Comtech EF Data SMS-458B - Manual (Page 72)

SMS-458B Modem Protection Switch Revision 2
Theory of Operation MN/SMS458B.IOM
4–12
data, and J3 is the IDR with ESC interface. The backup interface switch module can plug
into A10 slot only.
When the interface switch module is powered down or in the default position, all prime
interface switch module signals are routed between the terminal equipment and the prime
modem.
Modulator and/or demodulator signals can be independently switched to the backup
modem interface switch module. The fault lines from the modem connector are routed
through the interface switch modules to the M&C.
When using G.703 data switching, a buffered set of transmit data (SD) signals is switched
to the “hot standby” backup modulator and demodulator during prime modem operation,
or to the offline prime modulator and demodulator when a backup operation occurs.
4.2.1.2 Specification (IDR/G.703)
Circuits Supported SD, RD, EXC, TXD, TXC, TXO, RXD, RXC, RXO, BWO 1-4,
BWI 1-4, A1I, A1O, A2I, A2O, DEMOD FAULT.
Switching Format All signals switched with dry contacts.
Contact Arrangement Modulator signals: 16 poles.
Demodulator signals: 26 poles.
Spares: 2 poles.
Demodulator signals: 26 poles.
Spares: 2 poles.
Synthesized Data Source All ones Data Pattern.