Comtech EF Data SMS-758 - Manual (Page 93)

SMS-758 Modem Protection Switch Theory of Operation
MN/SMS758 Rev. 3 4–33
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
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 SWITCH
MOTHERBOARD
INSTRUCTION
DECODER
MOD RELAYS
DEMOD RELAYS
FAULTS
TRANSMIT DATA
TRANSMIT ESC
RECEIVE DATA
RECEIVE ESC
RECEIVE EXTERNAL
REFERENCE CLOCK
Figure 4-10. Prime IDR Interface Switch
TRANSMIT DATA
TRANSMIT ESC
RECEIVE DATA
RECEIVE ESC
RECEIVE EXTERNAL REFERENCE CLOCK
MOD AND DEMOD FAULTS
BACKUP C/U
DATA I/O DATA SWITCH
MOTHERBOARD
Figure 4-11. Backup IDR Interface Switch