Comtech EF Data CDM-600/600L - Manual (Page 176)

CDM-600/600L Open Network Satellite Modem Revision 3
Open Network Operations MN/CDM600L.IOM
12–4
12.4 IDR
Primary Data Rates Supported
G.703 1544 kbps SD, RD
RS-422 (Replaces 8K Overhead) 2048 kbps SD, RD
V.35 (Replaces 8K Overhead)
6312 kbps SD, RD
8448 kbps SD, RD
Engineering Service Channel
ESC Audio 2 duplex ADPCM channels
Audio Encoding CCITT G.721
Audio Interface Type 600 Ω transformer-balanced 4-wire
Audio Input Level
Nominal Input : 0dBm0 (-3dBm, 600
Ω)
Adjustment range: -6 to +8 dB, 2 dB steps
Audio Output Level Adjustment range: -6 to +8 dB, 2 dB steps
Audio Filtering Internal 300 to 3400 Hz input and output
ESC Data Interface Type RS-422
ESC Data Rate 8 kbps, also 64 kbps if ADPCM audio is not used
ESC Data Circuits Supported SD, ST, RD, RT, Octet in, Octet out
Data Signal Phasing
Per RS-449, data changes on the rising clock transition, is sampled on
the falling clock edge
Octet Timing Octet high with every 8 th bit, aligns with frame bit d8
Faults and Alarms
Backward Alarms Supported 4 input, 4 output
Backward Alarm Inputs 1 k Ω pull up to ground, set high to activate.
Backward Alarm Outputs Form C Relay, N/O, N/C, Com
12.4.1 IDR Primary Data Interfaces
When configured for IDR operation, the board performs these functions:
• Receives and performs clock and data recovery on incoming G.703 T1 and E1 pseudo-
ternary data.
• Clock dejitter is performed per G.823 and G.824, and any data decoding (AMI, B8Z5, or
HDB3) required per G.703 also is accomplished.
12.4.2 IDR Framing
Multiplexes in compliance with the standard IESS-308 96 kbps ESC overhead onto the data and
provides both the data and rate exchanged clock to the modulator portion of the base modem.
Performs the corresponding demultiplexing of Rx satellite data received from the demodulator
portion of the modem. Resulting G.703 data is optionally encoded (AMI, B8ZS, or HDB3) before
being output.