TM 11-5895-846-14
(a) Power amplifier. The PA amplifies
available at this panel for analysis.
SHF output of either an upconverter or an amplifier/mixer
6-6. Commmunications Subsystem
to a power level sufficient to provide 1000 watts (single
carrier case) at the antenna. Amplification in the PA is
equipment for processing voice, teletype, and data
accomplished by a five-cavity, tuneable klystron. The
signals. For transmission, these signals are sent to the
cavities are tuned by presetting counter dials to numbers
radio subsystem, normally as a phase-modulated, 70-
read from a drumtype tuning chart built into the klystron
MHz IF. In reception, a 70-MHz IF from the radio
front. Both the dials and tuning chart are accessible
subsystem is demodulated, decoded, and otherwise
through a door on the PA front panel. The PA design
prepared for use by the DCS/field user. Voice and
includes circuitry for protection against high load VSWR,
teletype circuits are transmitted and received through
power monitoring and low power alarm functions, and an
four junction boxes, each box having 100 feet of cable
output level control.
attached. Two boxes are utilized for 12 voice circuits
(b) High voltage power supply. The
and five teletype (FSK) circuits. The third box is utilized
HVPS provides all necessary voltages for the PA, and
for three high-level or four low-level teletype circuits. The
sequences turn-on power to prevent surge damage. The
fourth box is available for miscellaneous use through the
front panel of the power supply contains status and fault
CDF and VF patch panel.
indicators, as well as power, test, and monitor controls
a. Voice Frequency Circuit. User VF circuits are
and indicators. The unit is powered by three-phase,
processed through line conditioning units which are
50/60 Hz from the power distribution panel.
configured for only the following traffic modes.
(c) Waveguide switch. The output of
(1) 4-wire circuits employing either 1600 or
each PA is routed to a manually operated waveguide
2600 Hz in-band signalling.
transfer switch that serves to direct the power from a PA
(2) 2-wire circuits employing 20 Hz ringdown
to the antenna, while routing the output of the other PA to
line conditioning units can be configured to handle any of
a dummy load mounted at the upper rear part of rack 4.
these traffic modes in any combination. Each signalling
The switch is mounted in rack number 3. Actuation of
mode is converted to E & M signalling for proper MUX
the switch interchanges the role of each PA between
processing. Variations of user voice frequency levels are
being the on-line and off-line unit. With this switching
system, the off-line PA (connected to the dummy load)
patch panel provides facilities for emergency patching
may be operated for test or diagnostic purposes, or may
and circuit monitoring on both line and equipment side of
be entirely removed from the shelter without affecting the
each processing unit. Each of the 12, full duplex circuits
is routed through the echo suppressor included in the
d. Patch Panels.
line conditioning equipment.
(1) Comm track patch panel. The comm
b. Teletype Circuits. The four keyers change the
track patch panel is used to select the track IF output of
low-level teletype electrical impulses into frequency shift
either downconverter No. 1 or No. 5 for input to the
keying (FSK) and the four converters do the converse.
antenna control unit. The panel is also used to select
Inputs from the five FSK teletype inputs plus the four
either the comm track or beacon tracks modes. Beacon
internally-keyed teletype lines are fed to the TTY/FSK
signal tracking requires that one downconverter be
patch panel so they may be inserted into any of the nine
dedicated to tracking only.
channel inputs of the TTY filter bridge. A composite
(2) Transmit patch panel. The transmit patch
signal from the filter bridge will be fed to one channel of
panel is used to configure the transmit chain. The SHF
the multiplexer. Conversely, the received signal is fed
outputs of the upconverters, the RF inputs and outputs of
through the filter bridge and the converters to the
the amplifier/mixers, and the RF inputs of the power
junction boxes.
c. Data Circuits. There are six synchronized data
(3) RF test patch panel. The RF test patch
inputs, two asynchronous 75-ohm inputs, two
panel is used, in conjunction with the LNA
asynchronous 50-ohm inputs, and two asynchronous
control/translator, in testing the entire transmit/receive
user encrypted inputs that are 50 kb/s each. All data
chain. Upconverters No. 1 and No. 2 each provide a 5-
rates up to 512 kb/s are fed through the multiplexer. The
MHz output for use in the LNA control/translator. These
two asynchronous, 50 kb/s circuits are fed through the
5-MHz outputs appear on the RF test patch panel,
CV-3034 analog-to-digital converters which make the
together with attenuated SHF outputs from the PA's, and
signals compatible with the multiplexer. All data circuits
the SHF and 5-MHz inputs to the LNA control/translator.
enter or leave the shelter through data and clock
In addition, a sample of the received RF signal is
connectors.
6-11