P.11 versafec acm – summary of specifications – Comtech EF Data CDM-570A User Manual
Page 603
CDM-570A/570A Satellite Modem with Optional Packet Processor
MN-CDM570A
Appendix P
Revision 2
P–13
P.11 VersaFEC ACM – Summary of Specifications
System type
Adaptive Coding and Modulation, using BPSK, QPSK, 8-QAM , 16-QAM and
VersaFEC short-block LDPC coding – total of 12 ModCods
Symbol Rate Range
37-3000 ksps
Interface
10/100 Base T Ethernet, with auto-negotiated Congestion Control
Remote SNR reporting
Automatically reported from remote modem – built in function at the physical
layer – requires no additional overhead
Max span of data rate
7:1 over range of adaptation
Switch point (decreasing SNR) Corresponds to SNR (Eb/No) that gives BER = 5 x 10
-8
Switch point hysteresis
0.3 dB
Max fading rate
Approximately 1 dB/second (higher if Target Eb/No margin >1 dB)
Max ModCod update rate
One update every two seconds (no restriction on distance between ModCods)
Configurable parameters
•
Minimum and Maximum ModCod (ModCod0 through ModCod11)
•
Remote Demod Unlock Action: Maintain current ModCod
Go to minimum ModCod
•
Target Eb/No margin (0-4.5 dB, 0.5 dB steps)
System latency
54 ms max. (for a system operating at 100 ksps, and assuming a WAN
buffer of 20 ms, not including satellite path)
Monitored parameters
•
Tx and Rx ModCods
•
Local and Remote SNR
(-3.0 to +22.0dB, 0.1dB resolution, ±0.5 dB accuracy)
•
Config and monitor menus displaying data rate, modulation and code rate update
dynamically with ModCod
ModCod Modulation Code Rate Spectral Efficiency,
bps/Hz
Typical
SNR for
BER = 5 x 10
-8
Min. Data Rate
(kbps)
Max. Data Rate
(Mbps)
00
BPSK
0.488
0.49
2.4 dB
2.4
1.462
01
QPSK
0.533
1.07
2.2 dB
5.2
3.200
02
QPSK
0.631
1.26
2.7 dB
6.1
3.785
03
QPSK
0.706
1.41
3.4 dB
6.8
4.233
04
QPSK
0.803
1.61
3.8 dB
7.8
4.818
05
8-QAM
0.642
1.93
4.6 dB
9.3
5.782
06
8-QAM
0.711
2.13
5.2 dB
10.3
6.401
07
8-QAM
0.780
2.34
5.6 dB
11.3
7.021
08
16-QAM
0.731
2.93
6.3 dB
14.1
8.776
09
16-QAM
0.780
3.12
7.0 dB
15.0
9.361
10
16-QAM
0.829
3.32
7.5 dB
16.0
9.946
11
16-QAM
0.853
3.41
8.0 dB
16.4
10.239