Comtech EF Data SDM-9000 - Manual (Page 146)

Theory of Operation SDM-9000 Satellite Modem
5–18 Rev. 4
5.5 Interface
5.5.1 Description
The interface PCB fits in the middle slot of the modem chassis. The interface PCB
provides synchronous data interfacing for terrestrial data and overhead signals and a
means for modem fault reporting. The terrestrial interface functions include:
•
MUX ESC overhead into the data
•
DEMUX the received data
•
Buffering the received data
•
Monitoring and displaying the interface status without interruption of service
The following types of interfaces with options are available:
Options
Interface Type Interface P/N Base Buffer ESC RS
G.703 3971-1 X
G.703 3971-2 X X
G.703 (IDR) 3971-3 X X X
G.703 (8.448) 3971-4 X
G.703 (8.448) 3971-5 X
G.703 (8.448) 3971-6 X
G.703 5618-1 X
G.703 5618-2 X
G.703 (64K) 5618-3 X X
ECL 4477-11 X
ECL 4477-21 X X
ECL 4477-31 X X X
PECL 4477-12 X
PECL 4477-22 X
PECL 4477-32 X X
MIL-STD-188 4477-13 X
MIL-STD-188 4477-23 X X
MIL-STD-188 4477-33 X X X
Note: In addition, an optional plug-on module supports Reed-Solomon (RS) coding and
decoding. The Reed-Solomon Codec works in conjunction with the convolutional coding
and Viterbi decoding. This includes additional framing, interleaving, and processing to
provide concatenated FEC. This option can only be installed on interfaces with a buffer.
Refer to Appendix A for further Reed-Solomon information.
Figures 3-4, 3-5, and 3-6 show the interface PCBs. A block diagram of the interface PCB
is shown in Figure 5-6.