Comtech EF Data CRS-170A - Manual (Page 53)

CRS-170A L-Band 1:1 Redundancy Switch MN/CRS170A.IOM
Modem and Switch Configuration Revision 13
4–5
4.2.2 Configure CDM-625/A Carrier-in-Carrier® for Redundancy Operation
The Pre-Mapped Symbol Interface (PMSI) is associated with DoubleTalk ® Carrier-in-Carrier ® . It
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 1:1 redundancy, the PMSI is an EIA-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 CDM-625/A 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 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-170A).
• Chapter 5. CABLES
AND CONNECTIONS
• Appendix A. CABLE DRAWINGS