Comtech EF Data CDM-550T - Manual (Page 113)

CDM-550T Satellite Modem Revision 3
Summary Of Specifications MN/CDM550T.IOM
14.2 Demodulator
Data rate range, operating modes, de-scrambling, input impedance/return loss etc, as per Modulator
Input power range -30 to -60 dBm (desired carrier)
+35 dBC maximum composite, up to -5 dBm
FEC •
Viterbi: 3 bit soft decision
•
Sequential: 2 bit soft decision
•
Turbo Product Codec: 6 bit soft decision
Acquisition range ±1 to ±30 kHz, programmable in 1kHz increments
Acquisition time
Highly dependent on data rate, FEC rate, and demodulator acquisition range.
Examples:
¾ 250 ms average at 512 kbps, R1/2 QPSK, ± 30kHz acquisition sweep
range, 6dB Eb/No
¾ 5 s average at 16 kbps, R1/2 QPSK, ± 5kHz, 6dB Eb/No
¾ 21 s average at 8.2 kbps, R7/8 QPSK, ± 2kHz, 6dB Eb/No
Note that Rate 3/4 and Rate 7/8 FEC rates slow acquisition time considerably,
due to the additional time taken for the FEC 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
Guaranteed Eb/No:
(typical value in
parentheses)
5.4dB (4.9dB)
6.0dB (5.5dB)
6.7dB (6.2dB) Rate 3/4
Guaranteed Eb/No:
(typical value in
parentheses)
6.8dB (6.3dB)
7.4dB (6.9dB)
8.2dB (7.7dB) Rate 7/8
Guaranteed Eb/No:
(typical value in
parentheses)
7.7dB (7.2dB)
8.4dB (7.9dB)
9.0dB (8.6dB)
SEQUENTIAL @ 64 kbps BER
(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
Guaranteed Eb/No:
(typical value in
parentheses)
4.8dB (4.2dB)
5.2dB (4.5dB)
5.6dB (4.8dB) Rate 3/4
Guaranteed Eb/No:
(typical value in
parentheses)
5.8dB (5.3dB)
6.4dB (5.8dB)
6.9dB (6.3dB) Rate 7/8
Guaranteed Eb/No:
(typical value in
parentheses)
7.0dB (6.6dB)
7.5dB (7.2dB)
8.0dB (7.7dB)
SEQUENTIAL @ 1024 kbps BER
(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
Guaranteed Eb/No:
(typical value in
parentheses)
5.2dB (4.8dB)
5.7dB (5.2dB)
6.1dB (5.7dB) Rate 3/4
Guaranteed Eb/No:
(typical value in
parentheses)
5.9dB (5.5dB)
6.5dB (6.0dB)
7.0dB (6.5dB) Rate 7/8
Guaranteed Eb/No:
(typical value in
parentheses)
7.2dB (6.6dB)
7.7dB (7.2dB)
8.3dB (7.7dB)
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
Guaranteed Eb/No:
(typical value in
parentheses)
4.3dB (4.0dB)
4.4dB (4.1dB)
4.5dB (4.2dB) Rate 3/4
Guaranteed Eb/No:
(typical value in
parentheses)
5.6dB (4.7dB)
5.8dB (4.8dB)
6.0dB (5.2dB) Rate 7/8
Guaranteed Eb/No:
(typical value in
parentheses)
6.5dB (6.0dB)
6.7dB (6.2dB)
6.9dB (6.5dB)
SEQUENTIAL and RS 220,200 or
200,180 Outer Code @ 512 kbps
(two adjacent carriers, each 7 dB
higher than desired)
For:
BER=10
-7
BER=10 -8
Rate 1/2
Guaranteed Eb/No:
(typical value in
parentheses)
4.6dB (4.3dB)
4.8dB (4.5dB) Rate 3/4
Guaranteed Eb/No:
(typical value in
parentheses)
5.3dB (4.9dB)
5.6dB (5.3dB Rate 7/8
Guaranteed Eb/No:
(typical value in
parentheses)
6.0dB (5.7dB)
6.4dB (6.1dB)
14–3