Comtech EF Data CDM-570AL - Versafec-2 ACM

CDM-570A/570AL Satellite Modem with Optional Packet Processor
Revision 5
Adaptive Coding and Modulation (ACM) Option P–20 MN-CDM570A
P.10.2 VersaFEC-2 ACM
System Type
Adaptive Coding and Modulation, using BPSK, QPSK, 8-ARY, 16-ARY, 32-ARY and
VersaFEC-2 Short-block and Long Block LDPC coding - total of 74 ModCods
Symbol Rate Range 5 ksps to 3.0 Msps (Long)
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
9:1 over range of adaptation
Switch Point (decreasing SNR)
Corresponds to SNR (Es/No) that gives BER = 1 x 10
-8
(margin set to 0 dB)
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
1 update every 1.7 seconds
Configurable Parameters
• Maximum ModCod (ModCod00 through ModCod37, Long Block)
• Maximum ModCod (ModCod00 through ModCod35, Short Block)
• Remote Demod Unlock Action: Go to minimum ModCod
• Target SNR margin (0 to 4.5 dB, 0.5 dB steps)
System Latency @ 100 ksps
Long Block - 205 milliseconds max (not including WAN buffer, or satellite path)
Short Block – 40.4 milliseconds max (not including WAN buffer, or satellite path)
Monitored Parameters
• Tx and Rx ModCods
• Local and Remote SNR
(-3.0 dB 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
List of ModCods See Appendix B, Tables B-6 and B-7