CDM-570A/570AL Satellite Modem with Optional Packet Processor
Revision 5
Introduction 1–25 MN-CDM570A
FEC Type Modulation Code Rate
EDMAC limited?
Adaptive Coding
and Modulation
See Section 1.3.7.2
Important Note – where noted in this table: If EDMAC framing is employed, the upper
data rate will be reduced by 5% for data rates up to 2.048 Mbps, and by 1.6% for data
rates above 2.048 Mbps where EDMAC2 framing is used, or for Rate 21/44 BPSK/QPSK
Turbo, or Rate 5/16 BPSK Turbo.
1.3.7 VersaFEC Adaptive Coding and Modulation (ACM)
1.3.7.1 VersaFEC ACM (IP-ACM)
System Type
Adaptive Coding and Modulation, using BPSK, QPSK, 8-QAM , 16-QAM and
VersaFEC short-block LDPC coding – total of 12 ModCods
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
7:1 over range of adaptation
Switch Point (decreasing SNR)
Corresponds to SNR (Eb/No) that gives BER = 5 x 10
-8
Approximately 1 dB/second (higher if Target Eb/No margin >1 dB)
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
• 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
See Appendix B, Table B-3
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