Comtech EF Data CDM-625 User Manual
Page 13
CDM-625 Advanced Satellite Modem
Revision 15
Table of Contents
MN-CDM625
xi
7.5
Trellis Coding (FAST Option) ................................................................................................ 7–4
7.6
Turbo Product Codec (Hardware Option) ............................................................................. 7–5
7.7
TPC and Low Density Parity Check (LDPC) coding ................................................................. 7–6
7.7.1
About TPC/LDPC........................................................................................................................................ 7–6
7.7.2
LDPC versus TPC ........................................................................................................................................ 7–7
7.7.3
End-to-End Processing Delay ................................................................................................................. 7–10
7.8
VersaFEC
(Short-block LDPC) .............................................................................................. 7–11
7.8.1
VersaFEC Extensions ............................................................................................................................... 7–13
7.8.1.1 Extended CCM Codes......................................................................................................................... 7–13
7.8.1.2 Ultra-Low-Latency (ULL) Codes ......................................................................................................... 7–13
7.9
Uncoded Operation (No FEC) ............................................................................................. 7–14
CHAPTER 8.
AUTOMATIC UPLINK POWER CONTROL (AUPC) .................................... 8–1
8.1
Overview ............................................................................................................................ 8–1
8.2
Setting AUPC Parameters .................................................................................................... 8–2
8.2.1
Target Eb/No ............................................................................................................................................. 8–2
8.2.2
Max Range ................................................................................................................................................. 8–2
8.2.3
Alarm .......................................................................................................................................................... 8–3
8.2.4
Demod Unlock ........................................................................................................................................... 8–3
8.3
Compensation Rate ............................................................................................................. 8–3
8.4
Monitoring ......................................................................................................................... 8–4
CHAPTER 9.
CLOCK MODES AND DROP AND INSERT (D&I) ........................................ 9–1
9.1
Overview ............................................................................................................................ 9–1
9.2
Transmit Clocking ............................................................................................................... 9–1
9.2.1
Internal Clock ............................................................................................................................................. 9–1
9.2.2
TX Terrestrial.............................................................................................................................................. 9–2
9.2.3
RX Loop-Timed, RX=TX ............................................................................................................................. 9–2
9.2.4
RX Loop-Timed, RX<>TX (Asymmetric Loop Timing) ............................................................................ 9–2
9.2.5
External TT with ST = RX Satellite ............................................................................................................ 9–2
9.3
Receive Clocking ................................................................................................................. 9–4
9.3.1
Buffer Disabled (RX Satellite) ................................................................................................................... 9–4
9.3.2
Buffer Enabled, TX=RX (TX Terrestrial or Int (SCT) Clock) ..................................................................... 9–4
9.3.3
Buffer Enabled, RX<>TX (TX Terrestrial or Int (SCT) Clock) ................................................................... 9–4
9.4
X.21 Notes .......................................................................................................................... 9–6
9.5
Drop and Insert ................................................................................................................... 9–6