Library,

PB 161612

\^ecknlcal r\ot&

cjBoulder laboratories

92o. 1 1

1

DATA REDUCTION INSTRUMENTATION

FOR RADIO PROPAGATION RESEARCH

BY WALTER E. JOHNSON

U. S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS
THE NATIONAL BUREAU OF STANDARDS

Functions and Activities

The functions of the National Bureau of Standards are set forth in the Act of Congress, March

3, 1901, as amended by Congress in Public Law 619, 1950. These include the development and

maintenance of the national standards of measurement and the provision of means and methods for making measurements consistent with these standards: the determination of physical constants and

properties of materials; the development of methods and instruments for testing materials, devices,

and structures; advisory services to government agencies on scientific and technical problems: in- vention and development of devices to serve special needs of the Government; and the development

of standard practices, codes, and specifications. The work includes basic and applied research,

development, engineering, instrumentation, testing, evaluation, calibration services, and various

consultation and information services. Research projects are also performed for other government

agencies when the work relates to and supplements the basic program of the Bureau or when the

Bureau's unique competence is required. The scope of activities is suggested by the listing of

divisions and sections on the inside of the back cover.

Publications

The results of the Bureau's work take the form of either actual equipment and devices or published papers. These papers appear either in the Bureau's own series of publications or in the journals

of professional and scientific societies. The Bureau itself publishes three periodicals available from

the Government Printing Office: The Journal of Research, published in four separate sections,

presents complete scientific and technical papers; the Technical News Bulletin presents summary

and preliminary reports on work in progress; and Basic Radio Propagation Predictions provides

data for determining the best frequencies to use for radio communications throughout the world.

There are also five series of nonperiodical publications: Monographs, Applied Mathematics Series,

Handbooks. Miscellaneous Publications, and Technical Notes. Information on the Bureau's publications can be found in NBS Circular 460, Publications of the National Bureau of Standards ($1.25) and its Supplement ($1.50), available from the Superintendent

of Documents, Government Printing Office, Washington 25, D.C.
NATIONAL BUREAU OF STANDARDS

technical <

"7tete

in

July 1961

DATA REDUCTION INSTRUMENTATION

FOR RADIO PROPAGATION RESEARCH

by

Walter E. Johnson

NBS Technical Notes are designed to supplement the Bureau's regular publications program. They provide a means for making available scientific data that are of transient or limited interest. Technical Notes may be

listed or referred to in the open literature. They are for sale by the Office of Technical Services, U. S. Department of Commerce, Washington 25, D. C.

DISTRIBUTED BY

UNITED STATES DEPARTMENT OF COMMERCE

OFFICE OF TECHNICAL SERVICES

WASHINGTON 25, D. C.

Price $1.00

DATA REDUCTION INSTRUMENTATION

FOR RADIO PROPAGATION RESEARCH

by

Walter E. Johnson

ABSTRACT

An approach is given to the overall problem of Data Reduction

Instrumentation for Tropospheric Radio Propagation Research at the

National Bureau of Standards. The need for early coordinated planning

between those responsible for the data taking, data analysis, and data

reporting is emphasized. A multi-channel, magnetic tape system is

described as a successful solution to the data taking problem. Three

special purpose computers are described as solutions to the data analysis problem: a Spectrum Analyzer, a Distribution Analysis System,

and a Correlation Computer. Three computation aids are described as

aids for the reduction of data not recorded on magnetic tape: the Refractive Index Computer, the Amplitude Distribution Analyzer and Chart

Scaler, and the Punch Tape Data Translation System.

TABLE OF CONTENTS

Page

1 . INTRODUCTION 1

2. THE DATA RECORDING AND REPRODUCTION SYSTEM 2

2. 1 General Requirements 2

2.2 Magnetic Tape Data Recording System 3

2.3 Magnetic Tape Data Reproduction System 7

3. SPECIAL PURPOSE COMPUTERS 10

3.1 Spectrum Analyzer 10

3.2 Distribution Analysis System (DASY) 14

3.3 Correlation Computer 15

4. COMPUTATION AIDS 20

4.1 Refractive Index Computer 21

4.2 Amplitude Distribution Analyzer and Chart Scaler

(ADIACS) 24

4.3 Punch Tape Data Translation System 25

5. CONCLUSION 3

6. ACKNOWLEDGEMENT 31

7. REFERENCES 32

LIST OF FIGURES

1-2 Magnetic Tape Data Recording System 4 - 5

3 - 4 Magnetic Tape Data Reproduction System 8 - 9

5 - 6 Spectrum Analyzer 12-13

7-8 Distribution Analysis System (DA.SY) 16-17

9-10 Correlation Computer 18-19

11-12 Refractive Index Computer 22-23

13-14 Amplitude Distribution Analyzer and Chart Scaler

(ADIACS) 26-27

15 - 16 Punch Tape Data Translation System 28 - 29

DATA REDUCTION INSTRUMENTATION

FOR RADIO PROPAGATION RESEARCH

by

Walter E. Johnson

1. INTRODUCTION

The general subject of Data Reduction is pertinent to all basic and

applied research programs. A complete treatment of this subject, however, would necessitate presenting the theory of operation of a range of

data reduction devices varying from averaging voltmeters to general

purpose digital computers. This report is not intended to cover all of

the Data Reduction problems encountered in Radio Propagation Research.

The intent of this report is to present a "customized" approach to the

data reduction problem and to describe particular devices and systems

developed for this purpose.

Customizing the data reduction process must start with the initial

data recording and carry through to the final presentation. The theoretical results expected from a particular experiment should have a

strong influence on the methods of analysis to be used and on the choice

of recording systems. Conversely, advanced recording and analysis

techniques can many times suggest experiments that would not have

been feasible using older techniques.

Early coordinated planning is needed among those responsible for

the data recording, data analysis and data reporting. The type and

number of signals to be recorded should decide the choice of either a

digital or analogue recording system. The method of analysis should

dictate the choice of a time coding system and the calibration procedures. The desired final results should suggest analysis methods and

set overall accuracy requirements.
-2-

2. THE DATA RECORDING AND REPRODUCTION SYSTEM

2. 1 General Requirements

There are several general requirements which influence the choice

of any particular data recording and reproduction system. The system

selected must be capable of satisfying the experiment requirements for:

number of simultaneous recording channels, total length of recording,

expected bandwidth of the data, and type of data reduction planned.

The data from relatively simple short term experiments can be

adequately recorded and analyzed using standard strip chart recorders.

The majority of the experiments conducted in support of the Tropospheric

Propagation Research Program at the National Bureau of Standards,

Boulder Laboratories, however, demand a much more extensive system.

In almost all cases these experiments, or recording programs, require

the recording of from three to twelve simultaneous channels of information for continuous periods of time varying from one hour to several

days. The data frequencies expected range from zero up to several

hundred cps in some cases; in others, up to only a few cycles per

second.

The type of data reduction being planned must have a strong influence

upon the choice of the data recording and reproduction system. Planned

compatibility between the data reproduction system and the analysis

equipment can result in very large savings in both time and money.

The system should also be capable of considerable flexibility with respect

to the editing of the data before analysis. Editing raw field data is a very necessary part of most programs and results in great savings of

analysis time.
-3-

All of the above considerations have contributed to the selection

of multi- channel, FM magnetic tape recording systems as being an efficient means of recording Tropospheric Radio Propagation Research

Data.

2.2 Magnetic Tape Data Recording System

The field recording equipment shown in figures 1 and 2 consists of:

tape transport, recording oscillators, compensation generator, time

code generator, and calibration equipment. The tape transport is generally the largest and most expensive component of the basic field

recording equipment. The transports now in use are designed for either

one-half or one-inch tape and are capable of recording either seven or

fourteen simultaneous channels of data. Recording speeds are chosen

so as to faithfully reproduce the highest expected data frequency. A

recording speed of 0.6 ips is very commonly used where data frequencies

up to 100 cps are expected. Recording speeds up to 6 ips are used where

atmospheric disturbances may contribute data frequencies of several

hundred cps.

The recording oscillator is, very simply, an oscillator whose frequency is varied by the incoming data signal and whose output drives

one track of the recording head on the transport. The center frequency

of the oscillator is set by the tape speed being used. A center frequency

of 500 or 540 cps is used for 0. 6 ips, while a center frequency of 5000

or 5400 cps is used with a tape speed of 6 ips. An input voltage variation of plus or minus 1.5 volts is required to effect the maximum modulation capability of plus or minus 40%.
-4-

wQU

OSH<

OS

W

w S z

•—i w H

w

Oh

H

oSO

ftCO<

oSH

H ft p< wH

co

toO

i—i Q

oSOuw

oS<;<Qw

ft<;Hu—IHW

<;2u

CuO • H

ft
-5-

wH

COa59ou

«;H

<;pw

Oh<;HuI—I HWa

•i-t
-6-

The compensation generator is merely a crystal controlled, fixed

frequency oscillator whose output is recorded on a separate channel

of the tape transport. Its frequency is set the same as the center

frequency of the recording oscillators. This signal is used in the reproduction or playback process to compensate for wow and flutter

variations introduced by the mechanical tape driving equipment.

A time code generator and a calibration system may be considered

peripheral equipment to the data recording process but are nevertheless very vital to the overall objectives. A time code generator of

some type should be included in the plans for all recording programs.

Where data are recorded in the form of several ten minute blocks or

samples per reel of tape, it may be satisfactory to merely identify the

start of each block by a break or enhancement of the compensation signal.

Generally, however, it is necessary to provide a much more extensive

and precise time code. For this purpose, a time code generator is used

which produces a complete hours, minutes, and seconds code each

second. This code then provides the necessary information to the playback equipment for the selection and control of the data to the analysis

equipment.

Data calibration is universally accepted as necessary. It is not

always given the proper attention that it deserves. Individuals performing field calibrations must always be aware of the accuracy required

and how the calibrations will be utilized in the reduction process. The

method currently being used is to calibrate a simulated transducer

input in terms of the frequency as recorded on the magnetic tape. In

the case of a propagation signal, a signal generator voltage at the input

to the radio receiver is calibrated in terms of the frequency output of

the recording oscillator. The accuracy of this method can be made as

high as desired. It also provides great flexibility to the reproduction

process as the playback frequency is directly proportional to the tape

speed.
-7-

2.3 Magnetic Tape Data Reproduction System

The data reproduction process, generally accomplished at a central

facility in the laboratory, is much the reverse of the recording process.

The laboratory equipment shown in figures 3 and 4, consists of: tape

transport, FM signal discriminators, compensation discriminator,

search and control unit, calibration equipment, and editing equipment.

The transport used in the laboratory is in general very much the same

as the one used in the field. It must be compatible in terms of tape

width, tape speeds, and number of recording channels. In addition, it should have additional playback speeds and a fast forward or backward

search speed. One of the units in use at NBS-BL, is capable of nine

speeds from 0. 3 to 60 ips, either 12 or 14 channels on one-inch tape,

and has a bi-direction search speed of 12 ips.

The discriminator units re -convert the tape signal to the originally

recorded data signal. Data recorded at 0. 6 ips and played back at 60 ips

now have upper frequencies of 1 kc instead of the original 100 cps. The

compensation discriminator output is zero except for the contribution of

wow and flutter from the two tape transports. The data discriminator

outputs contain both the data information and the wow and flutter contributions. Proper combination of these two outputs essentially cancells

the effect of wow and flutter.

The search and control unit input is the tape signal recorded from

the time code generator. Each second of record time is read and displayed by the unit regardless of playback speed. This information is

used to control the transport while searching for information on a tape

reel. Once the information is located, the unit automatically switches

the transport to a pre- selected playback speed and provides an on-andoff signal to the analysis equipment.
-8-

TAPE

TRANSPORT

SEARCH AND

CONTROL UNIT

SIGNAL

DISCRIMINATOR

\

t

AUDIO

OSCILLATOR

SIGNAL

DISCRIMINATOR

COMPENSATION

DISCRIMINATOR

FREQUENCY

COUNTER

DATA

ANALYSIS

SYSTEM

STRIP CHART

RECORDER

Figure 3. MAGNETIC T^PE DATA REPRODUCTION SYSTEM
-9-

Figure 4. MAGNETIC TAPE DATA REPRODUCTION SYSTEM
-10-

Calibration and editing are accomplished with the help of the search

and control unit and with the assistance of such additional units as a

frequency counter, a signal generator, a strip chart recorder, and an

oscilloscope. Calibration is accomplished by setting a frequency count

into the discriminator and recording the associated output voltage.

Editing is generally accomplished with the assistance of recorder logbook information and either an oscilloscope or strip chart recorder.

Editing must be done so as to eliminate portions of the data tape that

contain calibration information, equipment failures, interference

signals, and tape drop-outs.

3. SPECIAL PURPOSE COMPUTERS

The use of special purpose computers is, in general, justified by

the demand for a particular type analysis. Most research laboratories

today either own or have available a high speed, general purpose

digital computer. The cost in both time and money of translation, programming and analysis of field data on general purpose computers in

many cases more than justifies the development of special purpose computers. These computers can be either digital or analog or combinations of both of the types and, in general, are developed for specific

type input data. The following text contains a description of three of

the special purpose computers currently in use.

3. 1 Spectrum Analyzer

Spectral analysis is one of the most widely used methods of describing radio propagation data [Thompson, 1959] . The Spectrum Analyzer

shown in figures 5 and 6, utilizes the heterodyne principle of mixing the
-11-

output of a variable frequency oscillator with the data signals to obtain

sidebands. The mixer is supplied with the data to be analyzed, together

with the output of a variable frequency oscillator; thus, any component

of the data can be made to produce sidebands. A tuned amplifier selects

only those sidebands from the mixer that come within its passband. The

bandwidth of the tuned amplifier is adjustable in two ranges from a fraction of a cycle per second to 45 cps.

The output from the tuned amplifier is rectified and applied as a d-c voltage to a potentiometric, strip-chart recorder which has a logarithmic response. The paper drive of the recorder may be coupled to

the oscillator controller frequency dial drive with a synchro system so

that the resultant record will be an accurate plot showing amplitude

versus frequency. The accuracy of the frequency indication is improved

through the use of identification marks made on the chart through the

keying action of the frequency dial on the oscillator controller.

The variable oscillator is motor driven to sweep through the range

of 3 kc to 5 kc, and the tuned amplifier will accept only 3 kc sidebands.

Therefore, the spectrum analyzer will automatically analyze all signals

from a lower practical limit of 3 cps to its maximum upper frequency of

2 kc, because these signals will produce a 3 kc sideband acceptable to the

tuned amplifier. If a 2 kc component should appear in the input signal,

the heterodyning will produce a low sideband of 3 kc and a high sideband

of 7 kc when the variable oscillator reaches 5 kc. The 3 kc sideband,

which is accepted by the tuned amplifier, now represents the 2 kc component in the input signal, and will vary in amplitude proportional to the

2 kc component.

A square-law network is incorporated as a portion of the rectifier

circuitry and may be switched in as desired. In square-law operation,

the square of the input voltage to the strip-chart recorder is recorded,

and in linear operation the direct rms input voltage is recorded.
-12-

Fpc Pi < W X P u rf

1— oo

PC

w

h ptf w

SYNCHRO MOTOR

CHART

DRIVE PdXT 1 OH5

SYNC

GENE"

wN

>*<HUw9 IT)

<D

•H
-13-

Figure 6. SPECTRUM ANALYZER
-14-

3.2 Distribution Analysis System

The Distribution Analysis System (DASY) shown in figures 7 and 8,

is a special purpose computer designed to analyze time varying data

recorded on magnetic tape [Norton, 1955; Crichlow, 19&0] . The following statistical parameters are deduced from the data:

(a) Cumulative amplitude distribution

(b) Fade rate vs level

(c) Fade or enhancement duration distribution at specific data

levels

(d) Distribution of the percent of time preset fade or enhancement

durations are exceeded, at specific data levels.

The incoming data are sampled 2 0, 000 times per second. These

samples are compared to a reference voltage and two pulse trains are

formed. One pulse train represents periods of time the data are above

the reference; the other, periods when the data are below the reference.

These two pulse trains contain all the necessary information to determine the four statistical parameters mentioned above.

With the 2 0, 000 per second sampling rate, it is possible to analyze

most field data when playing back the magnetic tape at one hundred times

the speed at which it was recorded. The effective sampling rate, relative to record time, is then 2 00 samples per second. This provides a resolution of five milliseconds in measuring fade or enhancement durations.

The input data can vary between the limits of plus and minus 7. 5

volts. The threshold sensitivity of the comparator circuit is plus or

minus five millivolts or less; d-c drift in reference voltage is 3 mv or

less in two hours. Thus, the threshold detection accuracy, relative to

the full scale input voltage, is better than 0. 1%.
-15-

A typical operation would be to calibrate the computer at ten reference voltages before starting the analysis. The reference selector is

then set to the first reference voltage and the data analyzed relative to

it. At the end of the analysis period, the resultant data are automatically

recorded on a digital printer and the reference selector steps to the

next reference voltage for a subsequent pass through the data. A complete analysis is performed about a reference level with each pass of

the data.

3.3 Correlation Computer

The correlation computer shown in figures 9 and 10, is a special

purpose analog computer designed to continuously perform the multiplication and integration or averaging required in solving the normal

ized correlation equations [Florman, 19&0] . The tape transport system,

which will provide a dynamic delay feature, has not as yet been procured.

The basic computer portion, however, is well developed and worthy of

report at this time.

Two random input signals, x1 and y* , are first applied to the servo

controlled signal conditioning amplifiers. The function of these amplifiers is to amplitude condition the incoming signals so as to equate their

variances over the averaging time to be used in the computation. The

two conditioned signals, x and y, are then applied to a sum and difference

circuit and then to squarers followed by averaging circuits. This succession of circuitry produces the variance of the sum of the signals and

the variance of their difference as follows:

o- 2

= <r 2 + or 2 + 2

, a = 2

^2(cr + or ) x + y x y xy x xy

2 2 2 2

cr = cr + cr - 2 cr = 2 (cr - cr ) x - y x y xy x xy
-16-

w

u

OH<u8 - J w < P H Pi° Q w

rf 1 1

UO^DH<HOo! 2 w o Q

S3H•—i

ft

<;o

Pi

w

u

H

<;o o

PiHou

H

S3

ft

w<

Pi

wH

2:

W S3 P

<;

u

In

HZ

a>

W £ n W H ? <: § w

PioH

wp

«£< J Jf p ft 6 < p oH

S3

ft<<P Ww

w

In

J

w

Pi

w £ w o 8 S3

W < h S

ft

w o

1-1 ft H

COawH

co

S*coco

i—i

CO

Sh<

<;zoI—I H

S3«•—•

PiH

co

I—t p

0)M

00

•H

ft
-17-

Figure 8. DISTRIBUTION ANALYSIS SYSTEM (DASY)
-18-

J< Pi goS n > h

gWft

fc < 1—1 p ' ,

PioHO -ib 31 X b

FERENTI SERVO

MPLIFIE] +

(M

X i—i 3

Ov] P ° co ^ h di i 1 ' 1 < p £

ING

REN lifi:

UMM IFFE amp: P< * u

co

p

SQUARING AVERAG

CIRCUI ^' 1 1 >s + t t X3

eg

b

>< i 1 a o

SQUAR] AND

VERAG CIRCUI

O <

1—4 t-M -i § a - . Pi

>> >N «2S + 1 Z H "1 - —

—

H

X

X

O Eh

J £ P Oh CO 5 ^ O2 p o Z £ w u

<;

w ri 1 1 02h 2 W fa ^5s w p, ^ k ^

"x >-

co £ < P X , [,

PiwH

OhOuO1-4 H

<;w

oi

piOuu

GO
-19-

Figure 10. CORRELATION COMPUTER
-20-

By further taking sums and differences of the above equations we

2 2 , 2

compute the covariance, cr , and the sum of the variances, cr + cr = L a , xy x y x

If we are only interested in the covariance, this quantity may of course

be recorded as an analog function of time for fixed delay (t) or as a function of r where this parameter is dynamically introduced by the

tape loop transport system.

The correlation coefficient is obtained through the use of a second

servo system which computes the ratio (K) of the covariance to the

2

variance cr . x

2 cr cr cr ^ ~ 2 2 2" p

"

cr + cr cr 0" , cr x y x x' y'

4. COMPUTATION AIDS

In some cases, field data are not recorded on magnetic tape or are

not recorded in a form suitable for direct analysis by special purpose

computers. In other cases, an analysis is to be performed that is sufficiently complicated or rare so as to not justify the development of a special purpose computer. In this latter case, the data from the magnetic tape equipment is digitized onto punched paper tape and programmed for analysis on the high speed, general purpose digital computer.

In the cases where field data is not recorded in the proper form,

several computation aids have been developed to either compute or

assist in the reduction of the data. The following three examples serve

to illustrate the equipment which has been developed to satisfy this

portion of the data reduction problem.
-21-

4. 1 Refractive Index Computer

The Refractive Index Computer [Johnson, 195 3] shown in figures

11 and 12, is a special purpose digital computer designed to solve the

following equation for the radio refractive index [Smith, 1953] .

6

K

l e N = (n-1) 10 = -t— (p + K

2 — RH)

In general, the data to be applied to this solution are in the form of

tabulated numerical values and as such are not readily adapted to a continuous or automatic type data reduction process.

Fig. 11 is a complete circuit diagram of the computer, and serves

to illustrate the simplicity of the circuit. The three independent variables of pressure, temperature, and relative humidity are introduced

as dial settings by the operator. A fourth dial permits the operator

to rebalance the bridge circuit, and the desired value of N is read

directly from this dial. The circuit constants and dial calibrations

have been adjusted so that the variables may be introduced directly in

terms of their recorded values. The units for pressure are millibars,

for temperature-degrees Centigrade and for relative humidity- percent.

A unique feature of this computer is the modification of a linear

ten-turn portentiometer so that its output to input voltage ratio vs

rotation equals the curve of the saturated water vapor term in the refractive index equation. Mechanical coupling of this element to the

e

g main temperature element effectively eliminates the term —- as a

variable in the equation.
22-

-vVWV

I—WW—wv\* — IO cm O

crro cr ro

LAaAA^—VWV—VWVN—^A/W^-AAA/V—V\A/V—WW—<»

•-©-

mo

in

^"st- ared

in

L..C

.0 O

cr ~ 5°

IT

00 lO

to" 5°

cr —

o q, O o

CD OQ

1 1 \

o

C/) o

o

ZQ-Zi
-23.

WHouXw

1—1 w>I—I

EhU

<;hW

i—i

0)

OX)
-24-

The refractive index equation may be considered as being composed

K, e

s of two parts: a wet term, equal to — ( K — RH), and a dry term,

K

T T

equal to — p. Many of the applications which require the solution of

this equation also require the individual values of the wet or dry contributions to N. Two switches are incorporated into the final circuit

which permit the computer to solve for either contribution and thereby

greatly increase its usefulness.

4.2 Amplitude Distribution Analyzer and Chart Scaler

Strip chart records continue to be the primary recording medium

for certain short term, low budget programs. The Amplitude Distribution Analyzer and Chart Scaler (ADIACS) shown in figures 13 and 14,

was developed to assist in the analysis of this type of record. The

analyzer consists basically of a chart scaler or follower, digital converter, code conversion matrix, numerical distribution totalizer, and

a sampling system.

The chart scaler is essentially the chart drive mechanism from the

same strip chart recorder as was used to record the field data. The

scaling pointer has the same radius as the original recording pen. As

the operator moves the pointer, following the recorded data, a mechanical digitizer attached to the pointer shaft rotates so that a full

scale trace of the chart produces a 100 count output from the digitizer.

This output is connected to a relay diode matrix which senses the level

of the retraced signal in terms of a two-digit decimal number. Ten

discrete levels may each be set by means of two selector switches.

They, in turn, are connected to the drive coils of ten impulse counters.

This arrangement causes the counters to register, at the sampling rate,

whenever the signal exceeds the particular pre-set level. The sampling
-25-

rate is controlled by a photo-cell sampling disk connected directly to

the chart drive mechanism. The sampling rate may be varied by changing the number of holes in the sampling disk. The chart drive speed

and the sampling rate are determined by the requirements of the particular data and the desired reduction accuracy.

The cumulative amplitude distribution for any desired sample

length is determined by plotting the ratio of the reading in any counter

to the total sample count versus the level position of the particular

counter.

4. 3 Punch Tape Data Translation System

Punched paper tape is a very useful medium in both the data recording and data analysis processes. Several different codes and formats

are used in the preparation of these tapes, however, and it is essential

that the data reduction program have equipment available capable of

performing a variety of different data translation operations.

The Punch Tape Data Translation System shown in figures 15 and

16, includes the following major components: tape reader, removable

patchboard type code conversion matrices, electrical input-output

typewriter, and tape punch. There are a variety of modes of operation

possible, capable of performing several different translation operations.

Perhaps the simplest mode of operation is direct copying of data

tapes. This operation involves only the use of the tape reader and punch

and certain driving circuitry. Another relatively simple mode of operation is the preparation of data or programming tapes from tabulated data,

In this mode, the typewriter is used to drive the tape punch through

a code conversion matrix. A third mode of operation utilizes the tape

reader, a code matrix, and the typewriter. In this mode, it is possible

to verify or tabulate in typewriter output format the data punched on

paper tape.
-26-

H

Pd< pd X W u J

<;u

Pi CO H

CO

J pd www > tO ESI w J 3 £ s £ w s o

PdoHUww pq W k co g W>Ww

CO

•—i uw

PdwH

Pi P W>

Pd

i—i Ou

PdwNI—1 Hl-H o—IQ

coO<P<

PiWw

<;u

coH

Pd<op<

PdwNo>—* H

PQ

i—i

pdH

co

i—t PWP

IDHi—i

Oh

ro

•rH w
-27-

Figure 14. AMPLITUDE DISTRIBUTION ANALYZER AND CHART SCALER

(ADIACS)
• 28

PUNCHED

TAPE

READER

BUFFER

MATRIX

r

BI-OCTAL

TO

ALPHA-NUMERIC

CONVERSION

PAPER

TAPE

PUNCH

BUFFER

MATRIX

DIRECT

REGENERATE

ALPHA -NUMERIC

TO

BI-OCTAL

CONVERSION

REMOVABLE PATCHBOARD

CONTROL PANEL

MANUAL

KEYBOARD

ENTRY

IBM TYPEWRITER

PRINTOUT

SECTION

J

IBM TYPEWRITER

ELECTRICAL OUTPUT

SECTION

TYPED PRINTOUT

Figure 15. PUNCHED TAPE DATA TRANSLATION SYSTEM
-29-

WH

co

!*COOi—< H<<

<;QW

Ph<cHKU

n£)

(U

•H
-30-

The complete mode of operation utilizes all of the components shown

on the diagram. In this mode, tape data is read by the reader, converted

for typewriter entry by a matrix, and typed out by the typewriter. Simultaneously, the typewriter signal is applied to another code conversion

matrix. This, in turn, drives the tape punch. Control flexibility allows

the operator to manually introduce programming commands at various

points in the preparation of the new tape.

5. CONCLUSION

All of the equipment described in this report is currently in use within the Radio Propagation Engineering Division of the National Bureau of

Standards, Boulder Laboratories. There are several sets of Magnetic

Tape Data Recording Systems in use at various field locations. The

Magnetic Tape Data Reproduction System and the Special Purpose Computers are operated as the Division's Data Reduction Facility. The

Computation Aids are generally developed for particular projects, and

are operated at any location by personnel responsible for the particular

reduction for which they were designed.

It has been the intent of this report to continually emphasize the

need for coordinated planning between those responsible for data taking,

data analysis, and data reporting. It is hoped that the techniques and

systems described here have served to adequately describe a successful

solution to the general problem of "Data Reduction for Tropospheric

Propagation Research".
-31-

6. ACKNOWLEDGEMENT

The development of certain equipments described in this report

has been the responsibility of certain individuals in the Data Reduction

Instrumentation Section. The author wishes to acknowledge the following

contributions: Mr. P. I. Wells and Mr. D. V. Glen for the Distribution

Analysis System; Mr. R. W. Hubbard and Mr. J. V. Cateora for the

Correlation Computer; Mr. J. A. Sykes for the Data Reduction Facility;

and Mr. R. A. Blumenhein for the Amplitude Distribution Analyzer and

Chart Scaler, and the Punch Tape Data Translation System.

-32-

REFERENCES

Crichlow, W. O. , C. J. Roubique, A. D. Spaulding, and W. M. Berry,

Determination of the amplitude -probability distribution of atmospheric radio noise from statistical moments, J. Research NBS 64D,

(Radio Prop. ), No. 1, 49-56 (Jan. I960).

Florman, E. F. , and R. W. Plush, Measured statistical characteristics

and narrow-band teletype message errors on a single- sideband 600-

mile-long ultrahigh-frequency tropospheric radio link, J. Research

NBS 64D, (Radio Prop. ), No. 2, 125-133 (Mar. I960).

Johnson, W. E. , An analogue computer for the solution of the radio refractive index equation, J. Research NBS 51, No. 6, 335-342

(Dec. I960).

Norton, K. A. , P. L. Rice, H. B. Janes, and A. P. Barsis, The rate

of fading in propagation through a turbulent atmosphere, Proc. IRE

43, No. 10, 1341-1353 (Oct. 1955).

Smith, E. K. and S. Weintraub, The constants in the equation for atmospheric refractive index at radio frequencies, Proc. IRE 41, No. 8,

1035-1037 (Aug. 1953).

Thompson, M. C, Jr., and H. B. Janes, Measurements of phase stability over a low-level tropospheric path, J. Research NBS 63D,

(Radio Prop. ), No. 1, 45-49 (July 1959).

USCOMM N8S.&

i. DEPARTMENT OF COMMERCE

Luther H. Hodges, Secretary

(NAL BURLAU OF STANDARDS

A. V. Astin, Director THE NATIONAL BUREAU OF STANDARDS

The scope of activities of tlie National Rurenu of Standards at its major laboratories in Washington, D.C., and Boulder,

Colorado, is suggested in the following listing of the divisions and sections engaged in /technical work. Tn general, each section carries out specialized research, development, and engineering in the field indicated hy its title. A brief description of the activities, and of the resultant publications, appears on the inside of the front cover. WASHINGTON, D.C.

Electricity. Resistance and Reactance. Electrochemistry. Electrical Instruments. Magnetic Measurements.

Dielectrics. Metrology. Photometry and Colorimetry. Refiactometry. Photographic Research. Length. Engineering

Metrology. Mass and Scale. Volumetry and Densimetry. Heat. Temperature Physics. Heat Measurements. Cryogenic Physics. Equation of State. Statistical Physics.

Radiation Physics. X-ray. Radioactivity. Radiation Theory. High Energy Radiation. Radiological Equipment.

Nucleonic Instrumentation. Neutron Physics.

Analytical and Inorganic Chemistry. Pure Substances. Spectrochemistry. Solution Chemistry. Analytical

Chemistry. Inorganic Chemistry.

Mechanics. Sound. Pressure and Vacuum. Fluid Mechanics. Engineering Mechanics. Rheology. Combustion

Controls. Organic and Fibrous Materials. Rubber. Textiles. Paper. Leather. Testing and Specifications. Polymer

Structure. Plastics. Dental Research. Metallurgy. Thermal Metallurgy. Chemical Metallurgy. Mechanical Metallurgy. Corrosion. Metal Physics'

Mineral Products. Engineering Ceramics. Glass. Refractories. Enameled Metals. Crystal Growth.

Physical Properties. Constitution and Microstructurc. Building Research. Structural Engineering. Fire Research. Mechanical Systems. Organic Building Materials^ Codes and Safety Standards. Heal Transfer. Inorganic Building Materials. Applied Mathematics. Numerical Analysis. Computation. Statistical Engineering. Mathematical Physics.

Data Processing Systems. Components and Techniques. Digital Circuitry. Digital Systems. Analog Systems.

Applications Engineering.

Atomic Physics. Spectroscopy. Radiomelry. Solid Stale Physics. Electron Physics. Atomic Physics.

Instrumentation. Engineering Electronics. Electron Devices. Electronic Instrumentation. Mechanical Instru- ments. Basic Instrumentation. Physical Chemistry. Thermochemistry. Surface Chemistry. Organic Chemistry. Molecular Spectroscopy. Molecular Kinetics. Mass Spectrometry. Molecular Structure and Radiation Chemistry.

• Office of Weights and Measures. BOULDER, COLO.

Otogenic Engineering. Cryogenic Equipment. Cryogenic Processes. Properties of Materials. Gas Liquefaction.

Ionosphere Research and Propagation. Low Frequency and Very Low Frequency Research. Ionosphere

Research. Prediction Services. Sun-Earth Relationships. Field Engineering. Radio Warning Services. Radio Propagation Engineering. Data Reduction Instrumentation. Radio Noise. Tiopospheric Measurements.

Tropospheric Analysis. Propagation -Terrain Effects. Radio-Meteorology. Lower Atmosphere Physics.

Radio Standards. High Frequency Electrical Standards. Radio Broadcast Service. Radio and Microwave

Materials. Atomic Frequency and Time Interval Standards. Electronic Calibration Center. Millimeter- Wave

Research. Miciowave Circuit Standards. Radio Systems. High Frequency and Very High Frequency Research. Modulation Reseaich. Antenna Research. Navigation Systems. Space Telecommunications.

Lppcr Atmosphere and Space Physics. Upper Atmosphere and Plasma Physics. Ionosphere and Exosphere

Scatter. Airglow and Aurora. Ionospheric Radio Astronomy.