G.E. Mucri-Wave Exhibit Type VA-2 (25 Channel)

• Document Type: CREST
• Collection: General CIA Records
• Document Number (FOIA) /ESDN (CREST): CIA-RDP78-02820A000100080014-7
• Release Decision: RIPPUB
• Original Classification: S
• Document Page Count: 2
• Document Creation Date: December 9, 2016
• Document Release Date: April 27, 2001
• Sequence Number: 14
• Publication Date: September 17, 1956
• Content Type: MEMO

Approved For Release 2001/07/16_: P78-02820A000100080014-7
17 September 1956
VA2 25 Channei.}
MEMORANDUMFOR TILE
SUBJECT: Micro
1. A visit
held in Washington, D.
in attendance were:
' E. Microwave Radio R
ber 1956. Agency 0C-XTa
bit
2. The G. E. ngineertng
up two terminal
s with 2 ft. parabolic dishes on apposite aides of a large room
Fre utilising four (4) channels in conjunotion with a Btroaberg
Car on Relaymatic Telephone Board. The equipment is capable of
-flve (25) channel operation employing time-division multiplex-
ing a "quadriphase system for channel timing. The manufacturer
anise the basic simplicity of the timing signal is a new approach
for time division syncronisation systems and is more adequate to meet
present day standards for microwave reliability.
3 The equipment operates in the 1700-10504C band for government
cations and will supply 20 watts of peak over to the antenna.
ve transmitter is crystal controlled (90MC overtone) with
es of amplification, and using a GL-2C3913 lighthouse tube
e final. Transmitter tuning is conventional and ray be metered
by tip jacks on the front panel. The output of the transmitter is
ugh a duplexer filter to a low loss stryonex coaxial trans-
Line to the antenna. A six (6) ft. parabolic reflector with
a dipole mounted in a. 'weatherproofed cup with a nominal beam width of
6 degrees, at the - 3db points, is normally used as the antenna system.
The diameter of the parabolic reflectors plus the transmission line
losses, bowever, are a function of the allowable system signal to noise
ratio. In a properly engineered system the manufacturer claimed a 30db
fade margin" i.e. the received signal could drop to 0000 of its
optimum value through pat* attenuation, transmitter power drop, antenna
misalignment etc. before the signal to noise retio would drop to an
unusable value.
Approved For Release 2001/07/16 : CIA-RDP78-02820A000100080014-7
25X1A9a
Approved For Release 2001/07/16 : CIA-RDP78-02820A000100080014-7
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4. The microwave receiver consists of * war able atenaustor, input
cavity,mixer, and i.f. amplifier. The transmit/receive frquencies are
separated by bomc and miser injection voltage is obtained from the trans
mitter to Obtain the bomc i.f. signal. Printed circuits are used In the
three (3) stage i.f. amplifier. The attenuator, a calibrated front panel
control, allows the operator to visually determine, in conjunction with
en external oscilloscope, the "operating margin? of the nr path, associated
with the receiver, without interuption of communications. The amplitude of
the received signal could be varied if system performance had changed from
Its normal operating status.
5. The master sync generator c
drives a, phase inverter
and frequency but of
toted with each phase laver
r produce two sine waves wh
.9291CC oacillator, the
es two sine eaves of
. A 90 degree phase
ich phase inverter
er by 90 degrees.
put consists of 4 sine eaves of the same frequency but
900 degrees and noted as phase A,B,C,D. To form a
S divider network is connected between any of the
put is utilized to trigger a saw tooth generator.
is of the resistors in the phase divider network,
11 cause the channel to be generated at the mid-
ted for that particular channel. With a
29 AC a complete "revolution" or frame
ds. In a, 25 channel system this time
croseconds with a 4 microsecond guard and
guard space. The presence of an audio
pulse to be formed earlier or later
tion is plue or minus one microse
ler to the transmit sync system
to detect the distinctive mark
ved wave train.
6. The *qui
re rear
e technic
around. hoar space
ing.
7. De
modify On es
mile in flat
d in a standard, W. E. reck with: the Unite
is desired. This arrangement permits a
k a unit shile in operation without *welkin
conserved compared to to conventional reck-
upon cae.lexi.ty of the system desired which may
ystem cot estimate is approximately $1000 per
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