Product specifications

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

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.

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