Figure 2-1. PSK modem interface.

TM 11-5820-803-12

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