Comtech EF Data CDM-425, Installation And Operation Manual

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CDM-425 Advanced Satellite Modem
Revision 0
Appendix K K–27 MN-CDM-425
K.12 Summary of Specifications
K.12.1 VersaFEC ACM
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 ksps to 4100 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 (Es/No) that gives BER = 5 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 2 seconds
Configurable Parameters
•
Minimum and Maximum ModCod (ModCod0 through ModCod11)
•
Remote Demod Unlock Action: Maintain current ModCod
Go to minimum ModCod
• Target SNR margin (0 to 4.5 dB, 0.5 dB steps)
System Latency 34 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