Comtech EF Data cdm-570a - Demodulator; BER Performance Specification

CDM-570A/570AL Satellite Modem with Optional Packet Processor
Revision 5
Introduction 1–18 MN-CDM570A
1.3.2 Demodulator
Data Rate Range, Operating modes, Descrambling, Input Impedance/Return Loss,
etc. are as specified in Section 1.3.1.
Parameter
Specification
Input Power Range
CDM-570AL or CDMR-570AL (L-Band) Desired Carrier: -130 + 10
log
(Symbol Rate) to -90 + 10
log
(Symbol
Rate); +40 dBc maximum composite, up to -10 dBm, absolute max.
CDM-570A (70/140 MHz) Desired Carrier: -30 to -60 dBm.
+35 dBc maximum composite, up to -5 dBm, absolute max.
FEC
• 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
• VersaFEC: 6 bit soft decision, proprietary
• VersaFEC-2: 8 bit soft decision, proprietary
Acquisition Range
±1 to ±32 kHz, programmable in 1 kHz increments, for symbol rates below 625 ksymbols/sec
±1 to ±200 kHz, 1 kHz increments, for symbol rates above 625 ksymbols/sec, L-Band only
Acquisition Time
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 E
b
/N
0
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 R-S/TPC
decoder to declare synchronization.
Clock Tracking Range
± 100 ppm min
Plesiochronous/
Doppler Buffer
Selectable size of ± 128, 256, 512, 1024, 2048, 4096, 8192, 16384 and 32768 bits
Size selection is displayed in bits and milliseconds. Supports asymmetric operation – when buffer is clocked
from Tx clock, Rx and Tx rates do not need to be identical.
Monitor Functions
Eb/No estimate, 2 to 16 dB (± 0.25 dB accuracy)
Corrected Bit Error Rate, 1E-3 to 1E-9
Frequency offset, ± 200 kHz range, 100 Hz resolution
Buffer fill state, in percent
Receive signal level monitor accuracy:
± 5 dB for CDM-570AL L-Band, ± 3 dB for CDM–570A over
specified min to max signal range
1.3.2.1 BER Performance Specification
BER Description
For
BER=
Rate
Guaranteed Eb/No ((typical value in parentheses)
VITERBI
(Met in the presence of two
adjacent carriers, each 7 dB higher
than the desired carrier)
10
-5
10
-6
10
-7
½ (BPSK, QPSK, OQPSK)
5.4 dB (4.9 dB)
6.0 dB (5.5 dB)
6.7 dB (6.2 dB)
¾ (QPSK, OPQSK)
6.8 dB (6.3 dB)
7.4 dB (6.9 dB)
8.2 dB (7.7 dB)
7/8 (QPSK, OPQSK)
7.7 dB (7.2 dB)
8.4 dB (7.9 dB)
9.0 dB (8.6 dB)
VITERBI and R-S 220,200 or
200,180 Outer Code
(With two adjacent carriers, each 7
dB higher than the desired carrier)
10
-5
10
-6
10
-7
½(BPSK, QPSK, OQPSK)
4.3 dB (4.0 dB)
4.4 dB (4.1 dB)
4.5 dB (4.2 dB)
¾ (QPSK, OPQSK)
5.6 dB (4.7 dB)
5.8 dB (4.8 dB)
6.0 dB (5.2 dB)
7/8 (QPSK, OPQSK)
6.5 dB (6.0 dB)
6.7 dB (6.2 dB)
6.9 dB (6.5 dB)
8-PSK/TCM/R-S CODEC
(With two adjacent carriers, each 7
dB higher than the desired carrier)
10
-5
10
-7
10
-8
2/3 8-PSK/TCM/R-S
6.3 dB (5.4 dB)
6.7 dB (5.8 dB)
6.9 dB (6.0 dB)