Comtech EF Data RCS10 - Manual (Page 217)

RCS10 Redundant Communication System Principles of Operation
TM058 - Rev. 2.3 Page 5-1
Section 5 - Principles of Operation
5.0 DMD10 Modem Principles of Operation
The Modem units contained in the RCS10 are designated as DMD10 modems. The DMD10 Modem
is designed in three major sections; Universal Interface, Baseband Processing, and Universal
Modem. Each section resides on a PC Card within the DMD10.
5.1 Universal Interface Modules (UIM)
The Universal Interface Modules (UIM) are field-replaceable modules that plug into the rear of the
RCS10. The UIMs provide the interconnection points (J3-J8) for terrestrial data and clock to the
modem. The UIMs also contain a connection port for an asynchronous data channel (J9) for use in
Earth Station to Earth Station (ES/ES) communications. Additionally, the UIM provides connection
points (J11) for Form-C modem status relays. An illustration of one UIM is shown in Figure 5-1, and
a functional block diagram is shown in Figure 5-1A. Any reference to the Universal Interface
Modules hereafter will be in singular terms as the modules are identical.
Before powering up the RCS10 or attaching cables to J12 (Sync Data RS422/RS485/V.35), the
following steps MUST be verified in order to avoid damage to the equipment. Ensure the following:
1. The cables must be wired correctly. Refer to Table 2-1, J12 Sync Data,
RS422/RS485/V.35;
2. The External Interface is programmed or supports the appropriate Interface type: RS232,
RS422, or V.35;
3. The Universal Interface Module (UIM) is configured for the appropriate Interface type:
RS232, RS422 or V.35.
This is EXTREMELY IMPORTANT as the Interface pins operate at different voltage levels
depending upon the Interface type selected. SERIOUS DAMAGE may occur, for example, if
the External Interface is operating at V.35 voltage levels and the Universal Interface is
configured for RS422 voltage levels.
5.1.1 Synchronous Interface
Synchronous Tx data and clock enters the UIM and is routed to either the RS-422, RS-232, or V.35
receiver as the selected monitor and control processor, where the signals are converted to an RS-
422 balanced format and sent to the Baseband (BB) Processor card. Receive data from the BB
processor card undergoes the reverse process where it is converted from RS-422 balanced format
and routed to the RS-422 or V.35 drivers.
5.1.2 G.703 Interface
Either balanced or unbalanced G.703 data is routed from the ‘Send Data In’ connections to the
G.703 receiver. The G.703 receiver recovers a clock from the data stream, converts the clock and
data to an RS-422 balanced format, and routes the clock and data to the Baseband Processor. The
reverse process is performed on the receive data stream where the G.703 data exits the modem at
the ‘Receive Data Out’ connection. The G.703 interface is designed to operate at the following rates;