Comtech EF Data CDM-Qx, Installation And Operation Manual

Page: 157 / 224

CDM-Qx Satellite Modem Revision 6
Summary of Specifications MN/CDMQx.IOM
A.2 Demodulator
FEC, Data rate range, operating modes, descrambling, input impedance/return loss etc, as
per Modulator
Input power range
(70/140MHz IF)
-15 to -45 dBm, < 2.048 Msps (desired carrier)
-15 to -40 dBm, > 2.048 and < 4.096 Msps (desired carrier)
-15 to -35 dBm > 4.096 Msps (desired carrier)
+35 dBc maximum composite, up to -5 dBm
Input power range
(L-Band)
-130 + 10log(Symbol Rate in Hz) minimum signal level
50dB AGC range
Acquisition range
±1 to ±32 kHz, Symbol rate > 64 ksps (70/140 MHz)
±1 to ± (Symbol rate/2) kHz , Symbol Rate <=64 ksps (70/140 MHz)
±1 to ±200 kHz, Symbol rate > 625 ksps (L-Band)
±1 to ± 32 kHz, 64 ksps < Symbol Rate <=625 ksps (L-Band)
±1 to ± (Symbol rate/2)kHz, Symbol Rate <=64ksps (L-Band)
Programmable in 1 kHz increments.
Acquisition time
Highly dependent on data rate, FEC rate, and demodulator acquisition range.
Note that Reed-Solomon increases acquisition time, due to the additional time taken for the
RS decoder to declare synchronization.
Clock tracking range
± 100 ppm min
VITERBI
BER performance
(met in the presence
of two adjacent
carriers, each 7 dB
higher than the
desired carrier)
For:
BER=10
-5
BER=10
-6
BER=10
-7
Rate 1/2 (B, Q)
Guaranteed Eb/No:
(typical value in
parentheses)
5.4 dB (4.9 dB)
6.0 dB (5.5 dB)
6.7 dB (6.2 dB)
Rate 3/4 (Q)
Guaranteed Eb/No:
(typical value in
parentheses)
6.8 dB (6.3 dB)
7.4 dB (6.9 dB)
8.2 dB (7.7 dB)
Rate 7/8 (Q)
Guaranteed Eb/No:
(typical value in
parentheses)
7.7 dB (7.2 dB)
8.4 dB (7.9 dB)
9.0 dB (8.6 dB)
VITERBI and RS
220,200 or 200,180
Outer Code BER
(with two adjacent
carriers, each 7 dB
higher than the
desired carrier)
For:
BER=10
-5
BER=10
-6
BER=10
-7
Rate 1/2 (B, Q)
Guaranteed Eb/No:
(typical value in
parentheses)
4.3 dB (4.0 dB)
4.4 dB (4.1 dB)
4.5 dB (4.2 dB)
Rate 3/4 (Q)
Guaranteed Eb/No:
(typical value in
parentheses)
5.6 dB (4.7 dB)
5.8 dB (4.8 dB)
6.0 dB (5.2 dB)
Rate 7/8 (Q)
Guaranteed Eb/No:
(typical value in
parentheses)
6.5 dB (6.0 dB)
6.7 dB (6.2 dB)
6.9 dB (6.5 dB)
A–3