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CDM-625A Advanced Satellite Modem
Introduction
1.4.2
Demodulator
Note: Data rate range, operating modes, descrambling, input impedance/return loss etc, as per Sect. 1.4.1 Modulator.
Input power range,
desired carrier
Maximum Composite
Operating Level
Absolute Maximum,
No Damage
FEC
Adaptive Equalizer
Acquisition range
Acquisition time
Clock tracking range
Clocking modes
LNB 10 MHz Reference
LNB Voltage
LNB Current Alarm
VITERBI BER performance
(met in the presence of two
adjacent carriers, each 7 dB
higher than the desired carrier)
VITERBI and RS 220,200 or
200,180 Outer Code BER (with
two adjacent carriers, each 7
dB higher than the desired
carrier)
950-2250 MHz band:
-130 + 10
(symbol rate) to -80 + 10
log
50-180 MHz band:
-105 + 10
(symbol rate) to -70 + 10
log
950-2250 MHz band:
102 – 10 log(symbol rate, desired carrier) dBC, +10 dBm max, with the additional requirement that within ±10 MHz of the
desired carrier, composite power is ≤ +30 dBC.
50-180 MHz band:
94 – 10 log(symbol rate, desired carrier) dBC, +10 dBm max, with the additional requirement that
within ± 10 MHz of the desired carrier, composite power is ≤ +30 dBc
+20 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
VersaFEC: 6 bit soft decision, proprietary
5-tap design, selectable on/off
Programmable in 1kHz increments, and subject to the following:
Below 64 ksymbols/sec: ±1 to ± (Rs/2) kHz, where Rs = symbol rate in ksymbols/sec
Between 64 and 389 ksymbols/sec: ± 1 up to a maximum of ± 32kHz
Above 389 ksymbols/sec: ±1 to ± (0.1Rs) kHz, up to a maximum of ± 200 kHz
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
2 s average at 18 kbps, R1/2 QPSK, ±10 kHz, 6dB Eb/No
Note: The use of Reed-Solomon, TPC, LDPC, VersaFEC increases acquisition time, due to the additional time taken for these
decoders to declare synchronization.
± 100 ppm min
Full range of clocking options supported – see plesiochronous/Doppler buffer section
On center conductor of L-Band input connector, selectable ON/OFF. Level: -3dBm ± 3 dB.
Source: either Internal modem reference or External reference
Performance: For phase noise, refer to L-Band modulator 10 MHz. Frequency stability same as the modulator 10 MHz
reference.
On center conductor of L-Band input connector, selectable ON/OFF, 13, 18 volts per DiSEq 4.2 and 24VDC at 500 mA
maximum.
Programmable MIN and MAX current alarms.
Rate 1/2 (B, Q, OQ)
Guaranteed Eb/No:
(typical value in parentheses)
For:
BER=10
5.4 dB (4.9 dB)
-5
BER=10
6.0 dB (5.5 dB)
-6
BER=10
6.7 dB (6.2 dB)
-7
Rate 1/2 (B, Q, OQ)
Guaranteed Eb/No:
(typical value in parentheses)
For:
BER=10
4.3 dB (4.0 dB)
-5
BER=10
4.4 dB (4.1 dB)
-6
BER=10
4.5 dB (4.2 dB)
-7
(symbol rate) dBm
log
(symbol rate) dBm
log
Rate 3/4 (Q, OQ)
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 3/4 (Q, OQ)
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)
1–16
Revision 0
MN-CDM625A
Rate 7/8 (Q, OQ)
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)
Rate 7/8 (Q, OQ)
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)
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