Demodulator - Comtech EF Data CDM-600 Installation And Operation Manual

CDM-600 Satellite Modem
Remote Control
0.00 0.10 0.20
0
-5
Comtech EF Data
CDM-600 Transmit
-10
Power Spectral Density,
referred to symbol rate
-15
-20
-25
-30
-35
-40
-45
-50
Spectral
density,
dB
-55
15.2

Demodulator

Data rate range, operating modes, de-scrambling, input impedance/return loss etc, as per
Modulator
Input power range
FEC
Acquisition range
Acquisition time
Clock tracking range
0.30 0.40 0.50 0.60
Intelsat
IESS 308/309
Limit
-30 to -60 dBm (desired carrier)
+35 dBC maximum composite, up to -5 dBm
Viterbi: 3 bit soft decision
Sequential: 2 bit soft decision
Trellis: Per IESS-310
Reed-Solomon(Open Network): Per IESS-308/309/310
Reed-Solomon(Closed Network): Proprietary
Turbo Product Codec: 6 bit soft decision, proprietary
LDPC: 5 bit soft decision, proprietary
±1 to ±32 kHz, programmable in 1kHz increments
Highly dependent on data rate, FEC rate, and demodulator acquisition range. Examples: 200 ms
average at 64 kbps, R1/2 QPSK, ±32 kHz acquisition sweep range, 6dB Eb/No
5 s average at 9.6 kbps, R1/2 QPSK, ±10 kHz, 6dB Eb/No
Note that Reed-Solomon increases acquisition time, due to the additional time taken for the RS
decoder to declare synchronization.
± 100 ppm min
0.70 0.80 0.90 1.00
CDM-600 Modulator
typically < -50 dB, and
guaranteed to be
< -45 dB at offsets
> 0.75 Rs
15–3
Revision 7
MN/CDM600.IOM
1.10 1.20 1.30 1.40
Symbol Rate, R
Intelsat
IESS 308/309
Limit
1.50
s