© Snemmwration Companraenr

The housing for the center section of the optical
system houses the motor driven segmentation drums,
Tt comprises four enclosure panels and four baffle
anemblies. The enclosure Panels are a heavy metal
floar, front, back and cover. Two Inside bafiles are
screwed to the floor, and two outside baffles screwed
‘0 the front panel form with them continuous seesen
tunnels which light from the object space
Teaches the mirrorstats on the rotating drans, The
center compartment can obviously not be made light
tight, bat all ite inner surfaces are coated with Diack
flack to dissipate unused light that cannot he pre
vented from entering the drum compartment through
the tunnels that lea! through the front panel,

The dram compartment is supplied with power
d 8 cord that passes up throngh the com parte
ment floor near the front, The motor is controlled by
a Iwo stage ewiteh on the hack Panel that first con.
nects a starting capacitar in the cireult, and then a
rimning capaciior, Two thruete are necessary to fully
actuate the ewitch in clther direction, and in starting
4 five second to ten second lapan between thrusts is
recommended iv give time for oscillations to damp
out before switching in the running capacitor,

The red phasing larap is mounted beside the motor
switch. This ie « neon Jamp with « built-in resistor
in the lamp socket for 110 volt Operation that flashes
cach time the right shutter has an opening in the
Jower moet position. Its operation may be hetter
observed under certain conditions if the red bullseye
te removed, Figure 8 gives the wiring
diagram of the synchronous motor, starting capacitors,
phasing lamp and switches, The motor connections
shown are for operation with the $20X speed reducer
or TYRPM of the drums For operation with the
34X speed reducer or 100 RPM of the dramas, reverse
either the red and black or green and yellow motor
leads,

[it sover panel of the cesiter compartment is peo
vided with a shaft hole and a covered olwervation
port, The upper drum shaft extends through the
shaft hole, and the phases indicator dial Je afixed to

cover concentric with the shaft. A chrome Plated
affixed to rotate with the shaft and
the dial, To the rear of tho dial and at one side, the
schedule of operating phieso soquences is affixed to the
cover under « prulective plastic sheet.

d. Opsnative Squrnce

Once all the mechanical Parte are properly phasod
it deacrthed elsewhere in thls report, the hest prox
dure for photographic testing is:

1, Decide which branch, left or sight is to he
tested, locate shutters and load cameras ec.
co!

_pequence
Rumbers that corresponds to the branch ant
drum selected, .

& Start the motor and switch to running cx
Pacitor.

4. With one person watching the moving dial
pointer, have a second Person call out the lamp
lashes until the lashes occur when the pointer
ie indicating red numbers on the inner circle
of the dial, showing the system in the even cycle
of operation.

§. The dial watcher then watches the first phase
sequence number on the outer circle at which
expovure is to he made, and releases the proper
shutter when the pointer reaches this position
in the odd cycle of operation.

& The second person then advances the filn and

the process ia Tepeated to produce an exposure
at the second phase

1. When phase sequence numbers in the even cycle
are reached, continue to proceed ae in 4, 5, and
6 above, except change “funer” to “outer” and
vicewerss, and change “even” to “odd” and
vice-versa,

5. Photographic Tests with Completed Camera
a Test Aaa

‘The completed segmentation camera was set up on
the 8th floor of « building where a view dows sn
Delaware River wes available through

wide windows. The. right-hand side of the
covered the Camden side of the Seld of view

‘The supporting frame work was first eet up on its
six jacks, levelled and bolted
on 2 12 foot x 4 foot lal

elewhere in this report. The rotating
drum assembly was set in position and bolted, ant
the covers asembled end bolted in. place, All seams

—SEeRET—



~~ SECRETF—

system is given on pages 3-22 through 3-26 of the
Advanced Reconnaissance Syaten:, Final Engincering
Report, June 30, 1956 (Contract AF3S(616)3104).
In this reference a simplified parallel channel system
‘sing four vidisons {lustrates the basic concept of
this appeoach. Detailed information ie given on
weight and power requirements of such a system,
Tt should be noted that regardless of the

of recording chosen, techniques are available for a»
sombling the information into one electrical channel
for trananission to the ground. These techniques
wero not considered aa a part of this section of the
study.

7. Conclusions

Our investigation of recording wideband video
information on magnetie tape has resulted in the
development of many improved techniques for
magnetic which are important for many
applications of magnetic recording. It has been
demonstrated that tape transport mechanisms can
he built in which tape can be ran at S00 inches per
second with the capeten speed controlled to an
accuraey of one past in 250,000 when the capstan epeed
is compared with a crystal oscillator. Magnetic heads
have been constructed which will permit the record-
ing and playback of informstion at frequencies in
oxcess of 2.5 megacycles at a signal-to-noise ratio of
40db with the above mentioned’ tape mechanism.
Multitrack heads with six channels on one-half inch
tape have exhibited beiter than 45dh adjacent
channel crosstalk. Frequency modulation has been
used for recording information on tape to provide
& video bandwidth of 25 kilocycles per inch per
second tape speed. It is estimated that the life of
magnetic heads in this application ie ahout 1,000

hours and that a given length of tape will he useable
for at least 10,000 and possibly 100,000 peseca over
the head with no loss in picture quality, provided a
tape Iubrieant is employed.

Back-to-back multiplexing, ic, encoders feoding
decoders directly without using the tape channels,
has been made to work suecessfally for the time-divi-
sion system, anid] for the frequency-division system to
a leeser extent. In both cases, the introduction of the
tape channels has brought on added difficulties which
were not overcome in our oxperimontal work. It ia
helievedl, however, that further work could result in
a successful system using either type of multiplexing.
The diffeulties are such, however, as to make this
general method of recording video information rather
Unattractive at the present time. Our conclusions in
this regard aro strengthened by the recent euccess of
the rotating-head-wheel system for video magnetic
recording in which heads scan transversely across the
tape. This type of equipment resulted in a successful
demonstration of the recording of monochrome telo-
vision pictures in the spring of 1956 by the Ampex
Corporation and of color television pletures in the
fall of 1957 by Commereial Electronic Products, RCA.
The high quality of these recordings when compared
with the reenlis of our multiplexed recordings, indi.
cates that further development should proceed along
the line of transverse recording, The use of » rotating
head wheel is considered to be a scrious disadvant-
age, however. It is hoped that developments in the
near future will result in a iransverec scanning head
using no moving parts, Tho development of such a
device would most certainly pave the way for the use
of transversely scanned recording for television-re~
connaimance applications.



—SEORET-

oscillator second harmonic, 21.2 megecycles and 23.8
megacycles, appear in the plate circuit; These plate
signals are transformer coupled to a germanium diode
(INGO) where they are rectified to form the video
information signal. .

‘The transformer end diode act as a double slope
detector as indicated in Figure 20, The signal fed
to the diode consists of two sldebande of equal ampli.
tude and disposed around the peak
of the response curve of the tuned transformer, As
the modulating

or decrease in amplitude together oo that they can
be added to drive the diode detector. The primary
advantage of the doubloalope detector is that fre-

would be required if the I single-slope detector
were to be employed. =

‘The detected signal

through the output multiplex unit where the com
plete video signal is reconstituted from the signals
om the five tape channels,

It will be recalled from clemeatary frequency
modulation theory that an accurate reproduction of
the modulating weveform of an FM signal requires
the transmission of both sidebands, For this reason

quency, and possibly more, depending on the index
of modulation, On this basis, a tape channel of two-
megacycles bandwidth could support an FM signal

* small modulation index fs used so that only first
order sidebands sre significant. Although the we
of higher frequency-modulating signals in such «
tystema would result in sidehands outside the pase
band of the chanacl, such use would be desirable from
the viewpoint of incresing channel

Tt has been determined that the transmission of
video by FM techniques through a channel of limited
bandwidth can result in serious distortion and a

26

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HAT
EF tre
att
heey
pil:
HG
dit

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ial

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|

modulation to a bandwidth of half the tape channel
capacity. Experimental oquipments have been con-
structed on other projects in which a video modula:
tion bandwidth of 5.0 megacycies has been reeorded
by FM means on « tape channel with bandwidth of
5.5 megacycles, giving « bandwidth utilisation factor
of 91 percent,

3. Improvements in Tape Handling

When the development recorder was first com-
Plied, tape tension was adjusted to four ounces, as
be ed fon aatentne asiae tension thet could
be weed for a wind of the magnetic tape,
At first, single lenge mete eee tae a develop.
mental recorder; however, cccasionally the tape
would slip off over the edge of the roll. Top flanges
of lucite were added in an attempt to prevent this,
Lucito was used 10 permit observation of the tape
without the use of holes or spokes in the flange. The
uso of these two flange reela has been entirely satis.
factory during several mouths of operation with both
10 and 0.5 mil Mylar bese tape.

In comparing magnetic head performance on the
developmental recorder and the loop machine, «
given head always performed much better on the
loop machine. As an example, head 6TF3Ag* re
sulted in 40 dh signal-to-noise ratio at two megacycles
and a speed of 400 ips on the loop machine but no

—SecRET-



DISTRIDUTION OF SUPPL MEAT TO PINAL ENOLNSSRING SPURTE

Copy No. 1

Copy No. 2&3

Copy No.

Copios No. 5 thru 9

Uopy Hou 10

Copius No. LL & 12
Copius Hon 13 & wu
Coplogs Ho. 15 thn 20

Coptan No. 21 thru 26

Copies No. 27 thru 35
Copies No. 36 thru hs
plua
reproducible

Copies Noe 46 thru 60

on
Contract AF33(616)=2576

Commander, ARDC

Attns RDZF1, ite Cole Victor Oonas
Post Offices Box 1395

Baltimore, Maryland

Rand Corporation

‘Attn: = My. John Mluntzickor

1700 Hain Straot, Santa onien, Calif.

Commander, AF Perconnal & Tris. Resnarels Gaulsi
Attn: Major Stanjey Valatk

Lackland Air Force fang

V0. Hox 1957

fan Antonie, Taxas

Lockhust Aireralt Corporation

Hlarlle Syuteun piviaion

Attn: Bre Jo i. Garter

Pout Offieo tn, LOh, Sumyvalo, coli,

Not ton Unlvernity
AGL Dre My Ke Hrederrtat
100 Commamonttts Aves, Hozton, dav,

Cowendoy, HANG
Attnz ROO, Bea ist Reming
Grif Clan AVN, How Youls

Coamavior, AbCIG
Attur CRZI, OM. Gol teeny. denen
tmabedeleas, Hevge,

Cramuncar, WANG
WPAFL, Oble
Attuz Chive)

Gemaomdor , WDD

Attn: HTN .
Yout Uffico Hox 262
Anplewood, Caldforudia

RCA Internal dintrl bution

Commande:, WD
Attus Weir :
P.O Rox 262, Inglewood, calif,

Coamamtor, vADC
WEAFD, Ohta
Attn: WCLEKA3



“qusrenes after the drum is rotated 180°,
‘This waa done in 40° stepe all the way around the
drum, It was conchded from the results of thers

direction more than 5 seconds during rotation, and
the sutocollimator was then squared to its mean
direction, :

A second autocollimator was pointed to observe the
reticle of the first along « line that cleared the drum
shaft, after a large flat had been squared to the Erst
autocollimator to Permit its transfer to the new
observing position. A fiat mirror was then clamped

by more than the allowable £15 seconds, The maxi.
mut error was about forty-five seconds, Seven faces
of the wpper drum excecded the fifteen second toler.
ance, the

flat cupported by a leveling table,
The two Lecetions mount folded optical systems

whose optical axes consist of the Parallel segments

FA smd GB, and the common segment

A and B are indieated on the uppar surlacna of te

Leections

‘dimensional requirements of the design, and the line

appear ss « blurred vertical bar against which it ig
easy to judge the
lines by moving the head slightly in s horizontal
rection during the observation, When the other
two plumb lines both “ppear centered in this bar, the

5

—SeGRET—




—— SECRET

C. KINESCOPE RECORDING

1. intreduetion

In the report for August 1, 1956, it wes noted that
the Siret sample of the new triode-gun magnetiofocus
kincecope was not significantly better than our best
pentode electrostatic tubes as to resolution. _

A second sample kineseope of the triode-gun
magneticfocus type was tested by Dr. 0. H. Schade,
who found it not up to his expectations. This tube
was given a similar series of tests in RCA-Camden—
pertinent duta is shown later in the report.

Concluding the evaluation program, two develop-
ment tubes were studied and the test data comparcd
with that of the tube referred to in the preceding
Paragraph, The percent kinescope response was not
an favorable as that of the reference tube.

As a result of these tests it is believed that light
scattering and “image spread” in the phosphor, of «
five-ineh tube, aro limiting the rendition of fine
detail (500 to 600 TV lines) as much as is the die
tribution in the beatin spot iteclf, Rather good pre-
vious evidence indicates that the improved P16
vhosphor was considerably hetter in this respect than
the P21 (which is widely used for kinescope Photog.
araphy). However, it now appears that a ten-inch P16
tuhe may he required to get a 560 TV-line response
of around 75 percent or better, as measured on the
phosphor, Fortunately, the special Eastman U.V. lens
will work about equally well at this image-to-ohject
Tatio,

Another cacouraging possibility is the development
of a radically-new transparent and thin Phosphor hy
the RCA Tube Department. It is expected that this

may produce satisfactory results in even the five
inch tube.

2. Ouiline of Procedure Used to Evaluate Kinescopes

For evaluation of these experimental triode-gun
magnetic-focus kinescopes, « nonochrome recording
chain was revised. A large diameter precision de-
flection yoke was put into operation with sufficient
power for full image deflection. A precision focus
coil was ulvo installed giving what wae considered to
he the beat magnetic focus that could be devised for
triode-gun kineseopes,

The 3 tubes under teat were as follows:
1. Kinescope PP 13548 Long-Triode S-inch,
P16 phosphor—this tube had been
evaluated by Dr. O. H. Schade and used in
this report ss a reference tube.
2, Kineseope PP 1507-1 Long-Triode S-inch, P16
Phosphor.
5. Kinescope PP 1508-1 Short-Triode S-inch, P16
phosphor.
The monochrome recording unit was equipped with
« photographic camera having a 30-inch bellows and
a Kodak Kinescope Ektar lens 425-1, 75 mm, /2.3
ultraviolet, mounted in reveree to penait « mag
nification of about 10.7:1 from kinescope to film. For
all dats taken, the lons was sot at £/¢, Exposures
were for five scconds.

A sine-wave signal gencrator was used and fre-
quencies of 6, 2, 4, 5% and 7 mogecycles were ex-
posed on Ansco Trisopan film, from the kinescopes
adjusted as follows:

1. For each kinescope, the grid hias was founil
which would give a density on film of approxi-
mately 1.6. This bias was reeorded as hi-lite
level for that particular tube.

2. Similarly, for oach tube, the bias was adjusted
to give a dim scanning line image on film
(within the density range of about 0,2 to 0.6).
This bias was recorded as hi-lite level for
that particular tube.

3. Blanking hise was also recorded.

4. For each tube, the d-c biss and the amplitude
of the sinusoidal test signal at 0.6 mogacycle
(representing relatively coarse picture detail)
wore adjusted 20 that the signal excursions
torresponded to the hilite and lolite bias
valnes, A film exposure was then made with
this 0.6-regacycle signal. :

5. The frequency was then changed successively
to 2,4, 5.5 and 7 megacycles, and exposures
made, keeping the signal excursions on the
arid et the same values as for 0.6 m
An attempt was sleo made to keep the d-c
bias component constant. Although this was
not fully achieved, it is believed that the d-c
hias shifts which occurred did not alter the
results appreciably since the kinescopes have
a reasonably constant “gamma” over the
range tsed,

31



feta ay

NOTICE: when government or other drawings, speci-
fteations or other data are used for any Purpose
other than in connection with a definitely related

government Operation, the U. s,
Government thereby incurs no responsibility, nor any
obligation whatsoever; and the t Govern ~

any rights
or permission to manufacture, use or sell any

ING OF THE ESPIONAGE LAWS, TITER 18,
U.S.C., SECTIONS 793 and 794. Tae
TRANSMISSION OR THE REVELATTON OF
TTS CONTENTS IN ANY MANNER TO AN
UNAUTHORIZED PERSON IS PRORTETTED

BY LAW,



Figers 18. 1125 Mapocyde Onde, Schemas Otro

+180

—

To Gee Bus of
Osc. Onwars

—4
Sete f

Ombd

3
cTM,,
.
tose af ee

Gere Bus Fron UeZ5me Ores

24.

tea S

Pe

+ Ifo”

Figure 19. Ovellister Driver. Schematte Dlogren

—SECRET



—SECRET

wer taped with black photographic Scotch Tape to angle of the segmentation camera
exclude light, . a design value of 64.172°. Figure
After some work on the bearing seats and drive contact prints made from the 36 negatives,
gear adjustment to reduce image jump, and after is trimmed and mounted in

12* x 12” x 114” eponge rubber pads were placod show the continuity of the some, The strip has been
under the six jacks that eupport the caruera, it was Presented in two sections to conserve the length of
considered to be in readiness for the tests, The drums the reproduetien,

and shutters were phased according to the scheme of The soound objective is accomplished hy comparing .
adjustment disemeed elsewhere in this report, and Pictures made when the segmentation drums are in
the dial pointer was set in proper relation to the Fotiow with corresponding pletaree anedo when the .

; jective
b, Teer Procsours te sccomplish hecause the pictures te be compared
The small Argus camera bodies were located to covpleds cangmtlameeesly. Diferences in ab,
ca gree Li he fc plane fw Tether conditions sod iiemination conditions,
of the segmentation camera, cameras
these ed cae See TiS ed Pered. Those were minimised by photographing one

side of the optical system from the upper and lower the entire operation occupying net more than ten te
drums, This arrangement required oach side

Segmentation camera to be completely light tight, the atmoephere were sometimes distinctly noticeable
but avoids the limitations that would arise were on

shutters ued at or near this focal planes, By

tripped. of optical speed, and film used. This
exposure time corresponded at the 7}, RPM drum

© Ducusson or Resuirs speed to the design pulsing time of 0.0015 second at
The teats had two main objectives: 100 RPM se explained elsewhere in this report. Ex-

L To show that the device is capable af photo- Posures were made on Eastman Panatomio-X fika and
graphing « continuous strip in a series of 36 tank developed in Microdol developer for alx minutes
partially overlapping segments which cover the at 68° F.
field for which the system hee been docigned. 4. Anuzyats or Mosac

2 To show that the quality of the images of distant AA moveic has been prepared from contact prints of
. objects i» not reduced by the motion of the the 35 mm negatives taken during the dynamic or

segmentation drums, moving drum tests. The sequence numbers of
The first objective was met, as far as fold the prints are indicated below each segment as shown
is concerned, by photographing the same field with in Figure 9. A photograph’ of the same scone wes

angle
from the size of the image and the focal length of or 4.13 inch, focal length lene, This is shown in
the view camers lent. If the focal length of the Figure 12, It was necessary to tilt the camera 45°
: view camera is f, and the distance on the view camera in the plane of the image in order to obtain the same
negative between the extreme points of the segments. erase om the 4” x 5” negative ex that given by
tion camera field is w, the segmentation camera fleld the segmentation system, ‘The Huear distance on the
angle is 2 cot~(2f/w), Measured in this way, the field negative corresponding to the coverage of the seg.

12
—SEGRET


om

w
Figure 13. Compares of Image Detelt between Stotic, A, ond Dynomic, B, Conditions from Scqvencs 12, Figwe ?

Figere 12. Photograph of Segmentation Scone Taken whh o 4x $

Senet



27 25 23 21 19 17 15 (3

PON et ri

uh
t

Laie



INPUT WRoM
Demoou. ator
Low-Pass|
= Fivrer
O-bBME

Fase 21. LowPon Miler oad Ampiiter

SEGRET

oureur



—_SECRET—

and even eycles aro identified by the flashes of a
lamp at the rear of the assembly. This lamp is ener.
sised by a cam and mieroswitch each time an opening
in the right rotating shutter reaches the lowermost
Position. The odd cycle is identified by the @ashes
occurring when the moving pointer is directed to-
ward red numbers in the outer cirele of phase se.
quence numbers (1 to 18 inclusive). During the
even cycle, the Aashes occur when the polnter indi.
cates red numbers in the inner circle. The even
cycle phase sequence numbers are 19 10 36 inclusive,

When the phase sequence number has heen identi
fied by observing the dial pointer positions in rele.
tion to the oceurrenes of the lamp flashes, the Parlio-
ular mirrorstat, drum, and optical system which are
functioning to Produce an image are identified: hy

the schedule of operating phase

Fig 1th iz alto attached to the back clthedree
compartment cover,

For example: If the rotating pointer is directed to
Position 1230 and the lamp flashed when it passed
position 11-29, the phase

bered position, It is not necemsary to know the phase
sequence number in order to check dram phasing,
Tn order to cheek the phasing of the rotating
shutters, the drums and the dial pointer must first
he properly Phased. A check for this is given in the

to the stability of the direction of the
drum chaft during rotation showed the dircction te
wander h am angle of about thirty seconds,

repens
a
th
t
i
i
ail
ihe

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t
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iu
pi
Hi
ple

ut
fiat

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)

10

li

13
4
15
16
27
18
19

BRES

—SECRET-

UST OF ILLUSTRATIONS

Seve eeeeesens

Kinescopes .......
Semitometric Curve for Anseo Trisopan Dev. 3 Minutes, D-16

16

16
16
9
20
21


Figure 16. Pleybeck Ampliec, Schometic Diogrem



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SECRET

Figure 13. ‘Video Recorder Block Diagram


Dbpntor
»PROSEF MX-2

OGe Preface) Que Own.

@ Final Engineering Repent, Zuel. |
Own. OF dot 57 iy, MESTMCTED TISTRIBITION |

al for release must be obtained

@ Cur eewotk

itd

®

DEFENSE ELECTRONIC Propucts : |
RADIO CORPORATION OF AMERICA : . |
. CAMDEN, N. 3, :
!

1

|

- AIO A



AIR FORCE
MALLISTIG MISSILE DIVISION

oe TECHNICAL UBRARY S=hieacins SORT
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ES orcument No c2 a LY A _ CO.

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Final Engineering Report

ices Be Soiains.

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ee gia



the of the the

the ple aad ee he Pan pci
Prisms adjusted to substantial parallelicm with the
rotation axis by repestedly tapping the metal prism
bese. Adjustmont was judged with an autocallinater
squared to the rotation axis by adjusting i and «
plane paralle! mounted on the end the shaft until
ar plan ar oan he ttealitr fr
drum that ere 180°

a large opted 2 fo the canals , the ites
ment could be transferred to « suitable position for

a Avxitlary Mechanics of tha Optien! Systera
a. Covens ano Baryres

In addition to the supporting framework of the
optical system, the aystem is provided with bales

exchide end trap undesired light as
bafiles sre finished with black
Sack on both surfaces, and the other interior sun
faces of the covers and the base on which the con

10

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mirrors
tight and light may be admaltted to them only
tripping the shutters. ‘Two shutters are provided,
may be moved from one optical systeze to the
by unserewing ileus from their flanges, Access
are provided for this purpose at the sides of the
panel of the cover for the center
upper and lower corners of each
accommodates one of the shutter

By

Peak

EF
A

—SEeRET-



2, Measurements on the Segmentating Drums .
a Dram Polygon Angles ....
b. Prism Mounting Faces .

3. Alignment of the Optical System ..
a. Alignment of Schmidt-type camera

b, Alignment of 35 mm Camera

4 Auxiliary Mechanics of the Optical System
& Covers and Baffles 00.00... es,
b, Camerss and Film Transport
Segmentation Compartment .
d. Operating Sequence ......... we oe

5. Photographic Tests with Completed Camera ..
a. Test Area ...........

or

sent Model the Design of «.New

2 Frequency Modulation Recording Channels

3. Improvements in Tape Handling ......

4 Reduction in Head Circuit Crosstalk

5S. Magnetic Tape Evaluation ‘

6. Multiplexing Systeme ....,
«, Frequency Multiplexing
b. Time Multiplexing ....,...

& Other Multiplexin,
clusions



——_SEORET-

mentation system scales 545”, The half angular
Coverage is determined by:

1
9, % angular coverage, = tan? —

. . ar
where 1 = the linear distance on negative, and
£ = focal length of the lens.

5.45”
Therefore; 9 = tan-t
234.13"

The photographs teken with the Argus camera
hody in the segmentation system have the standard
double frame 35 mm forme, or « picture sise of
0.945” x 142”, When wed with the image orthicon,
the usable area is 0.96" x 1.28”, The measured half
angular coverage of 384° can be compared with the
design value of 82.066" which is given in Progress
Report No. §, Teble I, p. 13. The sdditional
from the center of the lest frame to its edge,

= 384°

142”
© = tant —__ = 1.979, must he added to 32.086°,

2x38”
This gives a angular coverage of 33,156° for the
segmentation system with the 35 mm camera format,
The mearared value of 384° agrees with the deaign
value within 0.74%. The discrepancy is probably
due to use of the nominal value of focal length for
the calculation involving the 105 mm lens, A toler.
ance in foral lengths of commercial lenses may be
1 to 5%, The half angular coverage of the seg-
mentation system with the image orthicon will be
32.086° +- 0.965° = 38.051°,

Referring again to the Mouie in Figure 9 the odd
phase sequences, 1435, were taken with the right
optical system and covers the left half of the object
field as viewed from the camera position, The even
numbered frames wore taken hy the left optical eye
tem and covers the right half of the object field, The
distances to some of the prominent objects in the
frames are given helow: :

Frame Distance in
§ Nestical
‘Kimber Miles
13, 1s 236
3s 213
30, 36 452
6 438
2 16
12 01s
4 Oss
a seveaeasteee oo 4
1 George Washiogten School . ae

Examination of the contact Print made for frame
12, shows the width of « window Pane image in the

Goorgs Washington School to be 0.0075”, For the 38”
focal length optics, this represents « subtended angle

phase sequence frames 12 and 19 fer the static and
dynamle photographs. Figure 10 A is the static frame
and Figure 10 B is the dynamaia frame for sequence
RB Figure 11 A and Figure 11 B are the static and
dynamic frames, respectively, for sequence 19. Close
examination of thesa enlargezsents shows that there
is no deterioration in quality which may be attributed
to the rotation of the segmentation ‘drums during
exposure, During the course of the tests, it was
found that thermal afr currents were the predomi.
pictures,

The Schmidt optics have proven satisfactory, No
changes are recommended for these components,
although improvements are needed in the mechanical
mounts for the spherical micrors and the diagocal
inirrors, Gimbal mounts for the sphetical mirrors
would make alignment simpler. If a minimum weight
system is desired, considerable thought must be
Given to the possibility of using corrector plate and
spherical mirror segments of minimum sise. It. is
probable that the difficulty of alignment of these
segments will out woigh any advantages gained by
the use of the miximum size components, A study
should also be made of other possible folding arrange-
ments of the optical paths 20 that minimum spaee is
required. A study of the mutual alignment between
the segmentation assembly and each optical eystem
should be made co ac to devise adfarting procederees
and suitable mechanical mesns for attaining and
maintaining such alignment,

The optical spceiéeations on the reflecting prisms
were met hy the vemlor after agreement was reached
on a method of correction of the pyramidal error
which was present in the fret group of prisms re-

correct formulation and curing eyele for the cement
were determined, Further studies should be made'to
obtain tho maximum strength snd reliability of the
slass to metal bond. The meavurement of the pyram-
idal error and the hase angles of the prisms was

3

— SECRET



—CONFIDENTIAL__ Ap34183;

rn : . . N,
. . . . ‘
ws RESEARCH STUDY AND INVESTIGATION ON TELEVISION
Ts ‘TECHNIQUES FOR ADVANCED RECONNAISSANCE SYSTEMS (U)

"=." RADIO CORP OF AMERICA CAMDEN Nu
09 OCT 1957

coe “ Missile Div., .

‘Attn: WDTR; Inglewood, CA



ll. SUMMARY

sepects of the systems, the Photographic teste, and
recommendations for future systems,

B. Magnetic Video Recording Systeme:
A number of changes were made in the FM record:
ing system and the preseat status of this sysicm is
presented through block and schematic diagrams,
Considerable work wes accomplished in efforts to
reduee the flutter, skew and amptitude variations,
Head performance on the

larger reel motors, It was found that tape skew was
very low provided that the distance between the
ted faces of the edge guides was no more than
about one mil more than the width of the tape.

After being designed and constructed the baste
felay line from which « series of related handpens
filters could be derived wes found 10 be inadequate
It is atill believed that this approach is feasihie ent
is perhaps the only way now known which will
Provide frequency division multiplexing without
reliance on reverse playback. The use of other
multiplexing systems and recording methods is
discussed.

© Kinescope Recording:

Three kinescopes were tested two were

ment tubes and « third was a previously evaluated
tube used se a reference, The present J
response was not as favorable as that of the refer.
ened tube,

a2 measured on the Phoephor, The development ¢*
a pew thin transparent Phosphor hy the RCA tube
department may eventually permit satisfactory results
even im a five-ineh tube,


|. INTRODUCTION

‘This report represents the’ results obtained from
4 conthwuation of parts of an overall research and
it study program carried out under con-

tact number AF39(616)2576, The results contained
{irein sarve to supplement the information given in
Final Report of this Project MX.2226,
Final Engineering Report, dated Ocedber 9, 1957.

A. Optics, Ground imoging System

The delays experienced in obtaining the reflection
Prisms for the segmentation drums Prevented the
completion of the optical tests for inclusion in the
final report, Tho results of the optical tests on the
completed 38-inch focal length Schmidt cameras and

the completed unit are incladed. These show that
the optical equipment performs as predicted,

3. Mognetic Video Recording System

At the end of the time period covered by the Final
Report the status of seme phases of the magnetic
video recorder development were rather indecisive.
Daring this supplementary period the FM
syetern design was finalized and six channels com-
pleted. Complete cireuit diagrams of the FM record-

ing system incloding tape record and playback ampli-
Sera are shown in this report, Each of the six FM
channels provides excellent one megacycle video per-
formance with no interchannel crosstalk, Tape han-
were improved to the extent that

a Kinescope Recording
The material oa thie subject in the final report

was not complete, in that the

Kinescopes were not then available

Several

herein, give 2
of the o! tainable ph
Hieved that the results justify the predictions
all performance which were made in the fiual report.


—teeneT-

Frias nde {tch kine, from which the kiacope response curves given in Figure 22 were obtained,

are given helow:
Kinescope No, PP 1854-3
(References Kinescope)
Frequency of Sine Waves 06 me
LoLites (Film Density) ..........., taseeden 2

Hi-Lites (Film Density) ..........., see 1.66
Log E Hi-Lites (irom film Sensitometric Curve, Figure 23) 2.36
Log B Lo-Lites (from film Sensitometric Curve, Figure 23) 14s
Log E Difference |Log E Hi-Lite-Log E Lo-Lito] oo

Exposure Ratio (Antilog of Log E Difference) desceeesee gl
Percent Kinescope Response (derived from exposure ratio
taking ratio at 0.6 me ss 100%) wee eceeeceseeenes ree 100
Kinescope No. PP 1507-1
(Long Gun)
Frequency of Sina-IPaves 0.6 me
LoLites (Film Density) .., cessesenee St
Hi-Lites (Film Density) ... et eneneeee Lp

Log E Hi-Lites (from film Sensitometric Curve, Figure 23) 245
Log E Lo-Lites (from film Scnsitometric, Curve, Figure 23) 18

Log E Difference |Log E HiLite-Log E Lo-Lite} ......., 5
Exposure Ratio (Antilog of Log E Difference) . tee 446

Percent Kinescope Response (derived from exposure ratio
taking ratio at 0.6 mc cs 200%) fee eeeeeeeees Iga

Kinescope No. PP 1508.)
(Short Gun)
Frequency of Sine Waves 06 me
Lo-Lites (Film Density) .... . teeeeereces 16
Hi-Lites (Film Density) .. teereeee 6S
Log E Hé-Lites (from film Sensitometric Curve, Figure 23) 235
Log E Lo-Lites (from film Sensitometrie Curve, Figure 23) 135

Log E Difference |Log E HiLite-Log E Lo-Lite} .. 100
Exposure Ratio (Antilog af Log F Difference) ..... 100
Percent Kinescope Res;onse (derived from exposure ratio

taking ratio at 0.6 me as 100%) ...... sone eeceneseeen 100

* Converted to 1S hecwuse of signal fall-off at this frequency.

2 me
as
156

2268
lat
41
648
80

2me

La

4me = 5 Sme
US 2
146 118
235 2.08
156 14
c) 8B
49 471
60.5 9
4mc 5.5 mo
1.06 1.23
167 1.64
2.37 235
2.06 212
33 23
214 1.629
4a. 378
4me 55 me
A 6
138 lz
22 22
1.66 18s
a 37
3.48 2364
48 23.4

7me

172
105

BGREF

18

33.8

BagSeer

112°


Asee

Figure 13, Mecord Ampliters, Schematic Diegrem


oo

me
wer,

figure 14, FA Medoleter, Schematic Diogram


S : 957. ho projeet ben zt0 d

Rlectron’ Products of RCA for the Air Force under the direction of W,
Development Center. The coat act number is AFSS(616)3576. The present
° BOSS eaeante, the work started on subcontract 52-68 of Contract Noces

The purpose of this Project was:

1. To continue studies evaluating the feasibility of « 1
this type of specialised advance reconnaissance.

2 To
reliability,
3. To evaluate alternate approaches to any of the Problems where such seem
to have a chance of fulfilling the requirements,

ang, Cunstrect certain research models where such would be usefal in
evaluating the problem.

5. To study the electronic implementation of the interpretation and dis-

scmination of the information obtained by the reconnaissance system,
Sata Sea ier nr
Dptical Syutemny.
Cee Recane (magnetic), Qed

d. TV Transmitters

system for
for evaluation of component and

ey

t. Kinescope fecordiog orf phalearaplic wregte bre Juperdes,

& Information Presentation
h. Reliability Seadies
i, Transistor Applicabilities
rite idles were coordinated by preliminary systems examinations when,
ever deemed neressary so that the overall results would be mutually compatible,
are final report on this project reported fa full on al the toplee mentioned
. above except Optical Systems, Video Recording (magnetic) and Kinescope
Recording, additional work on these being cerriod past the contrect Period,
This report completes the reporting on these topics,
Defense Electronic Products (formerly Engineering Products Division) of
RCA was the prime contractor fer this proje, The work was
by subcontracts to the RCA Tube Division and to the RCA Laboratories Divitloa.





—— SECRET

estimated that the maximum time displacement error
between tracks was about 0.02 microsecond. This is
more than adequate to meet the timo delay error
requirements of a high quality video system.

This is very significant information relating to
multiplexing wide band video on- several parallel
magnetic tracks, This freedom from excessive tape
skew is one of the important factors which makes a
multiplex magnetic video recorder feasible.

4 Reduction in Head Cireult Crosstalk

The manner in which the six-channel head circuits
had originally bees wired amd cabled resulted in
exeessive interchannel crosstalk, about 20 db. An
inspection of the layout suggested that the crosstalk
resulted from inductive, capacitive and ground loop
coupling in the head cabling, The magnetic head
itself had been measured to have a, crosstalk factor
of sround 45 db. When the FM recording system was
first being considered it was assumed that the capture
effect in FM detection would make crosstalk between
tape tracks unimportant. Measurements indicated
that 20 db of crosstalk of the FM signal betwoon
channels resuliod in an interference signal about
20 db below the desired sigual after FM detection. An
analysis of this situation indicates that this should
he the case and there is no reason to expect any
capture effect. If the clannel 1 carrier frequency ix
1,30 megacycles and there ia 20 dh crosstalk of the
1.31 megacycle carrier channel in 2, the'13.1 megacycle
crosstalk signal will eet as an FM sideband with
respect to the channel 1 carrier. After Mmiting and
FM detection the crosstalk will appear as 2 10-kilo-
cycle signal on the output of the system, This was
the case in actual practice and pronounced bar pat-
ferns were obeorved when all six channels were
recorded almultaneously with either the same or
different video signals on each channel,

‘The wiring and cabling of the head cirenite, inelod-
ing the pre-amplifier unit mounted close to the head,
were changed to minimise all forme of coupling. The
crosstalk was then about 40 db and all six tape chan-
nels could be used without any interference between
channels, .

5. Magnetle Tape Evaluation

During the several months covered by this report
Practically continuous’ evaluation tests were con-
ducted on Reeves-Sounderalt and Minnesota Mining
magnetic tapes. During the early part of the period
only Reeves tapes could be used at all, as has boen
the case for about two years. Although Minnesota
Mining tapes havo beea consistently hetter with re

28

and appears to have # useful life of tens of thousands
of passes, Unfortunately no Reeves tape that we have
tested has equaled the freedom from drop-outs and
amplitude variations that is characteristic of nearly
every sample of Minncsote Mining instrumentation
or video tape that has been tested.

6. Multiplexing Systems
a. Furquencr Mutrivrexmc

At the beginning of the project it was proposed
that « frequency-division multiplexing system be used
to put wideband video information on a plurality of
tape channels. It was further proposed that con:
ventional bandpass filters be employed for this use
by reverse playback. When the point in the develop-
ment wes reached where the information in onc
frequency-division band was added to the adjacent
band an inherent limitation of the reverse playback
scheme. became apparent. The information in the
two bands did not add up properly but there was no
straightforward way of determining why, In a reverse
playback system ne part of the system can be evalu-
ated for the manner in which it will perform in the
Overall system. unlos tho whole system is working.
Any test that is made must invoke reverse playback
and little can be done to circumvent this limitation,

—SECRET—



— SECRET

Because of this time consuming difficulty the use of
reverse playback for phase correction was abandoned.

‘An effort was mado to develop a sct of bandpens
filters thet cond be used in a frequency-division
systema without dependence Upon reverse playback as
mentioned shove. Although this goal has often been
considered «mattainable, it was hoped that somo
recent developments might: offer new Possibility, In
tho course of consulting with filter experts within
RCA it was brought ont that ‘a system of deriving
a ecrles of related bandpasa filters from one multiple
tapped delay line is ideally suited for this application,
Such a systen: of filters derived from a widehand
constant-phaseshift delay line inherently has ideal
crossover characteristics and, if made correctly, rather
complete freedom from phase distortion, A filter of
this type suitable for this application was designed
and constructed. Unfortunately the basic delay line
was inadequate and there was insufficient time to
construct another delay line, It is our belief that this
approsch is feasible and is perhaps the only system

now known which will provide frequency-division
multiplexing without relianee on reverse Playback.

hb. Tose Mutrieuexine

A time-division multiplexing system that was avail.
able from another RCA activity was integrated into
the aix-channe! tape system for an evaluation in this
application. A color TV broadcast signal was ro-
corded by this system and the reproduction of the
aecording, while not of commercial quality, was
geod cnough to prove that the color information
could be reproducod. It was determined that the
Picture quality was being limited by mechanical
vibration in the development recorder. The capstan
is known to rotate at a very constant speed, However,
the magnetic head is mounted on the top panel of
the recorder and those vibrational components of
the panel whieh are rotary and centered on the
capetan axis result direetly in apparent tapespeed
variations, Such variations could be detected in the
capalan servo. These speed variations reaulted in time
Jitter heyond the accommodation of the thne-division
system ani were not overcome in our experiments,
The mechanical vibration arhes when high tape
speeds, of around 400 or 500 inches Per serond, are
used. A previous recorder built on the same general
Pattern for another RCA activity, but operating at
100 inches per second, did not exhibit this Imitation
as a result of mechanical vibration. By the time this
difficulty was noted there wae insufficient time to
make necessary corrections and a completely satis.
factory recording was not attainod.

& Ornsa Mouretaxinc Consinzrarions

The television magnetiorecording system which
has heen considered under this contract employs
what might be called optical time division multiplex
to permit one camera to look at 36 different side by
side images of the ground, Under the proposed
specifications this resulted in a camera video signal
of eight megacycles. Electrical muluplexing was
Proposed fur narrowing tho bandwidth so that these
signals could be recorded on and played back from
tape. Thus, optical multiplexing was used to incresse
the information rate on an electrical channel to the
extent that electrics) multiplexing was required to
narrow the bandwidth to put the information into
useable tape recorder form.

prey

size, weight, and performance of televieion cameras
exlating at tho time of the initiation of the contract.
Before the magnitude of the diffeulties of
multiplexed video was realized, it was believed that
the use of multiplexing wae in fact the best way to
proceed, ‘Two occurrences have altered our thinking.
The fret is thet high-quality miniature television
cameras are now available using vidicons and tran-
sistors, which give performance of the degree required
for reconnaissance work and which are so small, light
in weight, and economical of Power consumption that
several could be used in the place of one image
ccithioon camers. The second is our nogative result
with regard to the use of time or frequency-division
multiplex for eight- megacycle video

Another approsch to the problem which should be
fiven careful considoration when farther television
reconnalsance work is to be undertaken is the use
of optical multiplexing only to the extent that the
‘output of one camera may he recorded on magnetic
tape with its fuli bandwidth. If, for example, 36
cameras were used, each to look at just one image,
and 36 tracks were used on the tape, the recorded
signal on cach chennel could he one thirty-ixth of 8
megacycles or 222 kiloeycles. The recording of such
a signal could be handled with little difficulty, One
need not go to this oxtreme, however, to realize an
advantage. If, for. inssanee, six cameras were need,
cach optically multipleied to look at six images, and
the output of each recorded on one of six tracks, the
recorded bandwidth would be roughly 1.3 megacycles
oneach channel, A capability for this type recording
has been shown hy the studies reported here.

A more detaile! discussion of this parallel channel

29

— SECRET



Rene

made somewhat difienlt heoruse of the very weak fave drum
Teflection returned to the autosollimator by the mseal ta tien ditfecent design, sah ma sleeve bearings Inner
elimi-

to

Sealey and quality of the light resching the pickup means for alignment of the prisms
tube, ‘on the segmentation drums. Tt should also he made
The for the drums and prisms should re- the deegitat the locating pins and the pinholes te
quire that identifying numbers are Placed on each the drums ere square tothe drum facen aad the natn
Priam and on the mouating faces of the segmentation Priam hase surfaces, The high reduction
drum, 1s is recommended that the sogmeatation drtses speed reducer con: to the vibration problem.
he constructed to that the pram mounting surfaces A designed malti-poted motor Operating at

BR
e
E

collimator. In the construction of the mossie inva It should alo be mentioned that searing

the photographs made with the optical system, ir non be enclosed as « protection from dirt. A com: -
found that there was « slight alternate vertical die sive structural analysis should be made of « new
placement of adjacent pieture frames, These frames design to insure rigidity with Hight weight. The new
were taken alternately by the upper and lower oe design should make tho alignment of the segmentation
mentation drums. This indicated that the axes of drum auembly with respect to the optical systems
rotation of the two drums were not parallel, In view independent of the jacks that enpport and lent ake
of the fact that the high quality tapered roller bearing complete unit.

7



» 841837

DEFENSE DOCUMENTATION CENTER

FOR
SCIENTIFIC AND TECHNICAL INFORMATION

CAMERON STATION, ALEXANDRIA, VIRGINIA



AD 341837 7

DEFENSE DOCUMENTATION CENTER

FoR

SCIENTIFIC AND TECHNICAL INFORMATION
CAMERON STATION, ALEXANDRIA. VIRGINIA


—SECRET-

Tubes 18548 and 1507-1 each had the same anode
structure (4inch long tbe, and 18-inch limiting
aperture), and all tubes had support rods of “multi-
form” glass. Tube 1854-3 had « G2 ring (primarily a
corona device), which the later two did not have, and
its G1 was a stamped unit with special sperture-edge
beveling and pleting treatment. Tube 1507-1 had a
precision-machined Gl, of slightly smaller aperture.
Tuhe 1506-) had a thinly coined and drilled G) struc-
ture, with the same aperture diameter as 1507-1, but
its anode was 2 inches long with a somewhat smaller
limiting aperture than the other two.

Some messurements of response were also made in
the picture corners, but these turned out to be more
an evaluation of the focus modulator (dynamic focus)
device than of tube and deflection performance in
the corners, The dynamic focus wea not fully ade-
quate, but its performance can be made satisfactory.

‘When the main focus contro! was reset for optimum ~

in a given extreme corner, the 560 TV-line response

was generally in the order of 3¢ as good as at the
center,

Tt chould be noted that, in May 1957, 2 develep-
ment project started in the RCA Tube Department
which fe expected to result in a significant improve-
ment in resolution and fine-detail contrast for the
type of himescopes considered for this application. It
is expected that there should be very little decrease
in response around 200 TYV-lines and, even on a S-inch
tube, the 560 TV-line response in the central area of
the phosphor should be significantly better than that’
shown in the accompanying data.

The major change in kinescopes is the probable
use of a transparent phosphor, instead of 2 “trane-
Tucent” one. This should greatly reduce the image
deteriorations due to light scattering in the present
comparatively-thick granuler structure, and the flare
and halo caused by ambient light and reflections from
the front of the face plate.

RESTRISTIED MSTRBOTION

Approval jor rele
hon W DIR

ase must be obtained


—S5eReT_

three plumb, lines are in a single plane, By

and making notes of the im which C or D
might be moved to bring them into « commen plane
with A, and by noting the same with Tespect to B,
it is possible to deduce the adjustments that mus: be
puade im the pasitions of C and D to bring them
both into the plane of A and B, This requires patience
and care ‘but is not especially diffcult, With the

Tine segments AC and DB are scribed;

Segments AF and BG are laid out perpendicular
to AB, using the familiar compass and straight edge
mathod of Seomictry an indicated by the construction
about the arbitrary center K,

Spherical mirrors are located at F and G according
to the dimensional requirements of the design, ant

hall He at a corresponding point
G'. This ia brought about by suspending « plumb
line above the point M on AF, after which the eye
placed near A can observe when plumh lines A and
M, and the image of plumb line A in mirror F are in
® common plane, Coplanarity of these lines is at
tained hy lightly tapping the mirror to rotate it on
A vertical axis until they are observed to be in align-
ment. The center of F is then at F', The procedure
for mirror G. is identical,

Ateach of the points A and B are two plane mirrors
m and n The mirrors of each pair are
mipposed to lie in a single plane normal to plane
FABG and at 45° to line AB, as indicated by the linea

to the dimensional Féquirements of the design,
Mirrora m are adjusted by renioving corrector U and
placing an illuminated pinhole at the-location of its
center. The mirrore m are then adjusted until the
light from the pinhole which they reflect to mirror F
ia returned by them to two images of the pinhole that
substantially coincide with each other and with the
Pinhole. This is Possible because mirrors n reflect
the center of curvature of spherical mirror F to the
center of corrector U. The Planes of mirrors in are

line suspended shove A, This condition ia jadged
visually and should be maintained at every stage in
the adjustment of mirrore m, The same Procedure ia

6

wed to adjust mirrors n, Correctors U and V are then
restored to their nominel fanetioning poaitions Be
cause of their very low Power, the con
Teh AY be Ioeated and squared by ordinary
sighting means, taing the plumb lines suspended
above A, B, C, and D,

b, Avonmanr ov 35 sae Camuna Booms ar Foca.
PLans or Ornicar Srerex
A larg alurainised optical flat was placed at the
position J, see Figure 5, facing the Schmidt Optical
System under alignment.

at this point after the removal of the source,
The alide was held at the film plane by the 35 mer
camera body at A (the camera body wed was the
standard Argus, Modcl A). Rather than repeat the
shore procedare for the other Schmidt System, the
optical flat was removed and the system FAC was
used as a collimator for system DBG, The illuminated

C Drum ano Snurren Puasine
‘The operating eycle of the segmenting optical ey»
jem comprises a sequence of 36 exposure phases.
These phases are spaced at equal intervals of drum
and shutter rotation and therefore at equal intervals
of time when the parts are driven at uniform rote-
tional speeds. The drame normally rotate at 100
RPM, but for the PRUTpascs of photograph: lesthag, a
special speed reducer is weil to reduce this rate to
T%, RPM.
AT 100 RPM, the normal television exposure time
is 0.0015 second, doring which the mirrorstat drums
100

rotate w x 360° = 0015 = 09°, Wik & photo.
graphic shutter operating at Ky second, the drum
sped tbe X RPM where: = © 360° « %, = 0,99,

This makes X — T% RPM. At this peed, the

drame again rotate 0.9° during the exposure time of
tho second, which is used in photographie testing.

~SECRET—


of the motor direction to keep the upper dram
rotating to a0 seen from above, The
two speed are dimensionally interch,

optical sywtem, “Right” and “left” are referred to
an observer who views the system along the direction
of the light as It enters the drum compartment, Thus,
the shutters admit light alternately to the two
branches from tho lower dram, then alternately to

Connected
train, which is driven by a 3600 RPM synchrocoms
motor. It is important in the completely assembled
equipment that it be Possible to determine by 2
simple routine examination that these moving parte

checks easy.
A number has heen punched ox cach corner of the
Upper surface of each dram, ‘These are the mirror.

the numbering system that Appears in
(Progress Report #7, p. 10, F. 8, ete).

A dial is located on the top of the dri com;
ment cover, shown in Figure 6, and is provided with
a moving hand or poinier that rotates count

ingly ranges from 19 to 36 inclusive,
eighteen positions ahout the dial is, therefore, identi-

rfl
hil
eiag
af
He 5
fle
ply

Par

re
i
i
Hi
i

Li

it

'
|

E
F
E
i
i
ge.

Sar


UNCLASSIFIED

AD NUMBER
AD341837

CLASSIFICATION CHANGES

TO

confidential

FROM

secret

AUTHORITY

Group-3 DoDD5200.10, 26 Jul 1962

SORE SOR gery

THIS PAGE IS UNCLASSIFIED



tape tenslen in the zecardez and 16ounce tension in
the loop machine, Js appeared that tho tape tension
in the reorder was insufficient to prevent the forma

secommodats the incresse in the top frequency in the
FM spectrum from the FM modulators resulting from
recent changes in the multiplexing system. With the

adjusted for sight ounces tape tension, tape skew
measurements were made hy recording a two-mege-
cycle tignel on each of the six tracks, and then during
Playback various combinations of pairs of tracks
were added together and viewed on an oscilloscope.
Tape skew would result in relative time displacement
of the signals from two tracks and appear as « heavily
amplitude-modulated signal. it was estimated that

the tape tension was firet incrcascd to sixteen ounces,
and then it was found that the time period of these
amplitude variations matehed that of the rotary
stabilizer and not the fape reels.

‘Tho original mechanical design of the development
recorder included an rotary stabiliser in
the tape path, The span of tape between this stabiliser
and the capstan wae about 5 inches, and the point of
magnetic head contact wee about the middle of this

there could be no doubt that the problem was serious
since it did not permit the multiplexed information
in the several tracks across the width of the tape
to be added up properly.

Tt was decided to replace the rotary stabiliser with
« Bonvotating air tape guide. This is the same
size and in the same position as the rotary stabiliser;
it is, in fact, very similar to the stabilizer pulley
cxcopt that it does not rotate and the tape contacting
area has grooves which are supplied with air under
moderato pressures of around two to five pel, Tt was
then found that tape skew was very low provided
that the distance between the flanges of the edge
guides was ne more then about one mil mere than
the width of the tape. A aumber of samples of tape
were checked for tape width throughout their length.
Table 1 shows the results of measurements at scveral
points slong the entire length of two 3500 foot rolls
of magnetic tape.

Table 1
Results of measurements of tape widths
Sample No, 1 Sample No. 2
0.4976 inch 0.4967 inch
04974 0.4967
04971 0.4963
0.4974 04962
0.4974 0.4965
O4971 0.4969
0.4973 0.4968
0.4976
04972

The experience of other groups within RCA indi-
cates that O.S-inch wide tape could be obtained in
large quantities with « definite width maintained
within 2 or posstbly 1 mil throughout any roll snd
from roll to roll over a period of years. :

Using tape sample No. 1 with the tape guide set
for 0.4580 inch it was found that the signals from
any two tracks would always add in Phase. It was

7

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Figere 17, Demodvlator, Schematic Diogres

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B. MAGNITIC RECORDING
1. Introdection

‘Tho primary objective of the magnetic recording
studies was to evahzate the feasibility of nultiplexing
a wide-band video signal into several arrow band “
signals, recording thees signals on several channels
a multichannel tape recorder, playing them back at
a later time, and, from these recordings, reconstruct-
ing the original wideband video signal. Both fre-
uency-division and time-division multiplex systems
have been studied. Much time and effort have also
Deen spent on developing the techniques of magnetic
recording that allow the multiplexed signals to be
recorded on and played back from the tape.

The principal areas of effort covered by this re.
Port are:

1, Improvement of the fi edulation

modulators and demodultere

2. Modifieation of the tape transport mechanism

to minimize tape Sutter, skew, and amplitude
variations,

3. Reduetion of cromtalk heiween tape channels,

4 Selection of tape for heat performance.

5. Development of frequency.llvision filters with

minimum phase distortion.

6 Evaluation of an existing timedivision multi-

plex equipment in this pplication,

2. Frequency Modulation Recording Channels

During the period covered by this supplementary
Feport, many changes and improvements wore made
in the freq

The input and eutpat of the recording system are
the multiplexing units which will be discussed later
in the report. For this section it is sufficient to note
that the input multiplex unit converts the wide-hand
video input signal into several narrow-band signals
and that the output multiplex unit converte several
narrow-hant signals into one wide-hand video output
signal, .

As is indicated in Figare 18, the input multiplex
unit feeds eix identical channels in the tape recorder.
Five of these channels are used for the multiplexed
video while the sixth channel is used for synchroni-
sation to insure that playback and recording are
accomplished al the same speed so that a true repro-
duction of the input may be obteined on playback,

The narrow bandwidth recording channels were
designed to accept video information with a pasecband

18

signal is then recorded on the magnetic tape.

The signal on the tape ie picked up oa the play.
hack head and fod to a cascode amplifer, Figure 16.
The first part of the cascode amplifer’(14-CK603
tube) is located near the Playback head and the
second part (14-5670 tube) is located on the play.
back-amplifier chassis, In addition, the playback-
amplifier unit contains three GAHS and one 6CL6
amplifier tubes which amplify the, aignals to a level
suitable for feeding the demodulsiors, .

The demodulator unit, Figure 17, consists of a three
stage bandpass amplifer (3-GAH6's) with symmetrical
clipping to feed a 6C4 phase splitter. The outputs
of the phase splitter provide push-pull information
for the first grids of the two GAS6 doubly balanced
modulator tubes. At the same time, « 6CL6 oscillator,
Figure 18, generates an 11.25 megecycle signal which
4s amplified by a 6CL6 cscillator driver, Figure 19,
The driver is coupled to a bifilar transformer which
feeds « puslepull 11.25 le signal to the third
atids of the 6486 double balanced modulators, Al
though the ‘conduction angle of the third grids Is
nnall, the 11.25 megacycle signal is not doubled in
frequeney to 225 megacycles, as in a push-pull
doubler, since the conduction angle is accurately
controlled to reduce the second harmonic content in
the plate current of each tube to zero. Jn oriler to
obtain « good 22.5 megacycle null, a condition neces
sary to minimise the interfcring beat signals in the
detector output, a critical adjustment of the drive,
‘be bias, and grid resistors are neceesary. When these
tubes are unbalanced by the 1.3 megecyele signal,
eum and difference frequencies of the signal and the

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Figure 4. Closeup View of the end

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