Demodulator - Comtech EF Data CDM-570L Installation And Operation Manual

CDM-570L Satellite Modem with IP Module
0.00 0.10 0.20 0.30
0
-5
Comtech EF Data
CDM-570L Transmit
-10
Power Spectral Density,
referred to symbol rate
-15
-20
-25
-30
-35
-40
-45
Spectral
-50
density,
dB
-55

12.2 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
0.40 0.50 0.60
Intelsat
IESS 308/309
limit
Desired Carrier: -130 + 10 log(Symbol Rate) to -90 + 10 log(Symbol Rate)
+40 dBC maximum composite, up to -10 dBm, absolute max.
Viterbi: 3 bit soft decision
Trellis: Pragmatic TCM/8-PSK with closed network concatenated Reed-Solomon
Reed-Solomon(Closed Network): Proprietary
Turbo Product Codec: 4 bit soft decision, proprietary
±1 to ±32 kHz, programmable in 1kHz increments, for symbol rates below 625 ksymbols/sec
±1 to ±200 kHz, programmable in 1kHz increments, for symbol rates above 625 ksymbols/sec
Highly dependent on data rate, FEC rate, and demodulator acquisition range. Examples: 120 ms
average at 64 kbps, R1/2 QPSK, ±10 kHz acquisition sweep range, 6dB Eb/No
3.5 s average at 9.6 kbps, R1/2 QPSK, ±10 kHz, 6dB Eb/No
Note: Reed-Solomon and TPC increases acquisition time, due to the additional time taken for the
RS/TPC decoder to declare synchronization.
± 100 ppm min
0.70 0.80 0.90 1.00
CDM-570L Modulator
typically < -50 dB, and
guaranteed to be
< -45 dB at offsets
> 0.75 Rs
121
Revision 1
MN/CDM570L.IOM
1.10 1.20 1.30 1.40
Symbol Rate, Rs
Intelsat
IESS 308/309
limit
1.50