TM 11-5820-803-12
Figure 2-1. PSK modem interface.
Figure 2-2. Biphase PSK modulation
by system noise and the 70 MHz input power level is
variation at the downconverter output) and interface
lower and may vary over a considerable range.
network or cable (expected cable or network losses).
Detailed information on setting the internal range
selection switch is given in paragraph 2-20a.
(2) The PSK modem accepts input signal
power variations of 55 dB in any installation. The ability
to select either of two different ranges is provided to
c. Fault Alarm Monitor Signal Characteristics.
allow for differences in installations. The selectable
The PSK modem contains several on-line fault
ranges are 0 to -55 dBm or -20 to -75 dBm. Range
monitoring circuits which monitor the fault status of both
selection should be determined prior to installation by a
the transmitter and receiver. A relay contained in the
review of the earth terminal characteristics (expected
PSK modem is operated to provide a contact closure
power level and
2-2
