Comtech EF Data CRS-180 - Manual (Page 47)

CRS-180 70/140 MHz IF 1:1 Redundancy Switch MN/CRS180.IOM
Modem and Switch Configuration Revision 11
4–5
4.2.2 Configure Carrier-in-Carrier® for Redundancy Operation
The Pre-Mapped Symbol Interface (PMSI) is a function associated with DoubleTalk ® Carrier-in-
Carrier ® that permits the modulator in a selected unit to provide a direct copy of its output (the
outbound interferer) to the second modem. The other modem may then choose to take the
PMSI signal and use it for its own CnC reference. In this 1:1 redundancy, the PMSI is an RS-485
multi-drop bus system where one device transmits and the other device on the multi-drop bus is
configured to receive.
If you use Carrier-in-Carrier ® (CnC), you must configure the CnC control setting to Redundancy
mode using the modems’ front panel menus.
Do these steps to configure the CnC control setting for CDM-625/A 1:1 Redundancy:
Step Task
1 From the modem front panel top-level SELECT: menu – Use the ◄► arrow and ENTER keys to
select the PMSI control mode menu: SELECT: Configuration  CnC  PMSI-control
CnC PMSI mode: Redundancy
(Idle, Redundancy, Talk, Listen) (
)
Use the ▲ ▼arrow keys to select Redundancy, and then press ENTER.
2 You will now need to connect the two modems together via use of a 1:1 PMSI cable (note that this cable
bypasses the CRS-180).
• Chapter 5. CABLES AND CONNECTIONS
• Appendix A. CABLE DRAWINGS