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1.4.7.2
VersaFEC-2 ACM
System type
Symbol Rate Range
Interface
Remote SNR reporting
Max span of data rate
Switch point (decreasing SNR)
Switch point hysteresis
Max fading rate
Max ModCod update rate
Configurable parameters
System latency @ 100 ksps
Monitored parameters
List of ModCods
Introduction
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
37 ksps to 12.5 Msps (Long)
10/100 Base T Ethernet, with auto-negotiated Congestion Control
Automatically reported from remote modem – built in function at the physical layer –
requires no additional overhead
9:1 over range of adaptation
Corresponds to SNR (Es/No) that gives BER = 1 x 10
0.3 dB
Approximately 1 dB/second (higher if Target Eb/No margin > 1 dB)
1 update every 1.7 seconds
• 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)
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)
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
•
See Table 1-6 and Table 1-7
1–31
CDM-425 Advanced Satellite Modem
(margin set to 0 dB)
-8
MN-CDM-425
Revision 0
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