Comtech EF Data cdm-570a - Versafec-2 ACM (V2-ACM)

CDM-570A/570AL Satellite Modem with Optional Packet Processor
Revision 5
Introduction 1–26 MN-CDM570A
1.3.7.2 VersaFEC-2 ACM (V2-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
37.0 ksps to 3.0 Msps for the Long block. However, the Short block is limited to 2.0
Mbps (CCM) and 1.0 Msps (ACM).
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