TM 11-5895-846-14
b. After 39 dB of amplification in an LNA, the
signal is carried by coaxial cable to the receive antenna
entry port at the shelter wall. Within the shelter, the
received signal is divided five ways to provide equal
inputs to each of the five downconverters. The five way
signal division is accomplished by the combination of a
directional coupler and a 4-way power divider as shown
input to downconverter No. 1. This sample is routed to
the RCV TEST OUT jack on the RF test patch panel. In
the downconverters, the received SHF signal is
translated to an IF signal at either 70 or 700 MHz, as
desired. The IF outputs are routed to the IF patch panel
in rack 5 on the CSS side of the shelter, where patching
to the modems is performed. The track IF output of
either downconverter No. 1 or No. 5 (as selected at the
tracking module within the antenna control unit.
c. In the transmit portion of the radio subsystem,
patch panel goes to the on-line upconverter where it is
translated up to 700 MHz. After amplification and
filtering, the 700 MHz is translated to the transmit output
frequency of 7.9 to 8.4 GHz, as selected by the
frequency synthesizer in the upconverter.
This
frequency synthesizer is identical to and interchangeable
with the downconverter frequency synthesizer. The
signal at the selected transmit frequency is filtered and
amplified by an intermediate power amplifier in the
upconverter, to a level suitable for driving the
amplifier/mixer.
6-18