Comtech EF Data RCS20 - Manual (Page 33)

RCS20 M:N Redundancy Switch Revision 15
Theory of Operation MN-RCS20 and CD-RCS20
3–3
3.3.1 IF Switch Relays
The IFS20 contains 16 IF Switch Relays; eight uplink and eight downlink. The relays switch the IF signals
to the Backup units. The signals to each downlink relay pass through a splitter with a loss of about 3.5 dB
(including the loss due to energy splitting).
3.3.2 IFS20 Back Panel/Front Panel
See Section 5.3.
3.4 DDS20 Major Assemblies
The DDS20 Data Switch provides terrestrial interface and data signal switching for up to nine
independent pairs of Modulators and Demodulators. There are two parallel and independent backup
busses allowing any of the eight on-line Modulators and Demodulators to be switched to either of the
backup Modulators or Demodulators. The DDS20 has no internal power supply, it receives DC power
from the RCU20 through the cable that connects at J31.
3.4.1 Motherboard
The DDS20 Motherboard contains the modem connectors and backup busses.
3.4.2 Slide-In Data Switch Interface Modules
The DDS20 contains one slide-in data switch interface module for each prime modem, containing
terrestrial interface connectors and data switch relays.
3.4.3 Housing
The housing contains the card guides and mounting ears for the motherboard.
3.4.4 DDS20 Back Panel
The DDS20 back panel contains the electrical connections.