Comtech EF Data CRS-200 REDUNDANCY SWITCH - Manual (Page 26)

CRS-200 COMTECH COMMUNICATIONS CORPORATION
CRS-200 REDUNDANCY SWITCH - OPERATIONS MANUAL PAGE 24
8.3.1 SINGLE TRANSPONDER
If all modems are to be connected to the same transponder, it is necessary at this time
to configure each modem’s transmit side to the proper data rate, IF frequency and
output power level. Once this is done, the user must combine these carriers together
using BNC cables into a single power combiner. The output of the combiner is then
fed to the upconverter. Both the cables and the combiner must be the same
impedance as the modems to prevent mismatch.
On the receive side, the output of the downconverter must be attached by BNC cables
to a single splitter which in turn feeds all the receive IF ports of the modems.
When a traffic modem is taken offline, its transmit IF will automatically shut down
and be replaced by that of the redundant modem so that no interference occurs.
8.3.2 MULTIPLE TRANSPONDERS USING CRS-280 TRANSPONDER SWITCH
If, on the other hand, each modem is to be connected to its own transponder, then
the system requires the Comtech CRS-280 Transponder Switch. This connects to the
CRS-200 with a 25-pin control cable. Transmit and receive BNC cables connect to
the modems in use. The CRS-200 automatically senses the presence of the CRS-280
so that the CRS-200 will no longer suppress the transmit IF output of the offline
modem (Tx Traffic LED stays on). Instead, the Transponder Switch will switch the
redundant modem’s IF in place of the traffic modem being taken offline. This
arrangement is shown in Figure 5.