw idth is necessary to decrease distortion and thefrequency of errors due to these phenom ena;(d) that it is not certain that existing codes, some at least of which were n ot designed in the light .
of phenom ena peculiar to radio propagation, are m aking the best use o f the occupied b an d w id th ;** This Question replaces Question 44.
* This Study Programme replaces Study Programme 86.

— 123 —S.P. 133A(e) that, to assess the effectiveness of any error-detecting or error-correcting codes over radio
circuits, it is essential that realistic error statistics be know n for these radio circuits;
u n a n im o u s l y

1.

d e c id e s

th at the following studies should be carried out:

the review of the various codes in use and the study of new codes, leading to an economy of
bandw idth or transm ission time for a given quantity of inform ation preserving a given qualityof transmission, taking into account the phenom ena peculiar to radio propagation and thecom parison o f the various existing systems of m odulation from the point of view o f the band­
width occupied in relation to the am ount of inform ation transm itted in a given tim e for agiven pow er; *2. th at experimental determ ination of error statistics be m ade for operating radio circuits. On
the 3 out of 7 A RQ systems, this can conveniently be done by counting and printing out theerrors on “ idle alpha ” characters, while the system is in full operation. The result of theseexperiments will be a table, showing the frequency of occurrence of m errors in a sequence o f ndigits (m = 0, 1, 2, 3 ... and n = 7 , 14, 21 ...). W here this is possible, it may be useful to giveinform ation on the occurrence of the different types of error);3.

th at experimental determ ination of the relative frequencies of occurrence of m errors be
extended to values of n other than multiples of 7. This experiment may require a separate
experimental channel. The suggested range of values for n is between about 10 and 100, withparticular emphasis put on 15, 31, 63 and 127;4.

the study, in conjunction with the U .R .S.I., of the m ethods of com m unication theory th at are
best suited for practical application.

Note. - The statistical inform ation asked for under § 2 and 3 should, where possible, state theconditions of the channel: signal-to-noise ratio, fading characteristics, special noise or channel
disturbances, interference from other stations, etc.

* R elative to th is study, it is useful to co n sid er fo r rad io telep h o n y , the d eterm in atio n of th e relatio n sh ip betw een intellig ib ility
a n d th e sh ape an d w idth of the p assb an d of the receiver fo r signal-to-noise ratio s co n sisten t w ith :- ju st usable q u ality , o p e ra to r to o p erato r,- m arg in ally co m m ercial quality,- g o o d com m ercial quality,
tak in g in to ac co u n t th a t:
- in m any cases, the noise pow er is d istrib u ted uniform ly over th e audio-freq u en cy sp ectru m , w hile speech p o w er is d istrib u ted
unevenly over th e spectrum ;- w hen h ig h noise levels are p resent in th e co m m u n ic atio n system , an d th e signal-to-noise ra tio is c o n s ta n t,-th e'in tellig ib ility m ight
show a m axim um as a fu n ctio n of th e b an d w id th an d the d is trib u tio n of th e p o w er co rresp o n d in g to th e freq u en cies it co n tain s.
T h is d is trib u tio n of th e pow er m ay vary w ith fading.

Q. 180, 181— 124 —QUESTION 180(111)

USE OF INTERMITTENT COMMUNICATION IN RADIOTELEGRAPHYThe C.C.I.R.,(Los Angeles, 1959)

C O N S ID E R IN G(a) that the m ethod of interm ittent com m unication is coming into use, particularly for circuits
using meteoric ionization;(b) that interm ittent com m unication often enables the m ean telegraph speed to be increased
considerably, for a given quality of service, when the signals and interference at the receiverare random in character;(c) that insufficient data are so far available concerning the fields in which it would be opportune
to apply the principle of interm ittent com m unication;u n a n im o u s l yd e c id e sthat the following question should be studied:1.

under w hat conditions is the use of interm ittent com m unication advantageous in radio­
telegraphy ;2.

w hat advantages, as regards telegraph speed, can be expected from the use of interm ittent
com m unication under various conditions, as com pared with the usual uninterrupted m ethod;3.

w hat is the m ost rational course to be followed in the construction of equipm ent for the useof interm ittent com m unication under various conditions ?

Q U E ST IO N 181(111) *INFLUENCE ON LONG-DISTANCE HIGH-FREQUENCY COMMUNICATIONUSING FREQUENCY-SHIFT KEYING OF FREQUENCY DEVIATIONSASSOCIATED WITH PASSAGE THROUGH THE IONOSPHERE
The C.C.I.R.,(W arsaw, 1956 - Los Angeles, 1959)

C O N S ID E R IN G(a) that Recom m endation 246, § 3, recommends that, for frequency-shift systems w orking on
two conditions only and operating between 3 Mc/s and 30 Mc/s, the values of frequency-shift
should be 200, 400 and 500 c/s;(b) that study of frequency deviations, associated with passage through the ionosphere, has shownthat the resultant frequency variations may reach values of a few cycles per second, while
instantaneous deviations may reach much higher values (see D ocum ents of the V lth Plenary
Assembly, Geneva, 1951, Vol. II, page 79; Doc. 213 o f W arsaw, 1956; Doc. 133 of Los Angeles,
1959 and R eport 111);
that the following question should be studied:w hat minimum frequency-shift value is required for frequency-shift systems operating overlong distances by high-frequency ionospheric propagation, to take into account any possible
influence of frequency deviations ?
u n a n im o u s l yd e c id e s* This Question replaces Question 139.

Q. 182, 183— 125 —QUESTION 182(111) *F R E Q U E N C Y S T A B IL IT Y R E Q U IR E D F O R S IN G L E -S ID E B A N D ,IN D E P E N D E N T -S ID E B A N D A N D T E L E G R A P H S Y S T E M S
T O M A K E T H E U S E O F A U T O M A T IC F R E Q U E N C Y C O N T R O L S U P E R F L U O U SThe C .C.I.R.,(Los Angeles, 1959)

C O N S ID E R IN G(a) that it is the practice with suppressed or reduced carrier SSB (single-sideband) and ISB (independent-sideband) telephone systems, and with many telegraph systems, to em ploy a.f.c.
(autom atic frequency control), to adjust the receiver oscillator frequency in sympathy withfrequency variations of the transm itted signal;(b) that such a.f.c. systems are complex and give rise to difficulty under poor propagation
conditions;(c) that the frequency stability, which can now be achieved, is much higher than th at laid downin Recom m endation 233, and is approaching a value which could provide sufficient inherent
stability to enable a.f.c. to be dispensed w ith ;(d) th at frequency deviations, caused by the passage through the ionosphere, are not likely to
influence significantly the operation of SSB, ISB, and telegraph systems;
u n a n i m o u s l y d e c i d e s that the following question should be studied:what frequency stabilities are necessary for SSB, ISB and telegraph operation in fixed H F
systems, range 4000-30 000 kc/s, to make a.f.c. unnecessary, and how can these be achieved?

Q U E S T IO N 183(111) **F R E Q U E N C Y -S H IF T K E Y IN G
The C.C.I.R.,(Stockholm, 1948 - Los Angeles, 1959)

C O N S ID E R IN G(a) that frequency-shift keying is employed in radiotelegraphy for the fixed services and it has
also been extended to the mobile services;(b) th at it is desirable to standardize the m ain operating characteristics of systems employing
frequency-shift keying;(c) th at various technical factors influence the choice of operating characteristics in such systems,
in particular:
c.a the overlap of m arking and spacing signals due to m ultipath propagation (in this respecta small deviation is preferable);* This Question replaces Question 167.
** This Question replaces Question 20.

Q. 183, S.P. 183A

— 126 —

c.b the possible advantage of frequency diversity for reception (an advantage which increases

with deviation);c.c economy of bandwidth and the consequent necessity for controlling the shape,of the trans­mitted signals;
c.d instability of frequency, which is one reason for the relatively large deviation employed inmany existing equipments;
c.e the choice of receiving systems, whether with separate filters or with frequency discriminator;
unanimously decides that the following question should

be studied :1.

fixation of one or more standard values o f deviation for fixed and mobile services in thevarious frequency bands, having regard to the various factors, in particular:- the frequency spectrum resulting from the keying operation;- the degree of frequency diversity desired;- economy of bandwidth;- instability of frequencies;

2.

compilation o f a standard terminology regarding the characteristics of systems employing
frequency-shift keying.

STUDY PROGRAMME 183A(III) *FREQUENCY-SHIFT KEYINGThe C .C .I.R.,(Geneva, 1951 - London, 1953 - Los Angeles, 1959)CONSIDERING(a) that frequency-shift keying is employed in radiotelegraphy for the fixed services and has also
been extended to mobile services;(b) th at it is desirable to standardize the main operating characteristics of systems employing
frequency-shift keying;
unanimously decides that the following study should be carried out:1.

the determ ination, in each particular case, of recom m ended values of frequency shift foremissions using frequencies between 2 and 27 M c/s;

2,

the determ ination, in each particular case, of recommended values of frequency shift foremissions using frequencies below 2 Mc/s.

* .This Study Programme, which replaces Study Programme 41, was previously designated Study Programme 133(111).

S.P. 183B, Q. 232— 127 —ST U D Y P R O G R A M M E 183B(III) *FOUR-FREQUENCY DIPLEX SYSTEMSThe C.C.I.R.,(Warsaw, 1956 - Los Angeles, 1959)

C O N S ID E R IN G(a) th at there are in use, in the fixed radiotelegraph services, operating between 2 M c/s and 27 M c/s,
four-frequency diplex (or twinplex) systems, in which each of four frequencies is used totransm it one of the four possible com binations of m ark and space signals corresponding to
two telegraph channels; it being understood that either or both of the two telegraph channels
may be sub-channelled by time-division m ethods and th at the use of such systems may be
extended;(b) th at it desirable to standardize the main characteristics of four-frequency diplex systems;(c) th at it may sometimes be necessary to employ the same radio transm itter to w ork with m ore
than one receiving statio n ;(d) th at various technical factors influence the choice of operating characteristics in such systems,
in particular:- economy of bandwidth and the consequent need to control the shape o f the transm itted signals;- a relatively wide spacing between adjacent frequencies may be necessary for high telegraphspeeds;- the signal distortion due to propagation conditions;- the instability of the characteristics of certain receiver and transm itter elements, such as
oscillators, filters or discrim inators;
u n a n i m o u s l y d e c i d e s th at the following study should be carried out:
the determ ination of the relation between the minimum frequency spacing and the telegraphspeed over the range of telegraph speeds in practical use. This should be determ ined for bothsynchronous and non-synchronous operations.

Q U E ST IO N 232(111) **FACSIMILE TRANSMISSION OF DOCUMENTARY MATTEROYER COMBINED RADIO AND METALLIC CIRCUITSThe C.C.I.R.,(London, 1953 - Geneva, 1963)

C O N S ID E R IN G(a) th at increasing use is being m ade of facsimile telegraphy for the transm ission of docum entarym a tte r;(b) th at it is desirable to standardize the characterictics of the facsimile system em ployed for thispurpose;u n a n i m o u s l y d e c i d e s th at the following question should be studied:w hat are the requirem ents, imposed by the use of radio, on the characteristics o f systems forthe transm ission by facsimile of:- telegrams in the public service,- business documents,- docum ents of large size, such as meteorological charts ?

* T h is S tudy P ro g ram m e, w hich replaces S tudy P ro g ram m e 83, was previously designated S tudy P ro g ram m e 134 (H I).
** T h is Q uestion replaces Q uestion 94.

Q. 233, 280— 128 —QUESTION 233(111)
USE OF COMMON-FREQUENCY SYSTEMS ON INTERNATIONAL
RADIOTELEPHONE CIRCUITSThe C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) that relief of the present congestion of the H F (decametric) band is a m atter of urgency;(b) that, in certain cases, the use of the same frequency for both directions of transm ission (incom bination with the use of YODAS equipment), may result in im portant economies inspectrum utilization on international radiotelephone circuits;
unanimously decides that the following question should be studied:1.

w hat are the characteristics to be specified for international radiotelephone systems using theprinciples of com mon-frequency operation;2.

w hat should be the m inimum difference in level at the input to the receiver between thereceived signal from the distant station, and signals from the nearby transm itting station, toavoid interference between the w anted signal and th at from the nearby transm itter operatingon the same frequency;

3.

to w hat extent will the use of transm itting and receiving antennae, with different transm ission
characteristics, reduce the possibilities of application of this technique;,4.

to what extent will the possibilities of application of this technique be reduced by the presenceof different noise levels at the receiving locations;5.

what other factors should be taken into account when planning such systems, for example:- non-linearities in the transm itting and receiving equipment,- carrier-filter bandwidth,- frequency stability of the equipm ent?

,

Q U E S T IO N 280(111)

USE OF DIRECTIONAL ANTENNAE IN THE BAND 4 TO 27 5 Mc/s
Limitation of radiation outside the direction necessary for the service
T H E IN T E R N A T IO N A L F R E Q U E N C Y T E G IS T R A T IO N B O A R D ,the request by the Panel of Experts in Recommendation No. 38 of its Final Report,
Geneva, 1963, and a f t e r c o n s i d e r i n g :(a) that there is serious congestion in the frequency bands between 4 and 27-5 Mc/s;(b) that there is a need to adopt methods and regulations for the solution of the frequency
problems with which Administrations are confronted in the use of these bands;/ c) that occupation of the radio-frequency spectrum is represented, not only in time and band­
width, but also in the spatial distribution of the radiated power;
in v ie w o f

— 129 —Q. 280, 281(d) that this latter distribution can be effectively controlled by the use of directional antennae;(e) that the intent of Articles 12 and 14 of the R adio Regulations, Geneva, 1959, w ould seem tojustify further explicit requirem ents for the use of directional antennae in the bands between
4 and 27-5 Mc/s, as well as for quantitative lim itation of the intensity of radiation in directions
other than that required for the service;a n d i n v i e w o f N o. 180 of the International Telecommunication Convention, Geneva, 1959;d e c i d e s to submit the following urgent question to the C .C .I.R .:w hat are reasonable standards for the directivity of antennae in the various types of radio
services, and for various distances, in the bands between 4 and 27-5 Mc/s, including the widthof the main beam and the allowable intensity of radiation (effective radiated power) in direc­
tions of azimuth outside the main beam (such standards should reflect due regard for practicalconsiderations of construction and cost)?

Q U E ST IO N 281(111)

AUTOMATIC CONTROL OF THE OUTPUT POWER OF HF
TRANSMITTERS
T H E IN T E R N A T IO N A L F R E Q U E N C Y R E G IS T R A T IO N B O A R D ,o f the request of the Panel of Experts in Recom m endation No. 38 of its F inal R eport,
Geneva, 1963, and a f t e r c o n s i d e r i n g :in v ie w(a) that N o. 694 of the Radio Regulations, Geneva, 1959, requires th at all stations shall radiate
only as much pow er as is necessary to ensure a satisfactory service;'(b) that nevertheless, for a considerable part of the time, stations using frequencies in the bands
between 4 and 27-5 Mc/s, radiate powers considerably in excess of those necessary to ensure asatisfactory service;(c) th at manually operated methods of adjusting the power of transm itters are n ot fully adequate
to meet No. 694 of the Radio Regulations;(d) th at the use of autom atic control of the output power of transm itters would assist in reducing
the congestion in the H F spectrum;a n d i n v i e w o f N o. 180 of the International Telecommunication Convention, Geneva, 1959;d e c i d e s to submit the following urgent question to the C .C .I.R .:what are the m ost suitable methods for automatically controlling the output power of radiotransm itters operated in the H F bands to ensure, as far as is practicable, th at the radiatedpower is no greater than is necessary to ensure a satisfactory service?

S.P. 186

— 130 —STUDY PRO GRAM M E 186(111) *EFFICIENCY FACTOR
The C .C .I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) th at the efficiency factor, as defined in the List of definitions of essential telecommunication
term s (Part 1 , 1961, N o. 33.23) (see also Recom m endation 345), is very useful to define anddetermine the quality of a com m unication using autom atic error-correction;(b) th at the efficiency factor will be of use in the operation o f radiotelegraph telex circuits withfully-autom atic switching; *unanimously decides that the following studies should be carried o u t:1.

use of the efficiency factor for theoretical studies on point-to-point circuits;
the measurements should be effected in the following m anner for theoretical studies on pointto-point circuits:- duration of traffic observations for a m easurem ent: 15 m in.;- a count o f the num ber o f telegraph signals repeated in the course of these 15 m in.;- a count of the num ber of errors during these 15 min. (num ber of telegraph signals wrongly
translated);- a count of the num ber of telegraph signals received in the course o f these 15 m in.;- an indication should be given o f the type o f telegraph apparatus used and, w hen applicable,of the error-correcting system;- an indication of the m odulation rate;- an indication o f the maximum commercial speed, in words per m inute, at th at m odulationrate;- an indication of the average quality of reception during the m easurem ent (the quality to beshown by means of one of the codes recommended by the C.C.I.R., SIN PO or SIN PFEM O
code, or by a measurem ent of the average field-strength during the observation);- an indication of the date and time at which the observation was m ade;
- repetition of these measurem ent periods of 15 m in over a whole day, on a given frequency,
during the hours when this frequency is norm ally used, to take account o f the influence of
propagation conditions;2.

study of the continuous measurem ent of the efficiency factor on circuits used w ith fullyautom atic operation and study of its employment on such circuits.
M easurem ent of the efficiency factor itself is fairly simple, once agreem ent has beenreached on the value of two (or possibly one) tim e-constants, referring respectively to the timeinterval tlt during which the efficiency factor should exceed a certain limit, before a newcall can be set up, and the time interval t2 during which the channel efficiency should be lessthan some other limit, before an existing call should be interrupted. (The C.C.I.T.T. isconsidering fixing one limit only for the efficiency factor: 80%).
It is agreed that the time intervals t1 and t2 should be m uch shorter th an the value of
15 min. proposed in § 1 and the following values are under consideration by the C.C .I.T.T.:= 20 s and t2 = 60 s
The question of the continuous evaluation of the efficiency factor and its em ploym ent toremove the circuit from operation and to return it to operation should be studied in collabora­tion with the C.C.I.T.T.

* T h is S tudy P ro g ram m e, w hich to g eth er w ith S tudy P ro g ram m e 3B(III) replaces S tudy P ro g ram m e 132, d oes n o t arise
from any Q uestion u n d e r study.

— 131 —S.P. 186,187

It is suggested th at A dm inistrations should try to find an answer to the following question(in view of the urgency of the m atter, possibly before the I llr d Plenary Assembly of the
C.C.I.T.T.):- is the one value of 80% for the efficiency factor suitable, or would it be better to have twovalues;- are the suggested values for the time intervals acceptable, or are other values to be preferred ?

ST U D Y P R O G R A M M E 187(111) *IDENTIFICATION OF THE CARRIER FREQUENCY RELATIVE
TO THE ASSIGNED FREQUENCY OF AN EMISSION
The C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) th at in certain classes of emission, notably single-sideband and suppressed o r reduced carriertypes, the carrier frequency is not in the centre of the assigned frequency band and does nottherefore coincide with the assigned frequency;(b) th at the exchange o f operating inform ation, between the term inals of a radio circuit, is facilitated
if there is a simple m ethod of identifying the carrier frequency of such an em ission;(c) th at the assigned frequency forms a convenient reference, relative to which the carrier frequency
may be located;.
'■
u n a n i m o u s l y d e c i d e s that the following studies should be carried out:
investigation of the application o f the m ethod of carrier frequency identification (seeR eport 202) and assessment of the advantages to be gained by the use of such a m ethod.

* This Study Programme does not refer to any Question under study.

— 132 —LIST OF DOCUMENTS OF THE Xth PLENARY ASSEMBLY
CONCERNING STUDY GROUP III
D oc.

3

O rigin

Chairman,
Study Group 111

T itleR eference

Report by the Chairman, Study Group III(Dr. H. C. A . Van D uupen)

88

Netherlands

The use of radio circuits in association with
5-unit start-stop telegraph apparatus

Rec. 242
Rep. 108

118

United Kingdom

Use of radio circuits in association with
5-unit start-stop telegraph apparatus

Rep. 108

121

Netherlands

Terms related to ARQ-systems

Rec. 242
Res. 34

122

United Kingdom

The use of automatic error-correction of tele­graph signals transmitted over radio circuits- Errors during automatic rephasing whenusing the systems of Report 108

S.P. 128
Rep. 108

129

C.C.I.R. Secretariat

Bibliographic references in the volumes of the
C.C.I.R.

146

Netherlands

Performance of telegraph systems and re­ceivers153

C.C.I.R. Secretariat

Refinement of I.F.R.B. technical standards

Rec. 234
Rep. 105

Rep. of CCITT
W.P.

178

Transmission of facsimile and phototelegraphsignals over radio circuits

Rec. 243 & 244

191

High-frequency directional antennae - Re­plies to C.C.I.R. Circular AC/55

Circ. AC/55

201

Voice-frequency telegraphy over radio cir­
cuits

Q. 43

202

Quality index and efficiency factor

S.P. 132
Rep. 42

Telegraph distortion and error rate

S.P. 132

Some observations in long-distance HF com­munication using FSK, due to passage
through the ionosphere

Q. 181226

A suggestion for increasing the speed oftransmission of printed language on a tele­
printer circuit by use of phonetic alphabet

S.P. 86

227

A suggestion for increasing the transmission
rate in a teleprinter circuit without increasing
the bandwidth and baud speed

S.P. 86228

Helical rhombics

S.P. 130

Improvement obtainable from the use of
directional antennae

S.P. 130

233

India

Australia

II
I, II, V,
VI, X,XII, XIII

Effect of noise on telegraph transmission

225

XIV

I-XIV

164

203

O th erStudy
G ro u p s
co n cern ed

IX

X, XII— 133 —D o c.

T itleO riginR eference

O th e r
S tu d y
G ro u p s
co n cern ei

234

Australia

Proposed variations to Recommendation 242

S.P. 128

237

India

Information regarding high-frequency direc­
tional antennae used by radiocommunication
services in India

Circ. AC/55

X. XII

271

U.R.S.I.

Long-distance directivity of HF antennae

Circ. AC/55

VI, X

285

Study Group III

Summary record of the first meeting

-

-

363

Study Group III

Telegraphic distortion, quality index, errorrate, efficiency factor

Draft Rep.

—

364

Study Group III

Factor affecting quality of performance ofcomplete systems of the fixed services

Draft Rep.
S.P. 128—

368

Study Group III

Voice-frequency (carrier) telegraphy on radio
circuits

Rep.
S.P. 129—

369

Study Group III

Amendment to Annex 3/5 to Doc. 3(Doc. 3)-370

Sub-Group III-C

Bibliographic references in the volumes of the
C.C.I.R. - Suggested answer to Doc. 129(Doc. 129)-

417

Study Group III

Summary record of the second meeting

-

-

447

Sub-Group III-C

Bandwidth and signal-to-noise ratios in com­plete systems

Draft Rep.
S.P. 128—

479

Sub-Group III-B

Automatic error-correcting system for tele­graph signals transmitted over radio links

Draft Rec.
S.P. 128

XIV

480

Sub-Group III-B

Radiotelegraph circuits used in automatic
switched networks

Draft S.P.

—

502

Study Group III

Resolution in response to Recommendations
2 and 3 to the C.C.I.R. adopted at Geneva
in 1959 by the Administrative Radio Confer­ence - Optimum use of the radio spectrum

Rec. 2 and 3
to C.C.I.R.

523

Study Group III

Efficiency factor

Draft S.P.

524

Study Group III

Frequency stability required for single-side­band, independent-sideband and telegraphsystems to make the use of automatic fre­quency control superfluous

Draft Rec.
Q. 182

549

Sub-Group III-A

High-frequency directional antennae(Doc. 191)

607

Study Group III

Summary record of the third and last meeting

620

Study Group III

Proposed small amendment to Recommen­
dation 241

Rec. 241

644

Study Group III

International group of experts set up by
Resolution 1 - Summary record of the firstmeetingRes. 1

2128

Drafting Committee Intercontinental radiotelephone systems anduse of radio links in international telephone
circuits

Rec. 335

Principles of the devices used for achieving
privacy of radiotelephone conversations

Rec. 336-

Channel separation

Rec. 337

—

2129

„

2130

,,

,,

-

-

— 134 —
D oc.

2131

O rig inT itleDrafting Committee Bandwidth required at a telegraph or telephone receiver output

R eference

Rec. 338

2132

„

„

Bandwidths and signal-to-noise ratios in complete systems

Rec. 339

2133

„

,,

Facsimile transmission of meteorologicalcharts over radio circuits

Rec. 343

2134

„

„

Standardization of phototelegraph systems
for use on combined radio and metallic cir­
cuits

Rec. 344

2135

„

„

Four-frequency diplex systems

Rec. 346

2136

„

„

Classification of multi-channel radiotelegraphsystems for long-range circuits operating on
frequencies below about 30 Mc/s and desig­
nation of the channels in these systems

Rec. 347

2137

„

,,

Arrangement of channels in multi-channel
single-sideband and independent-sideband
transmitters for long-range circuits operating
at frequencies below 30 Mc/s

Rec. 348

2138

„

„

Facsimile transmission of documentary matter over combined radio and metallic circuits

Q. 2322139„„

Use of common-frequency systems on international radiotelephone circuits

Q. 2332140„„

Communication theory

S.P. 133A

2141

„

„

Identification of carrier frequency relative tothe assigned frequency of an emission

S.P. 187

2142

„

„

Some aspects of the application of communication theory

Rep. 196

2143

„

„

Arrangement of voice-frequency frequencyshift telegraph channels on radio circuits

Rep. 199

2144

„

„

Remote control signals for facsimile transmissions

Rep. 201

2145

„

„

Identification of carrier frequency relative tothe assigned frequency of an emission

Rep. 202

2146

„

„

Multi-path propagation on high frequency
radio circuits

Rep. 203

2147

„

„

Factor affecting quality of performance ofcomplete systems of the fixed services

Rep. 197

2148

,,

„

Voice-frequency (carrier) telegraphy on radio
circuits

Rep. 198

2149

„

„

Telegraphic distortion, error-rate

Rep. 200

*

2301

„

„

Optimum use of the radio-frequency spectrum

Res. 1

2302„„

Fading allowances for the various classes ofservice

Rec. 340

O th er
S tu d y
G ro u p s
concerned

— 135 —

D oc.

2303

O riginT itleDrafting Committee Bandwidth and signal-to-noise ratios in complete systems

R eferen ce

Rep. 195

2304

„

,,

Automatic error-correcting system for telegraph signals transmitted over radio links

Rec. 342

2305

,,

„

Radiotelegraph circuits used in automatic
switched networks

S.P. 3B

2306

,,

,,

Frequency stability required for single-sideband, independent-sideband and telegraphsystems to make the use of automatic fre­quency control superfluous

Rec. 349

2307

„

,,

Telegraphic distortion

Rec. 345

2308

„

„

Efficiency factor

S.P. 186

2393

„

„

Small amendment to Recommendation 241

Rec. 341

O th e r
S tu d y
G ro u p s
co n c ern ed

PAGE INTENTIONALLY LEFT BLANKPAGE LAISSEE EN BLANC INTENTIONNELLEMENT

Rec. 45

— 137 —

RECOMMENDATIONS OF SECTION D: MOBILE SERVICES■R E C O M M E N D A T IO N 45

AVOIDANCE OF INTERFERENCE FROM SHIPS’ RADARTO OTHER RADIOCOMMUNICATION APPARATUS ON BOARD(Q uestion 35)
The C .C.I.R.,(Geneva, 1951)

C O N S ID E R IN G(a) th at experience has proved that, with well-designed and properly installed radar, the possibilityof interference occurring in practice is very rem ote;(b) th at the possibility of interference to radio reception and to direction finding on a vessel,
other than that upon which the radar is located, is exceedingly rem ote and th at no instancesof such interference have been reported;(c) that, in the unlikely case where radar interference m ight result to radio reception abo ard aradar equipped vessel, the presence of such interference may be readily detected and identified
by listening on the radio receiver or direction finder;(d) that, where interference has occurred to radio reception aboard ships equipped w ith welldesigned radar, in each-case the cause of the interference has been faulty initial installationand has been removed by correcting the installation;
U N A N IM O U S L Y RECO M M E N D S

1.

th at Administrations shall see to it th at radar equipments placed aboard ships are well designed
and properly installed, so as not to cause interference to radio reception aboard the rad arequipped vessel. In this regard, particular attention shall be paid to shielding, bonding andto fitting line filters, especially in the m odulator circuits, for the conductors which are routed
between the m ajor com ponents of the installation;2.

th at the absence of interference shall be assured, either by test procedures of prototypes orby installation inspection procedures, whereby an investigation is made to determine w hethero r not there exists any noticeable interference to ships’ radio receivers or direction finders,
under practical conditions of installation and operation.

— 138 —Rec. 76

RECOMMENDATION 76
VOICE-OPERATED DEVICES FOR SHIP STATIONSAND CARRIER-OPERATED DEVICES FOR SHORE STATIONS(Question 32)
The C.C.I.R.,(Geneva, 1951)

C O N S ID E R IN G(a) that the essential characteristics o f the devices controlled by voice currents and acting on
the carrier wave in radiotelephone stations on board ships and of the carrier-operated devices
in receivers of coast stations are their “ operate ” and “ release ” tim es;(b) that the operate times of the devices should be short to minimize clipping, and their releasetimes should be sufficiently long to enable the devices to rem ain operated in the intervals
between words in norm al speech;
U N A N IM O U SL Y REC O M M E N D S

1.

that the operate and release times of the voice-operated carrier switching unit on the shipshould be as follows:
In p u t level(N o te 1)- 30 db- 20 db2.

N e t o p erate tim e(N o te 2)

N e t release tim e(N o te 3)less than 25 msless than 15 ms

between 75 and 170 ms
between 75 and 170 ms

that the operate time (N ote 4), of the carrier-operated device in the coast station receiver,should be as short as practicable to allow somewhat longer operate times in the ship’s appa­
ratus and should not exceed 5 ms when the carrier level at the input to the receiver is m ore
than 1 db above the level just necessary to operate the device. The required value of releasetime ( N ote 5), is dependent on several factors, including the time constants o f the autom atic
gain control of the radio receiver and a value between 10 and 50 ms is generally suitable.

Note 1. - Input level refers to the level of a test sinusoidal signal of frequency, corresponding to
the middle of the voice-frequency range relative to th at producing 100% m odulation.
Note 2. - N et operate time is the time which elapses between the instant the test signal is applied
to the input to the m odulator of the transm itter, and the instant when the carrier reaches
50% of its maximum amplitude.
Note 3. - N et release time is the time which elapses between the instant when the test signal is dis­connected and the instant the carrier is reduced to within 5 db of the maximum carrier sup­pression achieved.
Note 4. - Operate time of the carrier-operated device is the time which elapses between the sudden
application of a test signal simulating the carrier wave from the ship and the instant of openingof the receiving channel (the instant when the attenuation of the receiving channel is w ithin 5 dbof the final value of attenuation for the receiving condition).
Note 5. - Release time of the carrier-operated device is the tim e which elapses between the cessationof a test signal simulating the carrier wave from the ship and the instant of blocking of thereceiving channel (the instant when the attenuation of the receiving channel is w ithin 5 dbof the final value of attenuation in the blocked condition).

Rec. 77

— 139 —R E C O M M E N D A T IO N 77 *CONDITIONS NECESSARY FOR INTERCONNECTION
OF MOBILE RADIOTELEPHONE STATIONS(FOR INSTANCE, AUTOMOBILES, AIRCRAFT AND SHIPS)AND INTERNATIONAL TELEPHONE LINES(Q uestion 33)
The C.C.I.R.,(Geneva, 1951)

C O N S ID E R IN G(a) th at the conditions concerning which international agreement is necessary appear to be few
in num ber;(b) th at these conditions, if met, w ould perm it suitable interconnection between mobile rad io ­telephone stations and international telephone lines;
REC O M M E N D S

1.

th at mobile radiotelephone circuits, intended for connection to international telephonesystems, should term inate (on a two-wire basis, for the present at least), in such a way th at they
may be connected to international lines in the same m anner as other land-line connections;2.

th at the mobile radiotelephone circuits should accept from and deliver to the land-line system,
speech volumes conforming, as far as possible, to the C.C.I.R. and C.C.I.T.T. standards forconnections to international circuits;3.

th at the attenuation-frequency characteristics of the radio system (including the land-lines tothe radio receiver and radio transm itter), should be such that the grade o f transm ission is n o t
unduly affected; and, in particular, the effectively transm itted band should be n o t less th an
300 to 2600 c/s;

4.

th at the noise from a radio circuit, connected to an international circuit, should n ot be unduly
great and should be insufficient to operate echo suppressors or other devices on domestic
or international circuits frequently;

5.

that, for mobile radiotelephone stations, which may have to com municate with land stationsin m ore than one country, consideration be given to the necessity for agreement as to a m ethodo f signalling for use between the land mobile stations.

* The Roum anian P.R. reserved its opinion on this Recommendation.

— 140 —Rec. 218

RECOM M ENDATION 218 *PREVENTION OF INTERFERENCE TO RADIO RECEPTION ON SHIPS **(Question 34)
The C .C.I.R.,(Geneva, 1951 - W arsaw, 1956)CONSIDERING(a) that the M aritime Regional R adio Conference, Copenhagen (1948), recom m ended that the
C.C.I.R. study the question of interference to radio reception caused by electrical instal­lations on board ship;(b) that the Safety of Life at Sea Conference, London (1960, Chapter IV, Regulation 9), requested
that all steps be taken to eliminate, as far as possible, the causes of radio interference from elec­
trical and other apparatus on board sh ip ;( c) that electrical interference is caused by the unw anted excitation of the radio receiving equip­
ment, including the aerial, by fluctuating electromagnetic fields set up by other electricalinstallations;(d) that the fluctuation of electromagnetic fields, which gives rise to interference, is caused byabrupt changes in current in the source of interference, and by abrupt changes in the resistanceof conductors situated in electromagnetic fields;(e) that electrical interference may be transm itted by direct radiation and induction from thesource of interference itself, and also by re-radiation and induction from conductors whichcarry interfering currents;
UNANIMOUSLY RECOMMENDS
1. that the design, construction and installation of electrical equipm ent in ships should be such,that interference is minimized at its source (see also N o. 959 of the R adio Regulations, Geneva,
1959);
2.

that electrical equipm ent installed in ships should be efficiently m aintained to prevent any
increase in the level of interference which it causes;

3.

that antennae used for transm ission or reception should be erected, as far above and as far away
as possible from electrical machinery and from parts of the ship’s structure such as funnels,
stays and shrouds;

4. that the down-leads of antennae which are used exclusively for reception should be screened;that the screen should extend continuously from the receiver to a point which is as high aspracticable above the ship’s structure, and th at the screen should be effectively connectedto the earth term inal of the receiver;5.

that, frame or loop antennae used for direction finding, should be effectively screened againstelectrostatic interference;

6.

that the radio receiving room should be effectively screened and situated as high as practicablein the ship;

7.

that power converting plant, within the radio receiving room , should be housed in a separate
screened enclosure, unless the plant is self-screened;

8.

that the radio receiving equipm ent should be designed so th at it is effectively screened;* T his R ecom m endation replaces R ec o m m e n d atio n 78. C ertain references to th e R a d io R eg u latio n s h ave been in serted
subsequently.
** Interference from ra d a r an d o th e r electronic e q u ip m en t has n o t been specifically co n sid ered in fram in g th is R ec o m m e n d a­tio n . T he prevention of ra d a r interference is covered by R eco m m en d atio n 45.

— 141 —Rec. 218, 219

9.

th at suppressor filters, to prevent the propagation of interference, should be fitted at the sourcesof interference, preferably built into the interference-producing equipment, and th at in p arti­
cular :
9.1 the electrical ignition systems of internal com bustion engines, including those which may
be installed in lifeboats, should be fitted with suppressors;
9.2 the navigational instruments and associated equipm ent, which are installed in the neighbour­hood of the receiving antennae or the radio receiving room should, if necessary, be fitted with
suppressors, be screened, and the screen effectively earthed;
10. that cables in the vicinity of the receiving antennae or the radio receiving room , and cables
within the radio room , should be screened by enclosing them in metal conduits, unless thecables themselves are effectively screened;
11. th at twin cables should be used wherever possible: if single-core cable is necessary, the “ lead ”
and “ return r conductors should be fixed, as close to one another as possible, to avoid theform ation of lo o p s;
12. that suppressors should be fitted to cables at their point of entry into the radio receiving room ,unless they term inate close to the point of entry in equipm ent which itself provides adequate
screening and suppression;
13. that cables, ducts and pipes which do not term inate in the radio receiving room , should pre­ferably not be installed in the radio receiving ro o m ; if it is essential for them to pass throughthe radio receiving room , the ducts and pipes and the screening of the cables should be effec­
tively earthed;
14. that a copper earth-busbar should be fixed along the bulkheads and bonded at several points
to the ship’s structure and to the metal structure or screening of the radio receiving ro o m ;the screens of cables within and near to the radio receiving room , as well as the screens ofapparatus in the radio receiving room , should be effectively connected to the busbar;
15. that rigging should be either insulated from or bonded to the ship’s structure (stay th at are
subject to considerable tension can more conveniently be bonded);
16. that, for smaller vessels and those constructed of wood, the principles recom m ended should
be applied as far as is practicable;
17. th at particular care should be taken to minimize interference on the frequency bands used
for distress, safety and direction finding in the m aritim e service;
18. th at A dm inistrations should bring the above recom m endations to the attention of naval
architects, shipbuilders and those responsible for the m anufacture, installation and m ain­tenance of electrical equipment.

R E C O M M E N D A T IO N 219 *A L A R M S IG N A L F O R U S E O N T H E M A R IT IM E R A D IO T E L E P H O N Y
D IS T R E S S F R E Q U E N C Y O F 2182 kc/s
The C.C.I.R.,(Geneva, 1951 - London, 1953 - W arsaw, 1956)

C O N S ID E R IN G(a) th at it is desirable and practicable to establish an internationally agreed alarm signal for useon the calling and distress frequency of 2182 kc/s (see A rt. 36 of the R adio Regulations, Geneva,
1959);* This Recommendation replaces Recommendation 125.
subsequently.

Certain references to the R adio Regulations have been inserted

— 142 —Rec. 219(b) th at the alarm signal should be such as to:- provide reliable operation o f autom atic alarm equipm ent;
- provide a distinctive signal, which is readily recognized aurally, when received on a loud­speaker or headphones;- be capable of being received through interference from speech transm issions, throughother kinds of interference, and through noise;- avoid false responses when received either aurally or by autom atic m eans;- be capable of being produced by a simple m anual device, as well as by autom atic means;(c) that the alarm signal should be such as to perm it the construction of alarm equipment which
is rugged, dependable, stable in perform ance, of low cost, of easy production, of long life
with a minimum of maintenance, and which can be used with existing m aritim e radiotelephoneequipm ent;(d) that to help in clearing the calling and distress frequency channel of emissions from otherstations the alarm signal and detecting device should be effective beyond the range at whichspeech transm ission is satisfactory;(e) that the autom atic alarm equipm ent should be capable of operating, in as short a time as
possible, consistent with the avoidance of false responses;( f) th at the results of the further exam ination of this problem by the A dm inistrations which parti­
cipated in Study Programm e 29 (Geneva, 1951), are sufficiently conclusive to determine theessential characteristics of the signal, including tolerances th at should be recommended forinternational ado p tio n ;(g) that it is possible to specify the m inimum perform ance standards for autom atic alarm equip­
ment, for both transmission and reception, to such an extent th at future progress and develop­
m ent are not ham pered;(h) that it is undesirable that the specification of perform ance standards for autom atic alarm
equipment should exceed in scope the requirem ents already established by international
agreement for autom atic alarm devices, intended for the reception o f the international alarm
signal or the international distress signal in radiotelegraphy, normally transm itted on thefrequency 500 kc/s (see Nos. 1475 and 1476, and Appendix 20, § 1 of the R adio Regulations,Geneva, 1959; and Chapter IV, Regulation 10 of the Convention for th e Safety of Life atSea, London, 1960);
U N A N IM O U SL Y R EC O M M E N D S

1.

that the alarm signal described below should be adopted internationally, for use on the m ari­time radiotelephony calling and distress frequency of 2182 kc/s;
1.1 the alarm signal shall consist of tw o substantially sinusoidal audio-frequency tones, trans­
m itted alternately for a minimum period of 6 s. One tone shall have a frequency o f 2200 c/s
and the other a frequency of 1300 c/s. The duration of each tone shall be 250 ms;

1.2 the tolerance o f the frequency of each tone shall be db 1-5 %; the tolerance on the durationof each tone shall be ± 50 ms; the interval between successive tones shall n o t exceed 50 ms;
the ratio of the am plitude of the stronger tone to th at of the weaker shall be within the range
1 to 1-2;
1.3 when generated by autom atic means, the alarm signal shall be sent continuously for a periodof at least 30 s but not exceeding one m inute; when generated by other means, the signal shallbe sent as continuously as practicable over a period of approxim ately one m inute;2.,that the autom atic devices, intended for the reception o f the alarm signal in question, should
fulfill the following conditions:
2.1 the frequencies of maximum response of the tuned circuits, and other tone selecting devices,shall be subject to a tolerance of ± 1-5% in each instance; and the response shall n o t fall
below 50 % of the maximum response for frequencies within 3 % of the frequency of maximum
response;
2.2 in the absence of noise and interference, the autom atic receiving equipm ent shall be capableof operating from the alarm signal in a period of n ot less than four and n ot m ore than six
seconds;

— 143 —Rec. 219, 224

2.3 the autom atic receiving equipm ent shall respond to the alarm signal, under conditions ofinterm ittent interference caused by atm ospheric and powerful signals other th an the alarm
signal, preferably w ithout any m anual adjustm ent being required during any period of watch
m aintained by the equipm ent;
2.4 the equipment shall not be actuated by atm ospheric or by strong signals other th an the alarm
signal;3. . th at the autom atic alarm equipments, for both transm ission and reception on the calling anddistress frequency of 2182 kc/s, shall fulfill the following conditions:
3.1 the equipm ent shall be effective beyond the range at which speech transm ission is satisfactory;
3.2 the equipments shall be capable of withstanding vibration, humidity, changes of tem peratureand variations in power supply voltage equivalent to the severe conditions experienced onb oard ships at sea, and shall continue to operate under such conditions;
3.3 the equipm ent should, as far as practicable, give warning of faults th at w ould prevent theapparatus from perform ing its norm al functions during watch hours;
4.

that, before any type of autom atic alarm equipm ent for transm ission and reception on thecalling and distress frequency of 2182 kc/s is approved for use on ships, the A dm inistrations
having jurisdiction over those ships should be satisfied by practical tests, m ade under operating
conditions equivalent to those obtaining in practice, th at the equipm ent complies with theprovisions of § 1, 2 and 3 of this Recom mendation.

RECOMMENDATION 224 *TESTING OF 500 kc/s RADIOTELEGRAPH AUTO-ALARM
RECEIVING EQUIPMENT ON BOARD SHIPS.

(Question 108)

The C.C.I.R.,(W arsaw, 1956)

C O N S ID E R IN G

that, it is im portant for the safety of life at sea, th at radiotelegraph auto-alarm receiving
installations (including the antenna) are always in good working order on bo ard ships at sea;
U N A N IM O U SL Y R EC O M M EN D S

in addition to the requirements of C hapter IV of the International Convention for the Safetyof Life at Sea (London, 1960);
1.

th at all radiotelegraph auto-alarm receiving equipments, for use on the international callingand distress frequency of 500 kc/s should, wherever practicable, be provided specifically withmeans for autom atic warning of the following:

1.1 failure of any valve filament, whether the cathode is directly or indirectly heated;
1.2 m ajor variation or sustained failure of any source of voltage which is used for supplying valve
elements, where this would seriously affect the proper functioning of the apparatus, as laid
down in C hapter IV, Regulation 10 of the said Convention;* This Recommendation terminates the study of Question 108. The references to the International Convention for the
Safety-of-life at sea, London, 1960, have been inserted subsequently.

Rec. 224, 257— 144 —

1.3 any drop in voltage, or complete failure, o f the m ain power supply to the auto-alarm equip­
ment that would seriously affect the proper functioning of the equipm ent and where suchwarning is not already given by other means;
2. that provision should be made for listening to the output of the auto-alarm receiver;
3. that the proper functioning of auto-alarm installations should be checked periodically bylistening to signals on the auto-alarm receiver, with its norm al antenna connected, andby observing similar signals received on 500 kc/s on the ship’s main receiving installations;4. that measures should be taken to ensure th at the auto-alarm antenna is always in goodcondition;
5. that the design of auto-alarm equipment should be as simple as possible, consistent withreliable and efficient operation;
6. that, wherever practicable, measures should be taken to perm it reception on the auto-alarm
installation when the radio direction finder is being used;
7. that live test transm issions of the radiotelegraph auto-alarm signal should not be made.

R E C O M M E N D A T IO N 257 *SELECTIVE CALLING DEVICES FOR USE IN THE INTERNATIONAL VHF(METRIC) MARITIME MOBILE RADIOTELEPHONE SERVICE(Question 271 (X III))The C.C.I.R.,(Los Angeles, 1959)

C O N S ID E R IN G(a) that selective calling from coast stations to ship stations would expedite handling o f traffic,
particularly in public correspondence services;(b) that a selective calling system is faster and m ore positive than calling by voice;(c) that it overcomes the disadvantage and annoyance caused by vessels being required to listen
to all calls;(d) that it permits concentration of aural watches on the safety and calling channel 156-80 M c/s;(e) that a selective calling system is not subject to language difficulties;
U N A N IM O U SL Y RECO M M E N D S

1.

that a selective calling system for the international V H F maritime mobile radiotelephoneservice be standardized as soon as possible;

2.

that this selective calling system should have an international num bering system for such
public correspondence services;3.

that the system and the num bering plan should be capable o f providing a sufficient num berof individual non-conflicting codes;

4.

that the bandw idth required for the transm ission o f the code signals should n o t exceed the
maximum permissible emission bandw idth specified by regulations governing the maritim eservices;* The reference to the Radio Regulations has been inserted subsequently.

— 145 —Rec. 257, 258

5.

th a t the time required to select and transm it the code signal should be of the shortest possible
duration consistent with reliable operation;

6.

th at the system should be capable of satisfactory operation, with signal-to-noise ratios atleast equivalent to the minimum acceptable for satisfactory two-way speech transm ission;7.

th at the individual signalling com binations m ust be sufficient for adequately identifying
ships using selective signalling, considering that it might be possible to repeat codes in suffi­
ciently separated geographic areas, taking into account ships’ itineraries;

8.

th at the selective signalling, at any given coast station, should n o t be limited to vessels regularly
using that coast station. The numbering system should be planned so as to m ake thisunnecessary;

9.

th at the num ber code, assigned to a ship, should be distinctive and should be perm anently
associated with th a t ship;

10. th at the call should no t be prefixed by a long dash or other special signal, to attract attentiono f vessels n o t fitted with a selective calling device, as such calls should be m ade, preferably,on the frequency o f the com m on calling and safety channel 156-80 M c/s;
11. th a t the attention o f A dministrations should be draw n to the desirability o f their reaching
agreement upon the channel, or channels, th at should be used for selective calling. A ttention
should also be draw n to N ote 8 of Annex 1 of the Agreement on the international V H F m aritim e mobile radiotelephone service (The Hague, 1957) (see also Nos. 1214, 1361 an d 1362 o f theRadio Regulations, Geneva, 1959).

RECOMMENDATION 258 *SINGLE-SIDEBAND AERONAUTICAL AND MARITIME MOBILERADIOTELEPHONE EQUIPMENTS(Question 162)
The C .C.I.R.,(Los Angeles, 1959)

C O N S ID E R IN G

( a) th at the m ain advantages of single-sideband w orking (SBB), as com pared with double-side­band (DSB), for mobile radiotelephony, are as follows:
a.a reduction of bandw idth required per channel;
a.b increase in signal-to-noise ratio or, alternatively, reduction in transm itter pow er (and hence
antenna voltage), for the same signal-to-noise ratio, improvements dependent upon the degreeo f carrier suppression;a.c reduction of the type of distortion th at is due to selective fading;a.d reduction of interference, particularly that due to beat notes, between carriers dependent on
the degree o f carrier suppression;a.e reduction o f interference, due to cross-modulation between adjacent channel transm issions;(b) th at the disadvantages of SSB com pared with DSB for mobile radiotelephony, are as follows:* This Recommendation terminates the study of Question 162.
subsequently.

The references to the Radio Regulations have been inserted

— 146 —Rec. 258

b.a m ore rigorous requirem ents for-transm itter and receiver frequency stability;
b.b greater complexity of apparatus;
b.c higher prices of the equipm ent;b.d higher m aintenance costs for the equipm ent;b.e impracticability o f conversion of existing mobile DSB equipments for SSB operation;b . f D oppler effects, th at are significant for very high-speed mobile units;(c) that the M F-radiotelephony bands, used in the m aritime services (i.e. world-wide 1605 to
2850 kc/s and additionally, in Region 1, 3155 to 3800 kc/s):
c.a include the international calling and distress frequency 2182 kc/s;
c.b are shared with fixed services;
c.c are used by m any low tonnage ships, some compulsorily and others voluntarily fitted exclusively
with DSB M F-radiotelephony equipm ents;(d) th at the parts of the H F bands (i. e. 4000 kc/s and 23 000 kc/s for mobile maritim e and2850 kc/s to 24 000 kc/s for aeronautical use), allocated to the respective services;
d.a do not include any international distress frequency;
d.b are exclusively allocated to these services;( e) th at in the m aritime mobile services, the advantages of SSB operation predom inate over the
disadvantages to a greater extent in the H F than in the M F band;(f)that, in the m aritime mobile services, in the interests o f
safetyof life at sea, the introductionof SSB operation should not be allowed to discourage the extension of voluntary fitting of
DSB M F-radiotelephony equipm ent;
U N A N IM O U S L Y R EC O M M E N D S

1.

for the m aritim e mobile services (see also Appendices 15 and 17 to the Radio Regulations,Geneva, 1959, and Recom m endation N o. 28 o f the Adm inistration R adio Conference, Geneva,
1959);

1.1 th at SSB operation be introduced as far as operationally required in the M F and H F radio­
telephony bands;
1.2 th at coast stations be prepared to com municate w ith DSB and SSB shipborne equipm ent;
1.3 th at for SSB equipm ent the following technical characteristics be em ployed:
1.3.1 for an interim period the degree o f carrier reduction should be 16 to 26 db below thepeak envelope pow er and every endeavour should be m ade to achieve a carrier suppres­sion of at least 40 db as soon as possible;

1.3.2 the carrier frequency of the transm itters should be m aintained w ithin the following
tolerances:
1.3.2.1 forcoast stations ± 20 c/s;
1.3.2.2 forship stations the short-term limits (ofthe order of
15 min.) sh± 40 c/s *;1.3.2.3 forship stations long-term limits of ± 350
c/s (in the 8,
12, 16 andbands) and ± 100 c/s (in the 2 and 4 Mc/s bands) shouldbe perm itted for aninterim period and every endeavour should be m ade to achieve limits of± 1 0 0 c/s as soon as possible in all bands;
1.3.3 the carrier frequency stability o f SSB receivers should be m aintained within the follow­
ing tolerances:
1.3.3.1 for coast stations ± 20 c/s;
1.3.3.2 for ship stations the short-term limits should be ± 40 c/s *;* T h is value m ay be m a in ta in ed eith er m a n u ally o r b y o th e r m eans.

— 147 —Rec. 258

1.3.3.3 if spot frequency (i. e. fixed frequency pre-tuned) shipborne receivers are used,
long-term limits of ± 350 c/s should be perm itted for an interim period andevery endeavour should be m ade to achieve limits of ± 100 c/s as soon as
possible;
1.3.4 the upper sideband should be used (see Appendix 15, Section B and A ppendix 17 o f theR adio Regulations, Geneva, 1959);
1.3.5 the channel arrangem ents should be such, that two SSB channels are accom m odated
within each existing DSB channel and the bandw idth of the SSB emissions should be
kept within such limits as will perm it this to be done (it is proposed th at the precise
arrangem ent of these SSB channels should be further discussed at the A dm inistrative
R adio Conference);
1.3.6 the transm itter audio-frequency band should be 350 to 2700 c/s, w ith a perm itted
am plitude variation of 6 db;
1.3.7 the unw anted frequency m odulation of the SSB carrier should be'sufficiently low toprevent harm ful distortion;
1.3.8 in the M F m aritim e mobile radiotelephony bands, SSB ship stations should be able
to insert a carrier at a level sufficient to perm it satisfactory reception by DSB receivers
when com municating with DSB stations;1.3.9 in the particular case of transm issions on the radiotelephone calling and distress fre­quency 2182 kc/s, all transm issions should be m ade either by DSB, or by SSB, withcarrier insertion sufficient to perm it satisfactory reception by DSB receivers;
1.4 th at the attention o f A dm inistrations should be draw n to the fact that, there w ould be techni­
cal and operational advantages in designating certain frequencies for international com m onuse fo r ship-shore and inter-ship w orking;2. th at for the aeronautical mobile service, the Director, C.C.I.R. should:
2.1 formally acquaint the I.C.A.O. of the interest of the C .C.I.R. in the study o f SSB
working in the aeronautical and m aritim e mobile services;
2.2 invite the I.C.A.O. to advise the C.C.I.R. of any technical or operational problem s onwhich they would like the assistance of the C .C .I.R .;2.3 offer to keep the I.C.A .O . inform ed of progress made by the C.C.I.R. in the study of
the application of SSB working in the m aritim e mobile services;
2.4 request the I.C.A.O. to keep the C.C.I.R. inform ed of progress m ade by the I.C .A .O . inthe study of the application of SSB working in the aeronautical mobile services.

I

Rec. 422

— 148 —

RECOM M ENDATION 422 *PULSE TRANSMISSION FOR RADIO DIRECTION-FINDING(Question 61)
The C.C.I.R.,(London, 1953 - Geneva, 1963)

C O N S ID E R IN G(a) th at certain studies, extending over m any years, of the errors of direction finders show that,
under ideal conditions of site, equipm ent and operation, the use of pulse transmissions offers
only a slight improvement in accuracy over the use of continuous-wave transm issions;(b) that, in practice, unavoidable departures from the ideal conditions referred to in (a) would
tend to reduce this improvement in accuracy;(c) that pulse transm issions occupy wide bandw idths;
U N A N IM O U SL Y R EC O M M E N D S

that the use of pulse transmissions for radio direction-finding at frequencies below 20 000 kc/s
is generally undesirable.
ANNEX
The following errors in high-frequency direction finding can occur:
1.

observational errors introduced by the operator;

2.

instrum ental errors, including polarization errors and those due to deficiencies of the direc­
tion-finder site;

3.

errors due to radiation scattered from topographical features many wavelengths distantfrom the direction finder;

4.

errors due to lateral deviation in the ionosphere;

5.

errors due to wave interference caused by convergence of rays and by different modes of
propagation.
The advantage of a pulse emission over a continuous-wave emission lies in its ability toallow signals arriving over different paths to be separated, and so to reduce errors arisingfrom sources 4 and 5 above.
The degree of accuracy to be expected from the use of pulse emissions for radio direction
finding has been studied, and it is estim ated th at in m ost favourable circumstances, for afrequency of about 8000 kc/s, the standard deviation of a single rapidly observed bearing might
be about 3° for a continuous-wave emission and about 2° for a pulse emission. The corre­
sponding figures for the mean of ten such bearings taken in a period of five minutes are:continuous-wave 2-5°, pulse 1-7°.

* This Recommendation replaces Recommendation 126.

— 149 —Rec. 423

RECOM M ENDATION 423 *USE OF 8364 kc/s FOR RADIO DIRECTION-FINDING.
(Q uestion 21)
The C.C.I.R.,(Geneva, 1951 - W arsaw, 1956 - Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) Nos. 994, 997 and 1179 o f the Radio Regulations, Geneva, 1959;(b) th at land stations will, when the appropriate portions of Article 32, Section V of the R adio
Regulations, Geneva, 1959, become effective, keep watch during their service hours on theband 8356 kc/s to 8372 kc/s; of which 8364 kc/s is the centre;(c) th at Regulations 12 and 13 of Chapter IV of the Safety of Life at Sea C onvention (London,1960) indicate m inimum specifications for autom atic distress transm itters;(d) th at tests and operational experience have shown th at radio direction-finding at 8364 kc/s
may be a valuable aid (in conjunction with direction-finding at 500 kc/s), in finding theposition of both aircraft and ships in distress and survival craft;(e) th a t complete coverage cannot be obtained with direction-finding on only one frequency in
the H F (decametric) band because o f the lim itations caused by radio propagation conditions;(f) th at H F (decametric) radio direction-finding requires apparatus as free as possible from local
site error and polarization error;(g) th at the accuracy of the bearing will depend upon the field strength of the signal and thesignal/noise ratio;(h) th at in view of the rapid variation of the apparent azim uth of the bearing which is frequently
observed in H F (decametric) radio direction-finding, measurements should be m ade over several
minutes to obtain a m ore accurate m ean bearing; and th at the bearing and fix may be
improved subsequently by a further series of m easurem ents;(i) th at standardized distress transm issions are desirable;(j) that it is essential to have a means of rapid com m unication between the watch-keeping stationand the direction-finding stations;U N A N IM O U SL Y RECO M M E N D S

1. th at the site of the H F (decametric) radio direction-finding station should be, as far as possible:
1.1 flat and horizontal for a radius preferably of at least 200 m, with the surrounding neigh­bourhood flat and free from obstruction;
1.2 of high and uniform ground conductivity;
1.3 free from large metallic masses and objects likely to resonate at frequencies near to 8364 kc/s;
2.

th at the antenna system should be as free as possible from wave polarization erro r (e. g. A dcock
systems and spaced-loop systems);

3. th at the bandw idth of the direction-finding receiver, used when bearings are taken, should be
as narrow as possible, com patible with the m odulation and frequency stability of the signal
on 8364 kc/s, and that a broader bandw idth position should also be incorporated in thereceiver for watch-keeping purposes;
This Recommendation replaces Recommendation 252.

Rec. 423

— 150 —

4.

that the sensitivity of the direction-finding equipm ent should be such that it operates satis­
factorily with a field-strength as low as 5 jjiV/m;5.

that the bearing should be determined by an aural-null m ethod or by any other m ethod ofcom parable or better accuracy;

6.

th at the direction-finding equipm ent should be adjusted, balanced and calibrated at frequentintervals a t the frequency o f 8364 kc/s;

7.

that the signal radiated by survival craft should be as strong as possible and stable in frequency
to ensure the greatest accuracy in determining the bearings;

8.

th at the signals transm itted by survival craft should preferably include long dashes sent overa period of not less than five minutes for direction-finding purposes. The attention of Admi­
nistrations should be drawn to the precise form and content of such signals proposed by
France, U.S.A. and U nited Kingdom, given in Doc. 39 (France), 43 and 99 (U.S.A.) and44 (U nited K ingdom ) of Geneva, 1951, and to the question of whether it would be desirable
to use a com m on form of signal for both 500 kc/s and 8364 kc/s;

9.

that, to give as great accuracy of fix as possible, several widely-spaced and interconnected
direction-finding stations should be employed (see Annex);

10. th at the attention of A dm inistrations concerned should be drawn to the advantage of theirstudying further:
10.1 the m ost suitable type of netw ork for providing rapid com m unication between directionfinding stations and plotting centres;
10.2 the m ost suitable way in which inform ation should be exchanged between different stations
or networks (e. g. use of “ Q ” code);
10.3 the best way to evaluate the m ost probable fix (position) from bearings supplied by the
direction-finding stations;11. th at the attention of Adm inistrations should also be drawn to the fact th at world-wide direc­
tion-finding coverage cannot be obtained with only one frequency in the H F (decametric)
band.

ANNEX
A C C U R A C Y O F B E A R IN G S A T

8364 k c / s

A t distances greater than about 1200 km the root-m ean-square (r.m.s.) bearing error to
be expected with a m odern H F (decametric) direction-finding system is o f the order of 3° to 5°.
A t distances less than 1200 km the error progressively increases with decrease of distanceto values of the order o f 5° to 10°; at small distances, less than about 100 km, the error may
be even greater than 10°.
The above figures refer to the arithmetic m ean of bearings spread over an interval of not
more than about 10 min.

Rec. 424

— 151 —

RECOM M ENDATION 424 *BEARING AND POSITION CLASSIFICATION FOR DIRECTION-FINDING(Q uestion 159)
The C.C.I.R.,(Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) th at the procedure specified in Appendix 23, Section II, §§ 6 ,7 and 8, of the R adio Regulations,Geneva, 1959, refers particularly to the m aritime mobile radio direction-fipding service at
frequencies below 3000 kc/s;(b) th at there w ould be advantages in adopting an internationally agreed system for classifying
the accuracy of bearings and positions for all frequency b an d s;(c) th a t there w ould be advantages in adopting an internationally agreed type of signal for
direction-finding purposes;
U N A N IM O U S L Y R EC O M M E N D S

1.

th at a com m on system of classification of bearings and positions should be used in all frequency
bands;

2.

th at the accuracy of bearings should be classified as follow s:“ Class A ” : Probability of less than 1 in 20 th at the error exceeds 2°;“ Class B
Probability of less than 1 in 20 th at the error exceeds 5°;“ Class C
Probability of less than 1 in 20 that the error exceeds 10°;
“ Class D
Bearings whose accuracy is less than Class C;

3.

th at the accuracy of positions, determined from direction-finding bearings, should be expressedas Class N, where N is the error, or am ount o f uncertainty, in nautical miles, such th at the
chance that N is exceeded is 1 in 20;

4.

th at R eport 93, and the references below, should be used as a guide in determining the accuracyof bearings and positions by the objective (statistical) m ethod and the subjective (observational)
method, and the Annex to the R eport should be used as a guide to the accuracy o f bearings
to be expected from H F Adcock direction-finders;5.

th at signals for direction-finding purposes should include long dashes, each of at least 5 s
duration, but, where necessary, the direction-finding station should also be perm itted to
specify the type and duration of the signal.

B ib l io g r a p h y

1.

Ross, W. The estimation of the probable accuracy of high-frequency radio direction-finding bearings.
J.I.E.E., 94, Part III A, 15, 722 (1947).
2. Stansfield, R.G. Statistical theory of D.F. fixing. J.I.E.E., 94, Part III A, 15, 762 (1947).
3. B arfield, R.H. Statistical plotting methods for radio direction-finding. J.I.E.E., 94, Part III A, 15,673 (1947).
4. H opkins, H.G. D.F. plotting aid. Wireless Engineer, 33, 7, 173 (July, 1956).

* This Recommendation replaces Recommendation 253.

Rec. 425

— 152 —

RECOM M ENDATION 425 *TECHNICAL CHARACTERISTICS OF FREQUENCY-MODULATION VHF(METRIC) MARITIME MOBILE EQUIPMENTS(Q uestions 107, 161 and 164)
The C.C.I.R.,(W arsaw, 1956 - Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) th at Nos. 1359 to 1379 inclusive and A ppendix 18 of the Radio Regulations, Geneva, 1959,
stipulate the general procedure for the world-wide use by the international m aritim e mobile
service in the band 156-174 M c/s;(b) that the use of V H F (metric) equipm ents in the maritim e mobile service could reduce the useof M F (hectometric) m aritim e bands and thus tend to reduce congestion in these heavily
loaded bands;(c) th at the early introduction of the world-wide use of equipments operating at the frequency
156-8 Mc/s and other channels specified in Appendix 18 of the R adio R egulations, Geneva,
1959, could contribute to the safety of life at sea;(d) that it would be desirable to reach agreement upon essential technical characteristics forfrequency-modulated V H F (metric) radiotelephone equipments for use in internationalm aritime services to expedite the international use of such equipm ents;(e) that, in the inform al agreement on standardization of V H F (metric) channels for international
maritime radiotelephone services that was reached am ong certain countries during the Baltic
and N orth Sea Radiotelephone Conference, 1955 (see I.T.U . Circular letter 1683/55/R, dated
December 1955), it was considered that the equipm ent should employ frequency m odulation
and be capable of operating ultimately with a frequency spacing of 50 kc/s;(f) that, w ithout some further measure of agreement on channel allocations, it is n ot possible todecide all the technical characteristics needed to facilitate the design of equipm ent for inter­national V H F (metric) m aritim e mobile services;(g) that the International M aritim e V H F R adiotelephone Conference (The Hague, 1957), hadagreed am ong other m atters, upon a frequency allocation table using 4-6 Mc/s separation for
duplex operation in the V H F international m aritim e mobile radiotelephone service;U N A N IM O U SL Y R EC O M M E N D S * *1.

that the following characteristics for frequency-modulated V H F (metric) radiotelephoneequipments for the international m aritim e mobile services operating at 156-8 M c/s andother channels specified in A ppendix 18 to the Radio Regulations, Geneva, 1959, should
be adopted by A dm inistrations;
1.1 that, at present, the frequency deviation should n o t be greater th an ± 15 kc/s an d the
maximum deviation should be reviewed later if it is found in practice th at unacceptableadjacent channel interference occurs, particularly as the loading of the channels increases;
1.2 that all receivers should be capable of receiving satisfactorily emissions having a m axim um
deviation of ± 15 kc/s;

2.

that vertical polarization should be used;* T h is R eco m m en d atio n replaces R ec o m m e n d atio n 254.
** See also A ppendices 3, 4 an d 19 to th e R a d io R egulatio n s, G eneva, 1959.

— 153 —Rec. 425

3.

that, in the absence of fading and local screening, the protection ratio for com m on-channel
operation should be such th at the desired signal level exceeds the interfering signal level byat least 10 db. Each A dm inistration should provide for a further allowance, where appro­
priate, for fading and for fluctuations of a local nature (for instance, reflections from theterrain, sea, ships, docks, etc.);

4.

th at the equipm ent should be designed for a frequency separation between adjacent channelsof 50 kc/s;

5.

th at the frequency separation between the transm itting and receiving frequencies for duplex
working should be 4 6 M c/s;

6.

th at further study is required of means of selective calling. F o r this purpose reference ismade to Question 271 (XIII), R eport 320 and Resolution 19;

7. other essential param eters;
7.1 frequency m odulation with a pre-emphasis of 6 db/octave should be used (phase m odulation)with subsequent de-emphasis in the receiver;7.2 the output power of the ships’ transm itters should generally n o t exceed 20 w atts except in
special circumstances to be determ ined by individual A dm inistrations;
7.3 spurious emissions:7.3.1 the m ean power of spurious emissions due to harm onics of the carrier frequency should
not exceed 25 \j.W m easured at the antenna term inals of the transm itter when loadedwith a resistance equal to the nom inal antenna impedance;
7.3.2 the m ean power of spurious emissions falling in any other international V H F maritim emobile channel due to products of m odulation should n o t exceed 10 jaW, m easured
at the antenna term inals of the transm itter or receiver when loaded w ith a resistanceequal to the nom inal antenna impedance;
7.3.3 the m ean power output of any other spurious emission on any discrete frequency
within the international V H F m aritim e mobile band should not exceed 2-5 jj.W,
measured at the antenna term inals of the transm itter or receiver when loaded with aresistance equal to the nom inal antenna impedance;
7.3.4 in cases where Adm inistrations perm it exceptionally the use o f higher pow ered transm it­
ters, proportionate increases in the level of these spurious emissions may be permitted.
7.4 the audio-frequency bandw idth should be limited to 3000 c/s;
7.5 the frequency tolerance of the transm itter should not exceed 0-002%;
7.6 to minimize interference, special attention should be paid to the following receiver charac­
teristics :- stability,
selectivity,- receiver radiation,- interm odulation;
8.

equipments should be designed so that frequency changes between assigned channels can be
carried out rapidly, e. g., within a few seconds;

9.

th at care should be taken in the choice o f interm ediate frequencies for V H F receivers to avoid
interference from other services and, in particular, care should be taken to avoid interference
from other m aritime mobile services, especially those in the 500 kc/s and 2 M c/s bands.

Rec. 426

— 154 —

RECOM M ENDATION 426 *SPURIOUS EMISSIONS FROM FREQUENCY-MODULATED VHF(METRIC) MARITIME MOBILE EQUIPMENT(Question 161)
The C .C .I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) that spurious emissions from frequency-modulated V H F m aritim e mobile equipments arelikely to cause interference in the international V H F maritime mobile radiotelephone channels
if they are not adequately suppressed;(b) that such spurious emissions may be caused by:- harm onics of oscillators of transm itters and receivers,- m odulation products falling into other channels,- interm odulation products produced at receiving stations or generated at transm itting
stations,- interm odulation products caused by non-linear elements near the V H F transm itting or
receiving stations, especially when signals from two transm itters with a frequency spacingof 4-6 Mc/s are present,- parasitic oscillations,- transm itter noise;U N A N IM O U SL Y RECO M M E N D S

1. that for transm itters of the order of 20 W :1.1 the mean power of any spurious emission due to products of m odulation and falling in any
international V H F m aritim e mobile channel (other than the channel of the fundam ental
emission), should not exceed 10 tu.W measured at the antenna term inals of the transm itter or
receiver when loaded with a resistance equal to the nom inal antenna impedance;
1.2 the mean power of any other spurious emission on any discrete frequency within the inter­national V H F maritime mobile bands should n o t exceed 2-5 (A.W, m easured at the antenna
terminals of the transm itter or receiver when loaded with a resistance equal to the nom inal
antenna impedance;2.

th at where A dm inistrations permit, exceptionally, the use of higher pow ered transm itters,
proportionate increases in the level of these spurious emissions may be permitted.

* This Recommendation replaces Recommendation 255Jand R eport 113, and terminates the study of Q uestion 161.

Rec. 427

— 155 —

RECOM M ENDATION 427 *INTERFERENCE DUE TO INTERMODULATION PRODUCTS IN THE
VHF (METRIC) MARITIME MOBILE RADIOTELEPHONE SERVICE(Q uestion 164)
The C.C.I.R.,(Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) th at interm odulation products may cause serious interference in the operation o f the V H F
mobile maritime radiotelephone service;(b) th at interm odulation products may be generated and radiated at receiving stations andtransm itting stations, in the radio equipm ent itself or at external points (such as antenna
systems), where there is electrical non-linearity;(c) th at practical measures can be taken to minimize the generation of such interm odulation
products and to mitigate their harm ful effects;
U N A N IM O U SL Y R EC O M M E N D S

1.

th at Recom m endation 218, particularly §§ 3, 4 and 15, should be followed for the purposeof minimizing the generation of interm odulation products at points on ships external to thereceiver;2.

th at antennae, rigging, stays and structures, likely to cause interm odulation products, should bemaintained in such condition as to minimize the generation of interm odulation products;

3.

th at care should be taken, in the design and development of receivers, to minimize the possi­
bility of interference due to the generation o f interm odulation products in the receivers
themselves;

4. th at the range of interference, due to radiated interm odulation products, should be limited
to sea areas that are n o t norm ally navigated by ships and to shore areas th a t are clear ofcoast receiving stations;
5. th at the siting of coast stations should take into account the factors m entioned in § 4 above(see also No. 695 o f the R adio Regulations, Geneva, 1959);
6. th at frequency assignments in the V H F mobile m aritime radiotelephone band should, as far
as possible, take into account the possibility o f interference from interm odulation products(see also No. 695 of the R adio Regulations, Geneva, 1959);
7.

that where the service area permits, coast stations should use directive antennae (see also
N o. 695 of the R adio Regulations, Geneva, 1959);

8.

th at care should be taken in the use of the single-frequency channels to minimize interference,
due to interm odulation products, to the com m on calling and safety channel of 156-80 Mc/sand to the other channels specified in Appendix 18 to the Radio Regulations, Geneva, 1959
(see also No. 1363 of the R adio Regulations, Geneva, 1959);

9.

that frequency assignments to other services should, as far as possible, take into accountthe possibility of interference to the V H F mobile m aritim e radiotelephone service due to thegeneration of interm odulation products; in particular, powerful emissions from stations nearcoastal areas and with frequencies differing by about 4-6 Mc/s from one another, should be
avoided if possible.

* This Recommendation replaces Recommendation 256.

Rec. 428

— 156 —R E C O M M E N D A T IO N 428
D IR E C T IO N -F IN D IN G BY S H IP S IN T H E 2 M c/s BAND
(Question 206(XIII))The C .C .I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) that, according to the Convention for the Safety of Life at Sea, L ondon, 1960, the medium
frequency radiotelephony calling and distress frequency of 2182 kc/s will become of increasing
im portance to the safety o f life at sea;(b) that, in m ost distress cases, m erchant ships and fishing vessels and other surface craft par­ticipate in search and rescue;(c) that in addition to ships between 500 and 1600 tons gross tonnage, which are already required
to be fitted with medium frequency radiotelephone equipm ent if they do n ot carry medium
frequency radiotelegraph equipment, ships between 300 and 500 tons gross tonnage will also
be required to fit such equipment, in accordance with C hapter IV, Regulation 4 of the Conven­tion for the Safety of Life at Sea, London, 1960;(d) that a large num ber of ships of m ore than 1600 tons gross tonnage (which are compulsorily
fitted with medium frequency radiotelegraph equipment), are voluntarily fitted with medium
frequency radiotelephone equipm ent and th at the num ber o f such ships is increasing;(e) that the m ajority o f deep sea fishing vessels are fitted voluntarily with medium frequency
radiotelephone equipm ent;(f) th at an increasing num ber of ships are being fitted with direction-finding equipm ent capableo f taking bearings in the 2 Mc/s band;(g) th at direction finding and especially homing by ships is im portant in cases of distress;(h) th at Recom m endation 31 of the Convention for the Safety of Life at Sea conference, London,
1960, drew the attention of contracting governments to the studies being undertaken under
Question 206 (XIII) by the C .C .I.R .;(i) that technical studies in several countries have shown:i.a th at direction-finding, or at least homing, is usually possible in the 2 M c/s band on m any
ships;
i.bthat com pared with the problem s of direction-finding by ships in the lower parts of the m edium
frequency band, the m ain cause of error in direction-finding in the 2 M c/s band is re-radiationfrom various parts of the ships super-structures, masts, downleads, halyards, stays, derricks,
etc., and from other antennae;i.cthat errors caused by re-radiation effects, however, should be constant if the disposition andelectrical conditions of the re-radiators are constant and th at such errors can be taken into
account by calibrating the direction-finder;

i.d that direction-finding and hom ing is easier on board small ships than on larger ones, because
an increase in the size of ships and their super-structures, masts, etc., as given in i.b, leads toan increase of disturbing resonance effects;
i.ethat a reliable direction-finder calibration can be m ore readily obtained if it,is restricted to a
specific frequency such as 2182 kc/s, instead o f a wide frequency band;— 157i.f

Rec. 428

th at even where om nidirectional direction-finding, even on a specific frequency is difficult
or impossible (such as on board large vessels with strong re-radiation effects), hom ing will
nearly always be possible;
U N A N IM O U S L Y R EC O M M E N D S

1.

th at the following technical measures and precautions should be observed w hen installing
direction-finders capable of taking bearings in the 2 Mc/s band:

1.1 the antenna system, including the sense antenna, of the direction-finder should be erected as
far as possible away from any re-radiators;
1.2 the direction-finder antenna system should, preferably, be installed on the fore-and-aft lineof the ship;
1.3 if the direction-finder antenna system is fitted on a m ast, it should, preferably, be installed
symmetrically on top of the m ast and n o t to one side of it;
1.4 the effects caused by re-radiating antenna wires can be minimized by providing properly
located isolating switches for the antennae;
1.5 re-radiation from the rigging (e. g. stays, wire ropes, etc.) should be reduced by the insertiono f insulators such th at the resonant frequency of the longest portions is above the highest
frequency used for direction-finding;
1.6 the form ation of “ closed loops ”, e. g. by the rigging, should be avoided by inserting insulators
at appropriate points;
1.7 to avoid electrically-doubtful connections, the connecting points of movable parts o f the
rigging, and connections between masts and derricks, wire ropes, etc., should be short-circuited
as far as possible;2.

th at the following measures and precautions should be observed in the calibration o f direction­finders for the 2 Mc/s band:

2.1 the rigging, downleads, derricks, halyards, etc., should be in their sea-going positions;
2.2 any antennae that affect the direction-finder should, preferably, be isolated and other antennae
which cannot be isolated (for example, because of operational requirem ents), should be in thesame conditions as they will be when bearings are being taken at se a; the condition and electricalarrangem ent of all antennae should be noted on the direction-finder calibration ch a rts;
2.3 calibration should be carried out in an area well clear o f the shore and of other ships. If a
shore-based transm itter is used, calibration should be carried out on a line passing throughth at station and crossing the coast-line approxim ately at right angles. The transm itting
antenna should radiate vertically polarized waves from a single element, and care should betaken to avoid re-radiation from any object in the vicinity. The distance between the trans­
m itting antenna and the direction-finder should be great enough to avoid the calibration being
affected by the induction field of the transm itting antenna;
2.4 care should be taken to ensure that the direction-finder gives the correct sense on all bearings
and frequencies concerned;
2.5 the direction-finder calibration should, as a general rule, cover the full 360 degrees and, as
far as possible, should be m ade at sufficiently small bearing intervals (say, in steps of a few
degrees), to detect any sudden changes in the calibration curve (for example, re-entrant portions
where two or m ore different corrections exist for the same indicated bearing);
2.6 calibration at 2182 kc/s should be carried out at a frequency as near as possible to 2182 kc/s,
special attention being paid to N o. 1325 of the Radio Regulations, Geneva, 1959, and to the
avoidance of interference to established operations in adjacent channels;
3.

th at the calibration should be checked periodically, especially if the condition of the rigging,etc., has been altered since the last calibration;

— 158 —Rec. 428, 429

4. that on board ships equipped with a direction-finder, the frequency range of which includes the
2 Mc/s band, a calibration should be m ade to determine if the direction-finder could be used
w ithout modification for omnidirectional direction-finding, or at least for homing on thefrequency of 2182 kc/s;
5. that when Adm inistrations encourage the use of direction-finders on board ship, capable ofoperating in the 2 M c/s band, or at least on the international radiotelegraphy distress andcalling frequency of 2182 kc/s, they should also encourage the provision of suitable facilities
for the calibration of such direction-finder equipm ent;
6. that the D irector, C.C.I.R. should be invited to bring this Recom m endation to the attentionof the I.M .C.O. Reference is m ade to Recom m endation 31 of the Convention for the Safetyof Life at Sea, London, 1960;
7. that Adm inistrations should bring the above Recom m endations to the attention of those
responsible for the provision, installation, and m aintenance of direction-finders on ships;
8.

that Adm inistrations should continue the study of Q uestion 206(XIII).
ANNEX
W hen the above precautions and technical measures have been taken, under good condi­
tions an accuracy of about ± 2° can be attained in taking bearings in the 2 Mc/s band byreception of “ ground ” waves on board ships of less th an about 800 tons gross tonnage.
In unfavourable conditions, for example, when the ship is pitching and rolling, an accuracy of
about ± 5° can be obtained. On larger ships, the accuracy may be worse, but in m ost cases
it should usually be possible to use the direction-finder for hom ing purposes on 2182 kc/s.
Bearings taken by reception of skywaves, although variable in azim uth and sharpness, areuseful for homing into the ground wave range by utilizing their average value.

R E C O M M E N D A T IO N 429 *IN T E R F E R E N C E L EV EL O N T H E R A D IO T E L E G R A PH D IST R E SS
FR E Q U EN C Y(Study Program m e 171)
The C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) that the Safety of Life at Sea Conference, London, 1960, adopted the following Recom ­m endation (No. 27):
“ The Conference, recognizing that at present there is a tendency to increase the maximum
power of radiotelegraph installations, and this m ay lead to an increase in the interference
level of the radiotelegraph distress frequency, which may considerably im pair the use o f thisfrequency for safety purposes, recommends th at the International Telecom munication U nion
should be invited by the O rganization—(i. e. Intergovernm ental M aritim e Consultative
O rganization)—to consider w hat measures can be taken to prevent such an increase in theinterference level ” ;* This Recommendation concludes the study of Study Programme 171.

(b) the provisions o f the relevant Radio Regulations, Geneva, 1959;(c) the experience of coast station radio operators and ships’ radio officers;
U N A N IM O U SL Y RECO M M E N D S

1. th at the following measures should be taken to. reduce interference at 50Q kc/s;
1.1 messages prefixed by the Safety Signal, TTT, should be sent on a working frequency after an
initial announcem ent on 500 kc/s, in accordance with Nos. 1107 and 1492 of the Radio
Regulations, Geneva, 1959;
1.2 coast stations should use their working frequencies to reply to calls from ships on 500 kc/s,
in accordance with Nos. 1116 and 1117 of the Radio Regulations, Geneva, 1959;
1.3 coast stations m aking calls to ships on 500 kc/s should request ships to reply on their working
frequencies, as perm itted by Nos. 1023 and 1116 of the R adio Regulations, Geneva, 1959;
1.4 N o. 1092 of the R adio Regulations, Geneva, 1959, which forbids “ CQ ” calls to be m ade incongested areas, should be enforced by Adm inistrations;
1.5 greater use should be m ade o f the facilities provided under No. 972 o f the R adio Regulations,Geneva, 1959, for reducing power at ship stations, and coast stations as far as practicableshould use the m inimum necessary power, particularly at night, in accordance with N o. 694
of the R adio Regulations, Geneva, 1959;
1.6 steps should be taken by A dm inistrations to prevent unnecessary signalling on 500 kc/s,
particularly during distress, in accordance with Nos. 693, 1107 to 1113 inclusive, and 1445 of
the Radio Regulations, Geneva, 1959;
1.7 for Class A2 emissions on 500 kc/s the note frequencies used by various stations should, as far
as practicable, be spread over the range 450 to 1350 c/s;
1.8 prolonged calling on 500 kc/s by ships endeavouring to establish contact with distant coaststations should be avoided by greater use of H F channels or by relaying o f messages;
1.9 in areas where considerable use is m ade of 500 kc/s for calls and replies, the calling frequencies
assigned to coast stations should be spread over the band 497 to 503 kc/s in accordance with
N o. 1115 of the R adio Regulations, Geneva, 1959;
1.10 in Regions 1 and 3, the frequency of 512 kc/s may be used as a supplementary frequency forcalls and replies when 500 kc/s is being used for distress, in accordance with Nos. 1125 to1129 inclusive of the R adio Regulations, Geneva, 1959.

PAGE INTENTIONALLY LEFT BLANKPAGE LAISSEE EN BLANC INTENTIONNELLEMENT

Rep. 93

— 161 —R EPO R TS O F SEC TIO N D : M O BILE SERVICESR E P O R T 93 *H F (D EC A M ETR IC ) AND V H F (M E T R IC ) D IR E C T IO N -FIN D IN G
(Q uestion 159)
(W arsaw, 1956)
1.

Introduction
Two documents, 67 (U nited States of America) and 232 (U nited Kingdom), were subm itted
to the V U Ith Plenary Assembly in response to Question 106. A summ ary of these two docu­
ments, and of the discussion on them, is given below.
It was generally agreed that, whenever possible, the accuracy of bearings and positions andtheir classification, should be based on the probability concept.
The U nited K ingdom docum ent expresses bearing accuracies in the form of errors thatare exceeded on only 1 occasion in 20 and the U.S.A. docum ent gives the standard deviation
error. For ease of com parison of results, all accuracies have been expressed in a com m onform in this Report.

2. Accuracy of HF (decametric) bearings
The accuracy of H F (decametric) bearings depends principally upon the following factors:- type of direction finding (D F) equipment, for example, Adcock type,- type of site,- frequency,- range and signal strength,- ionospheric conditions, particularly diurnal variations,- am ount of interference,- num ber of bearings taken,- skill of the operator.
By day, the error which is exceeded on only 1 occasion in 20 (referred to subsequently
as the 95 % error), lies between about 3° and 10° for ranges of the order of 500 to 4000 km,
depending on the site, frequency, and whether a group o f bearings is taken or only one snap
bearing. M ore detailed data are given in the Annex. A t night, errors are somewhat greater,by am ounts of up to about 1°. A t distances less than 500 to 1600 km (depending on iono­
spheric conditions), the error progressively increases, and may rise to as large as 10° to 20°
until the ground wave or the E-layer mode of propagation predominates. In general, errors
are less at the higher frequencies.
3. Accuracy of VHF (metric) bearings
In the U nited Kingdom, the 95 % error of V H F aeronautical D F stations is generally
about 5°, but in the U.S.A. it has been found that the 95% error is usually about 12° on
transm issions from aircraft. The difference is probably due mainly to the effects of differences* This R eport was adopted unanimously.

— 162 —Rep. 93of siting, since with refinements in siting, the 95 % error is reduced to about 4° in the U.S.A.
A t long ranges, beyond the norm al service area, V H F-D F bearings in the U.S.A. have beenfound to be sporadic but the accuracy is sometimes as good as 6°.
4. Accuracy of HF (decametric) position fixing
The accuracy of position fixing depends principally on the “ geometry ” of the D F net­
w ork, its size and its disposition with respect to the transm itting station concerned, the degree
to which the various stations can take simultaneous bearings and act in unison, and thenum ber of stations in the network. The greatest accuracy is obtained when the m ost probableposition o f the transm itting station can be evaluated statistically, although in certain applica­
tions it is recognised that statistical evaluation may not be practicable or of operational
im portance. The accuracy of a D F fix can be expressed in terms of the size, position andorientation of the ellipse in which the transm itting station lies with a given probability.
Various methods for deriving and plotting probability ellipses are given in the referencesin Doc. 232 of Warsaw, 1956.
5. Accuracy of VHF (metric) position fixing
The accuracy of V H F position fixing can be determined in a m anner similar to that for
H F. But in the aeronautical service, which is one of the m ain users of V H F-D F, there is not
usually sufficient time to evaluate the accuracy of a fix because of the high speed of the aircraft.
A t V H F, the problem may be simpler than at H F because the D F networks, in general, will
be smaller and can more easily be controlled autom atically and have a central autom atic
display.
6. Classification of bearings in general
It was considered that it would be very advantageous to have a com m on classification
system of bearings for all frequency bands (M F, H F and V H F) and for all types of service, forexample, m aritime and aeronautical.
7. Classification of HF (decametric) bearings
The U.S.A. proposed a subjective m ethod of classification by the operator for describing
to the plotting centre the conditions under which a bearing has been taken. The factors thatthe operator should take into account are strength of signal, sharpness of the null, am ountof fading and interference, the am ount of goniometer swing required in taking the bearing andthe num ber of bearings that have been taken in the tim e available. The proposed system ofclassification is as follows:
Class A - Bearing appears g o o d , meeting the following requirem ents:
(1)
(2)
(3)
(4)
(5)
(6)

strong signal,
definite indication (sharp null, etc.),
negligible fading,negligible interference,less than 3° of arc of bearing swing,
observed repeatedly for an adequate period of time.

Class B - Bearing appears f a i r , being degraded by one or m ore of the following factors:
(1)
(2)
(3)
(4)
(5)
(6)

marginal signal strength,
blurr (blunting) of indication,fading and/or audio distortion,light interference,m ore than 3° but less than 5° of arc of bearing swing,short observation time.

Rep. 93

— 163 —Class C - Bearing appears p o o r , being degraded by one or m ore of the following facto rs:
(1)
(2)
(3)
(4)
(5)
(6)

inadequate signal strength,
severe blurr (blunting) of indication,
severe fading and/or audio distortion,strong interference,m ore than 5° of arc of bearing swing,insufficient observation time.

The U nited K ingdom proposed that the accuracy of a bearing should be evaluated statis­
tically from a knowledge of the five com ponent variances which m ake up the to tal varianceof the bearing, namely, instrum ental, site, propagation, random -sam pling and observational
components. The bearing would then be classified as follows:
Class A :Class B :Class C:Class D :8. Classification

Probability of less than 1in 20 that the error exceeds 2°,
Probability of less than 1in 20 that the error exceeds 5°,
Probability of less than 1in 20 that the error exceeds10°,
Bearings whose accuracy is less than that of Class C.
of VHF (metric) bearings

It was considered th at time alone prevents the classification of V H F bearings taken on
transm issions from aircraft and it is not possible for the operator to classify bearings. But the
U nited K ingdom suggested that it would be helpful if V H F aeronautical stations were classified,based upon flight-checking procedures.- All bearings would then be given the classificationof the station, unless they were taken under conditions inferior to those under which thestation was calibrated.
9. Classification of HF (decametric) position-fixesi

It was generally agreed th at the accuracy of a fix-position should, whenever tim e permits,
be given in term s of probability ellipses. The U nited Kingdom proposed th a t no formalclassification be adopted since the size and shape of the ellipse for a given probability depends
upon the “ geometry ” of the netw ork and the transm itting station, the ionospheric conditions,etc. W here time is im portant, the U.S.A. proposed th at the m ost probable fix position
would be given in degrees and minutes of latitude and longitude and should be classified
as the equivalent circle in which the transm itting station probably lies:
C lassification

L im it of area

G ood
F air
Poor
Estim ated

40 km, or less, radius
80 km, or less, radius
120 km, or less, radiusm ore than 120 km radius

10. Classification of VHF (metric) position-fixes
F o r the aeronautical service, it was considered th at classification in term s o f probability
ellipses was not likely to be practicable or useful. The U nited K ingdom m ade no proposals
on this point; the U.S.A. proposed the following classification:
C lassification

L im it of area

G ood
F air
Poor
Estim ated

4 km, or less, radius
8 km, or less, radius
12 km, or less, radiusm ore than 12 km radius

11. Aeronautical aspects
It was considered that since V H F-D F stations are widely used in civil aviation, Adminis­
trations should be invited to seek the advice of the International Civil Aviation O rganizationon all the aeronautical aspects of V H F direction finding and position finding.

Rep. 93

— 164 —

12. Type of signal for VHF (metric) direction finding
In general, the signal for V H F direction-finding purposes should include long dashes ofat least 5 seconds duration, but the D F station should also be perm itted to specify the durationo f the signal in certain circumstances. In the aeronautical service, the procedure laid downby the I.C.A.O. has been found satisfactory. This specifies two dashes of plain carrier, eachof approxim ately 10 seconds duration, followed by the call sign of the aircraft, unless anothersignal has been requested or is known to be required by the D F station.

ANNEX
A p p r o x im a t e

error

(in

d eg rees)T O BE EX CEED ED O N O N L Y

w h ic hmaybe

1 O C C A S IO N IN

expected20

Conditions: - H F Adcock direction finder- D aylight- Ranges between about 500 and 4000 km.

3 M c/sT ype of site

6 M c/s

9 M c/s

S ingle snap
b earin g

M ean of10 bearings
ta k en in
5 m inSingle snap
b earin g

M ean of10 bearings
tak en in
5 m inSingle snap
bearin g

M ean of10 bearings
ta k en in
5 m inVery good

7

6

6

5

6

4

Good, average

10

9

8

7

7

6

REPORT 317
PU B L IC A T IO N O F SER V IC E C O D E S IN U SE IN T H E IN T E R N A T IO N A L
T E L E G R A PH SER V ICE(R eso lu tio n 33)(Warsaw, 1956 - G eneva, 1963)1.

In conformity with the C.C.I.T. proposal (Doc. 471of W arsaw, 1956),
the separate volume
of codes to be published by the Secretary-General should contain the following d o cu m en ts:
1.1 Appendix 13, Section II to the R adio Regulations, Geneva, 1959: Miscellaneous abbreviations
and signals.
1.2 Appendix 16 to the Radio Regulations, Geneva, 1959.
1.3 Appendix 14 to the Radio Regulations, Geneva, 1959: Sinpo Code.
1.4

Appendix 14 to the Radio Regulations, Geneva, 1959: S i n p f e m o Code.

1.5 The Cable and Wireless Ltd. Facsimile R eporting Code.
1.6 C.C.I.T. Recom m endation H .l, Article 26: Code Expressions used in the International
Telex Service.
1.7 The International Telegraph Regulations.
1.8 Appendix 13, Section I to the R adio Regulations, Geneva, 1959: Q-code.
1.9 The Cable and Wireless Ltd. Service Code.
1.10 The Cable and Wireless Ltd. Z-Code.
2.

Remarks

2.1 The docum ents indicated under §§ 1.1 to 1.6 inclusive are to be included in the code bookw ithout any alteration, on the understanding, however, th at one item should be added tothe code under § 1.6, viz:
SVH Safety of life telex calland two items to the code under § 1.1, viz:
SLT Ship Letter Telegram
OL Ocean Letter
2.2 The docum ents summarized under §§ 1.7 to 1.10 inclusive are to be included in the code bookin p art only, as indicated below (see § 3).
2.3 The C .C.I.R. is of the opinion that in addition to the code docum ents m entioned above andproposed by the C.C.I.T. to be included in the code book, there exist one or two very im por­tant code docum ents which are not in the competence of the I.T.U ., but nevertheless, arewidely in use in the maritime mobile and aeronautical services, (e. g. (a) The International
Code of Signals, Vol. II and (b) Com m unication Codes and Abbreviations published by theInternational Civil Aviation Organization). However, their incorporation in the code bookwould m ake it too heavy and bulky and, in consequence, the C.C.I.R. proposes to the C.C.I.T.
th at only reference be made to them in the code book (see § 7.3).
3. Appendix 2 to Doc. 471 of Warsaw, 1956 (International Telegraph Regulations)
3.1 The C .C.I.R. is of the view that the suggestion made by the C.C.I.T. as to the p art of theInternational Telegraph Regulations to be inserted in the book should be accepted.
* This R eport, which replaces Report 90, was adopted unanimously.

Rep. 317

— 166 —

3.2 There is a possibility that the code words taken from the Cable and Wireless Service Coderesemble some aeronautical call signs, but this does n ot seem to be very serious as, to theknowledge of the C .C.I.R., no cases of confusion have ever arisen.
4.

Appendix 3 to Doc. 471 of W arsaw, 1956 (Q-code)

4.1 The five new code words put forw ard by the C.C.I.T. are acceptable. They have been notified
to A dm inistrations by the Secretary-General in his half-m onthly Notifications issued since the
A tlantic City R adio Conference.
4.2 The C.C.I.R. agrees to the C.C.I.T. suggestion to include only th at p art of the Q-code whichis reserved for all radio services (QRA-QUZ). The parts (QA A -QN Z and QOA-QQZ), which
are reserved for the aeronautical and m aritim e services respectively, should not be inserted.
This suggestion is also supported by the I.C.A.O.
5.

As to the Cable and Wireless Ltd. code and the Italcable code “ Dizionario delle Abbreviazioni Telegrafiche ”, Appendices 4 and 6 to the C.C.I.T. docum ent, respectively, the C.C.I.R.
has no comment. The Appendices should be accepted as they stand.

6.

Appendix 5 of Doc. 471 of W arsaw, 1956 (Cable and Wireless Ltd., Z-code)

6.1 This code, as stated in the last paragraph of § 8 of the C.C.I.T. docum ent, is widely used in
the fixed services.
6.2 Should, however, this Z-code be included in the code book, then the telegraph services will be
faced with the possibility of confusion with respect to the Z-series of call signs.
6.3 In view of the shortage of call signs, it would be out of the question to withdraw the Z series
from the Allocation Table of Call Signs, laid down in Article 19 of the R adio Regulations.
6.4 However, as far as the C.C.I.R. is aware, no such confusion has ever occurred in the past,very probably because of the Z-code being used in service messages only.
6.5 The C.C.I.R. therefore accepted the C.C.I.T. suggestion to include the Z-code on the under­
standing that the C.C.I.R. should re-examine the m atter if any confusion with Z-call signs
should arise in the future.
7.

Appendix 7 of Doc. 471 of W arsaw, 1956 (Arrangement of material within the code book)

7.1 In § 2 of A ppendix 7 of Doc. 471 of Warsaw, 1956, the C.C.I.T. suggested th at the book be
divided into three m ain sections.
7.2 Referring to § 2.3 o f this R eport, the C.C.I.R. accepted th at the code docum ents m entioned
there be inserted in the code book in a separate section.
7.3 As, however, they can be considered as belonging to the Miscellaneous Section (see section 4,
Appendix 7, Doc. 471 of W arsaw, 1956), it could be divided into two sub-sections, the firstsub-section containing S i n p o , S i n p f e m o , the Spelling analogy code and the Cable and WirelessLtd. Facsimile reporting code (§§ 1 and 2 of Appendix 7), and the second sub-section
containing a reference to codes not included in the book, e. g. the International Code of
Signals, Vol. II and the I.C.A.O. book on communication codes and abbreviations (see§2-4).
8.

Title of the code book
Taking into account the inclusion of codes relating to the telephone services and thereferences to non I.T.U . codes, the C.C.I.R. proposed th at .the C.C.I.T. suggestion concerning
the title (page 4, Doc. 471 of Warsaw, 1956) should be am ended as follows:“ Codes and Abbreviations for the International Telecom munication Services, publishedby the International Telecommunication U nion. ”

Rep. 317, 318— 167 —
9.

Unification
The C.C.I.R. is of the opinion th at it will be necessary for an operational need to beapparent and for operational experience to be obtained, before a study can be m ade of theunification of codes (see O pinion 20).

R E P O R T 318 *M A R IN E ID E N T IF IC A T IO N D EV IC ES(Q uestion 158)
(W arsaw, 1956 - Geneva, 1963)
1.

GeneralTwo documents, 53 (United K ingdom ) and 71 (U nited States of America), were subm itted
to the V H Ith Plenary Assembly in answer to Question 105 on th e identification of a response
on a m arine radar display.
This R eport summarizes the nature of the problem , the w ork that has been done, as
described in the two documents, and the m ain points arising out of the discussions at the
V IH th Plenary Assembly.

2.

Nature of the problem
There is a growing use of radar on ships to assist navigation and to prevent collision.
Ideally, it would be desirable for radar to give the navigator the same kind of inform ation
th a t he would obtain visually in clear weather. But, in the present state of rad ar development,
experience has shown that the rad ar inform ation might, with advantage, be supplemented
by additional inform ation, although there is not, as yet, uniform ity of opinion am ong thoseconcerned with m arine navigation, on the type of additional inform ation th at would be m ost
helpful to the navigator.
The radar installation on a ship gives, at any instant, only the bearing and position of theother ships. The course and speed of another ship by this means can then be obtained only
by plotting; and, in any case, the radar cannot give the future intentions o f the other ship.
This points to the need for an appropriate com m unication link as an element of any effective
m arine identification device employing the types of rad ar installation in current use.
A n identification device should be unam biguous and should be at least as good as theresolution of the associated radar, so th at there would be no confusion concerning the iden­tification of two adjacent echoes on the same bearing or at the same range. The additional
inform ation required, for example, m ight be the call letters of the other ship, so th at com m u­
nication could be established; or it might be the course and speed, or the aspect, of the othervessel.
So far, research has been directed tow ards the development of devices th at would identify
uniquely a particular echo of a ship on the radar screen of another ship or of a shore-based
station. Various proposals, e. g. the use of transponder techniques, have been given in thetwo documents m entioned and are described briefly in §§ 3 and 4.
* This R eport, which replaces R eport 92, was adopted unanimous.

Rep. 318
3.

— 168 —

Summary of Doc. 53 (United Kingdom)

3.1 Harbour radar identification
It was considered that suitable devices of the transponder type m ight facilitate the move­m ent of vessels in the approaches to a po rt or in a harbour, so th at the echo of the ship could
be identified on the harbour radar and com munication established as required. Identificationin range and bearing would be essential, so th at identification, by the use of norm al directionfinding (bearing only), would not norm ally be sufficient. There is less likelihood of confusion
in harbour radar identification, because ships would be identifying themselves to a single
harbour radar.
These transponder devices are used in conjunction with a radiocom m unication link
between the ship and the shore. On the ship either portable equipm ent or the ship’s own
radio installation may be used.
Portable radar transponders have been developed which operate in the 3 cm band of theharbour radar. The transponders, and, if necessary, the portable radiocom m unicationequipment, are taken on board the ship by the pilot. Identification is established by the
H arbour Controller requesting the pilot to switch on the transponder, when the response isseen on the harbour radar as a bright line on the bearing of the ship’s echo, with a gap,
corresponding to 1 mile range, commencing at the ship. T he ship is thus identified in range
and bearing. The range of the “ black-gap ” transponder is about 17 nautical miles.
This system would be suitable for use with any harb o u r radar operating in the 3 cm
band and no modification of the harbou r radar would be required.
A nother type of equipment has also been developed in which the output of a crystal
receiver is used to m odulate a V H F “ walkie-talkie ” transm itter which also serves to provide
com m unication with the shore. A t the harbour station, the V H F response from the ship is
fed into the video stage of the harbour radar. This gives a long radial echo along the bearingof the ship and commencing at a range slightly greater than the ship’s echo.
3.2 Inter-ship radar identification
The form er type o f transponder m entioned above would not be satisfactory for inter-ship
identification, because it might well be impossible to establish com m unication with a particular
unknow n ship to request that the transponder be switched o n ; and, moreover, ambiguity would
be unavoidable, when several independent identification processes were taking place on thesame channel.

4.

Summary of Doc. 71 (United States of America)

4.1 Doc. 71 (U nited States) of Warsaw, 1956, is based upon limited experience in the use ofm arine radar identification devices but also covers considerable study of the problem by the
R.T.C .M ., whose report thereon is attached to the docum ent cited as Annex 3. In sum m ary
it is observed that:
4.1.1 there are a num ber of technical m ethods for the identification of a rad ar response as
coming from a particular source. All known methods, however, require th at the source
have an active radar beacon to co-operate with the calling vessel. One solution might
be in the direction of a system similar to th at used by the military (IF F, Identification
Friend or Foe) and now coming into use for civil aviation in the U nited States of America
for identification of aircraft to airport radars.
4.1.2 In this type of system, each ship-borne radar should be capable of em itting a particularcalling or interrogating pulse or code. All vessels would m aintain a beacon on con­tinuous alert so that, on receipt of the interrogating pulse, each beacon would reply witha specific code identifying the vessel. This code, when displayed on the interrogating
vessel’s PPI adjacent to the rad ar echo from the vessel carrying the beacon, would
positively identify that echo. H aving identified all ships in the vicinity, a rad ar observer

— 169 —Rep. 318

could then contact any one of them directly by whatever com m unication m eans areavailable. Considerable experimentation has been carried out to realize a simplified
version of this method.
4.1.3 The use of a radar beacon system of the IF F type for marine identification would
require considerable expansion of the coding and display features o f any equipm ent
known to be currently available. It appears th at no attem pts to do this have as yet
been m ade in the commercial m arine field.
The relatively simplified technique where identification is obtained by energizing
the radar beacons one at a time in response to a dem and via a com m unications link,has been reduced to a practical m ethod and considerable related experim entation has
been carried out in connection with harbour radar installations. The feasibility ofthis system has therefore been dem onstrated, although the necessary beacons are notyet commercially available.
4.1.4 The principal practical aspect is, that there is no need to identify a particular rad ar echo
unless it is desired to com municate with the vessel associated with the echo. In narrowcongested waters this m ust be practically instantaneous. This seems to require aradiotelephone circuit connecting the observer of the ship-borne radar directly to his
counter-part on the bridge of the associated vessel. Ocean-going vessels, however,are not generally equipped with such means of com munication. Further, the multiple
language problem requires consideration in any international study of this subject.
The G reat Lakes area of N o rth America, where nearly all m erchant ships are fittedwith radar and radiotelephone and navigators speak the same language, is an outstanding
exception. Operational investigations of ship-to-ship identification devices have been
carried out therefore only in this area.
4.1.5 The num ber of vessels involved poses a technical difficulty in adapting an IF F system
for marine use, if each vessel were to have a distinct identifying code.
4.1.6 A system of the IF F type in its present form, due to its cost even in a comparatively
simple version, presents an economic factor of im portance. The complexity of the
microwave com ponents which contribute m ost to the cost of such equipm ent would be
double that required for prim ary radar alone. The economic factor, however, willundoubtedly be eased as time passes and new technical developments occur, as they
have, for instance, in the field of television.
4.2 A num ber of different types of devices or methods suggested for accomplishing identificationo f a positive or limited nature are outlined in the R .T.C .M . study referred to above. These
include:- responder beacons of various design,- passive devices,- D F identification using radar antennae,- suggestions other than identification.
F or further details on such types of devices, see Annex 3 to Doc. 71 (Warsaw).

5.

Discussion of documents
The discussion of the docum ents has brought out certain im portant differences in inter­ship identification and shore-based radar identification. In the form er case, after the identityof the unknow n ship has been established, there may well be difficulty in establishing com ­munication because of differences in language, type of radio installation and watch-keeping.
A t present, there is no international code on navigational manoeuvres, and “ navigation bycom munication ” would probably necessitate revision of the International Rules for thePrevention of Collision at Sea; it would probably raise new legal problem s, if, for example,
a ship were involved in a collision while executing a manoeuvre agreed in advance with anothership. On the other hand, the type of identification which is employed for h arb o u r control

Rep. 318

— 170 —

does not usually involve such difficulties beacuse the ship has on board a pilot who is receiving
advice from, and may com m unicate with, his own harbour radar station. R apid identificationis also very desirable in all such devices.
An inter-ship identification system would only become effective when the m ajority ofships were suitably equipped; and it should be borne in mind that the ship does not receive
any direct benefit from its own identification device. Thus, ships which themselves do notcarry radar are not likely to fit identification devices, particularly if the cost o f the device iscom parable with that of a radar installation.
6.

Future work
It was generally agreed in the discussions th at it would be m ost desirable for the C.C.I.R.
to obtain from responsible shipping and adm inistrative authorities, their views on the navi­
gational requirem ents th at should be m et by rad ar identification devices. However, at the
IX th Plenary Assembly, Los Angeles, 1959, the responsible authorities had not, in fact,advised the C .C.I.R. of any operational requirem ents for such devices and consequently thestudies were term inated.
B ib l io g r a p h y

1. P h i l l i p s , E.C. Marine traffic coordination. NFAS-ION-RTCA-RTCM Assembly, New York (Sep-'
tember, 1950).
2. J a n s k y , Jr., C.M., J a n s k y and B a i l e y . The retarded state of the science of marine navigation. IONRTCM-Assembly, New York (September, 1950).
3. Merchant Marine Council Proceedings (September, 1951).
4. W y l i e , F.J. The use of radar for preventing collisions at sea. Radio Advisory Service, Journal o f
the Institute o f Navigation (British), 6, 271 (1953).
5. W y l i e , F.J. Use of radar to avoid collision. Radio Advisory Service, Lloyds List & Shipping Gazette(January 5, 1954).
6. M i l w r i g h t , A.P.L. A beacon for ship identification. Royal Naval Scientific Service, Journal o f theInstitute o f Navigation (British) (April, 1954).
7. I s b i s t e r , E.J. and G r i s w o l d , W.R. Shore-based radar for harbour surveillance. Sperry Gyroscope Co.,Electrical Engineering, 71, 12, 1072-77 (December, 1952).
8. P h i l l i p s , E.C., NFAS and I s b i s t e r , E.J. Marine identification. Sperry Gyroscope Co., RTCM Spring
Assembly Meeting, New York (May, 1952).
9. Shore-based radar for New York harbor, a report, Port o f New York Authority (August, 1953).
10. H a r p e r , R.B. Pilot boat identification, harbor radar systems. Sperry Gyroscope Co., Paper presented
before Western Regional Meeting, Inst, o f Nov., Los Angeles, January 23,1954, published in Navigation.
11. Symposium papers, of the panel “ Radar plus what ”, delivered at RTCM Assembly Meeting, Boston,
Mass., 56-70 (October 13-15, 1954).
12. R o b e r t s , A. Radar beacons. M IT Rad. Lab. Series, Vol. 3, McGraw Hill (1947).
13. I s b i s t e r , E.J. RADENT beacon evaluation trials. Fall Assembly Meeting, RTCM, Chicago (1953).
14. S t o c k m a n , H. Communication by means of reflected power. Proc. IR E 36, 1196-1204(October, 1948).
15. RAMARK beacons, U.S. Coast Guard.
16. I s b i s t e r , E.J. and B u s b y , J.W. RAMARK beacons. Sperry Gyroscope Co., Navigation, 2, 357(June, 1951).
17. MICROWAVE POLARIS, U.S. Coast Guard.
18. You may have the answer. Merchant Marine Council Bulletin, U.S. Coast Guard (September, 1953).
19. Unpublished paper of Earl D. G r a y , McKeel Machine Co., Phila., Pa.
20. AUDAR Technical Bulletin, Radio Industries Corp.
21. K a m d r o n , Capt. R. Janus course broadcasting instrument (Bulletin), Seattle, Washington.
22. Marine identification problem, final report, Special Committee, No. 16, Radio-Technical Commission
for Marine Services, Washington, D.C. (See also Annex 3, Doc. 71 of Warsaw, 1956.)

— 171 —Rep. 319

R E P O R T . 319 *CHARACTERISTICS OF EQUIPMENT AND PRINCIPLES GOVERNING
THE ALLOCATION OF FREQUENCY CHANNELS IN THE VHF(METRIC) AND UHF (DECIMETRIC) LAND MOBILE SERVICES(Q u estio n 163(X III))(Geneva, 1963)
1.

Contributions relating to Question 163(XIII) have been received as follows:

1.1 Documents o f Los Angeles, 1959 :Docs. X III/4 (New Zealand), X III/2 and XIII/11 (F. R. of Germany), X III/30 (Japan),
XIII/32 (United Kingdom) and 180 (Sweden).
1.2 Documents o f Geneva, 1963 :Docs. XIII/1 (F. P. R. of Yugoslavia), X III/4 (Greece), X III/10 and 259 (P. R. of Poland),X III/24 (F. R. of Germany) and 222 (Australia).
2.

The technical inform ation contained in these contributions is given in the A nnex to thisR eport. These data are arranged in the table in the order of the geographical relationship ofcountries. It appears from this inform ation th a t it is difficult at present to reach complete
international standardization of the perform ance characteristics of land m obile equipm ent
operating in the V H F and U H F bands. However, it is desirable th at countries with com m onborder areas should reach agreement on some com m on characteristics, which w ould be helpfulin planning for the land mobile services.

3.

Some inform ation concerning interference between mobile services and broadcasting services
is given in the Final Acts of the Special Regional Conference, Geneva, 1960.

4.

Resolution 20 invites A dm inistrations to continue to send details of perform ance specifications
and also to send details o f practices for the allocation of channels in the V H F and U H F land
mobile services in operation in their respective countries to the C.C.I.R. for circulation.

5.

The study of Question 163 (XIII) should be continued.

* This Report, which replaces R eport 114, was adopted unanimously.

— 174 —Rep. 320

REPORT 320 *SELECTIVE CALLING DEVICES FOR THE INTERNATIONALMARITIME MOBILE RADIOTELEPHONE SERVICES(Question 160 and Study Programme 168)
(Geneva, 1963)
1.

Study Program m e 271A(XIII) states that Recom m endation 257 does n ot give a full reply to
Question 160 (Warsaw, 1956) and the trials of selective calling systems, described in Los
Angeles Docs. XIII/10, X III/18, X III/26 and Doc. 189, should be carried out with a view tocoming to a decision on the type of system th at should be adopted internationally.
The A dm inistrations of the Federal Republic of G erm any and the U.S.A. have carriedout com parative tests. Reference is m ade to Docs. 229 and 235 of Geneva, 1963.

2.

Study G roup X III has studied in great detail, during the session of the X th Plenary Assembly,
the results of these tests and has also taken into consideration Docs. X III/6, 8, 9, 11, 15, 19
and 21 of Geneva, 1963.

3.

Study G roup X III has come to the conclusion th at it is im portant th at the principal operational
and technical characteristics of a world-wide m aritim e selective calling system should bestandardized as soon as possible.
N o decision can be taken at present regarding the selective calling system to be adopted
on a world-wide basis and further tests including tests under practical operating conditions
should be made by Administrations.
Account was taken of the fact that different national selective calling systems, already inoperation on a limited scale, may expand in the absence of early international agreement and,for economic reasons, preclude international standardization.
To expedite agreement on a world-wide basis, the studies m ust be continued without
delay and attention is draw n to Resolution 19.

4.

The discussions during the X th Plenary Assembly have made it clear th at all selective callingsystems tested by the A dm inistrations of the Federal Republic of Germ any (Doc. 229) andthe U.S.A. (Doc. 235) are capable of operating at V H F-(F 3 operation).

5.

Question 271 (XIII) and Study Program m e 271A(XIII) require the determ ination of thetechnical characteristics for a selective calling device for use in the m aritim e V H F band only.
However, the view has been expressed in Docs. XIII/8, 15 and 21 of Geneva, 1963, th at it
would be advantageous for the world-wide selective calling system to be suitable also for
operation in the m aritime M F and H F bands, having regard to the probable additional
requirem ent for SSB, operating in accordance with Recom m endation 258.

6.

The tests, to be carried out by A dm inistrations in accordance with Resolution 19 have, there­
fore, to include the operation of selective calling systems, using classes of emission F3 at
V H F and A3, A3H, A3J at M F and H F. Interference, atmospherics and fading may impair
the reliable operation of any system. Tests should, therefore, take account of these factors.

7.

W ith A3J emissions, the frequency of the tones received may differ from those transm itted by
the coast stations, since the reintroduced carrier of the receiver on board ship may not exactly* This R eport was adopted unanimously.

— 175 —Rep. 320m atch the corresponding frequency of the suppressed carrier of the coast station transm itter.
This may be to the disadvantage of any selective calling system, which depends for its operation
on circuits which are very frequency-selective.
Consequently, doubt has been expressed during the discussions whether or n o t a selective
calling system depending on highly frequency-selective elements such as vibrating reed relays
will operate reliably on class A3J emissions in accordance with Recom m endation 258.
8.

The duration of the selective calling signal is of importance.
A signal of long duration or with m any signal elements may be m ore vulnerable to m utila­
tion by fading (e. g. sudden drop of field-strength), interference or atmospherics, than a short
signal or one with fewer signal elements.

9.

A system with a constant num ber of signal elements for each code might have an advantage
over a similar system with a variable num ber of signal elements, if the design of the au to ­matic receiving selector for the form er system includes a device to count the num ber o fsignal elements, thus providing additional protection against false calls.

10. The requirem ents of the tests to be carried out by Adm inistrations according to R esolution 19,
may be summarized as follow s:
10.1 As far as possible, the tests should be extended to the classes of emission:
F3 in the maritime .VHF band,
A3, A3H, A3J in the maritim e M F and H F bands.
10.2 Tests should also be carried out under practical operating conditions, including the effectsof fading, interference or atmospherics, and the reports should contain inform ation withregard t o :10.2.1 Reliability tests (ratio of calls received to calls transm itted), for high and low fieldstrengths;
10.2.2 Im munity against false calls (ratio of false calls received to calls transfnitted), causedby such phenom ena as speech m odulation, interm odulation, etc.;
10.2.3 A n indication of the complexity of the different receiving selectors, such as num ber oftubes, transistors, relays, and frequency-selective elem ents; also whether any com ponents
used are special or critical, especially as regards adjustm ent and m aintenance;
10.2.4 A n indication of the relative cost of typical equipm ents tested should, as far as possible,
be given.
11. Doc. XIII/19 (U.S.A.), of Los Angeles, 1959, contains a contribution on the subject of anum bering system for selective signalling in the m aritim e mobile services.
From the discussions during the X th Plenary Assembly, the conclusion was reached thata selective calling system, with a capability of approxim ately 60 000 individual signalling com ­binations, would be adequate.
Ships normally engaged on international voyages should, where required, be allocatedone individual code permanently assigned to that ship and this code should n o t be given to
any other ship to which the same calling channel has been assigned. A llocationo f codes toships normally engaged on voyages of a domestic nature could be done on a shared basis.
O n the assum ption that the international selective calling system to be adopted willcontain approxim ately 60 000 individual com binations, a decision will be required on thedivision of the num ber of codes, to be allocated:- individually to ships engaged on international voyages;- on a shared basis to ships on domestic voyages.
(A possible division could be 45 000 for ships on international voyages, and 15 000 forships on voyages of a domestic nature.)
The allocation of individual codes to ships engaged in international voyages could be best
done by the I.T.U . in the form of “ blocks ” of a relatively small num ber of codes to individual
A dministrations.

Rep. 320

— 176 —

An additional “ block of codes ” would be allocated to an A dm inistration when its
previous “ block ” was nearly exhausted.
If, eventually, all codes were allocated, a second channel for selective calling could be
brought into use, thus doubling the num ber of codes available. A nother designator toindicate the channel could then be added to the code num bering and another equal num berof code com binations would be added to the system.
A detailed consideration of the allocation plan and num bering system, including opera­
tional procedures in different frequency bands, can only take place after an international
selective calling system has been adopted.
12. A n exam ination of the patent situation, with respect both to the systems and the selective
calling equipments, shall be included in the report of the International W orking Party to be
set up in accordance with Resolution 19.

STUDY GROUP XIII
(Mobile Services)
Terms o f reference :To study technical and operating questions concerning the aeronautical, m aritime, land
mobile, radiolocation and radionavigation services (except services th at involve the use of earth
satellites which, at present, are the concern of Study G roup IV).

Chairman :Vice-Chairman :Mr. G. H. M. G l e a d l e (United Kingdom)
Mr. J. S u b e r g (Norway)

IN T R O D U C T IO N BY T H E C H A IR M A N , S T U D Y G R O U P XIU

1. Former Resolution 33 : Publication of service codes in use in the international radiotelegraphserviceA ction has been taken in § 1 and § 2 of form er Resolution 33. Opinion 21 has been
ad o pted‘concerning the operational necessity for the unification o f codes. R eport 317 is am ore up-to-date version o f R eport 90.
2. Question 158 and former Resolution 61 : Marine identification devices
Question 158, form er Resolution 61 and Recommendation 222 have been deleted as there
is no operational requirem ent evident. R eport 92, § 6, has been am ended accordingly, andappears as R eport 318.
3. Question 160 and Study Programme 168 : Selective calling devices for use in the international
maritime mobile radiotelephone service
The results o f extensive tests of the selective calling systems for V H F-FM services in the
U.S.A. and the Federal Republic of Germ any were discussed. Several other systems in use
in other countries were also examined. It was agreed th at tests of selective calling systems
should be carried out also on the H F and M F m aritime services and with double-sideband
and single-sideband am plitude-m odulation. The Question 160 and Study Program m e 168
have, therefore, been revised and bear the numbers Question 271 (XIII) and Study Program m e
271A(XIII) and R eport' 320 prepared on the discussions. Resolution 19 was adopted forsetting up an International W orking Party (C hairm an: Mr. Broersma, N etherlands), to examine
the results of the tests at M F and H F and, if possible, to prepare a draft R ecom m endation on
an international selective calling system for the m aritime service.
4. Question 161 : Spurious emissions from frequency-modulated maritime mobile equipment
The substance of R eport 113 and Recom m endation 255 have been com bined into Recom ­m endation 426 and Question 161 has been term inated.

— 178 —5. Question 163(XIII) and former Resolution 6 0 : Characteristics of equipments and principles
governing the allocation of channels in the VHF and UHF land mobile services
The technical specifications for land mobile equipment, which were subm itted by various
A dministrations, have been added to R eport 114, which appears as R eport 319, and an additionm ade to form er Resolution 60 (now renum bered Resolution 20), asking A dm inistrations tofurnish technical and operational inform ation on any agreements concerning the operationof land-mobile services in border areas. It is hoped to w ork tow ards a measure of inter­national standardization:- to limit m utual interference between land-mobile services of adjacent countries;- to perm it the operation of com m on land-m obile services.
6. Question 206 (XIII) : Direction-finding by ships in the 2 M c/s band
Recom m endation 428 has been adopted on the provision and calibration of equipments
in ships for taking bearings and for “ homing ” . This is especially im portant in cases of
distress and will be of interest to the I.M .C.O. The Question has been retained for further
study.
7. Study Programme 171 : Interference level on the radiotelegraph distress frequency
This study was referred to the I.T.U . by the Conference on the Safety o f Life at Sea,
London, 1960. Recom m endation 429 has been adopted and Study Program m e 171 ter­minated.
8. New Questions and Resolutions
Question 274(XIII): Facsimile transm ission o f meteorological charts for reception by ships.
Question 272(XIII): Signal-to-interference protection ratios and m inimum field-strengths
required in the mobile services.
Question 273(XIII): Use of classes of emission A 2H and A 3H on the distress frequencies .
500 kc/s and 2182 kc/s respectively.
Opinion 22: Emergency position-indicating radio beacons.
9. Cancelled Recommendations
The following Recom mendations have been cancelled, because their substance has been
incorporated in the R adio Regulations, or implemented in other ways, or because they are
redundant. Suitable notes have been inserted in the Complete List of Recom m endations.
Recom m endation 124: W atch on the radiotelephony distress-frequency of 2182 kc/s.
Recom m endation 222: Inter-ship radar identification.
Recom m endation 250: Signals m a y d a y and p a n .
Recom m endation 251: A ddition to Appendix 9 of the Radio Regulations.
10. Amended Recommendations
Recom m endation 126 (Pulse transm ission for radio direction-finding), has been recast
into a more appropriate form w ithout altering its substance and it appears as Recom m enda­
tion 422.
Recom m endation 254 (Technical characteristics o f V H F-FM m aritim e equipments),
has had a new section added to it concerning the choice o f interm ediate frequencies for recei­vers. It now appears as Recom m endation 425.
All Recom m endations were am ended where necessary to bring various references, etc.,
up-to-date.

— 179 —11. Recommendations and Resolutions of the Administrative Radio Conference, Geneva, 1959
Preliminary consideration was given to the question of whether the C .C.I.R. shouldtake up the study of Recom m endations Nos. 18, 22, 26, 27, 30, and Resolutions N os. 8 and
12 of the A dm inistrative R adio Conference, Geneva, 1959. N o decision was taken, however,as A dm inistrations needed m ore time to consider the m atter.
12. Terms of reference of Study Group XIH
The terms of reference were revised, as indicated on page 177.

I

— 180 —Op. 20, Res. 19

OPINION 20 *PUBLICATION OF THE “ CODES AND ABBREVIATIONS FOR
THE INTERNATIONAL TELECOMMUNICATION SERVICES”
BY THE INTERNATIONAL TELECOMMUNICATION UNIONThe C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) th at under the supervision of the C.C.I.T.T., with the cooperation o f the C.C.I.R., the firstedition of the “ Codes and Abbreviations for the International Telecommunications Services,published by the International Telecom munication U nion ” was issued in 1958;(b) th at a second edition of this book is in the course of preparation and will be published in 1963;(c) that A dm inistrations have not expressed a need for the unification of codes;
IS U N A N IM O U SL Y O F T H E O P IN IO N

1.

that under the supervision of the C.C.I.T.T., in cooperation with the C.C.I.R., the publication
m entioned in § (a ), should be kept up-to-date;2.

th at after the second edition has been published, A dm inistrations should express their views
as to whether th e re is an operational need for the unification of codes;

3.

that if A dm inistrations consider that there is an operational need for the unification of codes,
the C.C.I.T.T. should be asked to assume the supervision and responsibility for investigating
the extent to which unification might be possible. The C .C.I.R. should cooperate as neces­sary with the C.C.I.T.T.

RESOLUTION 19

SELECTIVE CALLING DEVICES FOR USE IN THE INTERNATIONALMARITIME MOBILE RADIOTELEPHONE SERVICE(Study Programme 271A (XIII))The C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) Question 271(XIII), Study Program m e 271A(XIII), Recom m endation 257 and R eport 320;(b) th at the results of a limited series of tests, carried out by the A dm inistrations of the Federal
Republic of G erm any and the U nited States of America, are given in Docs. 229 and 235
of Geneva, 1963;(c) that the tests of the selective calling systems, as m entioned in Study Program m e 271 A (X III),§ 1, have not been sufficient to enable a decision to be reached as to the system th at should
be adopted internationally;(d) th at Docs. X III/8, XIII/15 and XIII/21 of Geneva, 1963, express the view that the selective
calling system to be adopted should be suitable for operation in all m aritim e mobile rad io ­telephone bands (VHF, H F and M F), and be capable of working with single-sideband system s;(e) th a t it is im portant to standardize, with the least possible delay, the principal operational andtechnical characteristics of an international maritim e selective calling system;* This O pinion replaces Resolution 33.

— 181 —Res. 19, Q. 271

U N A N IM O U SL Y D EC ID ES

1.

th at Administrations should carry out further tests, including practical tests under opera­
tional conditions, to determine the suitability of the selective calling systems on all m aritim eradiotelephone services (VHF, H F and M F), with special regard to the tests proposed in§ 10 of R eport 320;2.

th at an International W orking Party should be form ed to prepare a comprehensive but briefreport based on the tests m entioned in § 1;

3.

th at the following A dm inistrations and International Organizations should be invited toparticipate in this International W orking Party;
N etherlands (Chairman),
Belgium,
U nited States of America,
France,Japan,
Federal Republic o f Germany,
U nited Kingdom,
U nion of Soviet Socialist Republics,
Comite International R adio M aritime,
International Cham ber of Shipping;

4. th at the tests m entioned in § 1 should be completed and the results sent to the C hairm anof the International W orking Party and to the Chairm an, Study G roup X III, by July, 1964;5.

th at the C hairm an of the International W orking Party should convene a meeting to preparea R eport and, if possible, a draft Recom m endation, for circulation to participants in thework o f Study G roup X III, by November, 1964;6.

th at Study G roup X III should hold an Interim Meeting about M arch, 1965, to prepare a
draft R eport and a draft Recom m endation, for circulation to A dm inistrations for theirconsideration with a view to subsequent adoption by the C.C.I.R.

QUESTION 271 (XIII) *SELECTIVE CALLING DEVICES FOR USE IN THE INTERNATIONALMARITIME MOBILERADIOTELEPHONE SERVICES
The C .C.I.R.,(W arsaw, 1956 - G eneva, 1963)

C O N S ID E R IN G(a) Recom m endation 425, in answer to Question 107, concerning V H F (metric) F M equipm ents
in the maritime mobile service;(b) th a t there may be advantages in the use of selective calling devices in the operation o f theinternational V H F, H F and M F maritime mobile radiotelephone services;(c) th at a selective calling device should provide for a sufficiently large num ber o f individual
non-conflicting signalling com binations;(d) th at the frequency bandw idth required for signalling should n o t exceed th at required forthe transm ission of speech;(e) th at the signalling equipm ent should operate reliably under poor transm ission conditions,th at is, when it is just possible to understand speech with norm al m odulation;( f) th a t the signal transm itting and receiving units should be capable of operating w ith the radiotransm itting and receiving equipments commonly available in ships;
This Question replaces Question 160.

Q. 271, S.P. 271A

— 182 —(g) th at the transm ission of a complete call num ber should be accomplished in as short a time
as possible;(h) th at the equipment should be low in cost and capable of operation under shipboard conditions
for long periods without excessive m aintenance;u n a n im o u s l yd e c id e sthat the following question should be studied:1. is there a need for a world-wide selective calling system in the V H F, H F and M F maritime
mobile radiotelephone services, and to w hat extent, and for w hat purposes can selective
calling be used with advantage;
2. w hat are the advantages and disadvantages in the use of the same selective calling system
in all three (VHF, H F and M F) maritime radiotelephone bands;
3. w hat are the operational requirem ents th at should be m et by any selective calling system
th at could be used for the purposes recommended in answer to § 1 of this Q uestion;
4. what are the essential technical characteristics of selective calling devices on which inter­national agreement is required (see R eport 320);
5. what selective calling systems are there which fulfil the operational and technical requirem ents
in answer to §§ 3 and 4?

STUDY PROGRAMME 271A (XIII) *SELECTIVE CALLING DEVICES FOR USE IN THE INTERNATIONALMARITIME MOBILE RADIOTELEPHONE SERVICES
The C.C.I.R.,(Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) th at Recom m endation 257 does not give a full reply to Q uestion 160;(b) th a t the essential technical characteristics of a selective calling system to be agreed uponneed further study, in accordance with Resolution 19 and R ep o rt 320;(c) th at it is desirable to standardize the m ain operating and technical characteristics;
u n a n im o u s l yd e c id e sthat the following study should be carried out:

1.

trials of selective calling systems, with a view to coming to a decision on the type of systemthat should be adopted internationally;

2.

consideration of the num ber of individual code com binations required and the principles
to be adopted in their allocation. In this connection, attention is draw n to Doc. XIII/19
of Los Angeles, 1959;

3.

determ ination of technical characteristics of the selective calling signal, in particular:
3.1 tone frequency or frequencies;
3.2 radio-frequency deviation in frequency-modulated systems and percentage m odulationin am plitude-m odulated systems;
3.3 com position and duration of signal;
3.4 transm ission sequences;
3.5 tolerances on the above param eters;
3.6 any other param eters requiring international standardization;

4.

degree of immunity of the systems from false operation and degree of their response towanted signals.

Note - See also §§ 6 and 10 of R eport 320.
* This Study Programme replaces Study Programme 168.

V

Q. 163— 183 —QUESTION 163 (XIII)

CHARACTERISTICS OF EQUIPMENTS AND PRINCIPLES GOVERNING
THE ALLOCATION OF CHANNELS IN THE VHF (METRIC)AND UHF (DECIMETRIC) LAND MOBILE SERVICES
The C.C.I.R.,(W arsaw, 1956)

C O N S ID E R IN G(a) th at an interchange of inform ation, on the requirem ents of A dm inistrations concerning thetechnical characteristics of equipments used in the V H F and U H F land mobile services,would be advantageous in the development o f those services;(b) th at an exchange of inform ation, am ong different countries concerning the practices applied
to the assignment of channels and the experience gained in the operation o f V H F and U H F
land mobile services, is of value in general;(c) th at a certain measure of agreement may be desirable on the characteristics of V H F and U H F
land mobile equipments that are usecj in the border areas o f neighbouring countries to m ini­
mize m utual interference;(d) th at a certain measure of agreement may also be desirable on the practices governing theallocation and use of channels in the V H F and U H F land mobile services in border areas;u n a n im o u s l yd e c id e sthat the following question should be studied:1.

w hat are the technical requirem ents of A dm inistrations, concerning equipm ents used in the
V H F and U H F land mobile services th at are of international importance in the developmento f such services, e. g. transm itter power, type o f antenna, emission characteristics, frequency
tolerance;2.

to w hat extent would it be desirable to standardize the perform ance characteristics of V H F
and U H F land mobile equipments internationally;3.

w hat are the broad practices adopted by A dm inistrations in the allocation of channels to thevarious kinds of user in the V H F and U H F land mobile service, e. g. channel separation,
geographical spacing of stations in the same and adjacent channels, frequency separation for
duplex operation, degree of frequency sharing in a particular service area;4.

to w hat extent is it desirable to reach international agreement on the practices for the allo­
cation of channels in the V H F and U H F land mobile service?

Res. 20

— 184 —RESOLUTION 20 *CHARACTERISTICS OF EQUIPMENTS AND PRINCIPLES GOVERNING
THE ALLOCATION OF CHANNELS IN THE VHF (METRIC)AND UHF (DECIMETRIC) LAND MOBILE SERVICES(Q uestio n 163 (X III))The C .C.I.R.,(Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) that land mobile services of various kinds are growing rapidly;(b ) that in border areas difficulties may arise between the services of different A dm inistrations;(c) that it would be advantageous if there were a sufficient m easure of agreement, where necessary,
between A dministrations on the characteristics of equipments and on the principles adopted
in the planning for land mobile services;»
U N A N IM O U SL Y D EC ID ES

1.

that A dministrations should consult together as necessary to resolve any difficulties concerning
their land mobile services and for the purpose of improving such services;2.

that those A dministrations which are interested in the provision of com m on land mobile ser­vices should consult together and should advise the C.C.I.R. of any technical and operational
problem s that require international study;

3.

that A dministrations should continue to submit technical specifications of land mobile
equipm ent used in their respective countries to the C hairm an of Study G roup X III and the
D irector, C.C.I.R. for circulation;4.

th at A dministrations should submit inform ation on practices adopted for the allocation ofchannels in the V H F and U H F land mobile services to the C hairm an of Study G roup X III
and the D irector, C.C.I.R. for circulation;

5.

that Administrations, which have reached agreement with adjacent countries on the operationof land mobile services in border areas, should submit to the C.C.I.R., technical and opera­
tional details of the agreement to assist other A dm inistrations with similar problems.

* This Resolution replaces Resolution 60.

Q. 206, Op. 21— 185 —QUESTION 206 (XIII)DIRECTION-FINDING BY SHIPS IN THE 2 Mc/s BAND
The C.C.I.R.,(Los Angeles, 1959)

C O N S ID E R IN G(a) th at the use of radiotelephony by ships in the 2 Mc/s band is increasing;(b) th at an increasing num ber of ships are being fitted with direction-finding equipm ent capableo f taking bearings in the 2 Mc/s band;(c) that the taking of accurate bearings, and especially “ hom ing ”, by ships is im portant in casesof distress;u n a n im o u s l yd e c id e sthat the following question should be studied:1.

w hat special technical measures and precautions should be taken in the design and theinstallation of 2 Mc/s direction-finding equipm ent for use on board ships for taking bearings,
or at least for “ hom ing ” ;2.

w hat is the order of accuracy to be expected from 2 Mc/s direction-finding equipm ents onboard ships, particularly on the international distress frequency of 2182 kc/s?

OPINION 21

EMERGENCY POSITION-INDICATING RADIO BEACONSThe C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) Recom m endation 48 of the Convention for the Safetyof Life at Sea,
London, 1960, andC hapter 9 of the R eport of the 7th session of the I.C.A.O. Com m unication Division(Doc. 8226-COM/552);(b) the discussions that took place in M ay-June 1962 in the Inter-Agency W orking G roup on
the Coordination of Safety at Sea and in the A ir;(c) the letter from I.C.A.O. in Doc. 393 of Geneva, 1963;(d) the letter from I.M .C.O. in Dpc. 393 of Geneva, 1963;
IS U N A N IM O U SL Y O F T H E O P IN IO N

th at the following questions should be addressed to both I.C.A.O. and I.M .C .O .:1.

are the beacons intended for homing only or for both alerting and hom ing;

2.

w hat class of stations (e. g. aircraft, ship, coast or aeronautical), are expected to receive thetransmissions from the beacons;3.

up to w hat distances m ust the beacon signals be receivable?

— 186 —Q. 272QUESTION 272 (XIII)

SIGNAL-TO-INTERFERENCE PROTECTION RATIOS AND MINIMUM
FIELD-STRENGTHS REQUIRED IN THE MOBILE SERVICES
The C .C .I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) that full effect should be given to the studies which the A dministrative Radio Conference,
Geneva, 1959, in its Recom m endation N o. 3, invited the C .C.I.R. to continue for all services;(b) th at for certain kinds of mobile services, partial data relating to interference protection ratios
and minimum field strengths required, exist in docum ents of some Conferences of the I.T.U .,for example, in the Final Acts of the International Administrative Aeronautical Radio Confer­ence, Geneva, 1948-1949 and of the Special Regional Conference, Geneva, 1960;(c) that such documents, however, do not constitute a complete and consistent set of data relat­
ing to all kinds of mobile services operating in all frequency ranges, particularly with respect
to V H F mobile services;u n a n im o u s l yd e c id e s

th at the following question should be studied:1.

w hat are the signal-to-interference protection ratios which define the threshold of harm ful
interference for the several mobile services;2.

w hat are the signal-to-noise ratios and the minimum field-strengths required for satisfactory
reception of the different classes of emission in the several mobile services;3.

w hat are the appropriate fading allowances in the several mobile services?

Note 1. - The above studies should be continued simultaneously and with the same urgency.
Note 2. - Particular attention should be given to those studies which will assist the further refine­m ent of the technical standards used by the International Frequency Registration Board.
Note 3. - The above-mentioned studies should be carried on perm anently and recom m endations
and possible revisions be published as soon as practicable.

Q. 273— 187 —QUESTION 273 (XIII)USE OF CLASSES OF EMISSION A2H AND A3H ON THE DISTRESSFREQUENCIES 500 kc/s AND 2182 kc/s RESPECTIVELYThe C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) that, for distress and safety purposes, the Convention for the Safety of Life at Sea (SOLAS)
prescribes the use of classes of emission as assigned by the Radio Regulations, Geneva, 1959
(SOLAS (London, 1960), C hapter IV, Reg. 9e, 9h(i), 12b, 12.f, 13c, 13/, 156 and 15/);(b) th at for distress and safety purposes, the Radio Regulations, Geneva, 1959, prescribe forships and survival craft:- Class A2 emission on 500 kc/s (see Nos. 973, 974, 994, 995 and 1134);- Class A3 emission on 2182 kc/s (see Nos. 983, 984, 994, 996 and 1337);( c) that, to the maximum extent possible, am plitude-m odulation systems should use single-side­band (SSB) emissions having characteristics in accordance with the relevant C.C.I.R . Recom ­mendations (No. 670 of the R adio Regulations, Geneva, 1959), and that SSB operation be
introduced as far as operationally required for radiotelephony in band 6 and band 7 (Recom­
mendation No. 28 of the A dministrative Radio Conference, Geneva, 1959);(d) th at in several countries, new m arine transm itters are being designed which m ake use of
SSB techniques;(e) th at SSB transm itters may easily and economically be adapted for Class A 2H and Class A3H
em ission;(f) th at until SSB emission is universally adopted in the M F m aritim e mobile service, there will
be a need for com munications between DSB and SSB stations;u n a n im o u s l yd e c id e sthat the following question should be studied:. I.

is Class A2H emission on 500 kc/s as effective as Class A2 for alarm, distress, urgency andsafety signals to be received by stations equipped for DSB reception by aural m eans o r auto­
matic receiving equipm ent;2.

is Class A3H emission on 2182 kc/s as effective as Class A3 for alarm , distress, urgency andsafety signals to be received by stations equipped for DSB reception by aural means or
autom atic receiving equipm ent?

Q. 274— 188 —QUESTION 274 (XIII)FACSIMILE TRANSMISSION OF METEOROLOGICAL CHARTSFOR RECEPTION BY SHIPSThe C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) th at meteorological charts are being transm itted extensively over radio circuits;(b) that the transm issions concerned are mainly intended for exchange of meteorological infor­
m ation in the fixed services;( c) that Chapter V, Regulation 46(ii), of the Convention for the Safety of Life at Sea, London,
1960, requests contracting Governm ents to encourage the transm ission o f suitable facsimile
weather charts;(d) that ships need to receive suitable meteorological charts;(e) th at an increasing num ber of ships is being fitted with equipm ent for receiving meteorologicalc h arts;(f) th at the W orld M eteorological O rganization (W .M .O.), in collaboration with the C.C.I.T.T.,
has standardized the equipm ent used for international meteorological transm issions (seeRecom m endations 60 and 61 of the Commission for Synoptic M eteorology, W .M .O. N o. 122. R.P. 50);(g) that the W .M .O. standards provide for various drum-speeds and indices of co-operation; thechoice, which depends on the type of charts transm itted, is left at present to the discretionof meteorological services;(h) that it is desirable to adopt a uniform practice for all facsimile transm issions of meteorologicalcharts intended for ships;(i) that certain characteristics, concerning meteorological facsimile transm issions by radio, arecontained in Recom m endation 343;
u n a n im o u s l yd e c id e sthat the following question should be studied jointly with

the W .M .O .:what steps should be taken to establish a uniform practice for facsimile transm issions ofmeteorological charts intended for reception by ships?
Note. - The D irector, C .C.I.R. is invited to bring this Q uestion to the attention of the I.M .C.O .

— 189 —Q. 282QUESTION 282 (XIII)USE OF A CONTROL TONE FOR AUTOMATIC GAIN CONTROLOF RECEIVERS IN SINGLE-SIDEBAND RADIOTELEPHONE SYSTEMSOPERATING IN THE HF MARITIME MOBILE BANDST H E IN T E R N A T IO N A L F R E Q U E N C Y R E G IS T R A T IO N B O A R D ,the request by the Panel of Experts in Recom m endation No. 38 o f its Final Report,
Geneva, 1963, and a f t e r c o n s i d e r i n g :in v ie w o f(a) th at Recom m endation 258 requires that a reduction in carrier-level to at least 40 db below
peak envelope power should be achieved as soon as possible on single-sideband radiotelephonesystems operating in the H F m aritim e mobile band;(b) th at this reduction in carrier pow er is desirable from the point of view o f the economic useof the radio-frequency spectrum, but virtually excludes the use o f the residual carrier for
autom atic gain control;(c) th at although autom atic gain control can be obtained from the speech m odulation, suchm odulation is not always present;andind e c id e sv ie wof

N o. 180 of the International Telecommunication Convention, Geneva, 1959;

to subm it the following urgent question to the C .C .I.R .:1.

w hat arrangem ents should be adopted in single-sideband radiotelephone systems in the H F
m aritim e mobile service, which use a carrier reduction o f at least 40 db in accordance with
Recom m endation 258, to control the gain of the receiver in the absence of speech m odulation;

2.

if the arrangem ents adopted employ an audio-frequency control tone, w hat characteristicsof the tone and of the equipm ent should be standardized, bearing in m ind the necessity forthe service to operate on a world-wide basis?

— 190 —LIST OF DOCUMENTS OF THE Xth PLENARY ASSEMBLY
CONCERNING STUDY GROUP XIII
D o c.

O riginT itleR eference

13

Chairman,
Study Group XIII

Report by Chairman of Study Group XIII
(Mr. G.H.M. Gleadle)

18

BelgiumInterference caused to FM reception by AM
and FM VHF mobile stations

120

Federal Republicof Germany

Direction-finding by ships in the 2 Mc/s band

129

C.C.I.R. Secretariat

Bibliographic references in the volumes of the
C.C.I.R.

141

BelgiumInterference to FM reception by emissions
from VHF (metric) mobile AM- and FMstations

153

C.C.I.R. Secretariat

Refinement of I.F.R.B. technical standards

169

SwedenUse of classes of emission A2H and A3H on
the distress frequencies 500 kc/s and 2182 kc/s
respectively

177

SwedenComparison of reception of classes of emis­
sion A3H and A3 on receivers designed for
A3 reception

179

Federal Republicof Germany

Direction-finding by ships in the 2 Mc/s band

Q. 206

222

Australia

Specification for radio equipment employedin privately-operated land and harbour mo­bile radiotelephone services

Res. 60

229

Federal Republicof Germany

Selective calling devices for use in the inter­national VHF (metric) maritime mobile
radiotelephone service

S.P. 168

235

United Statesof America

Tests of maritime radiotelephone selective
calling devices

Q. 160
S.P. 168Rec. 257 and 258

240

l.M.C.O.

Emergency position-indicating radio beacons(Correspondence between I.M.C.O. and
I.T.U.)

259

P.R. of Poland

Corrigendum to Doc. XIII/10 - Technicalcharacteristics of the equipment used in
Poland for the land mobile services

265

Study Group XIII

Amendment to Recommendation 251

O th erStudy
G ro u p s
concernedII
Q. 206
I-X1V
Q. 178Q. 163II

I, II, 111,
V, VI,
X, XII
Draft. Q.

Res. 60

305

Draft text submitted by Study Group XIII to
the Drafting Committee - Amendment to
Recomendation 254

Draft Rec.

306

Spurious emissions from frequency-modu­
lated VHF (metric) maritime mobile equip­
ment

Draft Rec.
Q. 161

310

Summary record of the first meeting

354

Interference level on the radiotelegraph dis­tress frequency

Draft Rec.

— 191 —D o c.

O riginT itleR eference

367

Study Group XIII

Direction-finding by ships in the 2 Mc/s band

Draft Rec.
Q. 206385”

Publication of the “ codes and abbreviations
for the international telecommunication ser­vices ” published by the International Tele­
communication Union

Draft Res.

386

Amendment to Report 92

Draft Rep.

390

Facsimile transmission of meteorologicalcharts for ships

Draft Q.

391

Signal-to-interference protection ratios andminimum field-strengths required in themobile services

Draft Q.

392

Use of classes of emission A2H and A3H on
the distress frequencies 500 kc/s and 2182 kc/s
respectively

Draft Q.

393

Emergency
beacons

Draft Res.

449

Summary record of the second meeting

460

Selective calling devices for use in the inter­national maritime mobile radiotelephoneservice

Draft Res.
S.P. 168

482

Amendment to Resolution 60

Draft Res.

493

Proposed revision of the documents of Study
Group XIII

503

Selective calling devices for the international
mobile radiotelephone services

Draft Rep.

507

Selective calling devices for use in the inter­national maritime mobile radiotelephone ser­
vices

Draft Q.

508

Selective calling devices for use in the inter­national maritime mobile radiotelephone ser­
vices

Draft S.P.

518

, Summary record of the third meeting

563

Summary record of the fourth meeting

632

Summary record of the fifth and last meeting

2121

Drafting Committee Technical characteristics of frequency-modu­
lation VHF (metric) maritime mobile equip­
ments

positioning' indicating

radio

Rec. 425

2122”

Spurious emissions from frequency-modu­
lated VHF (metric) maritime mobile equip­
ment

2178

”

Amendment to Recommendation 251

2179

”

Interference level on the radiotelegraph dis­tress frequency

Rec. 429

2180”

Direction-finding by ships in the 2 Mc/s band

Rec. 428

2181”

Publication of the “ codes and abbreviations
for the international telecommunication ser­vices ” published by the International Tele­
communication Union’ Op. 20

Rec. 426

O th er
S tudyG ro u p s
co n cern ed

I— 192 —O rigin2182

O th er
S tudyG ro u p s
co n cern ed

T itleRep. 318

Drafting Committee Amendment to Report 92

2183

”

Signal-to-interference protection ratios andminimum field strengths required in themobile services

Q. 2722184”

Use of classes of emission A2H and A3H on
the distress frequencies 500 kc/s and 2182 kc/s
respectively

Q. 273

2185”

Emergency
beacons

Op. 22

2189”

Facsimile transmission of meteorologicalcharts for reception in ships

Q. 274 .

2190”

Selective calling devices for use in the inter­national maritime mobile radiotelephoneserviceRes. 192346”

Selective calling devices for the international
mobile radiotelephone services

Rep. 320

2347”

Selective calling devices for use in the inter­national maritime mobile radiotelephoneservices

S.P. 271A

2348”

Selective calling devices for use in the inter­national maritime mobile radiotelephoneservices

Q. 271

2349”

Characteristics of equipment and principles
governing the allocation of channels in the
VHF (metric) and UHF (decimetric) land
mobile services

Res. 20

2351”

Characteristics of equipment and principles
governing the allocation of frequency chan­nels in the VHF (metric) and UHF (deci­
metric) land mobile services

Rep. 319

2359”

Revision of the documents of Study Group
XIII

Rec. 422, 423,
424, 427
Rep. 317
Res. 20

positioning-indicatingradio— 193 —Rec. 374

R E C O M M E N D A T IO N S O F SEC TIO N H : S T A N D A R D -F R E Q U E N C IE S
A N D TIM E-SIG N A LS

RECOMMENDATION 374 *STANDARD-FREQUENCY AND TIME-SIGNAL EMISSIONS(Question 140 (VII))(Geneva, 1951 - London, 1953 - W arsaw, 1956 Los Angeles, 1959 - Geneva, 1963)

The C.C.I.R.,
C O N S ID E R IN G(a) th at the Administrative Radio Conference, Geneva, 1959, allocated the frequency bands
20 kc/s ± 0-05 kc/s, 2-5 Mc/s ± 5 kc/s (2-5 Mc/s ± 2 kc/s in Region 1), 5 M c/s ± 5 kc/s,
10 Mc/s ± 5 kc/s, 15Mc/s ± 10 kc/s, 20 Mc/s ± 10 kc/s and 25 Mc/s ± 10 kc/s, requesting
the C.C.I.R. to study the question of establishing and operating a world-wide standardfrequency and time-signal service;(b) th at additional standard-frequencies and time-signals are em itted in the bands 4 to 9;(c) the provisions of Article 44, Section IV, of the R adio Regulations, Geneva, 1959;
U N A N IM O U SL Y RECO M M E N D S

1.

that the standard-frequency and time pulses at each transm itting station should be generated
from the same oscillator;

2.

th at the frequency should be m aintained constant each year with reference to atom ic
frequency standards, but be offset to keep the time pulses in close agreement with U T 2;
the offset to be used each year will be that adopted by the B.I.H. after consultation with theobservatories concerned. This offset is expressed in the time scale in which the frequency
of caesium has the value:/(C s) = 9 192 631 770 c/s **3.

th at the time-signals should consist of impulses repeated at intervals o f one second andm aintained within approximately 100 ms of universal tim e UT2. Changes in the phase of
the pulses should be exactly 50 ms and should be made simultaneously by the stations con­cerned ;4.

that frequency deviations at each transm itting station should not exceed 5 x 10~10;5.

that the m easured values of frequencies and time-signals should be published prom ptly andadvance notification should be given of major adjustments of emissions.

* This Recommendation replaces Recommendation 319.
** See U.R.S.I. Resolution 1 (1960).

Rec. 375

— 194 —

RECOM M ENDATION 375 *STANDARD-FREQUENCY AND TIME-SIGNAL EMISSIONSIN ADDITIONAL FREQUENCY BANDS(Q uestion 249 (VII))
The C.C.I.R.,(Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) th at intercontinental frequency synchronization has already been achieved by the use of thefrequency-stable emissions operating in band 4;(b) th at for m any purposes a world-wide tim e (epoch) synchronization with an accuracy greaterthan 1 ms is required;(c) that synchronization to 1 jxs may be extended to ranges greater than 2000 km by meanso f pulsed ground-wave signals;(d) th at line-of-sight transm issions in band 8, and predom inantly ground-wave signals in band 5,
provide a stable means of distributing time-signals and standard-frequencies on a more
local basis;
U N A N IM O U S L Y REC O M M E N D S

1.

th at existing studies of phase stability, over paths in bands 4 and 5, should be continued andinform ation on the results and m ethods o f m easurem ent disseminated as widely as possible;

2.

that the ultim ate stability and precision o f pulsed ground-wave navigation systems, should
be studied as fully as possible with the aim o f establishing intercontinental and possibly
world-wide tim e synchronization;3.

th at appropriate stations, existing in bands 5 and 6, should be employed as m uch as possiblefor distributing standard-frequencies by precise control of their carrier frequencies;

4.

th a t existing broadcasting stations, in bands 8 and 9, such as F M and television, should be
employed as m uch as possible for distribution o f standard-frequency and time-signals which
can be added to, or m ake use of, the existing m odulation w ithout interference to the norm al
program m e;

5.

th at a band of 200 kc/s, in the upper p art of band 8, would appear to be suitable for an effective
line-of-sight standard-frequency and time-signal service.

*

This Recommendation replaces Recommendation 320.

— 195 —Rec. 376

RECOMMENDATION 376 *A V O ID A N CE O F EX TER N A L IN T E R F E R E N C E W IT H E M IS S IO N S
O F T H E STA N D A R D -FR EQ U EN C Y SER V IC E IN T H E BAND S
A LLO CA TED T O T H A T SER V IC E

(Question 140 (VII))
The C.C.I.R.,(Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a ) the im portance and increasing use o f standard-frequency and time-signal emissions in th e
allocated b an d s;(b ) th at interference reduces the usefulness of the standard-frequency and time-signal service
to a serious degree;(c) that, despite the efforts m ade by A dm inistrations and the I.F.R .B . to clear the standardfrequency bands, some registered users, and m any unnotified emissions, rem ain in thesebands, which continue to cause interference with the standard-frequency services;
U N A N IM O U SL Y REC O M M E N D S

1. th at to avoid external interference, Adm inistrations and, if necessary, th e I.F.R .B . should
continue their efforts to clear the standard-frequency bands;
2.

that, in the territory under its jurisdiction, each A dm inistration should m ake every effort,
to prevent all users of the radio-frequency spectrum from operating other stations in thestandard-frequency bands, capable of causing harm ful interference to the standard-frequency
service; .

3. th at national m onitoring stations should carry out a regular search for external interfering:stations in the standard-frequency bands and should m ake every effort to identify each inter, fering station, if necessary with international co-operation;

4. that in each case of external interference the users of standard-frequency emissions should,
request the m onitoring service of their own country to identify the interfering station;
5. that, in cases o f external interference with the staridard-frequency service. A dm inistrations
should apply the provisions of Articles 14,15 and 16, of the R adio Regulations, Geneva, 1959,.
and, if desired, should send a copy of relevant correspondence to the I.F .R .B .;6. that, when interference is observed in the standard-frequency bands, even if the source cannot
definitely be identified, representatives of A dministrations, participating in the w ork o f
C.C.I.R. Study G roup VII, should exchange inform ation from users o f standard-frequency andtime-signal transmissions and from the m onitoring service. This may later perm it identi­
fication of the interfering station.
*** This Recommendation replaces Recommendation 321.

PAGE INTENTIONALLY LEFT BLANKPAGE LAISSEE EN BLANC INTENTIONNELLEMENT

— 197 —Rep. 267

R EPO R TS O F SEC TIO N H : S T A N D A R D -F R E Q U E N C IE S A N D T IM E-SIG N A LSREPORT 267 *ST A N D A R D -FR E Q U E N C IE S AND T IM E -SIG N A L S(Question 140 (VII))(Warsaw, 1956 - Los Angeles, 1959 - Geneva, 1963)
This R eport outlines the w ork of Study G roup VII in the interval between the IX th and theX th Plenary Assemblies.
F urther consideration has been given to the problem of meeting the need for time-signals
based on a uniform time scale, as well as for the time-signals related to universal time, w ithout
increasing the num ber of transmissions. Interference is still a pressing problem , b u t proposals
have been considered which might lead to an am elioration in the m ore seriously affected areas.
D em ands for increasing precision posed m any technical questions, and useful discussions ensued.
M uch interest centred on the employment of V LF for phase com parison of high accuracy. The
various Study Programm es indicate how Study G roup VII should proceed with its future work.
Recom m endation 374 concerning standard-frequency and time-signal emissions has beenrevised with a view to providing, on the same emission, for the needs of users who require uniform
frequency and those who require tim e inform ation. It is recommended, th at the em itted frequen­cies shall be maintained constant throughout each year by reference to atomic standards b ut offset
in frequency so th at the time pulses rem ain within approxim ately 100 ms of UT2. This tolerance
should ensure that changes in the adopted frequency offset and the 50 ms adjustm ents in the phaseof the time pulses will be required only occasionally.
Study G roup V II has noted with satisfaction that, in accordance with R esolution 53, of
the C.C.I.R., the A dministrative Radio Conference, Geneva, 1959, has allocated the frequency
20 kc/s ± 0-05 kc/s in band 4 for an international standard-frequency and time-signal service.
Particulars of the first station, WWVL, to be registered on this frequency are given in Table I,
together with the characteristics of the other stations know n to be operating regular standardfrequency and time-signal services. A n experimental Japanese emission, with very low radiatedpower, is also being em itted on 20 kc/s.
Figs. 1 and 2 are two schedules giving, where appropriate, the daily and hourly p attern ofemission and m odulation. The extent of the problem of m utual interference which exists inmany areas may be clearly seen from these diagram s: it is particularly severe in W estern Europe
and the F ar East. R eport 269 contains proposals for the reduction of this interference, involving
a degree of regional time sharing and a reduction in the periods of audio-frequency m odulation.
It is hoped that A dm inistrations will m ake m utual adjustm ent of their emission schedules andthereby attem pt to secure better use of the standard-frequency services for all users. R eso­lution 14 indicates the procedure to be followed to avoid the possibility o f interference from any
new standard-frequency stations and indicates th at the inform ation referred to in this Resolution
should be published in the fortnightly N otifications of the G eneral Secretariat and distributed
directly to the participants in the w ork of Study G roup VII.
Stations operating regular services at controlled frequencies outside the allocated bands are
given in Table II. It should be noted that all the U.S. Navy transm itters in band 4 are now
precisely frequency-controlled and participate in the international coordination of tim e and fre­quency, which now extends to m any stations listed in both Annexes and also to the stations operating* This Report, which replaces R eport 166, was adopted unanimously.

Rep. 267

— 198 —th e Loran-C transm issions at 100 kc/s on the E ast Coast o f the U nited States. Recom menda­
tio n 375 places emphasis on the study o f such pulsed navigational systems for long-range timesynchronization.
The disadvantage th a t the allocated frequencies between 2-5 Mc/s and 25 M c/s are subject
to considerable propagation irregularities (R eport 271), and the success already achieved withtransm issions in band 4 has led to Question 249(VII), which asks for recom m endations for the
distribution of standard-frequencies and time-signals above 30 Mc/s and below about 100 kc/s.
I t should be noted th at stations in the Republic o f South Africa and Sweden are now operatingin the upper p art o f band 8.
In addition to the m utual interference discussed above, effective use o f the services is impairedby other transmissions. Interference continues even though the efforts of Adm inistrations andof the I.F.R .B . have effected a considerable clearance of registered transm itters. Recom men­dation 376 urges A dm inistrations to clear the bands by m onitoring and, if possible, identify inter­fering stations as well as by applying Articles 14,15 and 16 of the R adio Regulations, Geneva, 1959.
In 1962, the I.F.R .B . sent a new circular letter on this subject to A dm inistrations and is in courseof analyzing the results of a special monitoring program m e which was carried out in cooperation
w ith A dm inistrations, with a view to approaching Adm inistrations believed to be responsible
for the out-of-band transmissions.
Increasing use is being m ade of band 4 on account of its wide coverage and the high phasestability of the received signals. Com parisons with locally generated signals can be m ade readily
to about 1 [xs corresponding to a frequency error of about 1 p art in 1011 in a period o f 24 hours.
F or a com parison tim e o f 1 hour, the frequency precision may be limited by diurnal variations
to the order of 1 p art in 109. Inform ation on transm itting and receiving stations is given in
R eport 268, together w ith supplem entary inform ation on typical recording methods.
In band 7, m easurem ents reported have shown th at in a measuring time o f a few minutes,
precision o f several parts in 109 is possible during the day (one hop E-layer propagation), andseveral parts in 108 during the night (multi-hop F-layer propagation). Second-to-second accuracyof the time-signals as received does n o t seem to be better th an 0-5 ms. In bands 8 and 9, extensive
experimental and theoretical studies summarized in R eport 271 have shown th at the instability
introduced by propagation is at least one order less than the instability of the best oscillators
currently available.
The W orking G roup of Study G roup VI, entrusted with the study of Resolution 7, has sug­gested th at use be m ade of standard-frequency emissions in a field-strength measurem ent p ro ­gramme. The tim e sharing plan for these emissions examined by Study G roup V II (R eport 269)
would provide a favourable background for carrying out such measurements. Those interested
in the measurem ents are advised to apply direct to the standard-frequency stations for any infor­
m ation they may require. Study Program m e 140B(VII) concerning the use of single-sideband
emissions would appear to provide a possible solution to this problem.
The increasing precision required in the distribution of time-signals emphasizes the needfor further study (see Study Program m e 250A(VII) and R eport 270), of the ways in which thismight be done within the present bands or in reduced bandwidth.
In the course of exam ination of the docum ents subm itted, it was found th at the use could beforeseen of artificial satellites for an accurate distribution of standard-frequencies and time-signals.
Study Program m e 249A(VII) raises the question o f w hat factors would have to be considered
for the im plem entation of such a system. The Study G roup learned with interest th a t Telstar I
had been used in August 1962 to relate clocks in the U.S.A. and U nited K ingdom w ith an accu­racy of about 1 jxs.
Q uestion 251 (VII) has been introduced to investigate tim ing code form ats and m ethods of
distribution by radio transm ission. As an example, a fast tim ing code giving tim e o f year withmillisecond resolution once per second, has been em itted experimentally by WW V for overa year. This has been used in the U.S.A. in connection w ith space telem etry work. It is hoped

— 199 —Rep. 267

th a t A dm inistrations will contribute to the form ulation o f standards for the form ats and distribu­
tion o f timing codes.
Study Program m e 250B(VII) has been introduced as a result o f the increasing precision inm any fields of frequency measurement. This proposes a close exam ination of th e various factors,some hitherto insignificant, which contribute to the instability of frequency-standards, an d theadoption o f criteria for the specification o f perform ance; proposals leading to agreements forterminology are also required.
Some of the w ork of U .R .S.I. is closely related to improvements in standards and m easure­m ent techniques and in determining errors introduced in propagation o f standard-frequencies
and time-signals. F or example, U .R.S.I. Resolution 2 (1960), asked th at an intensive effort
be m ade to determine the lim itations in accuracy in distributing and inter-com paring frequency
standards by means of transm issions in band 4. A lthough such m atters were in p a rt discussed
at the C .C.I.R. Interim Meeting, advantages are foreseen in arranging some discussions o f thistype in collaboration w ith U .R.S.I. It is hoped that, at future Interim Meetings, it will bepossible also to arrange one or two meetings with the representatives of U .R.S.I.

Rep. 267

T A B LE I
Characteristics o f standard-frequency and time-signal emissions in the allocated bands, at April, 1963
S ta tio n

A n ten n a (e )N um berofs im u l­ta n e o u s
tra n s ­C a rrie r
m is­
p o w ersio n s(kW )P e rio d ofo p e ra tio n

S ta n d a rd freq u en cies u sed

D u ra tio n of
em issio n

A ccu ­
ra c y offre­
q u en cy
an d
tim e
in te r­val s(2)(p a rts
in 10 ")

M e th o dofa d ju s tm e n t.
oftim esig n al

Steeringby thefrequency

H o u rs /d ay

C a rrie r(M c/s)M o d u la tio n(c/s)

T im e-signal(m in)A u d io ­m o d u la tio n(m in )

1

5

5

10

1; 1000

continuous

4 ineach 15.

±20

0-3

1

2

87.

2-5

1; 440;1000

10 ineach 20

10 ineach 20

±2

0-5

1

7

24

5

1

5 in
each 10

nil

±0-1

1

1

6

1

5

1; 1000

Horizontal
dipole

0-3

1

6

i1/.

5

1; 1000

10 ineach 1535 ineach 60

4 ineach 15
5 ineach 60

Vertical X/2.
dipoles;(X/2 dipole,
top-loadedfor 2*5 Mc/s)

2

3-4

7

24

2-5; 5;
10; 15

1; 1000

continuous

2

3

6

5

5; 10; 15

1; 440;
1000

0-5

•3

7

24

2-5; 5;
10

1

1

7

24

20

1

7

A p p ro x im a telo c a tio n

L a titu d e
L o n g itu d e

Type

ATA

New Delhi
India

28° 34' N
77° 19' E

Horizontal
dipole

2

FFH

Paris
France48° 59' N
02° 29' E

Radiating
tower

HBN0

Neuchatel
Switzerland

IAM

Rome
Italy

46° 58' N
06° 51' E
41° 52' N
12° 27' E

Horizontal
dipoleVertical
X/4

IBF

Turin
Italy

45° 03' N
07° 40' E

Steps of
50 ms
Steps of
50 ms

±5Steps of
50 ms

±5Steps of
50 ms

4 in
each 5;(nil at
15 Mc/s)±5

Steps of
50 ms

4 in
each 60

4 ineach 5±20

Steps of
50 ms

1

5 in
each 10nil±0-1

Steps of
50 ms

2-5

1; 1000

15 ineach 30

4 ineach 15±1

Steps of50 ms

19

5; 10;
15

1; 1000

10 in
5*4
each 120(3) hours/day (4)±5Multiplesof 10 ms

Tokyo
Japan

35° 42' N
139° 31' E

LOL0

Buenos Aires
Argentina

34° 37' S
58° 21' W

M SF0

Rugby
UnitedKingdom

52° 22' N
01° 11' W

Horizontal
quadrant
dipoles;(vertical
monopole,
2-5 Mc/s)

OMA

PragueCzechoslovak
S.R.

50° 07' N
14° 35' E

T

RWM-RES

Moscow
U.S.S.R.

56° 37' N
36° 36' E

WWV0Washington
D.C. U.S.A.

39° 00' N
76° 51' W

Vertical X/2
dipoles;(vertical X/4
for 2-5 Mc/s)

01
to 9

6

7

24

2-5; 5;
10; 15;20; 25

1; 440;600

continuous
(5)

2 in
each 5±0-1

Steps of
50 ms

WW VH0

HawaiiU.S.A.

20° 46' N
156° 28' W

Vertical X/2
dipoles;(vertical X/4
for 5 Mc/s)

2

3

7

23i/2

5; 10; 15

1; 440;600

continuous

3 in ,
each 5±1

Steps of
50 ms

W W V L0

Boulder
U.S.A.

40° 02' N
105° 27' W

Top-loaded
vertical

10(«)

1

7

24

002

nil

nil

nil

±0-05

nil

ZLFS

Lower Hutt
New Zealand

41° 14' S
174° 55' E

0-3

1

1

3

2-5

nil

nil

nil

±50

nil

ZUO0

Olifantsfontein
Republic ofSouth Africa

25° 58' S
28° 14' E

Horizontal
quadrant
dipole

4

1

7

24

5

1

continuous

nil

±1

Steps of
50 ms

ZUO0

Johannesburg
Republic ofSouth Africa

26° 11' S
28° 04' E

Horizontal
dipole

0-25

1

7

24

10

I

continuous

nil

±1

Steps of
50 ms

Rep. 267

N o te s to Table I
T h e d aily tra n sm issio n sch ed u le a n d h o u rly m o d u latio n schedule is given, w here ap p ro p ria te , in th e form of F igs. 1 a n d 2 su p p lem en ted by th e fo llow ing n o te s:(l) T h ese sta tio n s have in d icated th e ir p a rtic ip a tio n in the in te rn a tio n a l c o o rd in a tio n of tim e an d frequency. T h e tim e sig n als rem ain w ithin a b o u t 100 m s o f U T 2, an d th e frequency
is m a in ta in ed as c o n s ta n t as p o ssib le by reference to ato m ic o r m o lecu lar sta n d a rd s, an d a t th e offset from th e n o m in al value an n o u n c ed fo r each y ear b y th e B u rea u in te rn a tio n a l de I’H eu re.
(*) M e asu red w ith resp ect to th e an n o u n c ed offset in frequency.
(*) T im e sig n als a re ra d ia te d ac co rd in g to th e follow ing p ro g ram m e:
M in u tes p a st
Transm ission 'odd hour4 5 -4 6
C a ll sign
4 6 -5 0
S econds, p relim in ary signal
50-55
N o m o d u la tio n
55-60
S econds
60-61
C all sign
61-66
R h y th m ic sig n als, 61 p e r m inuteT h e sig n als a t 06, 08, 10 a n d 12 h o u rs a re tra n sm itte d by m o d u late d c a rrie r (A 2 signals). A t all o th e r tim es, te leg rap h ic ( A l) sig n als a re em itted .
R W M -R E S do es n o t o p e ra te fro m 0607 to 1345 U T o n th e first a n d th ird W ednesday o f each m o n th .
(4) F ro m 0500 to 0807 U T o n 5 M c/s an d from 0830 to 1207 U T o n 15 M c/s, ex cluding p erio d s o f tim e-sig n al tra n sm issio n s. __a(5) I n a d d itio n to o th e r tim in g signals a n d tim e an n ouncem ents, a special tim in g co d e is ra d ia te d 10 tim es p e r h o u r. C o n sistin g of 36 b it, 100 p ulse/sec. b in a ry -co d ed d ecim al code,
it gives the second, m in u te, h o u r a n d d ay of year. A com plete tim e fram e lasts o n e second an d th e co d e is b ro a d c a st fo r o n e m in u te in ea ch 5 -m in u te p e rio d ,'e x c e p t th e first a fte r th e h o u r.
T h s c c ce co n ta in s 100 c /s, 10 c/s a n d 1 c/s m a rk ers, w hich are locked to th e freq u en cy an d tim e-sig n als.
L a te r in 1963, th e new sta tio n a t F o r t C o llin s, C o lo ra d o , w ill rad iate 1 kW .

— 201 —JJY 0

— 200 —

D ays/
w eek

C a llsig n

Rep. 267

— 202 —

10

1 I' * \

12

14

16

18

20

I 1 1 ■ 1 I■

1 I '

22

24 UT

I

ATA
NEW D ELH I

10 M c/s: M o n d ay
to F rid ay

2-5 M c/s:
T u esd ay an d
F rid ayFFH
P A R ISfHE. UO rlA I E. L t********************************************************************************

5 M c/s

IA M
ROM A

5 M c/s: n o t
S undayIB F
T O R IN O

5 M c /s: n o t
S u n d ayi ii 11111111111111111 r rn

JJY
TOKYO

2 -5 ,5 ,1 0 ,1 5 M c/s

LOL
B U E N O S A IR E S

M SF
RUGBY

5, 10, 15 M c/s:
not- S un d ay********************************************************************************

2«5, 5, 10 M c/s

OM A
PRA HA

2-5 M c/s

RW M - RES
M OSKVA

15 M c/s
10 M c/s
5 M c/swwv

2-5 , 5, 10, 15,20,
25 M c/s

W A S H IN G T O N

WW VH
H A W A II

I

5, 10, 15 M c/s

2 -5 M c/s:
T u e sd a y :c a rrie r onlyZLFS
LOW ER HUTTI I I I I I I I I I I I I I I I I I I I I ITTO L IF A N T S F O N T E IN
JO H A N N E S B U R G

TU 0

2

4

6

I 1 1 1 1 1 1 F
Stationoperating

10

-j

12

14

(6

18

20

22

5, 10 M c/s

24 UT

1 1 1 1 1 1 1 1 1 1 1 1 1 1

Stationnot operating
F ig u r e

1

Daily emission schedule

Emission in alter­nate five-minuteperiods

— 203 —Rep. 267

H our
+

M in

0

5

10

15

20

25

3 0

3 5

4 0

45

50

55

60

| I » I I 1I I 1 I I I I I 1 I I I I I I I I n f H-l I I I I I I I I I I I I ! I I I I I I M I H I I I H -H-|
1O00

1000

i Oqo

P u lse of 5 cycles of 1000 c/s to n e, le n g th ­en ed to 100 m s a t th e begin n in g of each
. m in u te. C all sign a n d tim e (U T ) in M o rse

1000

1000

1000

Form of second and minute signals morseand voice announcements (A )P u lse of 5 cycles of 1000 c/s to n e : m in u tepulse len gthened to 100 m s fo llow ed b y 440
c/s to n e for 200 m s. C all sign in M orse.

1000

1 m s c a rrier b re a k rep ea ted 5 tim es every
seco n d an d 250 tim es a t m in u te, exact tim eb ein g sta rt o f first b re a k . C all sign in M orse.

1000

1000

1000

P u lse of 5 cycles o f 1000 c/s to n e , rep eated
4 tim es a t m in u te. C all sig n in M o rse an dvoice id en tificatio n

1000

P u lse of 5 cycles of 1000 c/s to n e rep ea ted
7 tim es a t m in u te. C a ll sign a n d tim e (U T )in M o rse : voice id en tificatio n a t h alf-h o u r.

ilOOOs

_LL

1000

_LL

440

1000

1000

440

440

1000

440

1000

P u lse of 5 cycles o f 1000 c/s to n e , 59th
p u lse o m itte d . C all sig n in M o rse : id e n ­tificatio n a n d tim e (U T — 3h) in voice.

1000

440

2 0 m s c a rrie r b re a k len g th en ed to 2 0 0 m s at
m in u te, exact tim e bein g end of b reak . C allsign a n d tim e (JST ) in M o rse a n d voice.
R a d io p ro p a g a tio n w arn in g s in le tte r c o d e :N (N o rm al), U (u n stab le) o r W (disturbed).
U p p e r : 2*5, 5, 10 M c/s L o w e r: 15 M c/s.

P ulse of 5 cycles o f 1000 c/s to n e, 100 ms
p u lse a t m in u te. C a ll sign in M o rse andvoice an n o u n cem en t.
P u lse of 5 cycles o f 1000 c/s to n e, 100 ms
pulse a t m in u te an d 500 m s p u lse every 5th
m in u te. L a st 5 pulses in ea ch q u a rte r h o u r
100 m s long. F ro m m in u te 55-60 in every
3rd h o u r 100 m s pulses len g th en ed to 500
m s a t m inutes. C all sig n in M orse.

1000

1000

1000

1000

P u lse of 5 cycles of 1000 c/s to n e, 59th
p u lse o m itte d a n d 60th rep ea ted 100 ms
later. R a d io p ro p a g a tio n forecasts (R P F )a n d g eophysical a le rt w arn in g s (IW D S ).
T im e code (second, m in u te, h o u r an d day
o f year) 10 tim es p e r h o u r. C all sign an dtim e (U T ) in M o rse ; tim e (U T — 5h) in voice.

•o
8H
A

A
IWDS

RPF

A
IWDS

A
RPF

P u lse of 6 cycles of 1200 c/s to n e, 59th
p u lse o m itted . R P F an d IW D S code
an n o u n cem en ts. C a ll sign an d tim e (U T )in M orse.
P ulse o f 5 cycles o f 1000 c/s to n e , len g th ­ened to a b o u t 0.5 s a t m in u te.

+ 0

□

M in

M o dulation:

H our

C a rrie r only

S econd pulses

440

T o n e freq u en cy , c/s

Figure 2
Hourly modulation schedule

N o em ission

IReP- 267

TA BLE II
Characteristics o f standard-frequency and time-signal emissions in additional bands, a t April, 1963
S ta tio n

C all
sign

A p p ro x im a telo c a tio n

CHU(l)

OttawaCanada

DCF77

A n ten n a (e )L a titu d e
L o n g itu d e

C a rrie r
po w er(k W )T ype

P erio d o f
o p e ra tio n

S ta n d a rd freq u en cies used

D u ra tio n o f em issio n

N u m b erofsim u l­ta n eo u s
tr a n s ­m is­
sio n sD ay s /w eek

H o u rs /d ay

C a rrie r(kc/s)

M o d u latio n(c/s)

T im e-signal(m in)A u d io ­m o d u latio n(m in)

A ccu ­
racy offre­
qu en cyandtim ein tervals(2)(p arts
in UP)

M eth o dofad ju stm en toftim esignal

0-3;
3; 5

3

7

24

3330;
7335;
14 6701(5)continuous

nil

±5

Steps of
50 ms

Mainflingen
F.R. ofG erm any

50° 01' N
09° 00' E

Omni­
directional

12

1

60

60

77-5

1; 200;
440

( 8)

(*■)

(0 .

Steps of
50 ms

Droitwich
UnitedKingdom

52° 16' N
02° 09' W

T

150

1

7

18-20

200

nil

nil

A3 broad­
cast conti­
nuously

±10

nil

GBRC)

Rugby
UnitedKingdom

52° 22' N
oi° i r w

Omni­
directional

300
40(3)

1

7

22(u )

161(04 x 5 (0per daynil±01

Steps of
50 ms

M SF0

Rugby
UnitedKingdom

52° 22' N
01° 11' W

Omni­
directional

10

I

7

1 (0

60

H15)

5 in
each 10

nil±01

Steps of
50 ms

Loran-C

Carolina Beach
N.C. U.S.A.

34° 04' N
77° 55' w

Omni­
directional

300

1

7

24

100

20(16)

continuous

nilof±0-05 Steps
50 ms

NAA(X)

Cutler,Maine, U.S.A.

44° 39' N
67° 17' W

Omni­
directional2000
i0 0 0 0

1

7

24

14-7

nil

nil

nil

±005

nil

NBA(»)

BalboaPanama Canal
Zone, U.S.A.

09° 04' N
79° 39' w

Omni­
directional300
30(:1)

17

2 4 (018

K12)continuous

nil

±005

Steps of
50 ms

NPG/NLK0

Jim Creek
Washington
U.S.A.
-----------------

48° 12' N
121° 55' W

Omni­
directional

1200
250{8)

I

7

24

18-6

nil

nil

nil

±005

nil

21° 25' N ;Lualualei
Hawaii, U.S.A. 158° 09' W
Annapolis
38° 59' N
NSS(l)
Maryland76° 27' W
U.S.A.
50° 08' N
Podebrady
OMA
Czechoslovaks R 15° 08' E
55° 45' N
Moscow
RWM-RES
37° 33' E
U.S.S.R.
59° 35' nEnkttpingSAZ
17° 08' E
Sweden59° 20' N
Stockholm
SAJ
18° 03' E
SwedenOmnidirectional

1 1000I 10001

1 7

2 4 (0

19-8

nil

nil

' nil

±005

nil

Omni­
directional

1000
1000

1

7

24

22-3

nil

nil

nil

±0-05

nil

T

5

1

7

24

50

K0

nil

± I

20

1

7

21(20)

100

1

23 hours
per day( 040 ineach 120

nil±5

Steps of
50 ms
Multiplesof 10 ms

01
(ERP)
006
(ERP)
2;
0-002

1

7

24

100 000

nil

nil

nil

± 5

nil

1

1(0

2 (0

150 000

nil

nil

10(0

±1

nil

1

7

2 3 (0

60

nil

nil

nil

±0-05

nil

1

7

24

100 000

nil±1

Steps of
50 ms

N PM 0W W VB0
zuo

Yagi (12 db)
Omni­
directional

39° 59' N
105° 16' W

Omni­
directional

Johannesburg
Republic ofSouth Africa

26° 11' S
28° 04' E

Omni­
directional(4 )0-05 j1; 100 000 continuous

)

I

■

Rep. 267

N otes to T a b le.II(>) T hese s ta tio n s have in d icated th e ir p articip atio n in th e in te rn a tio n a l c o o rd in a tio n o f tim e an d frequency. T h e tim e-sig n als rem ain w ithin a b o u t 100 m s o f U T 2, an d th e frequency
is m a in ta in ed as c o n s ta n t as possible by reference to ato m ic o r m o lecu lar sta n d a rd s, an d at the offset from the no m in al value an n o u n ced each year by th e B ureau in te rn a tio n a l de 1 H eure.
(*) M easured w ith resp ect to th e an n o u n ced offset in frequency.
(*) F ig u res give th e e stim ated radiated pow er.
(*> L a te r in 1963, the new sta tio n a t F o rt C ollins, C o lo ra d o , w ill ra d ia te 7 kW .
(‘) P ulses o f 200 cycles of 1000 c/s to n e : th e first pulse in each m in u te is p ro lo n g ed .
(•) M o n d ay to S atu rd a y .
( ’) T ra n sm issio n extends essentially from 0645 to 1035 an d 1900 to 0010 U T (I N o v em b e r — 28 F eb ru ary ) and from 1900to 0210 U T (I M arch — 31O cto b er).
(®) In te rn atio n a l type A l teleg rap h y tim e-signals from th e D e u tsch e H y d ro g rap h isch e In stitu t from 0700 to 0710, 1000 to 1010, 1900 to 1910,1930 to 1940, 2000 to 2010 U T an dd u rin g th e m inutes 0 0 to 10 o f each h o u r u n til th e e n d o f tra n sm issio n (see (’)).
.
A l teleg rap h y tim e-signals (c arrier w ith second-pulses) from the P h y sik alisch -T cch n isch e B u n d esan sta lt from 0728 to 0735, 1028 to 1035, 1911 to 1929, 1941 to 1959 U T an d d u rin g
th e m in u tes 57 to 59 o f each h o u r u n til th e end o f th e tra n sm issio n (see ( ’)).
C a rrie r w ith pulses every 2 m inutes from th e P hysikalisch-T echnisch e B u n d esan sta lt fro m 0645 to 0659 a n d 0736 to 0959 U T .
(•) C a r r i:r m o dulated w ith 440 c/s to n e from 0711 to 0727 an d w ith 200 c/s to n e fro m 1011 to 1027 U T .
(•«) T h e frequency o f the c o n tro llin g o scillato r varies by som e p a rts in 10 10 a n d increasin g slow ly a t th e rate o f a b o u t 1p a rt in 10* in one m o n th .
( n ) M ain ten an ce perio d from 1300 to 1430 U T ea ch d ay.
('*) A l telegraphy signals.
( I3) F rom 0255 to 0300, 0855 to 0900, 1455 to 1500 an d 2055 to 2100 U T .
('*) F rom 1430 to 1530 U T.
('») Pulses o f 5 cycles o f1000 c /s to n e : first pulse in each m in u te len g th en ed to 100 m s.
('*) Tim e pulses o cc u r ing ro u p s of 8 ,o n e m illisecond a p a rt; 20 g ro u p s p er second.
(*’) Except from 1300 to 2100 U T o n W ednesday.
( la) Except from 1800 to2300 U T o n
W ednesday.
( “ ) F ro m 1000 to 1100 U T , tra n sm issio n w ith o u t keying except fo r call-sign O M A a t th e beg in n in g o f ea ch q u a rte r-h o u r.
(«•) T ransm ission is in te rru p te d from 0007 to 0100, 1207 to 1300 an d 1607 to 1700 U T each d ay an d from 0607 to 1345 U T o n th e first an d th ird W ednesday o f each m o n th .
(2I) E ach F rid ay .
(“ ) F rom 0930 to 1130 U T .
( « ) 5 m inutes a t the beginning and 5 m inutes at the end of th e tra n sm issio n fo r identificatio n p u rp o ses only.
( 2‘) In te rru p tio n from 1430 to 1530 U T.

_ 205 —

Boulder
U.S.A.

— 204 —

45° 18' N Folded dipoles
75° 45' W and rhombic

REPORT 268 *STABILIZED FREQUENCY EMISSIONS AND MONITORING FACILITIESIN BANDS 4 AND 5(Recommendation 375 and Question 249 (VII))(Geneva, 1963)

1.

Introduction
The following Tables provide inform ation for those interested in the measurement o f
the received phase o f frequency-stabilized emissions in bands 4 and 5, w ith respect to local
frequency standards.
Table I lists frequency-stabilized transmissions, with some operating characteristics.
Table II lists laboratories measuring the received phase of emissions w ith respect to local
frequency standards.

2. Description of methods
2.1 Beat frequency recording
The incoming carrier is mixed w ith a locally generated signal o f the same nominal:
frequency. The beat frequency o f the resultant, represents the relative phase shift of th ereceived signal with respect to the local standard.
2.2 Photographs o f oscillograms
The incoming carrier modulates the beam intensity of an oscilloscope, whose linear sweepis triggered by a signal derived from the local frequency standard. W ith proper am plitude
adjustments, an incoming signal would produce alternate dashes and spaces of equal length,,
if noise were not present. The relative lateral m otion o f the dashes represents a phase shift,o f the received carrier with respect to the local standard and is recorded on an oscilloscope:
cam era with the m otion of the film at 90° to the oscilloscope sweep.
2.3 Servo
A servo system is used to bring a locally generated signal of the same nom inal frequency
into a constant phase relationship with respect to the received carrier. The relative phaseshift o f the received carrier, with respect to the local standard, is represented by the angularrotation o f the phase shifter shaft, which is usually recorded on a mechanical counter anda chart recorder.
F or further inform ation on different m ethods o f phase com parisons, reference is m a d e
to Doc. VII/5 of Geneva, 1962.

* This R eport was adopted unanimously.

Rep. 268

— 207 —

T able I

Stabilized carrier emissions in bands 4 and 5
C a rrie r pow er(kW )T ran sm issio n schedule

S tationc a ll sign
a n d ap p ro x im atelo c atio n

C a rrierfrequency(kc/s)

DCF77 Mainflingen,
F.R. of Germany

77-5

CYZ40
Ottawa, Canada

80

GBR Rugby,
United Kingdom

16

300

MSF Rugby,
United Kingdom

60

10

JG2AR
Tokyo, Japan

20

3

NAA
Cutler, Maine, U.S.A.

14-7

2000

1000

NBA Balboa,
Canal Zone, U.S.A.

18

300

NPG/NLK Jim Creek,
Washington, U.S.A.

18-6

NPM Lualualei,
Hawaii, U.S.A.

to an ten n ara d iatedF req u en cy
accuracy(p arts in 10 s)

d ays/w eek

h o u rs/d ay

6

10

±0-5

7

24

-

7

22

±0-5

7

1

±0-5

2

±5

7

24

±005

30

7

24

±005

1200

250

7

24

±0-05

19-8

1000

100

7

24

±005

NSS Annapolis,
Maryland, U.S.A.

22-3

1000

100

7

24

±005

OMA Podebrady,
Czechoslovak S.R.

50

5

7

24

± 1

RWM-RES
Moscow, U.S.S.R.

100

20

7

21

±5

WWVB Boulder,
Colorado, U.S.A.

60

50

7

7

* 23

±005

WWVL Boulder,
Colorado, U.S.A.

20

50

1

7

24

±0-05

12

40

— 208 —Rep. 268

T ableII

Laboratories measuring the received phase o f emissions in bands 4 and 5
A ddress

Australia
C.S.I.R.O. National Standards Laboratory,
Sydney, New South Wales

M eth o d

S tatio n s m o n ito red

GBR, NBA

Servo

Mount Stromlo Observatory, Canberra,
Australian Capital Territory

GBR

Beat frequency recording. P.M.G. Research Laboratories,
Melbourne, Victoria

GBR, NPM

Servo

Weapons Research Establishment,
Salisbury, South Australia

GBR, NBA

Beat frequency recording

Belgium
Free University of Brussels, Brussels

GBR, NAA

Oscilloscope photography

CanadaNational Research Council,
Physics Department, Ottawa

CYZ 40, GBR
MSF, NBA

Beat frequency recording(Atomic frequency standard)

FranceC.N.E.T., 196, rue de Paris
Bagneux (Seine)

GBR, NAA, NBA
Servo
NPM, NPG/NLK, NSS (atomic frequency standard)

India
National Physical Laboratory,
New Delhi
Italy
Istituto Superiore P. & T.,
Viale Trastevere, Roma
« Istituto Elettrotecnico Nazionale »Corso M. D ’Azeglio, 42, Torino
Japan
Tokyo Astronomical Observatory,
Mitaka, Tokyo
Radio Research Laboratories,
Koganei, Tokyo
New Zealand
Dominion Physical Laboratory,
Lower Hutt
F.R. o f Germany
Fernmeldetechnisches Zentralamt,
Darmstadt
Physikalisch-Technische-Bundesanstalt
Braunschweig

GBR

Oscilloscope

GBR, NBA

Servo

GBR, NBA

Beat frequency recording

NPM

Servo (atomic frequency
standard)

GBR

Beat frequency recording

DCF 77, MSF,
NAA, NBA

Beat frequency recording

DCF 77, GBR, NBA

Beat frequency recording(atomic frequency standard)Rep. 268

— 209 —
A ddress

SwedenResearch Institute of National Defense,
Stockholm

M eth o d

S tatio n s m o n ito red

GBR, NBA, NPM

Servo (atomic frequency
standard)

GBR, NAA, NBA,
NSS

Oscilloscope photography(atomic frequency standard)

National Physical Laboratory,
Teddington

GBR, MSF, NBA

Beat frequency recording andservo (atomic frequency
standard)

Post Office Research Station,
Dollis Hill, London

NBA

Servo
(atomic frequency standard)

Royal Greenwich Observatory,
Herstmonceux

GBR, NBA

Servo

Harvard University,
Cambridge, Massachusetts

GBR, NBA and others

Oscilloscope photography(atomic frequency standard)

U.S. National Bureau of Standards,
Boulder, Colorado

GBR, MSF, NBA,
WWVB, WWVL

Servo(atomic frequency standard)

U.S. Naval Observatory,
Washington, D.C.

GBR, NAA, NBA,
Servo
NPG/NLK, N,PM, NSS(atomic frequency standard)

U.S. Naval Observatory Sub-Station,
Richmond, Florida

GBR, NAA, NBA
Servo(atomic frequency standard)
NPG/NLK, NPM, NSS

U.S. Naval Research Laboratories,
Anacostia, Maryland, Code 5424

GBR, NAA, NBA
Servo
NPG/NLK, NPM, NSS(atomic frequency standard)

Switzerland
Observatoire Cantonal,
Neuchatel
Republic o f South Africa
Union Observatory, Johannesburg
United Kingdom

United States o f America

Rep. 269

— 210 —R E P O R T 269 *R E D U C T IO N O F M U TU A L IN T E R FE R E N C E BETW EEN STANDARDFR E Q U E N C Y AND T IM E -SIG N A L E M IS S IO N S(Q uestion 140(VII))(Geneva, 1963)
The degree of m utual interference between standard-frequency and time-signal emissions
continues to im pair the value of the services on the allocated frequencies. In recent years, theparticipation of an increasing num ber of stations in the international system of tim e and frequency
coordination, while it is to be welcomed, has raised difficulties in identifying and using synchro­nized signals from several stations in a geographically small area, where the times of arrival of
the signals are separated by only one or two milliseconds. The situation in W estern Europe, wherethese conditions exist, has been simplified by the decision of H BN and M SF to coordinate theirrespective emission schedules. A program m e of time-sharing has been agreed, each station
em itting time-signals in alternate 5-minute periods, the last 5-minute period in each hour being
left free for the reception of the time-signal emissions of RW M -RES (5 Mc/s). It would be
advantageous if O M A (2-5 Mc/s) could also bring its m odulation program m e into accord with
the new M SF schedule; a unified standard-frequency and time-signal service would thus be secured
over a large area of W estern Europe.
The presence of continuous tone m odulation on a num ber of emissions constitutes a prolificsource of interference with time-signal reception. By its nature, the tone m odulation is limited
essentially to applications requiring only low accuracy and it seems very desirable to restrict theextent of such m odulation. H BN and M SF have already eliminated all periods o f tone m odu­
lation from their schedules. IA M (5 Mc/s) has reduced the num ber of audio-frequencies usedfrom three to one (1000 c/s) and the total period of m odulation from 40 to 16 minutes per hour.
IBF (5 Mc/s) also intends to suppress all but 1000 c/s m odulation and this will be limited to 5 minutes
per hour. The periods of tone m odulation on F F H (2-5 Mc/s) will also be modified or reduced,
if this will contribute to a reduction of m utual interference on this frequency.
O ther approaches to the problem of the coexistence of several standard-frequency stations
are being made. Thus WWV, in addition to reducing progressively the tim e devoted to tone
m odulation has also, for the past three years, introduced a gap of 40 ms in the continuous m od­ulation in which the time-signals have been inserted. This technique has also been investigatedin Japan by means of special emissions using JJY (10 Mc/s), the length of the gap being
increased to 85 ms to perm it reception o f the time-signals from any other synchronized station
free o f interference from the tone m odulation [1]. This system allows the sim ultaneous emissionof both tone and pulse m odulation w ithout serious detrim ent to either, but it also requires theuse o f rather m ore complex equipm ent at the receiving station if the time inform ation is to be
extracted satisfactorily.
A n alternative to time-sharing is frequency-sharing, and Study Program m e 140B(VII) callsfor exam ination of the possibilities of single-sideband operation o f standard-frequency trans­mitters. This m ode of operation is in use for a num ber of the WWY frequencies and also by
IA M (5 Mc/s) and offers the possibility of reducing interference between two stations by using,* This Report was adopted unanimously.

Rep. 269, 270— 211 —

respectively, the upper and lower sidebands. Again it is apparent, th a t such a scheme would
dem and more advanced receiving equipm ent for best results.
The X th Plenary Assembly, C .C.I.R., afforded an opportunity for an exchange o f views
between A dministrations, but it should be emphasized th at bi-lateral or m ulti-lateral negotiations
between organizations operating standard-frequency services m ay lead to a m ore direct solutionof the interference problems in restricted regions. If the C hairm an and Vice-Chairman of C.C.I.R.
Study G roup VII, the D irector, C.C.I.R. and the I.F.R .B. are kept inform ed o f such nego­tiations, it will enable them to assist and expedite the w ork o f reducing interference.

B ib l io g r a p h y

1. C.C.I.R. Doc. 147 of Geneva, 1963.

R E P O R T 270 *F R E Q U E N C Y S P E C T R U M C O N SE R V A T IO N F O R H IG H
P R E C IS IO N T IM E -SIG N A LS
(Study Program m e 250A(VII))(Geneva, 1963)
There is a need for increasingly greater precision in the distribution of time-signals. The
bandw idth occupied by a system of distribution can be expected to increase to the allowablemaximum by factors such as the w idth of the allocated band, by lim itations im posed by thetransm ission m edium and considerations o f noise and interference.
A n example of a system, developed to exploit to the full the properties of the transm ission
medium, is the navigational system know n as Loran-C operating at 100 kc/s. This system has
been dem onstrated to be capable of high precision for the distribution of tim e inform ation. The
pulse in this system is chosen to be sufficiently brief in duration that, at ranges exceeding 2000 km ,its arrival can be detected before the arrival of the first ionospheric wave returned from the D-layer.
The relative delay was found by measurem ent to be 25 to 30 [ls. This leads to a pulse having
an equivalent bandw idth of 20 kc/s.
A t high frequencies, where long-distance propagation is wholly dependent upo n ionosphericpropagation, the precision with which time-signals can be received is lim ited by the characteristicsof the propagation medium. The bandw idths in use have been determ ined largely by adm in­istrative decision rather than by the physics of the problem . The waveform at present in use
for standard-frequency broadcasts is considered in Doc. VII/10 of Geneva, 1962 [1], where a
Fourier analysis is perform ed and examined. Similar w ork on other waveforms seems desirable.
It would also seem desirable to extend the study to include th e effects of noise an d propagation.
Certain aspects o f propagation in band 10 are considered in R ep o rt 271. A lthough this R ep o rt
has an application limited mainly to long-distance transm ission in bands 6 and 7, the analysis
of waveform and of propagation effects are of considerable general interest. H ere again noise
is likely to be an im portant factor and the study merits the inclusion of considerations o f nonG aussian noise.
Doc. VII/11 of Geneva, 1962 [2], contains inform ation about the effects of propagation uponfrequency measurements over long-distances. This and sim ilar data are useful for the building-up
o f inform ation for the evaluation of propagation conditions on time-signal accuracy.
This R eport was adopted unanimously.

Rep. 270, 271— 212 —

It is considered im portant th at further w ork should be based on Study Programm e 250A(VII).
Doc. V II/4 of Geneva, 1962 [3], refers briefly to proposed experiments and it is most desirable
that, as soon as possible, the experimental emission of alternative forms of time-signal should
be made. Adm inistrations should be requested to cooperate in the proposed experiment which
will study the characteristics of, for example, the “ sine-squared pulse ”, which appears to becapable of best tim e identification for a given bandwidth.
It is considered also that experiments of the kind referred to in Reference [3] should be
supplemented by laboratory experiments employing a m ultipath-propagation sim ulator, so thatsystematic com parisons may be m ade of different signals under various conditions of propagationand noise.

B ib l io g r a p h y

1. C.C.I.R. Doc. VTI/10 (U.S.A.) of Geneva, 1962. Time pulses on standard-frequency broadcasts.
2. C.C.I.R. Doc. VII/11 (Japan) of Geneva, 1962. Studies of the variation in HF standard-frequencies
as received.
3. C.C.I.R. Doc. VII/4 (U.R.S.I.) of Geneva, 1962. Frequency spectrum conservation for high-precisiontime-signals.

R E P O R T 271 *A CA U SE O F R E D U C E D STA BILITY AND ACCURACY IN STANDARDFR E Q U E N C Y AND T IM E -SIG N A L S AS R EC EIV ED(S tudy P ro g ram m e 250B(V II))
(Geneva, 1963)
It has been shown that the stability of standard-frequency signals may be adequately describedin term s of the frequency spectrum of the fluctuation A/ = f 0—f s of the instantaneous observed
frequency f 0 about its mean value f s. The fluctuation A / of the instantaneous frequency may
be considered to be a random continuous function of the tim e and this random function will
have somewhat the same appearance, when plotted on graph paper, as the envelope of a random
noise voltage as received at the output of a narrow band filter. Thus, there will be present a
continuous spectrum of fluctuation com ponents having periods ranging from zero up to the periodof tim e T over which the observations are made.
It is shown in [1], that the spectrum o f the fluctuations of a standard-frequency, observed
after propagation over a line-of-sight micro-wave link, may be divided into two additive com po­nents. One of these com ponents is associated with the signal prior to its emission over thelink, while the second com ponent represents the additional fluctuations which are added to thosepresent at the source as a result of propagation through the turbulent propagation medium.
The first part o f [1] deals with the com ponent of the spectrum associated with the propagation,
while the second p art of the report contains a brief discussion of the fluctuation spectrum ofsome of the m ore stable oscillators presently available in the U nited States. One of the im portant
conclusions is th at oscillator instability is an order of m agnitude larger than the propagation
instability and this represents, at the present state of the art, the controlling influence on the* This R eport was adopted unanimously.

— 213 —Rep. 271

stability of signals propagated over line-of-sight microwave links. This is in m arked contrast
to the stability of signals propagated via the ionosphere. Thus, it is know n th at ionospherically
propagated signals have an instability spectrum which is at least com parable to and possibly
substantially larger than that of the best currently available oscillators.
The fractional standard error of the average frequency of a good oscillator varies from
8 x 10_ n to 2 x 10~12, as the averaging time is varied from zero to 106 s and, for still longer averaging
times, varies inversely as the square ro o t of T. The contribution to this instability by a 50 km
line-of-sight path in Florida can be represented by a fractional standard error which varies fromabout 3 x 10-12 to 1 x 10-14, as the averaging time is varied from zero to 106 s and, for still longer
averaging times, varies inversely with T.
Article [1] also discusses the inaccuracy of time intervals which are m easured by counting
the num ber of cycles of an oscillator having a know n m ean frequency f s. The standard error
axes of a tim e interval T measured by counting the cycles of a good oscillator with a m ean frequency
f s = 50 Mc/s varies from about 1 x 10~8 to 2 x 10-6 s, as the tim e interval T is increased fromzero to 106 s and thereafter increases as the square root of T. The contribution to this standard
error by a 50 km line-of-sight path in Florida for a m ean frequency f s = 9 G c/s varies from6 x 10-11 to 1 x 10~8 s, as the time interval T varies from zero to 106 s and thereafter is independentof T.
Article [1] shows that the asym ptotic behaviour of the standard error ores of a timeinterval T, as T is allowed to increase w ithout limit, depends upon the behaviour o f the spectumof the oscillators at very low fluctuation frequencies and, since little is actually know n about
this spectrum at these very low fluctuation frequencies, the results for ojes given for large valuesof T are based merely on extrapolations of the m easured behaviour of the spectrum at higher
fluctuation frequencies.
In addition to providing the above inform ation on the effects of the troposphere on thestability of standard-frequency signals transm itted through it, the analysis in this R eport provides
an interesting confirmation of the Obukhov-K holm ogorov theory relative to the frequency
spectrum of atmospheric turbulence.

B ib l io g r a p h y

1.

N o r t o n , K.A., B a r r o w s , E., T h o m p s o n , M.C., Jr. and J a n e s , H.B. Variance of radio frequency
caused by atmospheric turbulence in line-of-sight transmissions. Trans. IRE, PGI (December 1962).

PAGE INTENTIONALLY LEFT BLANKPAGE LAISSEE EN BLANC INTENTIONNELLEMENT

— 215 —STUDY GROUP VII(Standard-frequencies and time-signals)
Terms o f reference:
O rganization of a world-wide service of ,standard-frequency and time-signal emissions.
Im provement of measurem ent accuracy.
Chairman :Vice-Chairman :M r. B. D e c a u x (France)
Professor M. B o e l l a (Italy)

IN T R O D U C T IO N B Y T H E C H A IR M A N , S T U D Y G R O U P V II

One cannot really say that any of the problem s under study by Study G roup V II havebeen “ liquidated ” . The field of activity of this Study G roup is continually widening andfrom one Plenary Assembly to another, the various problem s receive partial b u t progressively
better solutions; moreover, new solutions appear, which m ust in their tu rn be studied.
R eport 267 gives a general impression of the w ork of Study G roup VII.
The m ain problem s under study are:1.

Increase in accuracy of measurements m ade on standard-frequency emissions. This appears
in different guises:
1.1 Recom m endation 374 has tightened the tolerances on the frequency emitted from ± 5 x 10-9
to ± 5 X 10-10.
1.2 The same Recom m endation lays down, in accordance with an U .R .S.I. resolution, th at the
Bureau international de l ’H eure should fix, for each year, the offset between the em itted
frequency and the nom inal frequency, so that time-signals, derived from the em itted frequency,
should follow approxim ately Universal Time.
1.3 Definition and increase in stability of standard-frequency generators are the subject of Study
Program m e 250A(VII) and R eport 271.
1.4 The use of frequencies much lower or much higher th at those of the form er emissions should
allow interference due to propagation to be avoided (Question 249(VII) and Recom m en­dation 375).
1.5 New m ethods for the emission o f time-signals are likely to increase accuracy.
This isso when signals of special shape are used (Question 250(VII) and R eport 270), or artificial
satellites (Study Program m e 249A(VII).

2.

Reduction of interference, harmful to the standard-frequency service. This interference is of
two types:
2.1 M utual interference between stations of the service operating at the same frequency. Study
Program m e 140A(VII) and R eport 269 propose remedies, in particular by tim e-sharing
between the transm itters. Study Program m e 140B(VII) forsees the use of single-sideband
emissions, with the same object in view.
2.2 Interference caused by stations outside the standard-frequency service. Recom m endation 376
stresses yet again the urgency with which A dm inistrations should free the standard-frequency
bands.
3.

Tables of characteristics of emissions are given in R eports 267 and 268. The later, speciallyconcerned with emissions in bands 4 and 5, also gives a list of laboratories which m ake
regular measurements of these emissions.

Res. 14, Q. 140— 216 —RESOLUTION 14
STA N D A R D -FREQ U EN CY AND TIM E-SIG N A L E M IS S IO N S(Q uestion 140(VII))
The C .C .I.R.,(Geneva, 1963)

C O N S ID E R IN G

the provisions of A rt. 44, Section IV, of the R adio Regulations, Geneva, 1959;
U N A N IM O U SL Y D EC ID ES

1.

that, whenever an assignment to a station operating standard-frequency emissions is put
into service, the A dm inistration concerned shall notify this assignment to the I.F.R .B ., in
accordance with the provisions of Art. 9 of the R adio Regulations, Geneva, 1959; however,no notice should be subm itted to the I.F.R .B. until experimental investigations and co­ordination have been completed, in accordance with A rt. 44, Section IV, of the R adio Regu­
lations ;2.

that each A dm inistration should send all pertinent inform ation on standard-frequency stations(such as frequency offset, changes in the phase of time pulses, changes in transm ission schedule,etc.), to the Chairm an of Study G roup VII for forwarding, via the D irector, C.C.I.R. to the
I.T.U . for official publication;

3.

that cooperation of Study VII should continue with the I.A .U . (Com m ittee 31), the U.R.S.I.
and the B.I.H.

Q U E ST IO N 140(VII) *STA N D A RD -FR EQ U EN C Y AND T IM E -SIG N A L E M IS S IO N S
The C.C.I.R.,(Stockholm, 1948 - Geneva, 1951 - London, 1953 - W arsaw, 1956)

C O N S ID E R IN G(a) that the Administrative Radio Conference, Geneva, 1959, called for the study of the estab­lishment and operation of a world-wide standard-frequency and time-signal service;* This Question replaces Question 87.

— 217 —Q. 140, S.P. 140A(b) th at a num ber of stations are now regularly emitting standard-frequencies and timesignals in the bands allocated by this Conference;(c) th at some areas of the world are n o t yet adequately served;(d) th at the use of m ore stations than are technically necessary would diminish the utility ofthe service by producing harm ful interference;u n a n im o u s l yd e c id e s

th at the following question should be studied:1.

w hat measures can be recom m ended for increasing the effectiveness of the existing standardfrequency and time-signal service in the bands allocated by this Conference;2.

w hat measures can be recom m ended for the reduction o f m utual interference between standardfrequency and time-signal stations operating on the same frequency and whose service areas
overlap?

ST U D Y P R O G R A M M E 140A(VII) *STA N D A R D -FR EQ U EN C Y AND T IM E -SIG N A L E M IS S IO N S(Geneva, 1951 - London, 1953 - W arsaw, 1956 Los Angeles, 1959 - Geneva, 1963)

The C.C.I.R.,
C O N S ID E R IN G(a) th at Question 140(VII) and Recom m endation 374 call for inform ation on m ethods for
improving the usefulness of the existing standard-frequency and time-signal service;(b) that standard-frequency stations are operated simultaneously on the same carrier frequency;(c) th at standard-frequency emissions are also used as a means o f m easuring radio propagation
characteristics;
u n a n im o u s l yd e c id e s

th at the following studies should be carried out:

1.

an investigation of the possibilities of reducing m utual interference between emissions inthis service by:
1.1 shortening the program m e of continuous tone m odulation and o f announcem ents;
1.2 use of a m odulation which gives the required inform ation and accuracy with m inim um
bandw idth;
1.3 staggering the emissions in the allocated bands and using a convenient type of m odulation;
1.4 a convenient coordinated tim e-sharing o f frequencies for those areas where there is m utualinterference;2.

an investigation, with the assistance of Study G roup VI, into the desirability of staggering
the frequencies for radio propagation studies;3.

collection of inform ation On how standard-frequency emissions in bands 6 and 7 may becoordinated with emissions in other bands to give the best overall world-wide service.

* This Study Programme replaces Study Programme 155.

S.P. 140B, Q. 249— 218 —STUDY PROGRAMME 140B(VII)SIN G LE-SID EBA N D O P E R A T IO N F O R T H E STA NDA RD-FREQUENCY
A ND T IM E -SIG N A L SERV ICE
The C .C.I.R.,t(Geneva, 1963

C O N S ID E R IN G(a) th at N o. 465 of the R adio Regulations, Geneva, 1959, urges A dministrations to discontinue
the use of double-sideband radiotelephone transmissions in the fixed service, in the bands
below 30 M c/s;(b) th at an I.T .U . Panel of Experts, in September, 1961, listed technical and economic advantagesof single-sideband systems and urged A dm inistrations to accelerate the conversion of their
double-sideband radiotelephone systems, in the bands below 30 Mc/s, to single-sideband
systems and to complete such conversions by 1967 or earlier if possible;
th at the following studies should be carried out:
what improvements may be obtained in the distribution and use of standard-frequency
and time-signal emissions by the use of single-sideband operation, particularly in the bands
at 2-5; 5; 10; 15; 20 and 25 M c/s?
u n a n im o u s l yd e c id e s

Q U E ST IO N 249(VII) *STA N D A RD -FR EQ U EN C Y AND T IM E -SIG N A L E M IS S IO N S
IN A D D ITIO N A L FR EQ U E N C Y BANDSThe C.C.I.R.,(Warsaw, 1956 - Geneva, 1963)

C O N S ID E R IN G(a) that in certain regions, particularly in industrial centres, it is n ot always possible to obtainan adequate ratio of the w anted signal to the noise level with the existing standard-frequency
and time-signal service;(b) th at the bands allocated for standard-frequency and time-signal emissions are m ore usefulfor long-distance distribution than for local distribution;(c) that a better service is needed in certain areas and this service may be' given by use of fre­quencies in band 8 and higher;(d) that high accuracy frequency and time com parisons between distribution centres can bem ade using frequencies in bands 4 and 5;
th at the following question should be studied:w hat can be recommended for the distribution of standard-frequencies and time-signals,
above 30 Mc/s and below approxim ately 100 kc/s?
u n a n im o u s l yd e c id e s* This Question replaces Question 142.

— 219 —S.P. 249A, Q. 250

STUDY PROGRAMME 249A(VII)STA N D A R D -FREQ U EN CY AND T IM E -SIG N A L E M IS S IO N S
F R O M A R TIFIC IA L E A R T H SA TELLITESThe C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) th at continuing advances in com munications, particularly in space com m unications' andassociated science and technology, have increased the requirem ents for accuracy and service
range of standard-frequency and time-signal emissions;(b) th at the w ork of Study G roup IV describes radiocom m unication systems m aking use ofearth satellites which can be expected to give extensive coverage and good stability o f signals
over the ea rth ’s surface;u n a n im o u s l yd e c id e sthat the following studies should be carried out:

w hat are the technical factors to consider in recommending frequencies and in determining
the transm itting, m odulating and receiving techniques, which are im portant to the developmentof standard-frequency and time-signal emissions from artificial earth satellites?

Q U E S T IO N 250(VII) *STA BILITY O F STA N D A RD -FR EQ U EN CY AND T IM E -SIG N A L
E M IS S IO N S AS RECEIV ED
The C.C.I.R.,(Warsaw, 1956 - Los Angeles, 1959 - G eneva, 1963)

C O N S ID E R IN G(a) that the standard-frequency and time-signal emissions as received are less stable than at
the source, owing to phenom ena occurring in the propagation of radio waves, e. g. the D oppler
effect, diurnal variation and m ultipath interference;(b) th at errors, which occur during propagation, depend on the geographical location of boththe transm itter and receiver, as well as on the nature and condition of the medium, and are
generally different in different regions of the radio spectrum ;(c) th at special techniques of standard-frequency and time-signal emissions may im prove theaccuracy with which they can be received;(d) th at the accuracy with which standard-frequency and time-signal emissions can be received
may depend upon the design of the receiving equipm ent;u n a n im o u s l yd e c id e sthat the following question should be studied:1.

w hat are the causes of the reduction in the stability and accuracy of the standard-frequencies
and time-signals as received by the users;

2.

w hat is the m agnitude in statistical term s of the instability introduced by these causes;* This Question replaces Question 186.

Q. 250, S.P. 250A, S.P. 250B
3.

— 220 —

w hat are the m ost suitable techniques for transm itting and receiving standard-frequencies
and time-signals to obtain the best results in the reception o f :- standard-frequencies and time-signals as used by those requiring m oderate accuracy;- standard-frequencies and time-signals as used by those requiring the maximum possible
accuracy ?

ST U D Y P R O G R A M M E 250A(VII) *FR E Q U E N C Y S P E C T R U M C O N SER V A TIO N
F O R H IG H P R E C IS IO N TIM E -SIG N A L S
The C.C.I.R.,(Los Angeles, 1959)

C O N S ID E R IN G(a) th at higher precision in the radio distribution of time-signals necessitates, using present
techniques, the use of an increased bandw idth;(b) that newly developed techniques may, nevertheless, effect a considerable bandw idth economy;u n a n im o u s l yd e c id e sthat the following studies should be carried out:

1.

an investigation of the relationship between bandw idths required, and precisions obtainableat present for various carrier-to-noise ratios as may be encountered in practice;2.

an investigation of narrow band techniques to generate and broadcast high precision time
m arkers;

3.

an investigation of the characteristics of the radio paths involved th at limit the accuracy oftime-signals as received, and how these radio-path param eters affect the choice o f an optim um
method.

S T U D Y P R O G R A M M E 250B(VII)IN STA B ILITY O F STA N D A RD -FREQ U EN CY G EN ER A TO R S
The C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G

that the em ployment of high quality frequency standards in a wide range o f applications
has given rise to a need to specify, in convenient and precise terms, the various forms o f fre­quency instability which limit perform ance in relation to the increasingly stringent require­m ents;u n a n im o u s l yd e c id e s

th at the following studies should be carried out:

1.

how may the various forms of frequency instability, inherent in a standard-frequency generator,
be qualitatively described;

2.

how may the limitations of precision, imposed by various form s of frequency instability ina standard-frequency generator, be quantitatively expressed?

* This Study Programme was previously designated Study Programme 156 (VII).

Q. 251— 221 —Q U E S T IO N 251 (VII)ST A N D A R D IZ A T IO N O F T IM IN G C O D E S
The C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) th at continuing advances in com munications and electronic technology have shown a needfor the further development of methods of emission, distribution and recording o f tim e;(b) th at timing codes are being used by observatories, m onitoring and tracking stations locatedin various countries all over the w orld;u n a n im o u s l yd e c id e s

th at the following questions should be studied:1.

how can coded time-signals be distributed by radio emissions from earth or from space;2.

w hat standard form at should be used for timing codes?

— 222 —LIST OF DOCUMENTS OF THE Xth PLENARY ASSEMBLY
CONCERNING STUDY GROUP VII
D o c.

T itleO rig inR eference

7

Chairman,
Study Group VII

Report by Chairman of Study Group VII(Mr. B. Decaux)-

21

I.F.R.B.

Proposed amendment to Draft Recommen­
dation - Standard-frequency transmissions
and time-signals"

129

C.C.I.R. Secretariat

Bibliographic references in the volumes of
the C.C.I.R.

—

147

Japan

Studies on a time schedule of audio modu­
lation on standard-frequency and time-signaltransmissions

S.P. 155

260

U.S.S.R.

Data on standard-frequency and time-signaltransmissions for inclusion in the Draft Re­
port in Annex 7/11

Rep. 166

263

Czechoslovak S.R.

Comments on Docs. VI1/39 and VII/56

Q. 140
S.P. 155
Rep. 166

273

I.F.R.B.

Results of the special monitoring programme
for October, 1962 in the exclusive standardfrequency service bands, and action being
taken by the I.F.R.B. in attempting to clear
these bands of out-of-band transmissions

IFRB Circ.
No. 51284

Study Group VII

Summary record of the first meeting-

379

Study Group VII

Summary record of the second meeting

403

Study Group VII(Italy)Compatibility of European standard trans­missions on 5 Mc/s

404

Study Group VII

Single-sideband operation for the standardfrequency and time-signal service

Draft S.P.

411

Study Group VII

Standard-frequency transmissions and time
signals

Draft Res.

465

Study Group VII

Stabilized frequency transmissions and moni­
toring facilities in bands 4 and 5

Draft Rep.

466

Study Group VII

Revised Tables I and II of Report 166

Rep. 166

467

Study Group VII

Reduction of mutual interference between
standard-frequency and time-signal trans­missions

Draft Rep.

474

Study Group VII

Standard frequencies and time-signals

Draft Rep.

556

Study Group VII

Summary record of the third and last meeting

2088

Drafting CommitteeStandard-frequency and time-signal trans­missions in additional frequency bands

Rec. 375

Avoidance of external interference with trans­missions of the standard-frequency service inthe bands allocated to that service

Rec. 376

2089

2090

”

”

Standard-frequency and time-signal trans­missions in additional frequency bands

Q. 2492091””

Stability of standard-frequency and time-sig­
nal transmissions as received

Q. 2502092”

Timing code standardization

Q. 251O th erStudy
G ro u p s
concerned

I-XIV

— 223 —D o c.

O riginT itleR eference

2093

Drafting Committee Standard-frequency and time-signal transmissions

S.P. 140A

2094

Instability of standard-frequency standards
generators

S.P. 250B

2095

Standard-frequency and time-signal transmissions from artificial earth satellites

S.P. 249A

2096

Frequency spectrum conservation for highprecision time-signals

Rep. 2702107

A cause of reduced stability and accuracy instandard-frequency and time-signals as re­ceivedRep. 271

2186

Single-sideband operation for the standard- .
frequency and time-signal service

S.P. HOB

2187

Standard-frequency and time-signal transmissions

Res. 14

2188

Standard-frequency and time-signal transmissions

Rec. 374

2262

Stabilized frequency transmissions and monitoring facilities in bands 4 and 5

Rep. 268

2263

Reduction of, mutual interference between
standard-frequency and time-signal transmis­
sions

Rep. 269

2264

Standard-frequencies and time-signals

Rep. 267

O th erStudy
G ro u p s
co n cern ed

IPAGE INTENTIONALLY LEFT BLANKPAGE LAISSEE EN BLANC INTENTIONNELLEMENT

— 225 —Rec. 182

RECOMMENDATIONS OF SECTION J: MONITORING OF EMISSIONSR E C O M M E N D A T IO N 182
A U TO M A TIC M O N IT O R IN G O F O C C U PA N C Y O F T H E R A D IO -FR E Q U E N C Y
SP E C T R U M(Q u estio n 255(VIII))The C.C.I.R.,(W arsaw, 1956)

C O N S ID E R IN G(a) th at the increasing dem and for radio services requires the m ost efficient use of the radio­frequency spectrum;(b) th at the m ost efficient use of the spectrum can be arranged, only when the distribution intime, magnitude and direction of the signals occupying it is know n;(c) th at autom atic m onitoring equipm ent is now in use by A dm inistrations and th at further
development in autom atic observation is foreseen, including m ethods for the analysis ofreco rds;(d) that, by the use of autom atic m onitoring equipment, a num ber o f param eters can be evaluatedwhich are of considerable value in enabling m ore efficient utilization of the spectrum ;U N A N IM O U SL Y R EC O M M E N D S

1.

that, although autom atic m onitoring equipm ent will n ot completely replace m anual observa­
tions, it is a valuable aid. Adm inistrations should be encouraged to undertake the use andfurther development of such equipm ent;

2.

that, although further study is needed to enable A dm inistrations and frequency-planning
authorities to derive the greatest benefit from the records produced, it is desirable th at equip­
m ent should possess the following principal characteristics:- minimum 2 to ^ iv±Wo,- total frequency range
desirable 10 kc/s to 30 Mc/s or m ore;variable, typical range 100 to 1000 kc/s;- swept frequency range
variable, 30 to 180;
- num ber of sweeps per hourvariable; dependent on the desired frequency reso­- maximum rate of sweeping
lution for the band being swept and the class orclasses of emission being recorded;
1 [i.V/m or better;- sensitivity
variable; approxim ately 100 to 1000 c/s;
- resolving power- carrier frequency,- signal characteristics recorded- bandwidth,- field-strength,- duration of occupancy;
paper chart 20 c m x 3 2 cm for tw enty-four hours;- size of records
calibration at intervals o f 1, 10 or 100 kc/s as
appropriate.

3.

th at it is desirable that the records should also contain, if possible, the following inform ation:- nam e and location of m onitoring station;- date and period of recording;- frequency band;' - signal identification, as appropriate;- class of emission, as appropriate;- direction of signal;- noise level.

— 226 —Rec. 377

RECOMMENDATION 377 *A CCURACY O F FR E Q U E N C Y M E A SU R E M E N T S AT
M O N IT O R IN G STA TIO N S(Q uestio n 252(V III))The C.C.I.R.,(Stockholm, 1948 - W arsaw, 1956 - Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) the requirem ents of the Administrations, of international organizations carrying out m oni­
toring observations and of the I.F.R .B., in respect of the frequency measurem ents necessary
for the efficient perform ance o f their duties;(b) the general availability of suitable m onitoring equipm ents for frequency m easurem ents;(c) that it is desirable that the errors o f frequency m easurem ent shall n ot exceed one-tenth o f
the frequency tolerances specified in Appendix 3 to the R adio Regulations, Geneva, 1959;
U N A N IM O U S L Y REC O M M E N D S

that m onitoring equipments and procedures shall be such, th at frequency m easurem ents
shall be m ade with an accuracy equal to, o r better than, th at specified in the following table:

T ype of m easurem ent

A ccuracy

Measurements of the frequencies of stations, except broad­ ± 5 parts in 106 (or, where this would becasting stations, operating in the band 10 kc/s to 4000 kc/s less than ± 1 c/s, to an accuracy of ± 1 c/s)
Measurements of the frequencies of broadcasting stations,operating in the band 10 kc/s to 4000 kc/s

dh 1 c/s

Measurements of the frequencies of stations, except tele­vision broadcasting stations, operating in the band 4000
kc/s to 500 Mc/s

±1-5 parts in 10®

Measurements of the frequencies of stations, except tele­vision broadcasting stations, operating in the band 500
Mc/s to 10-5 Gc/s

± 1 part in 105

Measurements of the frequencies of television broadcastingstations, operating in the band 30 Mc/s to 1000 Mc/s

±100 c/s

Measurements of the frequencies of stations, operating
above 10-5 Gc/s

± 5 parts in 105

Note 1. - It is realized that, while the accuracies quoted above are sufficient for internationalm onitoring, higher accuracies may be needed to m eet national requirem ents.
Note 2. - F o r frequency m easurements m ade solely to investigate occupancy o f frequency channels,
the permissible error for stations operating in the band 10 kc/s to 30 M c/s is ± 3 p arts in 105.

* This Recommendation replaces Recommendation 322.

_ 227 —Rec. 378

RECOMMENDATION 378 *ACCURACY O F FIE L D -ST R E N G T H M EA SU R EM EN TS BY
M O N IT O R IN G STA T IO N S(Study Program m e 102(VIII))The C.C.I.R.,(London, 1953 - W arsaw, 1956 - Geneva, 1963)

C O N S ID E R IN G(a) th at field-strength m easurem ents are m ade by m onitoring stations in the frequency range
10 kc/s to 1 G c/s;(b) th at accurate measurements, for use in connection with the international registration andassignment o f frequencies, may be desirable;(c) th at the publication o f such data from m onitoring stations is also desirable;
U N A N IM O U SL Y R EC O M M E N D S

1.

that, to obtain the accuracy specified in § 2, the field-strength measuring equipm ent at m oni­
toring stations should be installed, calibrated and operated in accordance with the Annex
to this Recom m endation;

2.

that, except where there are lim itations due to receiver noise level, atm ospheric noise or
external interference, the accuracy to be expected in field-strength measurements, a t intensities
above 1 jiV/m, is as shown below:
Frequency band
Below 30 Mc/s
30 to 1000 Mc/s

3.

Accuracy o f measurement± 2 db± 3 dbth at when, because of lim itations o f measuring instrum ents, interference, signal instability
or for other reasons, the accuracies shown in § 2 are not obtainable, the m easurem ents should
nevertheless receive due consideration com mensurate with the accuracy indicated;

4. th at studies of m ethods and equipm ent for field-strength m easurem ents at m onitoring stations
should be continued.

ANNEX
1.

Fixed antenna installation

1.1 Frequencies o f 30 M c/s and below
It is recom m ended that, for frequencies o f 30 Mc/s and below, vertical antennae shorter
than one-fourth wavelength should be used, with ground systems consisting either of buried
radial conductors, at least twice the length of the antenna and spaced 30 degrees or lessapart, or of an equivalent ground screen.
It is necessary to ensure th at no significant distortion o f the field being m easured iscaused by obstructions, buildings, buried pipes, etc.
Vertical antennae, as described above, are recom m ended as standard for field-strengthm easurem ent by m onitoring stations, for ionospheric signals at frequencies of 30 Mc/s andbelow, for the following reasons:* This Recommendation replaces Recommendation 181.

— 228 —Rec. 378, 379

1.1.1 it is generally accepted th at random variations in polarization of ionospheric waves
are such, that the vertically polarized com ponent is, in general, substantially equal
to the horizontal com ponent;
1.1.2 the response of a vertical antenna, shorter than *4 of a wavelength, is substantiallyindependent of frequency.
1.2 Frequencies above 30 M cjs
Antennae for field-strength m easurem ent at frequencies above 30 Mc/s are recommended
to conform to the following conditions:1.2.1 The receiving antenna m ust have the same polarization as the transm itting antenna.
F o r these frequencies, short m onopole antennae, half-wave dipoles and high-gain
antennae are appropriate.
1.2.2 It is preferable that the antennae be located at a height of 10 m above ground.
1.2.3 Consideration should be given to environm ental conditions (e. g. terrain and obstruc­tions), to minimize factors reducing accuracy.
1.3 Antenna factor
The error in the determ ination of the antenna factor should be kept within 1 db. The
antenna factor takes into account coupling or mismatch losses between the antenna andthe receiver, in the parts not com m on to the measuring and calibrating circuits.
2.

ReceiverThe receiver should have high inherent stability with respect to gain, frequency, bandw idthand attenuation. Particular attention is draw n to the desirability of using voltage regulatorsand crystal controlled oscillators to limit the effect of the receiver on the overall accuracyof field-strength measurements. The m easuring equipm ent should be calibrated as required
to m aintain the accuracies given in § 2 of this Recom mendation.

B ib l io g r a p h y

1. Recommendations U.R.S.I., Commission 1 (1960).
2. S e l b y , M.C. Accurate RF voltages, Communications and Electronics, Trans. A.I.E.E., 6, 158-164(May 1953).

R E C O M M E N D A T IO N 379 *ID E N T IFIC A T IO N O F RA D IO STA TIO N S(Q uestion 256(VIII))The C.C.I.R.,(Geneva, 1951 - London, 1953 - Warsaw, 1956 Los Angeles, 1959 - Geneva, 1963)

C O N S ID E R IN G(a) that the Radio Regulations, Geneva, 1959, Article 19, set forth requirem ents for transm issionsof call signs and state that each radio station provided with a call sign from the international
series must, unless otherwise provided, transm it this call sign during the course of its em ission;* This Recommendation replaces Recommendation 323.

— 229 —Rec. 379(b) th at certain types of radio stations are exempted from the necessity of having an internationalcall sign, for example, stations which are identified by other m eans;(c) that, in some cases, the requirem ent of transm itting the identifying signal by interrupting
the traffic imposes difficulties;(d) that methods for identifying certain complex types of emissions have been evolved;
U N A N IM O U SL Y RECO M M E N D S

1.

th at for the purpose of identification, the identifying signal should be transm itted, using:

1.1 International M orse code using class A l, A2, F I or F2 emission, and transm itted preferably
at m anual speed; or
1.2 Five-unit code (International Telegraph Alphabet N o. 2) using class A l, A2 or F I emission,at the standardized speed of 50 bauds; or
1.3 Speech in clear;
2.

that, if the station does no t desire to interrupt traffic for identification, it should superim posethe identifying signal on the traffic by using the following m ethods:

2.1 Class F I emissions (especially for high-speed or multi-channel operation): A dditional m od­ulation (frequency of phase) of the carrier by the identifying signal in International M orse
code;
2.2 Single- or independent- sideband emissions : A mplitude keying of the reduced carrier or someother pilot frequency;
2.2.1 keying of the reduced carrier, with a difference in level of 5 db, gives a satisfactory
compromise between an acceptable degree distortion of the traffic signals and thesuitability for identification purposes, especially if the identifying signal is repeated;
2.3 Facsimile transmissions employing class A 4 em issions: A m plitude-m odulation, at a frequency
below the lowest used for the facsimile m odulation. W hen single-sideband transm ission
is used, am plitude keying, as in § 2.2 may be used;
3.

that, to avoid additional complexity in the equipm ent and operation of transm itting stations,
every reasonable effort should be made to provide m onitoring stations with equipm ent
suitable for the reception of identifying signals of all stations;4.

th at A dm inistrations should be encouraged to cooperate directly with one another in carryingout tests of identification methods. A dm inistrations are also invited to inform the I.F.R .B .
in advance of such tests of new methods of identification to facilitate cooperative observations
and also to afford other A dm inistrations the opportunity to become acquainted with suchmethods for the identification of radio stations.

I

PAGE INTENTIONALLY LEFT BLANKPAGE LAISSEE EN BLANC INTENTIONNELLEMENT

— 231 —Rep. 272

REPORTS OF SECTION J: MONITORING OF EMISSIONSR E P O R T 272 *F R E Q U E N C Y M E A SU R E M E N T S AT M O N IT O R IN G ST A T IO N S(Q uestion 252(V III»
(Warsaw, 1956 - Los Angeles, 1959 - Geneva, 1963)
Question 252(VIII) seeks inform ation on the desirable ratio of the error o f frequency
measurem ent to the permissible tolerances of emission and the accuracy required for fre­quencies extending up to, in certain cases, at least 10-5 Gc/s. .
Inform ation on equipm ent, accuracy of m easurem ent and m ethods is contained inDocs. V III/ 1(U.S.A.), VIII/13 (Japan), VIII/18 (Japan), VIII/27 (U nited K ingdom) and VIII/28(United Kingdom) of W ashington, 1962. The inform ation available at present may besummarized as follows.

1.

Equipment

1.1 W ith regard to measurem ents above 50 Mc/s, the frequency measuring equipm ents of theindividual countries differ so much that it is only possible to com m ent generally upon them.
Administrations, in general, prefer to make measurements with nearly the same equipm ent
as that which they use for frequency measurements below 50 Mc/s. The extension to ahigher frequency range is effected by the use of harm onics of either a secondary standard
or a stable oscillator or by the use of a frequency synthesis m ethod providing a single tunablefrequency. All equipm ents use direct reading dials in conjunction either with electronic
counters or with visual indicators such as pointer instruments or oscilloscopes.
1.2 W ith regard to the desirable ratio of the error of frequency measurements to the permissible
tolerance and the use o f statistical methods of evaluation, it may n ot be necessary or evendesirable to define the accuracy of frequency measurements in term s of a statistical calculationfor enforcement purposes or for reporting, if necessary, frequency measurements o f stations
to the I.F.R .B. Frequency measurements m ade on a statistical basis may be useful forinter-comparing frequency standards and, in such cases, they should be m ade to the greatest
possible accuracy. It would appear that, to treat a num ber of m easurem ents to a statisticalevaluation, it should be presumed th at the emissions did not themselves shift in frequency
between measurements or th at the various measurements were made simultaneously either
at different m onitoring stations or on different measuring equipments, but such is n o t usually
the case.
1.3 W hen an individual m easurem ent of a radio station is made, its accuracy can be estim atedfrom a knowledge of all of the factors (except perhaps th at of D oppler effect), which produced
the error. The sources of error which should be know n to the measurer, are: the maximum
error in the frequency standard of reference; the m aximum instability error of the transfer
oscillator and the error of setting th at oscillator to zero-beat with the signal. Inasm uch
as the direction of errors, other than that of the reference standard, will n ot usually be know n,
the errors of m easurem ent should be estimated as if they were all in the same direction after
allowing for any know n error of the reference standard.
* This Report, which replaces R eport 169, was adopted unanimously.

Rep. 272

— 232 —

1.4 It is considered, that a conservative ratio of error to tolerance as applied to the majorityo f frequency measurements, is to be preferred over a ratio difficult to obtain. W ith a con­servative ratio, the measuring equipm ent may be operated well within its capabilities witha greater degree of assurance th at all measurements meet the desired minimum accuracy.
1.5 The ratio of 1 to 10 between the error of m easurem ent and the tolerance appears to be areasonable general criterion to retain.
1.5.1 The absolute accuracy o f the secondary standard of a mobile frequency measurement
installation is determined by calibration. Although a stability of ± 1 p art in 109
or better can be achieved with currently available standards designed especially formobile use, the absolute accuracy may n o t exceed ± 1 p art in 107 where standard-fre­quency transmissions m ust be received over a sky-wave path. This problem could begreatly alleviated by the use of V LF standard-frequency emissions in areas where
the signal strength from such stations is adequate for the purpose. A nother approachis the use of an atom ic frequency standard. A portable atom ic frequency standard
is available with an absolute accuracy of ± 1 p art in 109, weighing about 10 kg andrequiring about 50 W o f power for its operation. Use of such frequency standards
in mobile installations would provide the desired 1 to 10 ratio of measurem ent error
to established tolerance.

2.

Accuracy of measurement

W ith regard to § 1 of Question 252(VIII), on the accuracy of frequency measurements
which can be accomplished at m onitoring stations, the following statem ents may be m ade:
2.1 Standard-frequencies are em itted with an accuracy of a few parts in 1010. Secondary
frequency standards, with a stability better than ± 1 p art in 109 per day, are available forboth mobile and fixed m onitoring stations. However, where dependence m ust be placedon sky-wave H F standard-frequency emissions, variations in the length of the propagation
path must be taken into account. W here the com parison period between the secondary
standard and the standard-frequency emissions is short (of the order of one m inute orless), the accuracy may at times be no better than ± 1 p art in 107. However, by selecting
a tim e of day for the com parison during which sky-wave propagation conditions are m ost
nearly stable (usually around noon of the path mid-point), and by continuing the com parison
over a period of several minutes, accuracy of a few parts in 108 is readily achievable. W here
ground wave H F or useable V L F/L F emissions from standard-frequency stations areavailable, the secondary standards may be m aintained to better than ± 1 p art in 108.
2.2 Table I lists the accuracy of m easurem ent o f various classes of emissions which can beattained under optim um conditions at fixed and mobile m onitoring stations; n is the integer
equal to, or immediately above, one thirtieth of the m easured frequency in Mc/s.
2.3 The methods of measurem ent usually employed result in the determ ination of the instan­taneous frequency as received. Therefore, when measuring distant stations, due regard m ust
be given to frequency shifts caused by varying propagation conditions (e. g. D oppler effect).
Errors, due to the use of a stable transfer oscillator, can be reduced to a negligible am ountby the use of an oscilloscope for zero-beat adjustment. In anticipation of the extensive
use of V L F/L F standard-frequency emissions, the desirability of future reduction of theRep. 272

— 233 —

error to an appropriate smaller value should be kept in mind. This is of particular im portancein connection with services in which a 1 to 10 ratio of m easurem ent error to station tolerance
cannot be achieved with a frequency standard having an accuracy of only ± 1 p art in 107.

T ableI

Accuracy o f measurement attainable under optimum conditions at fixed and mobile monitoring stations
F ix ed stations

M o b ile statio n s± 2 - 5 x l0 - 8 ± 0-5 n c/s± 4 x l 0 - 8± 0-5 n c/s

FI, Al±2-5 x 10-8 ± 0-5 n c/s ± 2-5 c/s± 4 x 10-8 ± 0-5 n c/s ± 2-5 c/s

FI, MUX±2-5 x 10-8 ± 0-5 n c/s ± 10 c/s± 4 x 10~8 ± 0-5 n c/s zh 10 c/s± 2 - 5 x l0 - 8 ± 100 c/s± 4 x l 0 - 8± 100 c/s

C lass of em ission

A0, A3, A3B

F3 using discrimi­
nating equipment

2.4 F or emissions with a discrete com ponent at the assigned frequency, which can be identified,the accuracy is practically the same as for unm odulated emissions. F or emissions having
discrete com ponents which can be identified at other th an the assigned frequency, the accuracy
is further limited by the accuracy with which the displacement is known.
2.5 U nder conditions of fading, and where the m easurem ent is m ade using a pattern on thescreen of an oscilloscope, the m easurem ent is perform ed only when there is sufficient signal
strength, e.g. A l stations are m easured only during on-keyed conditions and n o t during
a field-strength minimum period. U nder these conditions the accuracies listed in Table I
can be obtained.
2.6 U nder conditions of interference between two am plitude-m odulated stations, the frequencyof the weaker station can still be m easured with the accuracy indicated in Table I, if thecarriers of the wanted and unw anted stations are spaced by at least 40 c/s. W ith a fieldstrength ratio between the w anted and the unw anted stations of 1 to 1, good m easurem ents
may be m ade with the accuracy indicated in Table I, when the carriers are only spaced by
12 c/s. F or a field-strength ratio of 2 to 1, the minimum frequency spacing at which goodresults are obtained is 2 c/s. These high accuracies of m easurem ent are m ade possible,
even under conditions of interference by other stations, by visual observation of the Lissajous
patterns produced on the oscilloscope screen by com bining the heterodyne beat between
the received signal and the com parison frequency and a fixed standard-frequency of 1000 c/s.
By receiving mutually interfering stations on a direction finding equipment, their ratio of
signal strengths at the receiver input can be improved, thus making possible m easurem ents
with the accuracies shown in Table I at smaller carrier spacings.
2.7 Two interfering frequency-modulated stations can be m easured for unfavourable field-strength
ratios when the frequency separation between their carriers is at least 2 to 3 kc/s. The
measurements are taken during periods of no m odulation by heterodyning the w anted carrierRep. 272

— 234 —

with the com parison frequency and observing the results on a panoram ic display screen.
The accuracy will then be within ± 500 c/s. H ere too, by employing a direction-finding
technique, the received signal strength of the unw anted station may be sufficiently attenuated
to attain the accuracies indicated in Table I.
2.8 M easurem ents o f carrier instability can be made, either as a series of measurem ents of instan­taneous frequencies employing the oscilloscope m ethod or, in the case of rapid variationsof the carrier frequency, the centre frequency can be determined by means of a discriminator
equipment, or a panoram ic adaptor, resulting in an accuracy of m easurem ent o f the edge
frequencies of about ± 50 c/s.
2.9 Keyed carriers can be measured by the oscilloscope m ethod with the accuracies listed inTable I.
2.10 F or suppressed carriers, individual frequencies of the types listed under §§ 2.5, 2.6, 2.7, 2.8
and 2.9, which are contained in the emission spectrum, can be measured with the accuracies
listed in those paragraphs. F or a carrier n ot completely suppressed, the measurem ent canbe made with the accuracy indicated in § 2.6.

3.

Methods

3.1 W ith regard to preferred equipment and methods for the measurem ent of frequency of
frequency-modulated emissions, the carrier frequency may be m easured by any o f the usualm ethods during intervals of no m odulation. W ith modulation, it is com m on practice tomeasure the average frequency by means of a frequency counter. In many types of p ro ­gramme material, the peak excursions of an F M carrier in the positive and negative directions
may be considerably different while, at the same time, the average frequency will rem ainconstant. This non-symmetrical program m e material may result, for example, from certain
com binations of a fundam ental tone and its various harmonics. Then the average over a
period of several cycles at the lowest m odulating frequency will approxim ate the unm odulated
carrier frequency. Therefore, the averaging technique is valid under all norm al conditions,provided the period of the frequency count is long com pared with one cycle at th e lowest
m odulating frequency. Instabilities in the transm itter may, of course, result in a shift in
the average frequency of the carrier, so th at the frequency indicated by the counter would
be somewhat different than the unm odulated carrier frequency. ,3.2 W ith the availability of portable battery-operated frequency standards, stable to ± 1 p art
in 108 per day, U H F television stations operating with ± 1000 c/s tolerance may be measured
to the recom m ended accuracy. A daily check against standard-frequency emissions at
the optim um time of the day as regards propagation stability will suffice to achieve an accuracyof the standard considerably better than the ± 1 p art in 107 th at is required for these m ea­
surements. F or greater accuracy, such as might be involved where precision offset techniques
are used, very accurate measurements could be achieved by use of a portable atom ic standard.
VLF standard-frequency emissions also provide a means of improving the accuracy atmobile as well as fixed monitoring stations. Battery-operated equipm ent, com prising a
selective V LF receiver and phase or time com parison circuitry, may be used to perm it accurate
calibration o f the frequency standard. Such com parison equipment, in com bination witha battery-operated frequency standard and a transistorized electronic counter, provides aconvenient means of achieving a high degree of accuracy even under mobile conditions.
The im portance and potential usefulness of statistical analyses of frequency m easurem ent
data is described in Doc. V III/18 of W ashington, 1962. This docum ent also suggests am ethod of arriving at the accuracy Of a measurem ent of an unknow n frequency by obtaining
the standard deviation of a num ber of measurements made of a know n frequency.
In Doc. VIII/27 of W ashington, 1962, the overall accuracy o f frequency measurem ents,
attainable in the range 1 to 10 Gc/s, was indicated using a typical spectrum analyzer withthe following characteristics: varies from 8 kc/s (for a 250 kc/s sweep), to 100 kc/s ( f o r a

Rep. 272, 273— 235 —

70 Mc/s sweep), equivalent to ± 8 parts in 106 and d= 1 p art in 104 respectively at a frequency
o f 1 Gc/s. Thus, an accuracy of ± 1 p art in 105 would appear possible, in practice, for therange 1-10 Gc/s for the condition where the emission contains a known discrete com ponent
whose position relative to the unm odulated carrier frequency is accurately known. W here
it is possible to obtain a beat frequency output, the accuracy of m easurem ent may be increased
to ± 1 p art in 106 or even better.

REPORT 273 *FIE L D -ST R E N G T H M E A SU R E M E N T S AT M O N IT O R IN G ST A T IO N S(Study Programme 102(VIII))(Los Angeles, 1959 - Geneva, 1963)
Study Program m e 102(VIII) seeks inform ation on various aspects of the m easurem ent
of field-strength at m onitoring stations, including the preferred methods and equipm ent formaking such m easurem ents in connection with propagation studies, m easurem ent problem s
peculiar to certain special types of emissions (e.g., interrupted and reduced carriers andtelevision signals), m easurem ents in the presence of noise and interference; together withdeterm ination of the extent to which measurem ents at a distance can give useful inform ation
relative to harm onic levels at the transm itter itself; and a determ ination of the m ost usefulprogram m e which can be carried out in fulfilling the needs of the I.F.R .B ., other Study
G roups of the C.C.I.R. and other bodies.
The contributions (Docs. V III/6, V III/8, VIII/16, VIII/20 and VIII/22 of Los Angeles,
1959, together with Docs. V III/6 and VIII/25 of W ashington, 1962), are sum m arized herein.
In considering Study Program m e 102(VIII), reference should also be m ade to R eport 227
which contains useful inform ation.
1.

Preferred methods and equipment

1.1 M ethods o f measurement
A num ber of m ethods of making field-strength measurem ents at m onitoring stations
are described, including:- continuous recording over periods of several hours;- continual sampling at short intervals (for example, for 5 s every two minutes) (see § 1.2.6
for details);- sampling at longer intervals (for example, for 10 m in each 90 min).
In some instances, especially where a ground wave is being observed, a single shortperiod of measurem ent may suffice, depending upon the purpose for which the m easurem ent
is required.
In certain cases, e.g. measurem ents for the purpose of H F propagation studies, one may
require inform ation concerning the overall propagation conditions over a b and of frequencies.
The present m ethod of autom atic m onitoring of spectrum occupancy will yield only a very
rough impression of the propagation conditions, since it does n ot discriminate between thevarious path directions and cannot m ake allowance for the difference in distances between* This Report, which replaces R eport 170, was adopted unanimously.

Rep. 273

— 236 —

the transm itting stations and the location of the receiver. Therefore, it may be expedientto m ake short records lasting about 10 min, over the entire high-frequency band at intervalsof about 90 min, of stations know n to be working for 24 hours a day, so chosen that theranges of frequencies and distances of interest are well represented.
Time constants of the detector circuit for measuring non-interrupted carrier emissions
are selected according to the results desired, with values of the order of a few seconds on boththe charge and discharge cycles commonly used for average values. F o r quasi-peak values,
a short charge time constant with a much longer discharge tim e constant is needed.
F or the measurem ent of the quasi-peak values of field-strength of an emission withinterrupted carrier, a circuit may be employed with tim e-constants of 1 ms build-up time and
600 ms decay time. W hen this m ethod is n o t suitable (e.g. keyed pulses), because of toolong a build-up time, the measurem ent may be made by the substitution m ethod using acathode-ray oscilloscope.

1.2 Measuring and recording equipment
1.2.1 General
A typical field-strength recording installation consists of a suitable antenna, asensitive receiver with a bandw idth appropriate to the emission to be recorded andincluding provisions for converting the received signal into a corresponding directcurrent for operation of an associated recording device, and a standard signal generator
for use in calibrating the receiver in terms of radio-frequency voltage input levels.
To ensure minimum frequency drift, the conversion oscillators in the receivers are,wherever possible, controlled by quartz crystals. Stabilization of the alternating
current line voltage is provided by prim ary voltage regulators. Further protection
against fluctuation is obtained by stabilization of the d.c. voltages in the receiver.
Minimization of changes in receiver gain is accomplished by careful design o f receivercircuits, by the aforementioned voltage stabilization and by operating the equipm ent
at an essentially constant temperature.

1.2.2 Antennae
F or m easurem ents in the low, medium and high frequency-bands, a stub antenna
with impedance m atching transform ers or a wideband stub antenna with constantfeed impedance may be used. In some particular cases, however, a directional antenna
designed for a single frequency or a narrow band of frequencies may be preferred.
Field-strength measurements on V H F and U H F bands are best m ade by means o f a
wideband dipole or a special directional antenna (e.g. a dipole installed in a cornerreflector or parabolic reflector). In the upper p art of the U H F band and in the SH F
band successful use has been made of log-periodic antennae, either with or w ithout
parabolic reflectors, so installed that near optim um results, with low standing-wave
ratios, are achieved over a frequency range of 2/1 or greater.

1.2.3 Recorders
A lthough ink-line, strip-chart recorders continue in com m on use, direct recordingof the statistical distribution of the variations in field-strength by autom atic distribution
counters is also being done. A nother method, reported by the Federal Republic of
Germany, makes use of magnetic tape equipment. In this method, the variations of
the d.c. voltage on the a.v.c. line, representative of the field-strength, are transform ed
to audio frequencies (50 to 300 c/s), by means of an oscillator controlled by a reactancevalve and used to m odulate the am plitude of a low frequency carrier (about 5 kc/s).

— 237 —Rep. 273

1.2.4 The calibrating equipment
The calibration process involves two phases:- determ ination of the effective height of the receiving antenna, taking into accountlosses in the connecting transm ission line;- daily, or m ore frequent, receiver calibration, to eliminate possible errors due toprogressive changes in sensitivity.
Doc. VIII/6 of Los Angeles, 1959, suggests th at it is good practice to calibrate
initially the field-strength meters, for use on frequencies below about 30 Mc/s, on aloop antenna. The loop is placed at a small defined distance from a Lecher line
which is term inated with a resistance equal to its surge impedance, which can be coupled
to a radio-frequency source. If the current flowing in the Lecher line is know n, thefield intersecting the loop can be computed.
To determine the effective height of an antenna, the input signal to the receiveris com pared with the indication of a calibrated field-strength meter.
1.2.5 Frequency ranges involved
Although field-strength measurements have been made over alm ost the entire
usable spectrum, m ost of the activity up to the present has been concentrated, at fre­quencies below 1 Gc/s. As greater use is m ade of the microwave frequencies forspace-to-ground transmissions, it seems likely th at there will be increased activity infield-strength measurements in these higher frequency ranges. Examples o f m easure­m ent programmes for field-strength which are now under way, or have been concluded
in recent years, are:- in the 540 to 1600 kc/s broadcast band, continuous recordings have been madeduring the past two sunspot cycles;- V H F and U H F field-strength measurements (FM and television broadcast stations),
have been in progress since 1946 at various locations over paths having lengths
from 60 to 1000 km (38 to 633 miles);- certain monitoring stations in the U.S.A. are determining the field-strength ofexperimental U H F television stations located in aircraft. These experiments are donein connection with extending the service area;- a m onitoring station in the U nited K ingdom is m aking regular field-strength record­
ings of incoming radiotelegraph signals from Accra, Bombay and Colombo, as apartial contribution to Resolution 7 (Systematic sky-wave field-strength m easure­ments on frequencies between the approxim ate limits of 1-5 and 40 M c/s);- the station in the U nited Kingdom has also m ade long-term field-strength m easure­m ents of ten distant V H F (metric) and U H F (decimetric) transm itters and two
distant ionospheric-scatter transm itters and the data obtained have been summarized
and submitted to the C.C.I.R. (Doc. VIII/25 of Los Angeles, 1959).
1.2.6 Analysis o f the records
Recordings made in the 540 to 1600 kc/s broadcast band are analyzed, to obtainhourly median values of field-strength and from these data monthly median values
may be obtained. Particular attention is given to the second hour after sunset for them id-point of the path between transm itter and receiver. Values for other hours andfor levels other than the median may be obtained in a similar manner.
In the H F, V H F and U H F bands, it is often desirable to determine the upper
decile (F 10), the median (F50) and the lower decile (F 90) values. The m edian value, in
db relative to 1 fFV/m, is a desirable form of presentation of measurements at discrete
frequencies for propagation studies.
A system of analysis, which eliminates m uch of the hum an effort, is based upona m ethod of recording periodic samples of signal strength, using regular equipm ent
with simple modification rather than a continuous registration of signal levels. A timeRep. 273

— 238 —
switch operated by a synchronous m otor is provided in each recorder so th at a contact
is closed once every two minutes for a duration of about five seconds. This contact
is inserted in an appropriate circuit in the receiver, where it will cause the recording
instrum ent to respond by drawing an inked line with each operation of the switch.
The recorder chart will then show a series of transverse lines. W hen operated at theusual speed of about 75 mm (three inches) per hour, the paper will show 10 lines perinch, each having an am plitude with a known relationship to field-strength. It has
been found that 30 samples per hour will yield an accuracy adequate for m ost appli­
cations. After the recordings have been made, the charts are analyzed on equipment
specially constructed for this purpose. This equipment may consist of a photoelectric
cell arrangem ent for counting the hourly num ber of samples with am plitudes exceedinga pre-set level, while the chart paper moves through an appropriate optical system.
H ourly numbers of samples at each level are counted automatically and printed bymeans of an electrical counter and a sequential count printer. These num bers may bedirectly converted to equivalent percentages of time, for all signals exceeding given
levels. The data are thus available in hourly values, from which m onthly and yearly
distribution curves may be plotted, showing daily and seasonal variations of fieldstrength at any percentile levels.

2.

Preferred equipment and methods of measurement in the presence of noise and interference
N o particular problems are presented in measuring the field-strength of emissions withinterrupted carrier and of television video signals in the presence of noise and interference,as long as the noise and interference peak levels are below the level of the wanted signal,
since the quasi-peak indicating device will respond to the highest level present. However,in the case where the peaks of noise and interference are greater in intensity than the wanted
emission, other techniques m ust be used. In some instances, reduction of the receiver
bandw idth may be effective in eliminating unw anted emissions. The effect of high noise
peaks of short duration can possibly be avoided, by increasing the charge tim e-constant of
the detector sufficiently to minimize receiver response to the noise w ithout appreciablereduction in the indicated level o f the w anted signal. The efficacy o f such expedients would,of course, depend on circumstances and very likely would n o t be valid under conditionso f heavy fading. Doc. VIII/16 of Los Angeles, 1959, describes a m ethod used in Japan,
for the measurem ent of emissions in the presence of adjadent channel interference, usinga panoram ic unit attached to the equipm ent, so th at an interfering emission may be separated
from the w anted signal and the field-strength represented by the deflection of the oscilloscope
trace caused by the interrupted carrier under study, may be determined by com parison witha signal from the equipm ent used for calibration purposes.

3.

Determination, at a distance, of relative radiation levels of fundamental and harmonic frequencies
of an emission
It would appear that this m atter should be considered in two parts:- conditions where both the fundam ental and the harm onic emissions to be m easured arriveat the measuring point over a ground-wave or line-of-sight path;- where either the fundam ental or the harm onic emission, or both, arrive at the m easuringsite over a sky-wave path.
The situation as regards these two modes ,of propagation will be considered separately.

3.1 Measurement o f radiation levels under conditions o f ground-wave or line-of-sight propagation
Study G roup V, in response to a request for assistance on this m atter, has referred Study
G roup V III to R eport 227. This R eport contains detailed inform ation on m aking andevaluating such measurements, taking into account instrum ent errors, differing attenuation
rates at different frequencies and other variables.

— 239 —Rep. 273

3.2 Measurements o f radiation levels where sky-wave paths are involved
Study G roup I has considered this m atter, as evidenced by Recom m endation 329 andStudy Programm e 182 (I). Likewise, Study G roup VI, in R eports 252 and 257, reviews p ro ­gress. which has been made in determining the best m ethod of calculating the field-strength
at a distance from the transm itter (ionospheric propagation), and describes plans for further
study of this m atter.
It is expected that the results of the further deliberations of Study G roup I and VI will
be of benefit to the international m onitoring system in its efforts to minimize interference
from spurious emissions. Pending the outcome of these deliberations, it w ould be highly
desirable for stations in the international m onitoring system to have certain guide-lines whichmight be followed in obtaining evidence of possible excessive radiation at the harm onic
frequency. While such evidence would not be conclusive, it m ight serve as an indication
th at close-in measurements should be m ade to verify the existence of harm onics at excessive
levels. Appendix 4 of the Radio Regulations, Geneva, 1959, gives power lim itations on
spurious emissions as measured at the antenna transm ission line input. A lthough theseemissions may readily be measured a t th at point, there is no simple means of converting
the spurious power lim itations given in Appendix 4 to equivalent field-strength at a distance.
Since it is the actual radiated spurious field-strength rather than the pow er into the antenna
which is of prim ary concern as an interference source, it m ight be well to consider establish­
ment of a lim itation on spurious emissions, in term s of the m axim um unattenuated fieldstrength at about 1600 m (1 mile). Having once established such a limit, the maximum
allowable inverse-distance field could readily be determined. Since the attenuation would
actually increase m ore rapidly than inversely with the distance, the m easured value o f the
spurious emission would be a conservative index of the actual radiated field, especially if
the condition continues over a period o f several days. This lim itation would be in addition
to, rather than a substitute for, the lim itations on spurious power input to the antenna tran s­
mission line specified in Appendix 4. Admittedly, the results could not be com pared directlywith measurements m ade at the transm itter. However, it would appear th at such standards
m ight be of help to m onitoring personnel in bringing about a reduction of interference due
to harm onic radiation.

4.

Additional propagation studies that are desirable
Resolution 7 points out the need for experimental data in the frequency range from
1*5 to 40 Mc/s for paths of different lengths and directions and requests th at A dm inistrations
and Members of the C.C.I.R. render assistance to Study G roup VI on this m atter.

B ibliography

1. C hapin , E.W. Field-strength measurements, L.D. Report 6.3.1. (1 October, 1958) Federal Com­
munications Commission, Washington, 25, D.C.
2. Selby , M.C. Accurate RF voltages. Trans. A.I.E.E. (Communications and Electronics), 6, 158-164(May 1953).

Rep. 274

— 240 —R E P O R T 274 *M E A SU R E M E N T O F S-VALUES AT M O N IT O R IN G STA TIO N S(Q uestion 189)

(Geneva, 1963)
Question 189 asked that the correlation between field-strength values, and the S-values of the
QSA scale and the SIM PO and SIM PFEM O codes be studied. Docs. VIII/16 (Japan), V III/17(Japan), VIII/21 (U.S.A.), V III/26 (United Kingdom), VIII/31 (Portugal), and VIII/35 (India)
of W ashington, 1962, referred to this matter.
Table I, derived from these documents, dem onstrates the wide ranges of both field-strengthand receiver input signal that are associated with S-values. It is evident th at such measurements
are influenced to a considerable extent by the equipm ent in use, the type of service, and reception
conditions. S-meters have widely differing characteristics, and may vary in equipments of thesame type. The subjective S-values of the QSA scale also differ widely with the o perator’s ability.
It is concluded that a m ethod based on S-values is unlikely to meet the requirem ent for a
rapid m ethod of field-strength measurem ent with sufficient accuracy to be of use to the m onitoring
services. In consequence, this R eport term inates the study o f Q uestion 189.

T able I

Correlation between QSA scale and field-strength or receiver input voltage
F ield stren g th
(db rel. 1 p.V/m)

R eceiver in p u t signal(db rel. 1 p.V)

QSA
Scale

D oc.
V I II/17
Fixed
Services

D oc.
V I II/17
R o u tin e
M o n ito rin g

O

O

D oc.
V III/21(2)

D o c.
V III/35
A3
M o d u latio n

D o c.
V III/1 6
(3)

0
1
2
3

15-38
20-42

4

25-46
30-65

' 5

(—30)—(-(-15)(-2 4 M + 3 0 )
6-45

0-18
18-30
30-42

10-55

42-54

10-65

>54

5-16

D oc.
VIII/31
A l, A2
M o d u latio n
<•>

<11
11-22

< 15

22-31

15-23
23-41

6-20

31-45

41-59

21-35
>36

45-56
>56

59-77
>77

12-20

< (-1 0 )(-9 ) -( + 5 )

18-28
26-37
33-45

O Based o n statistic ally stable sam ples of results, and using th e an ten n a system of R e p o rt 278.
(2) C o n fo rm ity of o p erato rs stan d a rd s w as im proved by use of special reference eq u ip m en t.
(3) T hese values represent th e b est accuracy o b ta in ed using c a lib ra te d a n ten n a, receiver a n d S-m eter.
(4) B ased o n m easurem ents in b an d s 5, 6, 7 an d 8.

* This Report was adopted unanimously.

D o c.
V III/31
A3
M o d u latio n(4)

— 241 —Rep. 275

REPORT 275 *B A N D W ID TH M E A SU R E M E N T BY M O N IT O R IN G STA TIO N S(Study Programme 207(VIII))(London, 1953 - Warsaw, 1956 - Los Angeles, 1959 - Geneva, 1963)

1.

General discussion of measurement techniques, considering the definition of occupied band­
width - No. 90 of the Radio Regulations, Geneva, 1959

1.1

Measurement o f power ratios
The present definition of occupied bandw idth suggests the principle described in Recom ­m endation 327, § 1.2 of measuring the ratio of the total power to the parts rem aining outsideof the bandw idth being measured. It would be necessary to locate the upper and lower
edges of the band, by totalling the power in the out-of-band com ponents on the high side
until the 0-5 % value is obtained and then repeating this procedure for out-of-band com ponents
below the band, starting in each case sufficiently far from the centre frequency so th at noappreciable energy is om itted from measurement.

1.2 Limitations in the accuracy o f bandwidth measurements made at a distance from the transmitter
A lthough a determ ination of occupied bandw idth of an emission, by the m ethod of
measuring total power and out-of-band power, can be accomplished when the m easurem ents
are made near the transm itter, this m ethod is not generally applicable to m easurem ents at
a distance from the transm itter because of the presence of interfering emissions or noise which
tend to mask the out-of-band signal com ponents of interest. This is particularly true in thecrowded M F (band 6) and H F (band 7) portions of the spectrum, regions of prim ary interest
to international m onitoring stations.
In spite of the very definite lim itations which observations at a distance place upon theaccuracy of measurements of occupied bandw idth, approxim ate determ inations have beenfound of value when m onitoring the spectrum for enforcement of bandw idth limitations.
However, these non-precise measurem ents m ade at a distance, which are subject to inaccuracies
for the reasons previously enum erated, should be considered as advisory only. W here
greater accuracy is required measurements at the transm itter may be desirable.
1.3 Bandwidth measuring method which appears to be practicable fo r use at international moni­
toring stations
It is the practice of some A dministrations, in evaluating spectrum occupancy of anemission from a distant transm itter, to use the m ethod described in Recom m endation 327,
§ 1.1. In using this m ethod, the occupied bandw idth is considered to include discrete com­ponents attenuated less than 26 db below the peak level of the emissions. This procedure
adm ittedly will not give a precise measurem ent of occupied bandw idth in terms of the definitionin the Radio Regulations, Geneva, 1959. F or example, it is possible th at a particularemission will have num erous low level com ponents on either side of the m ain emission such,th at their sum on each side would be equal to much m ore th an 0-5 % of the total m ean power
while having none of these discrete com ponents exceed the —26 db level. In such a case,the occupied bandw idth, as ■determined at the transm itter by measuring power ratios, would
presumably be somewhat greater than when measured at a distance by the m ethod described* This Report, which replaces Report 172, was adopted unanimously.

Rep. 275

— 242 —

in Recom m endation 327, § 1.1. The equipm ent described below will display the spectra,
distribution of an emission in term s of significant discrete components.
2.

Representative bandwidth measuring equipment

2.1 A spectrum analyzer, of the type described in Recom m endation 327, § 1.1, is suitable for use
at m onitoring stations. W ith this equipm ent emission spectrum is analyzed by passing eachcom ponent successively through a narrow -band filter of fixed frequency, by heterodyning
the signal with an external frequency, varied either automatically or manually.
F or the measurem ent of narrow -band emissions, a spectrum analyzer having a highdegree of resolution is desirable so that an accurate display of the emission spectral distri­bution may be obtained. A typical instrum ent has a maximum resolution of 10 c/s andprovides a swept frequency range adjustable from 1 kc/s to 100 kc/s, together with a sweep
rate adjustable from 1 to 30 sweeps per second.
F or the analysis of wide-band emissions, spectrum analyzers are available which incor­
porate a complete receiver as well as those designed for use with general purpose receivers.
A typical instrum ent covers a frequency range from 10 Mc/s to 44 Gc/s with a sweep width
continuously variable from 200 kc/s or less to as much as 70 Mc/s (at the higher frequencies).
The sweep rate is adjustable from 1 to 60 sweeps per second.
A m ajor shortcom ing of spectrum analyzers, which use a single filter to sweep theentire band under surveillance, is the incompatibility between high resolution and rapid sweep
rates, especially where a band of considerable width m ust be studied. A fast sweep rate isnecessary to obtain a representative display of transient com ponents. However, as thesweep rate is increased, the resolution becomes poorer so th at significant com ponents of theemission will no t be displayed accurately. A num ber of systems have been devised to m ini­
mize the sweep-rate versus resolution limitations. One m ethod involves the division of theband to be observed into as many as eighteen sub-bands, each, of which is individually swept.
The eighteen outputs are then displayed one at a tim e on a single cathode-ray tube or simul­
taneously on separate tubes.
2.2 A n energy spectrum recorder is described in Doc. VIII/13 of Los Angeles, 1959. This
device makes a chart record of spectrum occupancy in term s of available power from astandard antenna.
2.3 A device for measuring frequency shift, especially in questions concerning the m onitoringof complicated emissions and those types of emissions using a synchronous high speed m ulti­
channel system, is described in Doc. VIII/29 of W ashington, 1962. This device permits
simultaneous measurements of frequency shift of multiplex channels as well as a visual checkon the frequency shift signals.
3.

A somewhat different approach to the m easurem ent o f bandw idth is described as follows(see Doc. VIII/10 (Federal Republic of Germany) of Los Angeles, 1959):
Endeavours have been made to determine the bandw idth occupied by an emission by
way of the signal shape instead of by analyzing the spectrum. Such experiments have beenm ade for Class A l emissions only, starting from the fact th at the bandw idth occupied is afunction of the shortest build-up (and decay) time of the em itted signals (see Recom m en­dation 328, § 2.1.3).
As regards the effect of fading, a com parison between 60 single measurem ents of A lemissions taken at the transm itter and in the far field (up to 425 km), resulted in a maximum
deviation o f 16%. The average value of the deviations am ounted to 4-8%. The differencesin the results of the measurements at the transm itter and those taken far away may be explainedby the deformation due to the fading effects of the signals. M easurem ents made under
extreme fading conditions will no t yield satisfactory results.
The effect of interference was investigated by superim posing a received non-fading A lsignal with a simulated interference signal o f variable frequency generated locally. It was
found th at the wanted signals could still be evaluated with a signal-to-interference ratio as
low as 35 db. W ith signal-to-interference ratios lower than 35 db, evaluation was no longer
possible, because the 10% value of the wanted signal could n ot then be recognized.

4.

Spectrum analyzers may also be valuable in the recognition and classification o f emissions,particularly complex emissions. M any types of emissions have certain peculiar com binations

— 243 —Rep. 275, 276

o f characteristics which, when viewed on a spectrum analyzer by a ^trained observer, may
provide valuable inform ation leading to the recognition of the emission. Photographs ofspectrum analyzer displays of know n emissions may be kept available to the m onitoring
observer for reference and for com parison with questionable emissions.
Spectrum analyzers have also been used to advantage in connection with frequency
measurements in the presence of interference, where m atching of the frequency of the m ea­
suring equipm ent against the unknow n frequency by aural m ethods is difficult. By observing
the two signals on the spectrum analyzer, the frequency o f the measuring equipm ent may be
adjusted to th at of the unknow n carrier or to other discrete com ponents in the signal.
5.

Results that have been obtained using the m ethod of m easurem ent in which discrete com po­nents attenuated less than 26 db are considered to be w ithin the band, show th at satisfactorymeasurem ents of the spectra and bandw idt’n s of emissions can be obtained, except underadverse conditions of fading, noise or interference. These m easurem ents can be o f consider­able value in detecting emissions using excessive bandw idth which may cause interference.

6. A dditional inform ation concerning measurem ent of bandw idth may be found in R ecom ­m endation 327 (Volume I).
,
7. Conclusion
To explore fully the possible accuracy of observations a t m onitoring stations in approx­
imating occupied bandw idth, as defined in N o. 90 of the R adio Regulations, Geneva, 1959,
studies will be required to com pare such approxim ations with measurements m ade at thetransm itter for the various types o f emission and for regular traffic signals.

REPORT 276 *M O N IT O R IN G O F R A D IO E M IS S IO N S F R O M SPA C EC R A FTAT FIX ED M O N IT O R IN G ST A T IO N S(Question 188(VHI))(Geneva, 1963)
Q uestion 188(VIII) seeks inform ation concerning m ethods and equipm ent desirable form easurem ent at fixed m onitoring stations o f emissions from spacecraft and practical meansof identification by m onitoring stations of emissions from specific spacecraft.
Inform ation concerning these m atters is contained in Docs. VIII/3 (U.S.A.) an d VIII/15(Japan) o f W ashington, 1962. The inform ation in these docum ents may be summ arized
as follow s:
1.

Techniques o f measurement

1.1 General .
The m ain factors influencing the necessity for different techniques of m onitoring obser­
vation and m easurem ent of emissions from spacecraft as contrasted with observations and* This R eport was adopted unanimously.

Rep. 276

— 244 —

measurements of emissions originating from fixed or mobile radio stations on or near theearth are, with reference to spacecraft:- the difference between received and transm itted frequency, and the varying nature of thereceived frequency, caused by the D oppler effect;- the generally weaker field-strength at the earth receiving point, due to distance and lowtransm itter power;- the relatively short time that a signal from a near-earth orbiting satellite is receivable ata fixed m onitoring point.
A dm inistrations launching spacecraft will, of necessity, continue to provide for therequired accurate tracking and telemetry reception to meet their special needs. However,m onitoring stations responsible for the enforcement of domestic laws and regulations andengaging in international m onitoring, pursuant to A rt. 13 of the Radio Regulations, Geneva,
1959, will participate in space m onitoring as a natural and necessary extension of their regularm onitoring facilities, techniques and operations.

1.2 Frequency measurements
W hen there is a relative velocity between the spacecraft and the m onitoring station,a difference of frequency proportional to the relative velocity arises between the transm itted
and received signals owing to D oppler-shift effect. The apparent frequency of the transm itterin the case of an active satellite, as measured by a fixed m onitoring station, is higher than
the source frequency when the satellite is approaching the monitoring station and lower
when it is receding. A measurem ent gives the source frequency only at the instant when
the relative velocity between the source and the m onitoring station is zero.
To determine the source frequency and the extent of D oppler shift, the basic requirem ent
is a rapid frequency-measuring technique and a means of accurately timing each measurement.
If frequency measurements are taken every few seconds and plotted against time, a curve
is obtained from which the frequency at the point where the rate of change is greatest can be
estimated with reasonably good accuracy, possibly to within ± 1 part in 106.
Doc. VIII/15 of W ashington, 1962, describes a frequency measuring m ethod whichuses a discriminator, the object of which is to represent on a cathode-ray oscilloscope
the waveform obtained by mixing the receiver output with a low-frequency saw-tooth wave
(e.g. 25 or 50 c/s) from a separate source. The discrim inator is used to determine the trans­
m itted frequency by measuring the constantly changing frequency of the D oppler shift.
When the figure remains stationary on the oscilloscope, the receiver output frequency is anexact multiple of the standard low-frequency. F rom the value of this exact m ultiple andthe local oscillator frequency in the receiver, the exact frequency can be determined. Bymeasuring the frequency each time the figure on the oscilloscope becomes stationary andplotting this against time, the curve of D oppler shift may be drawn.

1.3 Bandwidth measurements
The apparent bandw idth of a near-earth satellite, transm itted as m easured at a fixedm onitoring station, varies because of the Doppler-shift effect in the same m anner as described
for the carrier frequency. A lthouth not of practical significance at present from an inter­
ference standpoint, it should be realized th at the frequency shift is slightly greater for signal
com ponents near the upper edge of the spectrum of the emission than for those near the
lower edge. This difference could am ount to hundreds of cycles per second for the wide
bandw idths proposed for some of the future spacecraft transmissions, on frequencies above
1000 Mc/s. This effect causes the apparent bandw idth as observed at the fixed m onitoring
point to vary slightly. However, it is doubtful th at the currently available spectrum analyzers
have sufficient resolution to detect it when the entire signal is being observed, under operating
conditions of weak signal and relatively high background noise.

— 245 —2.

Rep. 276

Equipment and facility requirements

2.1 GeneralIn general, as in m ore conventional m onitoring surveillance, equipment for m onitoringsignals from spacecraft m ust have adequate flexibility to cover a wide range of frequencies,in contrast to the spot frequency coverage that suffices for the needs of a research or operating
space agency. The location of the m onitoring station should be such that interference fromm an-m ade signals and noise is at a minimum.
Autom atic sweeping of a band of frequencies, by varying the receiver tuning, and au to ­matic recording of intercepted signals on a chart-type ink-line field-strength recorder, may
assist in “ acquiring ” space signals and in timing their periods of reception.
An electronic counter, providing printed frequency and time records, has been founduseful to meet the requirem ent of taking high-speed measurem ents to follow the D oppler shift.
F or bandw idth measurements, it is desirable to employ a camera to photograph thespectrum display for later analysis. The exact tim e of taking the picture should be recordedon the film at the time o f exposure.
Although good results have been obtained by tracking the satellite signals by m anualadjustment of antenna azim uth and elevation, and by m anual adjustm ent of the receivertuning to follow the D oppler frequency shift, autom atic tracking of both is suggested, if
practicable. F urther studies should be undertaken to determine practicable means to p ro ­vide such tracking capabilities. Autom atic antenna and receiver tracking will become ofm ore im portance for satisfactory m onitoring at frequencies above 1000 Mc/s.

2.2 Antennae
Antennae ranging from fixed dipoles to log-periodic types capable of being rotated inazim uth and adjusted in elevation have been tested. The latter type has been employed
for frequencies between 50 and 5000 Mc/s and has provided good general coverage overa 10 to 1 frequency range in a single antenna. O ther antennae used successfully include
a multi-bay Yagi, single and twin helical, conical helix, dipole with corner reflector, foldedcrossed doublets with half-wave phasing stubs between the doublets, 4-element folded dipole(in-phase array), and a series of uni-directional “ V ” antennae with a selective switchingarrangem ent to change orientation. Studies are progressing for use of parabolic reflectors
o f up to about 8-4 m (28 ft) in diameter, for m onitoring antennae to be used for frequencies
in the 4000 M c/s range and higher and using various antenna elements including a wide-band
log-periodic array. Because of the quite sharp directivity of such high gain antennae, consi­
derable care is required in acquiring and tracking the signals from the spacecraft.

2.3 Receivers
F or economic reasons, and because a general-coverage receiver is required at m onitoring
stations, the extremely low noise figures possible for fixed-frequency receivers used for spaceresearch and operational purposes are not equalled by available m onitoring receivers. H ow ­ever, the receiver should have a relatively low noise figure and be capable of receiving signals
in the order of, a few hundredths of a microvolt at the receiver input, and should have a wide
range of adjustable bandw idth to perm it reception of both wide and narrow -band tran s­
missions from spacecraft.
2.4 Specialized equipment
To facilitate “ acquisition ” of the signal from a spacecraft, it is desirable to be able
to sweep a narrow band of frequencies automatically and to record the received signals bothaurally and on a field-strength recorder. A sweeping device has been developed for thispurpose, using a semi-conductor diode as a voltage variable capacitor applied to theRep. 276

— 246 —

frequency-determining circuits of the receiver. In operation, the sweeping device is set tovary the receiver frequency over a band greater than the am ount o f predicted D oppler shift.

3.

Identification of transmissions from spacecraft
Considerable thought has been given to the extent of the need by space Administrations
and by monitoring stations for a call-sign or other special identifying signal to facilitate
identification of emissions from spacecraft and o f the effects of installation of equipment
for that purpose. It has been concluded th at neither need is great enough at present, norlikely to be in the near future, to w arrant pressing for the use of an identifying signal.
The techniques employed for space research and operations in satellite and other space­
craft tracking, and foreseen for com munications and other uses of space emissions, aresuch that special identifying signals are normally n ot essential. There normally being no
requirem ent on the part of the tracker and user for identifying signals, to require their use
to facilitate m onitoring observations could impose lim itations adversely affecting reliability,
weight, cost and operation of the system involved.
It has been found possible to identify emissions from particular satellites from signal
characteristics and ephemeris data. It would thus appear th at the provisions of Article 19,
N o. 737 of the Radio Regulations, Geneva, 1959, relating to recognized means o f identifi­
cation other than call-signs, will be m et if A dm inistrations launching satellites and otherspace vehicles will continue to m ake such inform ation currently available to monitoring
services. The following inform ation will assist in identification:- carrier frequencies;- orbit tim e;- angle of inclination of orbit to equator;- equator crossing time and longitude of crossing;- perigee and apogee distances, and- signal characteristics such as type of m odulation and bandw idth for each frequency.
In addition, data on the transm itter power, antenna characteristic including antennapolarization and other related param eters will be useful in the prediction of reception.
From the ephemeris data, m onitoring stations have been able to calculate when a p ar­
ticular satellite will be above the horizon for a particular m onitoring station and the distances
involved, to predict reception and assist in identification. A considerable am ount of pub­lished inform ation is available, regarding the techniques of satellite and spacecraft tracking
and the problem associated therew ith (see Bibliography and Recom m endation 350).

3.1 Special aids fo r determining satellite positions and expected reception times
Graphical and slide rule aids have been found useful for determining reception time
for spacecraft based on past reception data (see Doc. VIII/3 of Geneva, 1962).

3.2 Direction finding as an identification aid
To supplement determ ination of the exact time of closest approach of a satellite to amonitoring station, by noting the centre point of the maximum rate of D oppler shift of thecarrier frequency, a curve can be plotted to show the change in direction of arrival of thesignal with time, as determined by direction-finder bearings or orientation of a highly direc­
tional receiving antenna. The maximum angular rate of change will occur when the satellite
is nearest to the m onitoring station during a particular pass and the inform ation obtained

— 247 —Rep. 276

by this m ethod should agree closely with the inform ation obtained from the frequency/tim e
curve.
3.3 Future possibilities fo r monitoring procedures involving transmissions from spacecraft
Procedures have been discussed herein for identification of transmissions from space­
craft, based on past experience of com paring the m easured and observed signal characteristics
with published inform ation, and by com paring the tim e of closest approach to a m onitoring
station - as determined from the m easured D oppler shift of the carrier frequency and fromvarying azim uth (bearing) - with ephemeris data. W ith the expectation of increased useof operational satellites, imm ediate positive identification by m onitoring stations o f all inter­
cepted spacecraft emissions by these methods may become too time-consuming. T here­
fore, the following additional procedures may be necessary:- a com munications system involving either passive or active satellites could be identified
by the identifying signal of the ground station reflected from or relayed by the satellite,
even if this did not immediately identify the particular satellite of a multi-satellite system,and- in enforcement-type m onitoring of spacecraft emissions, particularly w hen noncom ­pliance with radio regulations or cases of interference are observed, m onitoring stations
could log all possible inform ation concerning frequency and bandw idth measurem ents,
direction of signal arrival, type of m odulation and other signal characteristics, together
with accurate times o f observation and measurem ents, and request identification, basedon these data, from identification and tracking centres.
The tim e th at the satellite is closest to the m onitoring location on a given pass, as deter­
mined from Doppler-shift measurements, and the carrier frequency as m easured for thistime, will be of Utmost im portance to the space centre in effecting identification.
However, further consideration might be given to the incorporation o f an appropriate
identifying signal.
B ibliography

1. Smithsonian Contribution to Astrophysics, Vol. 2, 10, U.S.A. Government Printing Office.
2. Various papers in Proc. IRE, 48, (April 1960), particularly:(a) H u tc h in so n , H.P. and A r e n d t, P.R. Ionospheric scintillations of satellite signals.
(b) W eiffenbach, G.C. Measurement of the Doppler-shift of radio transmissions from satellites.

Rep. 277

— 248 —R E P O R T 277 *M E A SU R E M E N T S AT M O B IL E M O N IT O R IN G STA TIO N S(Question 144)
(Los Angeles, 1959 - Geneva, 1963)
1.

Types of measurement
Subject to the lim itations necessarily imposed by mobile operation, the size of suitable
instrum ents and power consumption, it is considered to be practical to employ mobile stations
to m ake all the measurements of emissions normally made at fixed m onitoring stations.
Typical measurements and ranges are:

1.1 Frequency m easurem ent:
1.2 Field-strength measurem ent:^

10 kc/s to above 10 Gc/s
10 kc/s to above 10 Gc/s

1.5

Bandwidth measurem ent:
D irection finding - with loops:- with dipole arrays:- with horns:
Autom atic m onitoring of occupancy:

10 kc/s to above 10 Gc/s
10 kc/s to 20 Mc/s
20 Mc/s to above 1 Gc/s
1 Gc/s to 10 Gc/s
10 kc/s to above 300 Mc/s

1.6
1.7

Percentage m odulation, FM deviation:
Video waveform measurem ent of television emissions:

10 kc/s to 1 Gc/s
40 Mc/s to 890 Mc/s

1.3
1.4

Mobile m onitoring stations are particularly valuable for m onitoring low-power stations
and stations at frequencies above 30 Mc/s whose range is limited.
In addition to the use of equipm ent installed in a vehicle, certain measurem ents canalso be made using portable equipment. Experience shows th at separate mobile m onitoring
units, specifically designed for selected types of measurem ent, lend themselves m ore readily
to operational use rather than a single vehicle equipped to make all classes of measurem ent.
2. Types of equipment
It is considered undesirable, to have to use special equipm ent for the mobile m onitoring
service and regular stock types of equipm ent with small dimensions, low weight and low
power consum ption are preferred. Since mobile equipm ent is subjected to vibration andshock, robust construction, together with shock-m ounting of com ponents, is im portant.
W ith the exception of some portable units, the equipm ent is normally designed for operation
at standard mains voltage and frequency.
It is preferred that instruments, such as frequency standards, which are sensitive totem perature changes, be designed to reach and m aintain operating tem perature in as shorta time as possible, so that continuous application of power will n o t be necessary or so th atonly limited circuits will require continuous power. As an alternative, standards which arelocked in synchronizm with V LF standard-frequency emissions should prove useful.
2.1 Frequency standards and associated measuring equipment
The frequency standard should be capable of m aintaining a frequency stability of
one part in 108 per day or better, after nom inal warm-up periods and under the operating* This Report, which replaces R eport 168, was adopted unanimously.

— 249 —Rep. 277

conditions normally encountered in the mobile service. Currently available frequency stand­ards, specifically designed for mobile use, are capable of stabilities of ± 1 p art in 108 or better
under field conditions.

2.2 Field-strength measuring equipment
The extent to which field-strength measuring instrum ents should be provided in a mobile
m onitoring station depends upon the purposes of the measurements. For regulation enforce­
ment purposes, continuous coverage up to at least 1000 Mc/s is desirable. F o r obtaining
propagation data, highly sensitive recorders operating on a fixed frequency have certain
advantages, although the instruments used for enforcement measurements may also be used
for this purpose with some com prom ise in sensitivity and frequency stability.
This discussion will deal only with tunable continuous coverage instruments.
W herever possible, field-strength measurements should be m ade in an area where thesignal field is relatively undisturbed by local reflections and re-radiation. W here there isstrong dependence on location, measurements may be m ade in terms of m edian values, therecording being made continuously as a function of location or time.
The mobile station itself may contribute errors and the calibration includes antenna,
receiver and recording equipment. It is desirable, therefore, th at the equipm ent be portable
so that measurements can be m ade away from the vehicle. To avoid directivity effects whenmeasurements are m ade from the vehicle in m otion, om nidirectional antennae are used.
Since measurements of harm onic attenuation may involve comparatively weak signals, it isdesirable that the field intensity meter be capable of the m easurem ent of signal levels of theorder of 1 fxV/m. The instrum ent should likewise be immune to overloading from strong
signals of 1 V/m or more. To attain satisfactory accuracies, considering th a t undisturbed
fields are the exception at frequencies above 30 Mc/s, the errors contributed by the instrum ent
itself should be less than ± 2 db. It is desirable that circuitry be incorporated for determ i­nation of peak and quasi-peak levels of pulsed emissions, as well as for the average field
intensity of amplitude- and frequency-modulated and similar emissions.

2.3 Bandwidth measuring equipment
Authorized bandw idths, for stations assigned to the various V H F an d U H F services,vary from less than 1 kc/s for radiotelegraph services to several Mc/s for television broadcast
services. Mobile m onitoring stations should, therefore, be equipped with spectrum analyzers
having very flexible characteristics including a sweep width of 20 kc/s or less for narrow band
emissions and with the capability of displaying at least 5 Mc/s of spectrum at a tim e on
certain broadband emissions.
The sweep rate should be variable from about 1 to 30 sweeps per second to perm it
optim um utility for various types of observation. Provision should be made for either linear
or logarithmic display of signal levels and calibrated scales should be provided for direct
measurement of level ratios.
Mobile measurements of bandw idth may be m ade by a frequency occupancy recorder,
for those types of m odulation for which no measurem ent m ethod of higher accuracy exists,
or when it seems impracticable to carry out such measurements in the mobile service becauseof the high technical expense involved. W ith telegraph signals for instance, the bandw idth
can be determined from the signal element with the shortest rise time (see Doc. V III/10 of
Los Angeles, 1959). In the V H F band, estimated bandwidths can also be read off theoscillograph screen of a panoram ic set with a calibrated frequency scale. The m easurem ent
of bandw idth can also be m ade by a m ethod of frequency analysis, using a very narrow( ± 1 0 0 c/s) filter to measure the m agnitude of the spectrum com ponents passing throughthe filter in relation to the carrier.

Rep. 277

— 250 —

2.4 Direction-finding equipment
It is desirable that the m onitoring receivers in a mobile installation also serve as receivers
for the mobile direction finder. Light weight, compactness, high sensitivity, effective shielding,stability, robust construction and low power consum ption are desirable features for mobile
monitoring receivers. Furtherm ore, receivers for mobile m onitoring should provide con­tinuous tuning coverage of as wide a frequency range as possible. Accurate calibration of theorder of 1 kc/s at 30 Mc/s and below, and 10 kc/s above 30 Mc/s is highly desirable. Accuracyof frequency resetting of the order of 1 p art in 104 or better is also desirable. Althoughband-switching is preferable, plug-in radio-frequency units for different bands may reducethe circuit complexity.
The loop rotater should preferably be installed in the approxim ate centre o f the roofof the vehicle, with the loop socket extending through the ro o f and with the azimuth scaleand rotating mechanism (usually a hand wheel) inside the vehicle at a convenient location.
A num ber of plug-in-loops with different electrical characteristics will perm it optim um
results to be obtained over a wide range of frequencies.
D irectional antennae are needed to extend the frequency range above the limits of loop
antennae. Desirable characteristics are: high directivity, broadband frequency coverage,
high gain, horizontal and vertical polarization and small size. A ntennae types in use arehorizontal and vertical dipoles, Yagi-beam, helical and rotatable H-type Adcock, whileparabolic, horn type or corner-reflector antennae can be used above 300 Mc/s.
A n antenna finding, increasing acceptance above 1 Gc/s, is a broadband horn covering
approxim ately a 2 to 1 frequency range. F or added gain and directivity, the horn may bem ounted in a parabolic reflector.
2.5 Automatic monitoring o f occupancy measuring equipment
M onitoring of spectrum occupancy, at specified locations or along specified paths, may
be made in the mobile m onitoring unit, by means of a frequency spectrum recorder or bymeans of a panoram ic adaptor.
The latter permits visual observations to be m ade over a relatively small band of fre­quencies while the vehicle is in motion.
1.6 Modulation measurement equipment
It is desirable to provide facilities for measurem ent or percentage m odulation of both
amplitude- and frequency-modulated emissions. F o r the former, a cathode-ray oscilloscopewith a wide band vertical amplifier usable up to 10 Mc/s or m ore is desirable. F o r m easur­
ing m odulation deviation of FM emissions, an instrum ent capable of accurate measurem ent
of carrier deviation, over a range from ± 5 kc/s or less to ± 1 0 0 kc/s or more, is desirable
and should be capable of indicating instantaneous values. An overall accuracy of 5% or
better is highly desirable. A cathode-ray oscilloscope may be used as an indicator for the
carrier deviation meter to permit measurements of instantaneous peaks of deviation of FM
stations.
2.7 Television measuring equipment
M easurements of the characteristics of the video waveform of television transm issions
can be m ade with instruments specially designed for the purpose. Cathode-ray oscilloscope
display of the various portions of the video signal is desirable so th at individual picturelines or segments thereof, as well as individual synchronizing pulses, may be observed. P ro­vision should also be m ade for viewing the entire picture on a screen of adequate size topermit evaluation of the picture quality.
2.8 Power supplies
To provide adequate power for large mobile m onitoring units, a separate pow er unit
either integral with the vehicle or m ounted on a trailer may be used. An engine-alternator— 251 —Rep. 277

unit of 5 kW rating is usually adequate for this purpose. F or the smaller mobile m onitoring
units, an alternator of about 500 watts driven by the vehicle fan belt is a useful source of power.
3.

Accuracies and limitations of measurement
M ost of the measurements listed in § 1 of this R eport can be as readily perform ed withmobile as with fixed facilities, generally with little or no com prom ise in desirable accuracy.

3.1 Frequency measurements
Mobile frequency standards are available which will m aintain stability better than
± 1 part in 10® per day under field conditions.
By means of frequency synthesizers or electronic counters, it is often possible to obtain
direct measurements of the frequency of emissions w ithout recourse to auxiliary interpolating
instrum ents over a range of frequencies extending above 100 Mc/s. Transfer oscillator tech­niques may be used at much higher frequencies with interpolation between the transfer
oscillator and the frequency standard being m ade with an electronic counter or other appro■ priate means. M easurem ent accuracies, within the desirable limit of ± 1 p art in 107, may
be accomplished under optim um conditions when the nature of the carrier is such, th a t a
precise zero beat may be obtained or where direct counting techniques m ay be used.
On F M emissions, frequency averaging techniques with an electronic counter will provide
an accuracy of 1 part in 106 or better.
3.2 Field-strength measurements
The accuracy o f field-strength measurements above 30 Mc/s is limited, n o t so m uch
by the instruments themselves, as by the local conditions which tend to distort the electro­
magnetic field, so that a considerable variation in field-strength over relatively short distances
may be expected. This problem may be alleviated to some extent by m aking several m easure­m ents at each m easuring location moving the antenna a few feet horizontally between
measurements. U nder average conditions, even when appropriate precautions are taken to
ensure optim um accuracy, the accuracy cannot be depended upon to be better than ± 2 db.
If large numbers of measurements are made as functions of time, location or distance, etc.,
the statistical evaluation will yield values of the quasi-maximum, quasi-m inimum and medianvalues with an accuracy of about ± 3 db or better, depending somewhat on the distributionof field-strengths. A m ajor lim itation of portable or mobile field-strength meters is thelimited sensitivity, particularly at the higher frequencies. In the lower portion o f the spec­
trum , up to several Mc/s, atm ospheric noise is likely to be a limiting factor on the usable
sensitivity, while at higher frequencies the noise introduced by the instrum ent itself becomesim portant. U nder average field conditions and depending upon the frequency involved, theminimum field-strength, which may be measured with portable instruments with the accuracies
m entioned above, will range from about 2 to 100 fxV/m in the frequency range from 10 kc/s
to 1000 Mc/s.
3.3 Bandwidth measurements
Generally, the same limitations apply on measurements of bandw idth by mobile instal­lations as for measurements at fixed m onitoring stations. The same m easuring instrum ents
are applicable to both types of installation. One advantage of mobile as contrasted with
fixed installations is that, in the case of the former, measurements can often be m ade imme­
diately adjacent to the transm itter, eliminating some of the measurem ent problem s (such as
those associated with interference and noise), which are m entioned in R eport 275.
3.4 Direction finding
A m ajor lim itation of loop-type direction finders is their polarization error in the presenceof signals with significant skywave components. A further serious lim itation of a direction­finder, which depends upon the,direction of arrival of the wave front, is the likelihood of local
reflections or re-radiation from nearby objects such as buildings, transm ission and telephone

— 252 —Rep. 277

lines, etc. In an area where the wave is relatively free from distortion due to local conditions,where the path of arrival is essentially horizontal (vertically polarized wave), and taking into
account possible errors introduced in orienting the direction-finder azimuth scale, accuraciesof the order of ± 5° with vehicle-mounted loop-type direction-finders are typical, withsomewhat greater accuracy at frequencies below about 5 Mc/s. However, where the wave
has been distorted by local conditions or where skywave com ponents are present, bearing
nulls are likely to be obscured or to deviate widely from the true direction of the emission
source.
W here the ground wave is predom inant (i.e. the ratio of ground-wave to reflected waves
being at least 6 db), direction-finding loops may be used in the frequency range 10 kc/s to
30 Mc/s. The accuracy obtained depends upon the signal level and the equipm ent used.
Typical values for a direction-finding null 1° wide are:10 kc/s: 50 (xV/m,1000 kc/s: 15 (xV/m,
20 Mc/s: lOtxV/m.
For the bearings of horizontally polarized signals (line-of-sight) at frequencies above
30 Mc/s, Yagi-beam antennae may be used in a maximum signal d /f m ethod with an angularwidth of bearing indication of ± 15°.
F or measurements m ade from a vehicle in motion, no proper bearing seems possible
because of multiple reflections from nearby objects. However, when equipped with a visualindicator, mobile direction-finding sets will allow determ ination of a median value of thevarying indications and hence yield an approxim ate direction.
3.5 M onitoring o f occupancy o f the radio-frequency spectrum
The accuracy obtainable from a frequency spectrum occupancy recorder depends upon
the receiver and the overall calibration. Equipm ent used in the Federal Republic of G erm any
has the following characteristics:- Sensitivity: better than 1 [xV/m.
- Accuracy of field-strength indications: ± 3 db at angles of incidence below 60°.
- Frequency stability of receiver: ± 5 parts in 105 ± 40 c/s (where ± 40 c/s is the band­
width of the filter).
- Accuracy of reading tim e m arkers: ± 1 m in or ± 30 s.
- Adjustable maximum frequency spread on the recording strip by choice of appropriate
gear reduction: 100 c/s per mm. When m onitoring above 30 Mc/s by means of panoram ic
sets the resolving power may be about 400 c/s.
3.6 Percentage modulation
Cathode-ray oscilloscopes, with the desirable characteristics for measurem ent of per­centage modulation of am plitude-m odulated signals, are available. Accuracy of such meas­
urements can usually be maintained within ± 5 %. F o r measurem ent of carrier deviation,
instrum ents are available which meet the desirable characteristics listed in § 2.6. Selfcontained calibrators are provided to m aintain an instrum ent accuracy better than 5 %.
3.7 Television measurements
Instrum ents are available for perform ance of all desirable television measurements andobservations mentioned in § 2.7. M easurement accuracy of the various instrum ents in m ost
cases approaches or equals that of measurements which can be perform ed at a fixed location.
Com parative level measurements of com ponents of the com posite video waveform, forexample, can usually be m ade with an accuracy of 5 to 10%.
Measurements and observations, which may be perform ed with the equipm ent installed
in a mobile television enforcement unit in the U .S.A., include:Rep. 277, 278— 253 —- frequency measurements of television station carriers (including chrom inance sub-carrier
frequency of colour emissions);- the precision frequency measuring equipm ent covers a frequency range of 20 to 1000 M c/s
with an accuracy under optim um conditions of 5 parts in 107;
- measurements of synchronizing pulse waveform and timing, video waveform and of colour
video phase relationships;- checking of video levels with respect to synchronizing pulse levels;- measurements of bandw idth of television emissions including observations of spurious
emissions at all frequencies between 54 Mc/s and 890 M c/s;
- percentage of m odulation rate of vision and sound emissions;- measurements of distortion and noise level at audio frequencies.

REPORT 278 *A U TO M A TIC M O N IT O R IN G O F O C C U PA N C Y O F T H E
R A D IO -FR E Q U E N C Y S P E C T R U M(Question 255(VIII))(Los Angeles, 1959 - Geneva, 1963)
This R eport takes into 'consideration the docum ents presented up to the X th Plenary
Assembly of the C.C.I.R., Geneva, 1963.
1.

Doc. VIII/2 (U.S.A.) of Washington, 1962

1.1 In considering the accuracy of autom atic m onitoring equipm ent in determining bandw idthsof emissions, due consideration should be given to relating measurements of narrow -band
emissions of the order of 2 kc/s or less to the characteristics of the particular instrum ent
in use. It has been determined, for example, th at in some instrum ents which mechanicallysweep a frequency range and resolve the bandw idth presentation by selective circuits, theshape factor of the selective circuits is such as to complicate bandw idth determ inations atother than accurately know n com parison levels. The variation of received signal levels
due to propagation conditions, together with other factors, impose restrictions on the accuracyof indicated signal bandw idth of narrow -band signals. Consideration should therefore be
given to the need for an analysis of the relative distribution of the signal level and the resolv­
ing capability of the instrum ent at several input levels. F o r signals with bandw idths ofseveral kc/s, the errors contributed by the above-mentioned equipment lim itations becomeless im portant. Nevertheless, it may be desirable, in the interest of correlating data obtainedwith different instruments, to take into account their resolving power and the repetition rateand duration of discrete com ponents of the observed signals.
In determining the accuracy of field-strength measurem ents m ade by autom atic devices,the polarization and directivity of the antennae are im portant factors. In the 3 to 30 M c/s
range, where signals received over sky-wave paths contain both horizontally and verticallypolarized com ponents to a significant extent, a decision m ust be made as to the com ponent
to be measured. Since the vertical angle of arrival is m ost commonly less th an 45°, lesserror will usually be introduced by measuring the vertically-polarized com ponent rather than* This R eport, which replaces Report 167, was adopted unanimously.

Rep. 278

— 254 —

the horizontally-polarized com ponent. W here greater accuracy is required, an appropriate
correction may be applied, based upon a com puted value for the vertical angle of arrivalof the wave front.
M easurem ent of the vertically-polarized com ponent may readily be accomplished byusing a vertical receiving antenna, the electrical length of which is appreciably less than
one-quarter wave, for the frequency band under study. To reduce errors due to non-homogeneous earth in the vicinity of the antenna, a ground screen, together with radial groundwires extending out at least 30 m (100 ft.) in all directions has been found beneficial. The
level of signal input to the recorder may be measured by com parison with a calibrated standard
radio-frequency signal generator. The antenna effective height is determined by comparison
with measurements made with an accurate field-strength meter using an antenna of likepolarization.
In evaluating the field-strength data thus obtained, due allowance m ust be made forerrors introduced by the various instruments. Allowance m ust also be m ade for fluctuations
in signal-level, since, during the sweeping process, the receiver is tuned to a particular signal
for only a small proportion of the time.
1.2 M easurem ent of signal-to-noise ratio prim arily involves a com parison between signal andno-signal conditions making use of the same techniques as for field-strength measurements.
In this instance too, variations in signal-level due to propagation m ust be taken into account.
In the lower portion of the H F range, the problem is somewhat complicated, especially during
the warm m onths of the year, by the generally high level of atm ospheric noise, which is subject
to wide variations in level, both instantaneous and over significant periods of time. The
effect of receiver bandw idth and of the bandpass characteristics will also need to be considered,
so that satisfactory correlation between measurements m ade with different equipm ent may
be accomplished.
1.3 The preferred means of analyzing and evaluating autom atic m onitoring records depends
primarily upon the inform ation desired. In some instances, it may be desirable to obtain
inform ation concerning the direction of arrival of the various signals in the frequency band
under study; this would provide data relating to the determ ination of channel occupancy
with respect to the different azimuths o f origin of the emissions. F o r example, a long-range
direction finder may be associated with the autom atic recorder in such a way th at the azimuth
would be advanced a small increm ent (such as one or two degrees) at the start of each sweepof the autom atic recorder. Signal nulls and maxima could readily be determined by inspec­tion of the chart. Additionally, data could be extracted from such recordings which would
indicate occupancy in a given azim uth at regular intervals of time. In congested bands,
the use o f a directional antenna would also aid in reducing overlapping of signal traces.
Identification of the type of emission, by analysis of autom atic recorder indications,is subject to shortcomings with narrow -bandw idth emissions, because of lim itations in the
resolving pow er of the instrument. However, those emissions occupying a significant band­
width, such as multi-element tone printers, m ultiple-com ponent multiplex, wide-shift simplex
or multiplex and certain transient types of emissions, can frequently be catalogued by inspectionof recorder indications, together with precise frequency increm ent chart calibration.
1.4 The degree to which records may be analyzed by autom atic means would appear to be an
economic rather than a technological m atter. Because o f the variety o f data normallyavailable from the autom atic recorder, equipm ent for complete autom atic analysis would
necessarily be quite complicated. Such an analyzing system might employ transducers toconvert chart com ponents into digital or analogue data which could be handled by electronic
data-processing equipment.

2.

Doc. VHI/8 (Federal Republic of Germany) of Washington, 1962
The m ethod of measurem ent described below permits the field-strength to be recorded
continuously instead of in steps. F rom such field-strength recordings, the bandw idth andsignal-to-noise ratios may be readily determined.

— 255

Rep. 278

A potentiom eter is mechanically coupled to the recording head of the occupancy recorder,
supplying a d.c. voltage directly proportional to the relative position of the recording stylus
on the recording sheet. After suitable amplification, this d.c. voltage is applied to the timebase (x-plates) of a cathode-ray oscilloscope, thus providing a frequency scale exactly insynchronization with the sweep of the occupancy recorder.
The intermediate-frequency output of the receiver is connected to a multi-section analyz­
ing filter (quartz crystal), the bandwidth of which is variable in steps between 30 and 100 c/s.
After detection, the filtered signal is amplified in a logarithm ic amplifier and fed sim ulta­
neously to the measuring (Y) plates of the oscilloscope and to the occupancy recorder. By
special arrangements, the Y-axis is calibrated linearly over a range of 80 db. The oscillo­
scope screen, of the long-persistence type, allows direct observation during a full sweep of
the occupancy-recorder. A utom atic recording is effected by photographing the screenpresentation of any individual sweep by means of a 35-mm camera. The shutter release
may be actuated automatically, by means of a special control contact in the occupancy recorder.
By means of a simple counter device, such as is used in telephone exchanges, it may easily
be arranged that each single or any nth sweep is exposed on the film. Correlation between
the photographed oscillograms and their corresponding sweep num bers is easily ascertainedby photographing the counter, together with the spectrum pattern.
Evaluation of the oscillograms may readily be perform ed by projecting the developed
negative on to the occupancy recording sheet, so that both frequency calibrating scales are
made to coincide. The field-strength and bandw idth of a w anted emission, as well as
its am plitude ratio relative to an unw anted signal, may thus be determined easily. The values
taken from the photographs are, of course, instantaneous values present at a particularpoint of the spectrum a t the m om ent when the filter swept through it.
The foregoing characteristics point to the lim itations of the proposed m ethod. Setting
aside for the m om ent the influence of fading, which will be dealt with further below, theproposed m ethod is suitable for recording continuous line spectra as well as periodicallyand quasi-periodically keyed emissions, i.e. practically any binary telegraph systems
encountered in practice. Some difficulties arise, however, in the representation of no n ­periodic pulse emissions and of types of emissions with m odulation envelopes which don ot vary periodically; e.g. A3, A3 A, A3B; in these cases, however, the am plitude o f thecarrier (or residual carrier) is recorded correctly.
The extent of the frequency range that can be explored is limited by the bandw idth of
the analyzing filter which, to assure the desired resolution characteristic, should n o t be larger
than 100 c/s, and by the exploration speed which should n ot greatly exceed 60 s per sweep.
Since, for the intended purpose, the exploration rate with a filter width of 100 c/s should
be 5000 c/s per second *, the maximum sweep range would be 300 kc/s wide. Recordingsof signals subjected to fading can, of course, only show instantaneous values of the fieldstrength. The received field undergoes irregular variations between limits th a t can only be
estimated by taking a large num ber of sequential photographs. Any estimate of the actual
field-strength will norm ally be accurate within ± 4 db. The smaller the scanning range, thebetter the field-strength maximum will be discernible. If, in special cases, a m ore accuratem easurem ent o f the statistical variation of the field-strength is desired, a conventional singlefrequency recording with subsequent analysis should be made.

3.

Doc. Vm /12 (Japan) of Washington, 1962

3.1 The recording system is of the disruptive-discharge type, so th at the records can be examinedin the course of recording. Moreover, the recorded lines are very thin and the field-strengtho f signals can be indicated by the thickness of the lines.

* T h e tim e increm ent for any d iscreet spectrum co m ponent of th e sweep sig n al is in th is case 20 m s; th e scanning speedof spectrum analyzers given in A nnex I to R ecom m endation 327 are considerab ly low er, because fine analysis of th e spectrum isdesired. In m o st cases, how ever, th e indication of field-strength, as found from th e o scillogram s, w ill b e en tirely a d e q u ate togive an o verall p ic tu re of th e co n d itio n s in the frequency range explored. T his h o ld s tru e sim ilarly fo r the b a n d w id th an d signalto-noise ratio s of the recorded em issions.

Rep. 278

— 256 —

3.2 Since the filter in the recording unit (the rate o f sweep being taken into account), has a passband 30 c/s wide, it resolves the frequencies very well. This enables one to identify thetype of emission from the recording.
3.3 The frequency stability of the receiver unit is better than 1 p art in 106 and the frequency
scale (capable of calibration against the standard frequency), can be m arked at 10 kc/s intervals.
Therefore, the accuracy of reading the frequency is 300 c/s.
3.4 To determine the relative field-strength of each of the vertically recorded lines, a variableattenuator is placed at the intermediate-frequency stage in the receiver unit, and is inserted
autom atically step-by-step in succession at each fixed tim e o f sweeping. Thus, the relative
field-strength can be obtained from the am ount of attenuation inserted.
Furtherm ore, to sm ooth the overall gain/frequency characteristics of the equipment,
including the antenna system used, a vertical omnidirectional loaded antenna of wide band­
width is used (the structure and electrical characteristics o f which are shown in Figs. 1, 2 and 3).
3.5 Accuracy in determining bandwidthThis equipm ent is to record the relative distribution of the spectra of signals above
a certain level, but it is not intended that the occupied bandw idth, as laid down in the R adio
Regulations, Geneva, 1959, should be read from the recorded lines. Therefore, as thewidth of the spectrum of each signal at a certain level is considered as a bandwidth, studies
were carried out to determine the accuracy with which the bandw idth might be estimatedin this case.
This equipment, when used with a 100 kc/s swept frequency range and 60 sweeps perhour, is capable of determining the bandw idth of the spectra of various types of emissions
at a given level to an accuracy of about 100 c/s.
3.6 Accuracy in determining field-strength
The m ethod of measurem ent of field-strength by means of this equipm ent is the sameas described in § 3.4. In this case, the larger the num ber o f sweeps per step in the attenuator,
the higher the accuracy of reading the recorded lines. Considered from the propagation
characteristics, however, because of variations in field-strength, the increase in the num berof sweeps and the prolongation of measurem ent brings a lack of reliability to the results.
On the other hand, in the field of reception at the m onitoring stations in Japan, alm ost
all radio waves, excluding those in the standard broadcasting service, are less than about
55 db (1 (TV/m = 0 db). The lowest field-strength that this equipment is capable of recordingis —10 db.
From various viewpoints above, it is concluded th at it is best to complete one operationof measurem ent in a period not exceeding 20 minutes at 60 sweeps per hour, the num bero f sweeps per step of the attenuator being 2, and the attenuator having 10 steps o f 6 db each,that is, 60 db.
W here measurements are taken with the 100 kc/s swept frequency range by the use of
the equipm ent with the above characteristics:- the overall gain deviation of the vertical omnidirectional loaded antenna and the receiverunit within the swept frequency range is within ± 0-8 db;- the accuracy of reading the field-strength from the result of recording is within ± 4 db;- the error of the attenuator at the intermediate-frequency stage is within ± 1 db.
Taken altogether, the accuracy of determ ination of the relative field-strength is ± 6 db.
Further, if a suitable emission is selected from am ong those recorded and its field-strengthis measured individually, the relative field-strength of each emission can then be obtained.
3.7 Capability o f automatic monitoring equipment in determining signal-to-noise ratios
The lowest signal-to-noise ratio (for an equivalent noise bandw idth of 10 kc/s) that
this equipm ent is capable o f recording, is less than —10 db at the input term inal o f thereceiver, when the equipm ent is in the optim um condition of recording. In case o f higher

— 257 —Rep. 278

values than this, the signal-to-noise ratio can be determined by measurem ent of the intensities
of signal and noise in the same way as the field intensity m entioned above.

4.

Doc. VIII/11 (Japan) of Washington, 1962

4.1 Measurement o f relative field-strength
A variable attenuator is added to the receiver unit of the equipment, the attenuation is
automatically increased step-by-step in succession at each specified num ber of times ofsweeping, and the signal output is recorded. The relative field-strength o f each signal isdetermined by the attenuation inserted immediately before the recorded line fades out.
The absolute field-strength is obtained as follows: the absolute value of the wanted
signal am ong those recorded is m easured by means of a second field-strength meter, and,on the basis of this value, the absolute value of other signals is derived from the relative
field-strength.
The total attenuation should be 60 db, to be equally divided into about ten steps.
desirable to m ake the num ber of times of sweeping two per step in the attenuator.

It is

The duration of each measurem ent should be about 20 minutes, taking account offluctuation in field-strength due to variation in the radio propagation characteristics.
A n antenna, with good frequency characteristics such as a vertical omnidirectionalloaded antenna, should be used. (Such an antenna is illustrated in Fig. 1, and its charac­
teristics are given in Figs. 2 and 3.)
5.

Occupancy-vacancy recorder
A nother type of equipm ent now in use is called an “ occupancy-vacancy recorder ” .
This system indicates, by an inked line on a strip recorder, the presence or absence of a signal.
As the instrum ent scans the spectrum, a continuous line is draw n on the chart to indicate
the presence of signals. In the absence of a signal, the recorder and frequency scanningmechanism stop for a pre-set interval. If no signal appears during this interval, the recordermakes a dot on the chart, the system moves forw ard a small increment and repeats the p ro ­cedure. W hen signals are again encountered, the device moves on steadily until the next
vacant spot is found. The equipm ent is provided with a special circuit th at autom aticallyadjusts the sensitivity to one or two pre-set values, the sensitivity being changed alternately
at the end of each scan. Each scan makes a new trace, roughly parallel to the previous
one. In this manner, approxim ately 48 hours of data can be placed on a single strip.

Rep. 278

— 258 —

Top-loading resistor

Vertical conductor
Radial conductor

Coaxial cable

Matching transformer

F igure 1

Vertical omnidirectional loaded antenna

Loading resistor: 250 ohms
Radial conductor length: 8 m
Vertical conductor length: 8 m

Rep. 278

— 259 —

F igure 2

Impedance characteristics o f a vertical omnidirectional loaded antenna(see Fig. 1)

Effective height, he/f (m)SWR: 2-0 (except at 2 Mc/s),(The points on the curve represent the frequency in Mc/s)

2

4

6

8

10

12

14

16

18

20

22

Frequency (Mc/s)
F igure 3

Effective height o f a vertical omnidirectional loaded antenna(see Fig. 1)

24

26

Rep. 279

— 260 —REPORT 279 *VISU A L M O N IT O R IN G O F T H E RA D IO -FR EQ U E N C Y SPE C T R U M(Question 191 (VIII))(Geneva, 1963)
Question 191(VIII) seeks inform ation on preferred equipm ent and preferred methods forvisual m onitoring of broad ranges of the radio-frequency spectrum. The following is areport of progress to date, as summarized from the responses to this Question (Docs. VIII/9(U.S.A.), V III/19 (Belgium), and VIII/26 (United Kingdom) of W ashington, 1962).
Except for the use of spectrum analyzers for signal analysis, and use of panoramic-type
receivers or adapters for observation of limited widths of the radio spectrum, stations of
the international monitoring system have reported little actual experience in visual m oni­
toring operations. F urther development of methods and procedures must await actual
experience in the use of broadband spectroscopes at m onitoring stations.
1.

Spectrum analyzers are valuable in the recognition and classification of emissions especiallythe complex emission. The spectrum analyzer is a scanning type of instrum ent arranged
to display, on a cathode-ray tube, the spectral contents of the frequency band under exami­
nation. Spectrum analyzers of various types are under development or in operational use.
•

1.1 A spectrum analyzer, described in Doc. VIII/26, can be used as a panoram ic receiver covering
the frequency range of 25 Mc/s to 140 Mc/s and employing a wide sweep. The width of
the sweep can be varied continuously between 1 % and 55 % of the tuned frequency. Two
output filters are incorporated, one with 7 kc/s bandw idth for sweeps up to 5 Mc/s, the otherwith 35 kc/s bandw idth for sweeps of over 5 Mc/s. Resolution varies from 8 kc/s for a
250 kc/s sweep to 100 kc/s for a 70 Mc/s sweep. Sensitivity varies between + 4 8 db and+ 5 4 db relative to 1 [xV across 75 ohms, for frequencies of 25 Mc/s and 40 Mc/s respectively,
to give full deflection on the screen. Frequency m arkers at 10 Mc/s intervals and at 2 Mc/sintervals can be applied at will, appearing as a bright (or dark) spot on the trace, the 10 Mc/sm arkers being distinguished by double spots.
1.2 The principle on design of a spectroscope is described in Doc. VIII/9. The first of theseunits is expected to cover the frequency range 100 Mc/s to 1000 Mc/s. The ultim ate rangeof the equipm ent is expected to be 14 kc/s to 10 Gc/s. The principle involved is th at ofheterodyning the incoming signals by means of a local sweeping oscillator to produce anintermediate-frequency. Increased selectivity is obtained by further conversion to a second
lower intermediate-frequency. Selective filter bandwidths of 5 Mc/s, 1 Mc/s and 400 kc/s
are obtained at 775 Mc/s. The first intermediate-frequency of 775 Mc/s is converted down
to 30 Mc/s where, using crystal filters, bandwidths of 25 kc/s and 5 kc/s are obtainable,
enabling relatively fine spectral details to be observed. This allows selection of the desired
bandw idth and resolution com mensurate with the sweep rate selected which should be con­tinuously variable over a wide range. Read-out may be either linear or logarithmic. In thelatter instance, a separate amplifier is provided to give a dynamic range of 140 db for displayof relative signal strengths. A large cathode-ray tube (17 inch) is used for displaying thespectrum, the vertical displacement being a function of the signal strength and the horizontal

This R eport was adopted unanimously.

— 261 —Rep. 279

sweep being synchronized with the sweep of the local radio-frequency heterodyning oscillator.
The average overall sensitivity of the equipm ent at 5 Mc/s bandw idth should be approxi­
mately —90 dbm. Tests have indicated that 100 to 1000 Mc/s wide band R F amplifiers for
R F spectroscope use are capable of a 6-9 db noise figure, a gain of 25-40 db, a sensitivity of—105 dbm and an image rejection of better than 60 db.
1.3 A wide-band spectrum analyzer is available commercially which can be used by m onitoring
stations for visual observation of a band 70 Mc/s wide in the range 10 M c/s to 44 Gc/s.
W ith two dispersion ranges, 0 to 70 Mc/s and 0 to 5 Mc/s, it can be used for broadband
observations of up to 70 Mc/s. The analyzer is norm ally equipped with a 5-inch display
oscilloscope; however, a 17-inch oscilloscope is available for comprehensive frequency m oni­
toring.

2.

It has been found that a panoram ic view of a broad portion of the radio-frequency spectrum
can be presented on a cathode-ray tube, by the use of suitable sweep circuits in the radio
receiver or in an associated panoram ic adapter. Panoram ic receivers or panoram ic adapters
are under development or in operational use.

2.1 A panoram ic receiver is described in Doc. VIII/26, which consists of an H F com m unication
receiver and a panoram ic adapter in a single cabinet, to provide a visual oscilloscope display
in any selected band between 1 and 30 Mc/s. Scanning is limited to a band lying between two
adjacent multiples of 1 Mc/s. Sweep width can be varied continuously between 60 kc/s
and 1-04 Mc/s. The frequency of the sweep can be either 1 or 10 per second. O utput
filters 1-2 kc/s, 3 kc/s, and 8 kc/s are provided. Either linear or logarithmic presentations
are available. 100 kc/s frequency markers can be applied at will.
2.2 Panoram ic equipment, designed for visual supervision of mobile services operating in the
V H F bands, is described in Doc. V III/19. A panoram ic adapter .used with a V H F receiver
covers the bands 30 to 180 Mc/s or 85 to 300 Mc/s with an intermediate-frequency of 21-4 Mc/s.
Spectrum width is F 2 Mc/s. The selective filters consist of three fairly low frequency(2 Mc/s) amplification stages, in the form of three double-tuned transform ers adjusted below
the critical coupling. Visual display is m ade on a 5-inch oscilloscope.
2.3 A second type is not associated with an external receiver and does not include sound. The
radio-frequency spectrum from 70 to 190 Mc/s is examined in small sub-bands of 10 M c/s;
harm onics from a 1 Mc/s crystal oscillator are introduced into the pre-amplifiers; reference
markers at 1 Mc/s intervals are thereby obtained on the oscilloscope. Visual display is m ade
on a 5-inch oscilloscope (Doc. V III/19).

3.

Cathode-ray tubes of various size are employed for visual observation. A 17-inch tube
with a P-7 screen and am ber filter is suggested on the basis of studies to date. F urther
development may make practical the use of larger tubes, or multiple-trace tubes, to extend
the frequency axis of display (Doc. VIII/9).

4.

To provide a uniform response in am plitude read out on the broadband spectroscope display,
it is of course necessary to employ wideband antennae. In using the spectroscope for sim ul­taneous observation of a large part of the spectrum, it is necessary to com prom ise on theselection of the antennae. The antennae giving the best results with spectroscopes are:rhombics, log-periodic types, and vertical antennae which are shorter than a quarter wave­
length at the highest frequency under observation (Doc. VIII/9).

5.

Recent developments in the design of broadband amplifiers, and their availability, leave
few, if any difficulties regarding the broadband R F amplifier units for spectroscopes. One

Rep. 279, 280—262 —

wideband amplifier has a frequency response flat within ± 1-5 db from 1 kc/s to 200 Mc/s.
a voltage gain of 20 db, a noise figure of 9 db and a rise time of less than 0*0026 y.s (Doc,VIII/9).

6.

Conclusions' W ithin the next few years, it is expected th at various types of “ broadband ” spectro­
scopes for visual m onitoring will become available for use at monitoring stations. The
trend in design and construction of spectrum analyzers is towards an increasing value of
total scanning excursion (sweep width).
Several units will probably be required to simultaneously cover the spectrum from
10 kc/s to 1000 M c/s; however, at the present time no need has been shown for such simul­
taneous coverage. R ather, a m onitoring station will probably find it m ore convenient toobserve only one broad segment of the spectrum at a time.
Actual experience is needed in developing operating m ethods and techniques in the useof “ broadband ” spectroscopes for m onitoring purposes. Therefore, it is advisable thatstudies under Question 191 (VIII) be continued.

REPORT 280 *ID E N T IFIC A T IO N O F R A D IO ST A TIO N S(Question 256(VIII))(Warsaw, 1956 - Los Angeles, 1959 - Geneva, 1963)
1.

This R eport summarizes the contributions and discussions in response to Q uestion 256(VIII).
It also retains that m aterial from R eport 280 which was considered to have an application
to the adoption by A dministrations and operating agencies either o f the provisions of Recom ­m endation 379 or of other methods of identification and operating procedures relating
thereto, as discussed in this Report.

2.

Since the IX th Plenary Assembly, some progress has been made, particularly with respect
to phase-m odulation of multichannel FSK systems, whereby the identifying signal can besent simultaneously into all circuits using the same sub-carrier. This results in centralizationo f identifying signals (Doc. VIII/14 (Japan) of W ashington, 1962).
2.1 The sub-carrier is directly phase-m odulated by the m odulator circuit added to the trans­
m itting term inal equipment, and the identifying signal can be supplied sim ultaneously to all
circuits using the same sub-carrier, by means of a distribution amplifier.
Because of the small m odulation index required, a simple device consisting o f a single
transistor is sufficient for the purpose. The m odulated signal is keyed in M orse code andits am plitude adjusted so that, whatever the class o f amplification, the specified m odulationindex is independent of the frequency of the emission, type o f emission, etc. The m odulationindex can be measured accurately during the operation tim e o f the circuit regardless o f trafficin progress.
The intelligibility of the identifying signal is affected by the m odulation index and them odulating frequency. In F I or F6 emission, the m odulation index is suitable a t 0*05 andno great difference in intelligibility occurs for m odulating frequencies between 500 to 1000 c/s.
In a com posite circuit of F I and F6 emissions, it is desirable to have the m odulation index
greater than 0*05 and the m odulating frequency no less than 600 c/s.
* This Report, which replaces R eport 171, was adopted unanimously.

— 263 —Rep. 280, 281

3.

Two additional m ethods have been used for identifying F I emissions sim ultaneously withtraffic:
3.1 One m ethod (Doc. 468, of W arsaw, 1956), is to superimpose an audio-frequency m odulation
which produces a phase-m odulation at the transm itter output. A low-level am plitude-m odulation is applied to the exciter and this ultim ately produces phase-m odulation through thelimiting action of the following class C amplifier. The audio tone is keyed and applied
across the com m on cathode resistor of the balanced m odulator. This results in the p ro ­duction of additional sidebands on either side of the m ain carrier with a displacement depend­ing on the frequency of the audio tone employed.
It has been found th at satisfactory identification is obtained w ithout interference totraffic if the am plitude of the sidebands is about 32 db below th at of the carrier. C ontinuous
repetition of the identifying signal at a rate o f 8 w.p.m. is' used. The keying device consistsof a notched “ keying wheel ” through which a beam of light is projected thereby operatinga photo-electric cell. A n ordinary com munications receiver, with the beat-frequency oscil­
lator turned off, is used for reception of the keyed identifying signal.
3.2 A nother m ethod has been developed which superimposes on the carrier an additional fre­quency-m odulation at small index and at 400 c/s, keyed by the identifying signal. The con­ditions under which the m ethod is used and the results obtained are described in D oc. 183
o f Los Angeles, 1959.

4.

Keyed am plitude-m oduiation, which is superim posed on frequency-modulation for identifying
signals has, for economic reasons, not been generally applied because the m ethod used
employed high-level m odulation.
A m ethod for identifying single-sideband multi-channel systems by the insertion of akeyed audio tone on one of the channels was found to be unsatisfactory due, particularly,
to the difficulties encountered by m onitoring observers.

R E P O R T 281 *ID E N T IFIC A T IO N O F SO U R C E S O F IN T E R FE R E N C E T O R A D IO
R E C E P T IO N
(Q uestion 257(VIII))(Geneva, 1963)
This R eport shows progress made, m ethods used, and suggests future procedure, as noted
in Docs. V III/7, VIII/23 and V III/30 o f W ashington, 1962.
A t the date of this Report, one can only give a partial answer to Question 257(VIII). M uch
w ork has been done, b ut the ultim ate production o f a catalogue ** is complex. U niform
standards of measurem ent between the various countries have n o t yet been developed, and suchstandards are essential to m ake a catalogue of international value.
The preparation of a catalogue should proceed in the following order of im portance:- inform ation primarily for use at m onitoring stations to aid in solving cases o f harm ful
interference at international level;- inform ation to aid in identifying the sources of industrial interference.
* T h is R e p o rt w as ad o p ted unanim ously.
** T h e te rm “ catalo g u e ” , as used in th is R e p o rt, denotes a n index of in fo rm atio n such as p h o to g ra p h s, m ag n etic-tap e reco rd ­ings, w ritten descriptions, draw ings, etc., describing th e interference.

Rep. 281

— 264 —The replies to Q uestion 257(VIII), relating to television interference have been quite adequate,
although uniform standards of measurem ent and portrayal have n ot been developed.
Inform ation on interference to television, obtained so far, has em braced interference causedby, or due to, the following:- faulty adjustm ent of the television receiver,- defects in television receivers,- inherent design defects in the television receiver,- ignition interference,- com m unication equipment,- domestic electrical apparatus,- devices with “ break ” contacts,- Radar,- receiver radiation,- high voltage power lines,- neon signs,- lighting equipment,- electro-medical devices,- calculating machines and cash registers,- m ultipath reception,- video interference from aural emissions,- high-frequency generators for industrial use.
There are m any other specific cases that may be included in some o f the broad categories
above.
It has been pointed out, in some of the replies to Q uestion 257(VIII), th at the degree ofdistortion of the television picture resulting from the interference will vary slightly w ith the classor characteristic of the receiver, but the m ain features of the distortion are m aintained. From
this it may be assumed that the standards for the catalogue of television interference need not
be as rigid as the standards for catalogues of interference to other services such as those using
the H F portion of the spectrum (3 to 30 Mc/s). This is because H F measuring equipm ent varies
over wide limits in such characteristics as:- bandwidth,- selectivity characteristic,- characteristics of oscilloscopes, spectroscopes and others.
The reply to Question 257(VIII), regarding a catalogue of interference in the H F range (3 to30 Mc/s), that would be of use to m onitoring stations, is n o t complete.
The procedures for preparing this catalogue involve search of the literature and publications
relating to interference, principally for the purpose of determining how the characteristics aredescribed or illustrated (see Bibliography).
Reviews have been m ade of listed descriptions, illustrations, magnetic-tape recordings andfilms used by A dm inistrations and private industry. Inform ation from m any professional engi­
neering groups is being used in the study.
A large p art of the data developed thus far has been for the specific use of m onitoring per­sonnel and trainees.
Some of the m onitoring stations have made aural tape recordings, oscilloscope photographs,
and written descriptions of individual characteristics of interference.
F rom reports received in reply to Question 257(VIII), it is apparent th at nothing has beenfound to date in the published w ork of the C.I.S.P.R. which can be directly related to this study;
however, full account should be taken of future C.I.S.P.R. work.
The need for a catalogue of interference characteristics of radiations and uniform standardsof measurem ent is urgent and is particularly desirable as aids to personnel at m onitoring stations.
Means m ust be found to publish such a catalogue.
To accelerate the assembly and publication of the available inform ation, Resolution 16 has
been adopted.

— 265 —Rep. 281

B ib l io g r a p h y

1. Radio interference suppression techniques (A Guide for Manufacturers). Signal Corps Engineering
Laboratories, Fort Monmouth, New Jersey.
2. M e r r i m a n , H.O. Radio interference from electrical apparatus and systems, Department of Transport,
Telecommunication Division, Canada.
3. H ale, A.P. Electrical interference. Philosophical Library, Inc., New York, and the Orpington Press,
Ltd, Orpington, Kent.
4. S tephens, G.L. Radio interference suppression (as applied to radio and television reception). Pub­lished for Wireless World by Iliffe and Sons, Ltd, London.
5. R o w e , F.D. H o w to locate an d elim inate radio a n d television interference. John F. Rider Publisher,Inc., New York.
6. D arr, J. Eliminating man-made interference. Howard W. Sons and Co., Inc. The Bobbs-Merrill
Company, Inc., Indianapolis and New York.
7. R and , P.S. Television interference. Remington Rand, Inc., New York.
8. R and , P.S. Television interference handbook. The Nelson Publishing Co., Redding Ridge, Connecticut.
9. A general review o f TVI causes, effects and solutions. (WTVIC Interference Aids), Cannon & Sullivan
Technical Publications, Los Angeles, California.
10. Stoker , W.C. and Siefert, W.W. Shielding for diathermy. Bulletin No. 59, Renselaer Polytechnic
Institute, Troy, New York.
11. For shielding o f radiated interference from fluorescent lamps. Corning Glass Works, Corning, NewYork.
12. TVI Committee Operation (Suggestion kit for interference elimination). American Radio Relay
League, West Hartford, Connecticut.
13. Location o f radio interference on rural power systems. Bulletin of Technical Standards Division,
U.S. Department of Agriculture, U.S. Government Printing Office, Washington, D.C.
14. A practical handbook for location and prevention o f radio interference from overhead power lines.
U.S. Naval Civil Engineering Research and Evaluation Laboratory, Port Hueneme, California.
15. K lause, R.G. Radio interference aspects of high frequency stabilized welding transformers. (Paper
presented at district meeting of A.I.E.E., October 4, 1950).
16. Bibliography on radio-frequency interference. Trans IRE, RFI-4, 1 (February 1962).
17. K neller, K rookovets and F etter. Interference from industrial equipment to television reception.
(Moscow, 1962).

Rep. 282

— 266 —REPORT 282 *IN T E R N A T IO N A L M O N IT O R IN G FA C IL IT IE S
Reply to Recommendation No. 5 of the Administrative Radio Conference,
Geneva, 1959

(Resolution 15)(Geneva, 1963)
W ith reference to Recom m endation N o. 5, adopted by the Administrative R adio Conference,
Geneva, 1959, the I.F.R.B. has prepared a m ap (see Fig. 1), showing the distribution of m onitoring
stations throughout the world notified to the I.T .U . and participating in the international m oni­
toring system, in the bands below 28 Mc/s.
F or this purpose the world has been divided into 10 m ain areas, each divided into a num bero f sub-areas; the boundaries of the m ain areas are printed in heavy lines, while those of the subareas are shown by thinner lines, and correspond to the G eographical Zones for broadcasting
given in the Annex to Appendix 1 of the Radio Regulations, Geneva, 1959. The numbers shown
inside circles on the map are the code num bers assigned to the various m ain areas, while the codenum bering for the sub-areas is that used in the said Annex to A ppendix 1 to the R adio Regulations,Geneva, 1959.
The num bers appearing between brackets on the m ap represent the num ber of m onitoring
stations notified to the I.T.U . for the sub-areas concerned.
Considering the practicality of establishing new m onitoring stations, experience has indicatedth at A dm inistrations will continue to locate and operate m onitoring stations prim arily to serve
their own domestic needs and to fulfil their obligations under Nos. 675 and 676 o f the R adio
Regulations, Geneva, 1959. Cooperating A dm inistrations will use p art of the time o f suchstations, to m ake monitoring observations at the request of the I.F.R .B . and to furnish dataon spectrum-occupancy for use by the I.F.R .B . Thus, from a practical viewpoint, it would
appear that expansion of the international m onitoring system to close present gaps in the world
coverage depends almost entirely upon:- establishment of m onitoring facilities by countries having none at present but having thedesire and domestic need for such facilities;- expansion of the num ber of stations where a country has at present a system inadequate
to meet its own needs;- expansion of monitoring positions or other facilities at existing stations, or readjustm ent
of w ork effort, to provide m ore data for the I.F.R .B .;- co-operation in the international m onitoring effort by A dm inistrations having m onitoring
stations, but not yet furnishing spectrum-occupancy or other m onitoring d ata to satisfy
the requirem ents of the I.F.R.B.
Accordingly, it is suggested th at the best approach to obtain expansion of internationalm onitoring facilities to secure the desired results which prom pted Recom m endation N o. 5, is for
the U nion and the I.F.R.B. to follow up §§ 1 and 2 o f this Recom m endation relating to the required
efforts of Administrations, as envisaged in A rt. 13 of the R adio Regulations, Geneva, 1959.
* This Report was adopted unanimously.

— 267 —Figure 1

Rep. 282

PAGE INTENTIONALLY LEFT BLANKPAGE LAISSEE EN BLANC INTENTIONNELLEMENT

— 269 —STU D Y G R O U P V III(International monitoring)Terms o f reference:
To study technical and operating problems, the solution of which depends principallyon considerations of a technical character relating to m onitoring stations participating in
the international m onitoring system with regard to:
1. in collaboration with the I.F.R .B., ways in which harmful interference can be verified andreported, in accordance with the International Telecommunications Convention and theR adio Regulations;2.

the development of m ethods and procedures to be used by m onitoring stations in determ ining
occupancy of the radio-frequency spectrum and the characteristics of emissions and in locating
the source of an emission by direction-finding techniques;

3. specifications regarding the selection of sites, antennae and other equipment and instrum en­tation.

Chairman :Mr. G.S. Turner (U.S.A.)
Vice-Chairman : Mr. M. A m aro Vieira (Portugal)

IN T R O D U C T IO N BY TH E C H A IR M A N , S T U D Y G R O U P V III

1.

Subjects on which action has, in principle, been concluded

1.1 Organization o f an international monitoring system
R eport 282 shows the international m onitoring facilities.
Resolution 15 urges the A dm inistrations concerned to extend the international m oni­
toring system on a world-wide scale.
1.2 A lthough no Question is under study, R eport 277 was brought up-to-date in Geneva con­cerning measurements at mobile monitoring stations.
1.3 The contributions to Question 189 show that correlation between measured S-values and fieldstrength was not possible to a sufficient degree of accuracy. R eport 274 therefore term inates
the study of this Question.

2.

Subjects on which partial answers already exist but which require further study

2.1 Recom m endation 377 and R eport 272, dealing with frequency measurements at monitoring
stations, are am ong the texts which m ust be revised repeatedly to take account o f advancesin electronic techniques.
2.2 Field strength measurements at monitoring stations. While Study Programm e 102(VIII) has
rem ained unchanged since Warsaw, 1956, Recom m endation 378 and R eport 273 wereredrafted. A new Question 253(VIII) was adopted, asking for an expeditious m ethod ofdetermining field-strength in m onitoring stations.

— 270 —2.3 The inform ation available on bandwidth measurements was insufficient to perm it a Recom ­m endation to be issued. R eport 275 and Study Program m e 207(VIII) deal with this problem.
2.4 Identification o f radio stations. Recom m endation 379, R eport 280 and Question 256(VIII)
represent modifications to previous texts. O pinion 11 was adopted, asking the I.F.R .B . toprepare a list o f stations using special means o f identification.
2.5 Recom m endation 182 concerning automatic monitoring o f occupancy o f the radio-frequency
spectrum remains unchanged, while R eport 278 considerably modifies the preceding text,
in that it includes the contents' of the various contributions.
2.6 R eport 281, Identification o f sources o f interference to radio reception is the first step tow ards
the production of a “ catalogue ” or, in other words, an index of inform ation such as photo­graphs, magnetic tape recordings, written descriptions, drawings, etc. describing the inter­
ference.
In Resolution 16, Adm inistrations are encouraged to send to the C .C.I.R. Secretariat
all inform ation to be published in such a catalogue.
2.7 In the field of Visual monitoring o f the radio frequency spectrum, R eport 279 shows the present
status of this technique. It is expected th at in the future various “ broadband ” spectro­
scopes will become available.
2.8 The present knowledge of monitoring at fix e d monitoring stations o f radio transmissions fromspacecraft is laid down in R eport 276.

3.

New Questions

3.1 Monitoring o f sweeping-type pulse emissions. Question 226(VIII) was adopted by corres­
pondence in 1962.
The following three questions were adopted by the C.C.I.R. X th Plenary Assembly,
Geneva, 1963.
3.2 Direction finding at monitoring stations : Question 254(VII1).
3.3 Types and methods o f assistance by monitoring stations to the operation o f various radio services :Question 259(VIII).
3.4 Antennae fo r monitoring stations : Q uestion 258(VIII).
3.5 D uring its meeting in Geneva, February 1963, the Plan Sub-Committee for A sia subm itted
to the C.C.I.R. Question 275(VIII): M onitoring in new and developing countries.

— 271 —Res. 15RESOLUTION 15
E X T E N S IO N O F T H E IN T E R N A T IO N A L M O N IT O R IN G
SY ST E M T O A W O R L D -W ID E SCALEThe C .C.I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) th at Recom m endation N o. 5 of the R adio Regulations, Geneva, 1959, stresses the urgent
need for improvement in the international m onitoring system and invites A dm inistrations
to make every effort to develop m onitoring facilities;(b) th a t there are still wide areas of the world where the facilities available to the internationalm onitoring system are inadequate or non-existent;( c) th at it is of utm ost im portance, to satisfy the needs of the I.F.R .B. laid down by the R adio
Regulations, th at all countries having domestic m onitoring facilities m ake them available
for international m onitoring to the maximum possible extent;(d) th a t it is recognized th at certain stations may participate in only a limited p art o f the whole
field of m onitoring;>(e) the im portance, for the safety of life at sea and in the air, of the international m onitoring
system in ensuring the correct use of the radio-frequency spectrum by the mobile services;
U N A N IM O U SL Y D E C ID E S

1.

th a t all A dm inistrations now participating in the international m onitoring system should beurged to continue to do so to the maximum extent possible;2.

th a t A dm inistrations who do not at present participate in the international m onitoring
system should be urged to m ake monitoring facilities available to th at system, in accordancewith Art. 13 of the R adio Regulations, Geneva, 1959;

3.

th a t A dm inistrations located in those areas o f the world where m onitoring facilities are
inadequate (as indicated by R eport 282), should be urged to prom ote the establishm ent ofm onitoring stations for their own use and m ake them available for international m onitoring,in accordance with Art. 13 of the R adio Regulations, Geneva, 1959;

4.

th at A dm inistrations should m onitor radio stations in the mobile services systematically,in particular those stations serving maritime and aeronautical needs.

•I— 272 —Res. 16, Op. 11

RESOLUTION 16
ID E N T IFIC A T IO N O F SO U R C E S O F IN T E R FE R E N C E
T O RA D IO R E C E P T IO N

(Question 257(VIII))The C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G

the urgent need for the collection of visual and/or aural records of the typical characteristicso f various classes o f interfering radiations, as an aid to personnel at stations in the inter­national m onitoring system;U N A N IM O U SL Y D EC ID ES

1.

'that each Adm inistration should be encouraged to provide the C.C.I.R. Secretariat with infor­
m ation on the typical characteristics of interfering radiations, such inform ation to be published
as a catalogue; *2. that A dm inistrations should subm it inform ation in the following order of priority;
2.1 inform ation primarily for use at m onitoring stations, which would assist in solving, at inter­national level, cases of harm ful interference;
2.2 inform ation which would assist in identifying sources of industrial interference.

OPINION 11
L IS T O F STA T IO N S U SIN G SPE C IA L M EA N S O F ID E N T IFIC A T IO N

(Question 256(VIII))The C.C.I.R.,(Geneva, 1963)

C O N S ID E R IN G(a) that the R adio Regulations, Geneva, 1959, set forth requirem ents for transm ission of iden­
tifying signals by radio stations;(b) that certain types of radio stations are exempted from the necessity of having a call signfrom the international series, for example, stations which are identified by other m eans;(c) that many stations using complex or special types of emissions cannot be identified by ordi­
nary means;* T he te rm “ catalogue ”, as used in th is R eso lu tio n , d en o tes an index o f in fo rm atio n such as p h o to g ra p h s, m ag n etic-tap erecordings, w ord descriptions, draw ings, etc., describing interferen ce (see also R e p o rt 281).

— 273 —Op. 11, Q. 188(d) that the m onitoring stations participating in the international m onitoring system need tobe supplied with all the available inform ation on means of identification used by radio stations;IS U N A N IM O U SL Y O F T H E O P IN IO N

1.

that the I.F.R .B. should be asked to prepare, on the basis of inform ation received from
Administrations, the list of stations which use special identification m eans; this list to containthe identifying signal, frequency, m ethod of identification used, time of identification, andother pertinent inform ation;2.

th at this list should be kept up-to-date by appropriate supplements.

QUESTION 188(VIII)M O N IT O R IN G AT FIX ED M O N IT O R IN G STA TIO N S
O F R A D IO E M IS S IO N S F R O M SPA CECRA FTThe C.C.I.R.,(Los Angeles, 1959)

C O N S ID E R IN G(a) th at the rapid advances in recent years in space technology, including the successful launchingof earth satellites, portend greatly expanded activity in outer space, including the likely
eventual establishments of “ space platform s ” ;(b) th at radio will play a m ajor part in these space activities as regards com m unication, navigationand data collection and transm ission;(c) th at “ space platform s ” might find a variety of uses in the telecommunication field;(d) th at the accurate measurem ent at a fixed m onitoring station of frequency, spectrum occupancy
and certain other technical characteristics of emissions from transm itters on the spacecraft
and platforms, will tend to be m ore difficult than on fixed or relatively slow moving sourcesof emission on or near the earth;u n a n im o u s l yd e c id e s

th at the following question should be studied:1.

to w hat extent will the techniques of measurement, from fixed monitoring stations on theearth, of emissions from spacecraft differ from those for emissions originating from or near
the earth;2.

w hat are the requirem ents for specialized equipm ent or associated facilities for perform ing
frequency, spectrum occupancy, and other measurements of emissions from spacecraft;3.

w hat practical means can be devised for the identification, by m onitoring stations, of emissions
from specific spacecraft?

iQ. 191— 274 —QUESTION 191 (VIII)
V ISU A L M O N IT O R IN G O F T H E RA D IO -FR EQ U EN C Y SPE C T R U M

The C.G.I.R.,(Los Angeles, 1959)

C ONSIDERING( a) that every useful means of m onitoring observation and measurem ent should be employed atm onitoring stations, including visual methods employing a radio-frequency spectroscope;(b) that a panoram ic view of a portion of the radio-frequency spectrum can be presented on acathode-ray tube by the employment of suitable sweep circuits in the radio receiver or inan associated panoram ic adapter;( c) that the simultaneous presentation of broad ranges of the spectrum on one or m ore cathoderay tubes would provide for a rapid determ ination of spectrum occupancy, frequency, am pli­tude and harm onic content (if one or m ore octaves are presented) of individual signals, andbroadband coverage characteristics of signals, including interference;(d) that, although panoram ic adapters have been employed to some extent in m onitoring stations
as an adjunct to aural m onitoring, it appears th at m ore inform ation can be obtained visually
by monitoring observers, particularly in broadband visual presentation of the spectrum ;u n a n im o u s l y

1.

d e c id e s

th a t th e f o llo w in g q u e s tio n s h o u ld b e s tu d ie d :w hat are the preferred equipm ent and the preferred m ethods for visual m onitoring of broad
ranges of the radio-frequency spectrum with regard to:

1.1 receivers and associated frequency-sweep circuits;
1.2 cathode-ray tubes (including practicable size);
1.3 antennae and associated broadband amplifiers and impedance-matching circuits;2.

what radio-frequency ranges can be presented simultaneously on one or m ore cathode-ray
tubes of a spectroscope, taking into consideration the frequency characteristics of the antennae,
amplifiers and receivers to allow relative com parisons throughout the portion of the spectrum
under visual observation;3.

w hat adaptation of circuitry of the equipm ent specified in § 1 would be required for a tem ­porary increase in the resolution of the spectroscope;4.

what are the desirable operating methods and techniques to obtain m axim um benefit fromvisual m onitoring with a radio-frequency spectroscope, either when used alone or when used
as an adjunct to aural m onitoring?

Q. 226, 252— 275 —QUESTION 226(VIII)M O N IT O R IN G O F S W E E PIN G -T Y PE P U L S E E M IS S IO N S
The C .C .I.R.,(1962)

CO N SID ERIN G(a)th e in c r e a s in g u s e b e in g m a d e o f v e r y s h o r t d u r a tio n p u ls e -e m is s io n s w h ic h m a y b e m o d u la t e dinv a r io u s

w ays

and

w h ic ha re fr e q u e n c y -sw e p t

overw id e r a n g e s o f th e r a d io -fr e q u e n c y

sp e c tr u m ;(b)t h a t t h e s e e m is s io n s m a y , in s o m e in s ta n c e s , b e s o u r c e s o f in te r fe r e n c e t o o th e r t r a n s m is s io n s ,r e q u ir in g id e n t if ic a t io n a n d m e a s u r e m e n t b y m o n it o r in g s t a t io n s t o a s s is t in r e s o lv in g s u c hin te r fe r e n c e ;(c)th a t s p e c ia l f a c ilitie s a n d t e c h n iq u e s a r e r e q u ir e d b y m o n it o r in g s t a t io n s t o r e c e iv e , m e a s u r e
a n d id e n tify s ig n a ls o f th is ty p e ;d e c id e s

1.

th a t th e f o llo w in g q u e s tio n s h o u ld b e s tu d ie d :w h a t is t h e e x t e n t o f in t e r f e r e n c e c a u s e d b y s w e e p in g - t y p e p u ls e t r a n s m is s io n s a s t h e y p a s s
th r o u g h , o r te m p o r a r ily r e s t o n o r n e a r , th e fr e q u e n c y o f o th e r t r a n s m is s io n s ;2.

w h a t a r e t h e p r e fe r r e d f a c ilitie s a n dt e c h n iq u e s t o

p e r m it r e c e p tio nandm easu rem en t b y

m o n ito r in g s ta tio n s o f th e s e s w e e p in g -ty p e p u ls e e m is s io n s ;

3.

how

m a y t h e s e s w e e p in g - t y p e p u ls e t r a n s m is s io n s b e id e n t if ie d a s t o s o u r c e b y m o n it o r in gs ta tio n s ?

QUESTION 252(VIII) *FR E Q U E N C Y M E A SU R E M E N T S AT M O N IT O R IN G STA TIO N S
The C .C .I.R.,(Warsaw, 1956 - Geneva, 1963)

CO NSIDERING

th at it is desirable to improve the accuracy, speed and convenience of frequency m easure­ments, particularly under conditions of fading, interference, carrier instability, etc., including
the case of suppressed or keyed carriers;
u n a n im o u s l y d e c id e sthat the following question should be studied:1.

w hat are the accuracy and speed of frequency measurements which can be accom plished
at m onitoring stations, especially under the conditions set forth above;2.

w hat are the difficulties in meeting the required accuracy (Recommendation 377), due tolim itations set by:* This Question replaces Question 145.

— 276 —Q. 252, 253, 254
2.1 the measuring equipm ent;

2.2 propagation effects such as fading;
2.3 interference due to other transm issions;
2.4 the type of m odulation, particularly for wideband transmissions in the frequency range
500 Mc/s to 10 Gc/s;
3.

to w hat extent can errors be usefully reduced in practice by statistical processing of themeasurem ent data when measurements are taken at successive times or under different con­ditions ?

QUESTION 253(VI1I)
E X P E D IT IO U S M E T H O D O F D E T E R M IN IN G FIE L D -ST R E N G T H
IN T H E IN T E R N A T IO N A L M O N IT O R IN G SY STEM
The C.C.I.R.,(Geneva, 1963)CONSIDERING(a) that a need exists for m onitoring stations to measure field-strength, by expeditious means;(b) that accuracies laid down in Recom m endation 378 are not always necessary in monitoring
observations;(c) that, according to studies m ade to date (see R eport 274), it is impossible to correlate fieldstrength values with S-values to sufficient accuracy;
u n a n im o u s l yd e c id e sthat the following questions should be studied:1.

what form of installation is suitable for the expeditious m easurem ent of field-strength atm onitoring stations;2.

w hat specification for the perform ance o f the equipm ent (antenna, transm ission line, receiverand calibrating source) is practicable;3.

w hat accuracy of m easurem ent is desirable and practicable?

QUESTION 254(VIII)
D IR E C T IO N -F IN D IN G AT M O N IT O R IN G STA TIO N S
The C.C.I.R.,(Geneva, 1963)

C O NSIDERING(a) that direction-finding measurements in some cases have very great significance for A dm in­istrations and the I.F.R .B . in the investigation o f harm ful interference and in their concern
with efficient use of the radio-frequency spectrum ;(b) that, while the techniques of direction-finding are well know n, the m ethods and procedures
best suited to the international m onitoring system are n ot established;Q. 254, 255— 277 —(c)th a t t h e a c c u r a c y o f b e a r in g s m a y b e im p r o v e d b y c e r t a in p r o c e d u r e s , e .g ., b y t h e s t a t is t ic a l
tr e a tm e n t o f m u ltip le b e a r in g s o r b y t a k in g r e fe r e n c e b e a r in g s o n k n o w n s t a t io n s ;u n a n im o u s l yd e c id e s

th a t t h e f o llo w in g q u e s tio n s h o u ld b e s tu d ie d :w h a t m e t h o d s o f d ir e c t io n - f in d in g a n d w h a t p r o c e d u r e s f o r im p r o v in g t h e a c c u r a c y o f b e a r in g s
ca n b e re c o m m e n d e d fo r:-

fix e d m o n it o r in g s t a t io n s ;-m o b ile m o n ito r in g s ta tio n s ?

QUESTION 255(VI1I) *A U T O M A T IC M O N IT O R IN G O F O C C U PA N C Y O F T H E
R A D IO -FR E Q U E N C Y S P E C T R U M
The C.C.I.R.,(Warsaw, 1956 - Geneva, 1963)CONSIDERING(a) th at the rapidly increasing dem and for radio services continues to require the m ost efficientuse of the radio-frequency spectrum;(b) th at the m ost efficient use of the spectrum can be made only when its occupancy is know n;(c) th at autom atic m onitoring is recommended as a valuable aid to determining the occupancy
o f the spectrum ; and the desirable characteristics of such equipm ent have been alreadyrecommended in Recom m endation 182;(d) th at it is desirable to m ake further studies of equipm ent characteristics and to determ ine
the means whereby the greatest benefit may be derived from autom atic m onitoring records;
u n a n im o u s l yd e c id e s

th at the following question should be studied:1.

w hat is the accuracy of autom atic m onitoring equipm ent in determining frequency, bandw idthand field-strength;2.

w hat is the capability of autom atic m onitoring equipm ent in determining signal-to-noise
ra tio s;

3.

w hat are the best means of analyzing and evaluating autom atic m onitoring records, both
singly and collectively;

4.

is it possible to analyze present records by autom atic means and, if not, w hat modifications
are necessary to enable this to be done?

* This Question replaces Question 143.

— 278 —Q. 256, 257

Q U E S T IO N 256(VIII) *ID E N T IFIC A T IO N O F RA D IO STA TIO N S

The C.C.I.R.,(London, 1953 - Los Angeles, 1959 - Geneva, 1963)CONSIDERING(a) that Article 19, Section I of the R adio Regulations, Geneva, 1959, requires that the identifying
signal be transm itted by m ethods which, in accordance with C.C.I.R. Recom mendations,do not need special term inal equipment for reception;(b) th at special methods for identifying certain complex types of emissions have been evolved(Recom m endation 379 and R eport 280);(c) that, however, there may be now, or in the future, some types of emissions to which thepresently recommended m ethods of identification cannot be applied satisfactorily;u n a n im o u s l yd e c id e sthat the following question should be studied:1.

which are the types of emissions that cannot be identified by the m ethods of identification
recommended by the C.C.I.R. or set forth in the R adio Regulations, Geneva, 1959;2.

what satisfactory m ethods can be evolved for the identification of such emissions?

Q U E S T IO N 257(VIII) **ID E N T IFIC A T IO N O F S O U R C E S O F IN T E R FE R E N C E
T O RA D IO R E C E P T IO N

The C.C.I.R.,(Los Angeles, 1959 - Geneva, 1963)

c o n s id e r in g(a) that interference-causing radiations have individual characteristics which, when observed
aurally or visually, often enable an experienced m onitoring observer to identify the type ofequipm ent producing the radiations;(b) th at a list of all electrical and electronic equipm ent, which might at times cause radio inter­
ference, would include practically every device that uses electricity;(c) that it would be helpful in solution of interference problems for both m onitoring observers
and radio station operators to com pare interfering signals with a ready reference o f all typesof such signals which perm it cataloguing of individual signal characteristics;* This Question replaces Question 187.
** This Question replaces Question 190.

Q. 257, 258— 279 —(d) that individual characteristics m entioned in § (c) might include, but not be limited to, fre­quency range, distance range, on-off cycles, times of day the source equipm ent is m ost gener­
ally used, characteristic note or tone, degree o f frequency stability, usual bandw idth, typeof signal as viewed on oscilloscope or panoram ic presentation, type of source equipm ent
and cause of radiations;u n a n im o u s l yd e c id e sthat the following question should be studied:1.

what are the preferred methods and form of listing by written description, m agnetic taperecording and pictorial presentation, as appropriate, the individual characteristics o f allobserved types o f interfering radiations;2.

w hat uniform standards of measurem ent should be adopted at m onitoring stations for thecollection of data to be sent to the C.C.I.R. Secretariat for implementation o f the catalogue? *QUESTION 258(VIII)A N TENNAE F O R M O N IT O R IN G STA TIO N S
The C.C.I.R!,(Geneva, 1963)

c o n s id e r in g(a) th at the effectiveness of a monitoring station in providing adequate surveillance over theradio-frequency spectrum is determined to a m ajor extent by the electrical characteristics ofthe available m onitoring antennae;(b) th at substantial progress has been m ade in recent years in the development of broadband
antennae having improved characteristics as regards frequency coverage, directivity and g ain ;(c) th at the anticipated future need for providing m onitoring station facilities to perm it obser­
vations and measurem ents of transmissions from spacecraft will require specialized antennae,taking into account the relatively weak signals involved and the high antenna directivity
required;u n a n im o u s l yd e c id e s

th at the following question should be studied:1.

to what extent do currently available antennae fulfil m onitoring station requirem ents, taking
into account such aspects as: means of varying both horizontal and vertical directivity, gain,
space lim itations;2.

w hat are the desirable characteristics of antenna systems for m onitoring in the various fre­quency bands of interest and for various propagation modes;

3.

in which areas should further antenna development work be directed in an effort to improvem onitoring antenna characteristics?

* See Resolution 16 and Report 281.

QUESTION 259(VIII)T Y PE S AND M E T H O D S O F A SSISTA N CE BY M O N IT O R IN G STA TIO N S
T O T H E O P E R A T IO N O F V A RIO U S RA D IO SERV ICESThe C.C.I.R.,(Geneva, 1963)

C ONSIDERING(a) th a t m onitoring stations in the international m onitoring system exist for the purpose ofincreasing the effectiveness of radiocom m unications throughout the various radio services;(b) th at techniques progress so rapidly, particularly in new fields such as space telecommuni­
cations, that conditions may exist whereby neither the A dm inistration concerned nor theinternational monitoring system may be aware of the full potentialities of m onitoring functions
for rendering assistance to radio services;( c) th a t the attention of all C.C.I.R. Study G roups and all A dm inistrations should be called toavailable m onitoring functions, for the purpose th at they be alerted to keep the internationalm onitoring system advised of types and methods of assistance th at could be initiated or
expanded to use the full potentialities of th at system;u n a n im o u s l yd e c id e s

th at the following question should be studied:w hat m onitoring functions not now being performed, or n ot being rendered to full capability,
could be initiated or expanded to provide improved assistance to A dm inistrations or to
the I.F.R.B. ?

STUDY PROGRAMME 102(VIII) *F IE L D -S T R E N G T H M E A SU R E M EN TS AT M O N IT O R IN G STA TIO N S
The C.C.I.R.,(London, 1953 - Warsaw, 1956)

C ONSIDERING(a) th at Recom m endation 378—Accuracy of field-strength m easurem ents by m onitoring stations—does not cover all aspects of the problem , and that it recommends th at studies, relating
to methods and equipment for use at m onitoring stations, should be continued;(b) th a t the im portance of collecting com parable field-strength data for the purpose of making
propagation studies is increasing;u n a n im o u s l y

1.

d e c id e sthat the following studies should be carried out:taking into account the previous work of the C.C.I.R. in this field, w hat are the preferred
equipm ent and the preferred methods for measuring the field-strength of emissions for p ro p a­gations studies at m onitoring stations;* This Study Programme, which replaces Study Programme 69, does not refer to any Question under study.

— 281 —S.P. 102, 207

am ong other factors the following should be stu d ied :- the m ethods for measuring the field strength,- the measuring and recording equipment,- the total frequency range,- the calibrating equipment,- the methods for analyzing the records,- the m ost effective form of presentation and distribution o f these data for the benefit ofvarious bodies, for example the I.F .R .B .;2. w hat are the m ost useful program m es of propagation studies in the different frequency ranges
th at can be carried out at m onitoring stations bearing in mind
- the needs of the I.F.R .B., Study G roups of the C.C.I.R. and other bodies,- the various distances and the particular paths over which propagation d ata are required;
3. w hat are the equipment and methods to be preferred for measuring the field-strength ofemissions- with interrupted carrier,- with reduced carrier,- with other types of signals, including television signals;
4. what are the equipment and methods to be preferred for measuring the field-strength ofemissions of the types given'in § 3 in the presence of noise and interference;
5. to w hat extent the determ ination of the relative levels of the field-strength of the fundam ental
and o f the harm onic frequencies o f an emission measured at a distance can give usable data
about the relative levels measured at the transm itter itself?

STUDY PROGRAMME 207(VIII) *B A N D W ID TH M E A SU R E M E N T S BY M O N IT O R IN G ST A T IO N S
The C.C.I.R.,(London, 1953 - W arsaw, 1956 - Geneva, 1963)CONSIDERING(a) th at it is desirable that m onitoring stations should be able to measure the bandw idth ofemissions;(b) th at the I.F.R .B. requires practical optim um standards concerning bandw idth m easurem ents
by m onitoring stations;(c) th at determ ination of the occupied bandw dith of an emission, by the m ethod of measuring
total power and out-of-band power, in accordance with the principle suggested in the present
definition of occupied bandw idth (see N o. 90 of the R adio Regulations, Geneva, 1959),
is not generally applicable to measurements made at a distance from the transm itter;u n a n im o u s l yd e c id e sthat the following studies should be carried out:

determ ination of the most suitable equipm ent and methods for the m easurem ent of the
bandw idth of emissions by m onitoring stations, taking into account;1.

the w ork of the C.C.I.R. concerning measurements of bandw idth m ade near the transm itter;* This Study Programme, which replaces Study Programme 103, does not refer to any Question under study.

S.P. 207, Q. 275— 282 —

2.

the necessity for m onitoring stations to examine various classes of emissions and to makemeasurements on a fading signal in the presence o f noise and interference;3.

the current impracticability, with present equipment, of m aking measurements of the band­
width at a distance from the transm itter, which would conform to the terms of the definitionof occupied bandw idth in the R adio Regulations, Geneva, 1959.

QUESTION 275(VIII) *M O N IT O R IN G SE R V IC E S IN T H E N EW AND D E V E L O PIN GC O U N TR IES(Question No. 2 of the P lan Sub-committee for Asia, Geneva, 1963)(Geneva, 1963)
The Plan Sub-Committee for Asia,
C ONSIDERING(a) the im portance of radio-frequency m onitoring in the improvement o f general operation of
the expanding radio services;(b) the need for establishing m ore radio monitoring stations in the various parts of the world,which up to now have had very little or no radio m onitoring services capable of participatingin the international m onitoring services;
req uests

th e

C.C.I.R. t o s t u d y t h e f o l l o w i n g q u e s t i o n :1.

which radio m onitoring services should be started by the new and developing countries inthis field;2.

w hat guidance can be given in the establishment and organization of a radio m onitoring
service;3.

what facilities should the m onitoring equipm ent provide and what are the suitable charac­
teristics for such equipm ent?

Explanatory n o te : There is a great need for starting some radio m onitoring service for conser­
vation of spectrum space, for the avoidance o f harm ful interference and for finding new
frequencies which the new countries need for their radio services. G uidance in these m atterswould be helpful.

* This Question was adopted unanimously by the Xth Plenary Assembly of the C.C.I.R., Geneva, 1963.

— 283 —LIST OF DOCUMENTS OF THE Xth PLENARY ASSEMBLY
CONCERNING STUDY GROUP VIII
O riginD oc.

T itleR eferen ce

Chairman,
Study Group VIII

Report by Chairman of Study Group VIII
(Mr. G.S. Turner)

— ^

28

United Statesof America

Types and methods of assistance by monitoring stations to the operation of various
radio services

Draft Q.

104

Japan

Measurement of S-values at monitoring stations

Q. 189129

C.C.I.R. Secretariat

Bibliographic references in the volumes of
the C.C.I.R.

—

151

United Statesof America

Antennae for monitoring stations - Draft
Question

Draft Q.

152

United Statesof America

Direction-finding at monitoring stations Draft Question

Draft Q.

311

Study Group VIII

Identification of sources of interference toradio reception

Draft Q.

326

Summary record of the first meeting—

362

Monitoring at fixed monitoring stations ofradio transmissions from space vehicles

Draft Rep.

406

Expeditious method of determining signalstrength in the international monitoring
systemDraft Q.

407

Direction finding at monitoring stations

Draft Q.

409

Measurement of S-values at monitoring
stations

Draft Rep.

410

Bandwidth measurement by monitoring
stations

Rep.
S.P.

427

Identification of sources of interference toradio reception

Draft Rep.

428

Identification of sources of interference toradio reception

Draft Res.

429

List of stations using special identification
means

Draft Res.

440

Extension of the international monitoring
system to a world-wide scale

Draft Res.

441

Types and methods of assistance by monitoring stations to the operation of various radio
services

Draft Q.

442

Antennae for monitoring stations

Draft Q.

443

Report of Sub-Group VIII-B to Study Group
VIII

Rep.

499

Field-strength measurements at monitoring
stations

Draft Rep.

534

Summary record of the second meeting .

—579

Summary record of the third and last meeting—

Accuracy of frequency measurements atmonitoring stations

Rec. 377

2071

Drafting Committee

O th er
S tu d y
G ro u p s
co n cern ed

I-XIV

— 284 —
D oc.

2072
2073

O rigin

Drafting Committee

T itleR eferen ce

Automatic monitoring of occupancy of theradio frequency spectrum

Q. 255Frequency measurements at monitoring
stations

Q. 252

2074

Identification of radio stations

Q. 2562075

Bandwidth measurements by monitoring
stations

S.P. 207

2076

Automatic monitoring of occupancy of theradio-frequency spectrum

Rep. 278

2077

Measurements at mobile monitoring stations

Rep. 277

2078

Identification of radio stations

Rep. 280

2079

Visual monitoring of the radio-frequency
spectrum

Rep. 279

2080

International monitoring facilities

Rep. 282

2196

Accuracy of field-strength measurements bymonitoring stations

Rec. 378

2197

Identification of radio stations

Rec. 379

2198

Frequency measurements at monitoring
stations

Rep. 272

2199

Identification of sources of interference toradio reception

Q. 257

2201

Monitoring at fixed monitoring stations ofradio transmissions from spacecraft

Rep. 276

2202

Expeditious method of determining fieldstrength in the international monitoring
system

Q. 2532203

Direction finding at monitoring stations

Q. 254

2204

Measurement of S-values at monitoring
stations

Rep. 274

2205

Bandwidth measurement by monitoring
stations

Rep. 275

2206

Identification of sources of interference toradio reception

Res. 16

2207

List of stations using special identificationmeans

Op. 112208

Extension of the international monitoring
system to a world-wide scale

Res. 152209

Types and methods of assistance by monitoring stations to the operation of various radio
services

Q. 2592210

Antennae for monitoring stations

Q. 2582280

Identification of sources of interference toradio reception

Rep. 281

2281

Field-strength measurements at monitoring
stations

Rep. 273

P R IN T E D I N S W IT Z E R L A N D