Comtech EF Data SMS-758 - Manual (Page 97)

SMS-758 Modem Protection Switch Theory of Operation
MN/SMS758 Rev. 3 4–37
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
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 4-12. Prime 2:N IDR Interface Switch (1877)