Comtech EF Data SLM-5650C CyberLynx, Инструкция по установке и эксплуатации

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SLM-5650C / SLM-5650C-ODU Satellite Modem
Revision 1
Appendix C C–2 MN-SLM-5650C
C.2 Processing Flow and Symbol Rate Calculation
The modem supports Ethernet interface and provides options for framing, modulation and
spreading. Figure C-1 shows the processing flow for these functions.
Figure C-1. SLM-5650C/ SLM-5650C-ODU – Feature Block Diagram
The symbol rate S
R
(Carrier 3dB Bandwidth) is a function of the programmed data bit rate B
R
with
FEC encoding, modulation, and transport overhead factors as shown in the equation
“
S
R
=B
R
/M
O
C
R
F
RS
F
T
F
C
” (referred to hereafter as “Equation 1”), containing the following
Operands:
•
Operand 1 – M
O
= Modulation Order ‘1’ if BPSK
‘2’ if QPSK
‘3’ if 8PSK
‘4’ if 16QAM
•
Operand 2 –
C
R
= Code Rate of the FEC (e.g., CR = 0.75 if stated FEC code rate = “3/4”)
•
Operand 3 –
F
c
= AUPC Mode Framing Factor, where:
o
F
C
= 15/16 if AUPC Mode is enabled;
o
F
C
= 1 if neither feature is enabled.
Only one of these two features (AUPC Mode or ACPC Mode) may be enabled
at any given time.
•
Operand 4 – F
T
= TRANSEC Framing Factor, where:
o
F
T
= N*16/[N*16+3], where ‘N’ is the selected Frame Length in AES blocks per
frame, in the range of 1 to 16.
o
F
T
= 1 if the TRANSEC encryption is disabled.
If the DSSS feature is enabled, then the simple equation for Chip Rate (SC)
equivalent to (Bw) of the spread signal is: “SC=K*SR” where ‘K’ is the
programmed spreading factor (e.g. 2, 4, 8, 16, 32, 64, up to 512)