Comtech EF Data CRS-170A - Manual (Page 36)

CRS-170A L-Band 1:1 Redundancy Switch MN/CRS170A.IOM
Introduction Revision 13
1–16
redundant power to the CRS-170A through the CRS-150. The SMS-301 itself has redundant power
supplies, and feeds power to the CRS-170A through the control cable. Online/Backup Modem
configuration matching is provided by the CRS-150 controller communication with the CDM-600L
(CLM-9600L) modem. The SMS-301 does not automatically configure the Backup Modem.
Operation with two CDM-600L (CLM-9600L) modems requires an additional CRS-150 1:1 switch
for terrestrial data switching and 1:1 control, while operation with two SDM-300L3 modems
requires an additional SMS-301 1:1 switch to handle terrestrial data and control. Thus, there are
three functional configurations for the CRS-170A.
1.3.3.1 Operation with CDM-600L (CLM-9600L) Modems and CRS-150
Switch
CRS-150 1:1 Redundancy Switch Installation and Operation Manual (CEFD P/N
MN/CRS150.IOM)
THE CRS-150 IS AN ACCESSORY PRODUCT DESIGNED SPECIFICALLY FOR THE COMTECH
EF DATA CDM-600 AND CDM-600L (CLM-9600L) MODEMS, AND MUST NOT BE USED
WITH ANY OTHER EQUIPMENT.
Figure 1-10. CRS-150 1:1 Redundancy Switch
The CRS-150 1:1 Redundancy Switch (Figure 1-10) connects to Online and Backup modems,
monitors the fault status of these units, and controls the routing of data to and from the units.
IF signals, 10MHz reference signals, DC power for the BUC and LNB, and FSK signaling to the BUC
are switched in the CRS-170A under control of the CRS-150. In the case of an equipment failure,
automatic switching takes place to protect the traffic circuit.
At the heart of the CRS-150 is a Controller State Machine that is responsible for fault monitoring
and control of switching functions – it is implemented in a Complex Programmable Logic Device
(CPLD).
The CRS-150 derives its operating power from the Online and Backup modems via extra power-
carrying wires in the data cable from each modem. Similarly, the CRS-170A derives its +12V
power from both modems through 'Y' cable connection to the same cables. The required online
and offline control signals are also included in these cables. A diode sharing arrangement with a