RCS20 M:N Redundancy Switch
Revision 15
Electrical Interfaces
MN-RCS20 and CD-RCS20
5–3
5.2.3
Expansion Slots
There are six expansion slots (numbered 0 through 5). The following cards may be inserted into the slots,
as shown in Figure 5-2:
•
Reference Distribution Module (shown installed in Slot 0)
•
CPU Terrestrial I/O Card (shown installed in Slot 1)
•
Bank Control I/O Card (shown installed in Slot 2)
The cards that are currently occupying the expansion slots may be viewed from the front menu screen by
accessing the EXPANSION SLOT MONITOR Screen (see Chapter 4).
WARNING
The RCU20 MUST be powered down when installing / removing the bank control
I/O AND when cabling up to the IFS20 or DDS20 with the CA3429 cables. Failure to
do so can result in damage to the bank control I/O and cause loss of redundancy in
the system.
5.2.3.1
Reference Distribution Module
The Reference Distribution Module RDM (Figure 5-3) is an optional RCU20 expansion card that is used
to buffer and distribute earth station frequency reference(s) to the external reference input of modems
that are connected to an RCS20. The RDM automatically switches between EXT A, EXT B or Internal
References based upon onboard Clock Activity Detect circuits.
Figure 5-3 Reference Distribution Module
Each of the ports on the RDM is a Female BNC Connector. Port function is as follows:
Ref Des Signal Name
Description
J1
EXT A IN
Primary Internal Reference Input
J2
EXT B IN
Secondary Internal Reference Input
J3
OUT 1
Reference Output 1
J4
OUT 2
Reference Output 2
J5
OUT 3
Reference Output 3
J6
OUT 4
Reference Output 4
