Mocomtech CRS-300 - Manual (Page 25)

CRS-300 1:10 Redundancy Switch Revision 16
Introduction MN/CRS300.IOM
1–3
NOTE
the CRS-300). For detailed information on remote addressing schemes, refer to Appendix B.
ADDRESSING SCHEME INFORMATION.
TMI Monitoring: Terrestrial user clock and data signals to and from a traffic modem are routed
through a TMI via a set of relays. This is arranged so that the de-energized (unpowered) state
connects the data signals directly through to the traffic modem. If the power supplies to the
system are lost, or if a traffic-carrying TMI is removed, no interruption of the traffic occurs. It
should also be noted that, in normal circumstances where the redundant modem is not in service, no
data is carried through the CRS-300 backplane – all data is routed via the TMI.
CRS-350 Option: Where protection of the IDR overhead signals (backward alarms, audio ESC,
data ESC, etc.) is desired, the CRS-350 module may be added.
CRS-280/280L Option: The CRS-280 (70/140 MHz) Switch is required when one or more
modem within the redundancy group connects to more than one up/down converter. This occurs
when the modems connect to more than one transponder on the same antenna polarization, or
when modem redundancy needs to span two or more polarizations or antennas.
Operation with the CRS-280L (L-Band) Switch is necessary when one or more modems within
the redundancy group connect to the other polarization of the antenna or to multiple antennas.
Refer to the CRS-280L 1:N Redundancy Switch Installation and Operation Manual
for detailed information about this optional switch.
The system may forgo using the CRS-280/280L and, in its place, passively combine or split the
modulator outputs and demodulator inputs when the entire group of modems is connected to the
same up/down converter. In these applications, the CRS-300 mutes the faulted modem’s Tx
carrier and enables the standby unit’s carrier.
Figure 1-2 depicts an operational schematic for the CRS-280/280L interface.