Theory of Operation
SMS-758 Modem Protection Switch
4–32
MN/SMS758 Rev. 3
Backward Alarm 1 In
BWI1
12
Backward Alarm 2 In
BWI2
13
Backward Alarm 3 In
BWI3
14
Backward Alarm 4 In
BWI4
15
ADPCM 1 Audio In
A1I-A
A1I-B
45
29
ADPCM 1 Audio Out
A1O-A
A1O-B
46
30
ADPCM 2 Audio In
A2I-A
A2I-B
47
31
ADPCM 2 Audio Out
A2O-A
A2O-B
48
32
Demod Fault Relay
DF-C
DF-NO
16
50
Modulator Fault
MF
49
Demodulator Fault
DF
33
Deferred Maintenance Alarm
DMA
17
Note: MF and DF inputs are only on the prime and backup modem interface connectors,
not on the terrestrial data connector.
