Comtech EF Data SMS-758 - Manual (Page 101)

SMS-758 Modem Protection Switch Theory of Operation
MN/SMS758 Rev. 3 4–41
Primary Alarm Out PRI_COM
PRI_NO
PRI_NC 10
43
27
Secondary Alarm Out SEC_COM
SEC_CO
SEC_NO 11
44
28
Modulator Fault MF 49
Demodulator Fault DF 33
TRANSMIT DATA
TRANSMIT ESC
RECEIVE DATA
RECEIVE EXTERNAL
REFERENCE CLOCK
RECEIVE ESC
TX S/B TX
TX
PRIME C/U
DATA I/O
RX
TERRESTRIAL
DATA I/O
RX
B/U #1 AND B/U #2
DATA PATH
SELECTION
RX S/B
RX
NOTE: THE RELAYS ARE SHOWN IN THE NON-ENERGIZED
POSITION CONNECTING THE TERRESTRIAL DATA AND
PRIME MODEM CONNECTORS TOGETHER. STANDBY (S/B)
SIGNALS ARE ROUTED TO THE OFFLINE BACKUP MODEM.
TRANSMIT DATA
RECEIVE DATA
RECEIVE ESC
TRANSMIT ESC
RECEIVE EXTERNAL
REFERENCE CLOCK
MOD AND DEMOD FAULTS
DATA SW ITCH
MOTHERBOARD
INSTRUCTION
DECODER
TX RELAYS
RX RELAYS
FAULTS
TRANSMIT DATA
TRANSMIT ESC
RECEIVE DATA
RECEIVE ESC
RECEIVE EXTERNAL
REFERENCE CLOCK
Figure 4-14. Prime 2:N IBS Interface Switch (1695)