M7/M7L/M7LT Modular Satellite Modem
Maintenance
M7/M7L/M7LT - Rev. 0.05
3-79
3. Bit Rate
4. FEC Code Rate
5. Scrambler (Normally Enabled in IESS 308/309 mode
– See “Using The Proper Scramble”
below)
6. Clock sources set per system requirements.
7. Reed-Solomon Codec settings if enabled
8. IBS Multiplexer settings if enabled
9. External reference set properly
3.7.2.2.
Modulator
1. Output Level
2. Carrier Enable
3. The L-Band modem can also supply power and reference to a BUC.
3.7.2.3.
Demodulator
1. Carrier Acquisition Mode and Acquisition Range
2. The L-Band modems with L-Band Receive can be set to supply power at either 13 or 18
VDC and/or a 10 MHz reference signal on the receive input connector for coupling to the
LNB via the receive cable.
3.7.3.
Using the Proper Scrambler
The modem has
an “Auto” mode used to automatically select the preferred scrambler setting in any
FEC or other dependent mode. This replaces the previous “IESS 308” or “IESS-309” or “auto modes”
used in legacy Datum modems. There is no IESS Standard covering the Turbo Product Codes FEC.
The Auto mode is highly recommended. Following are the settings chosen by the modem when in
Auto Scrambler mode:
When TPC is either not installed or not enabled the preferred scrambler and descrambler is
automatically selected to “IESS 308” or “IESS 309”. See below for the difference.
When TPC is enabled but the IBS multiplexer option is not installed or not enabled “Auto” uses
the new Scrambler and Descrambler option #7 “TPC Sync” this uses a synchronous scrambler
specific to the TPC Codec.
When both TPC and IB
S multiplexer are installed and enabled Auto uses the “IESS 308” option.
Remember that the scrambler and descrambler may be set independently in each link direction.
3.7.3.1.
IESS-308 Scrambler Mode Operation
With no mux or RS, the self-synchronizing Intelsat scrambler is used
With just the IBS mux enabled, the IBS synchronous scrambler is used
With just the RS enabled, the RS synchronous scrambler is used
With both IBS Mux and RS enabled, the IBS synchronous scrambler is used.
3.7.3.2.
IESS-309 Scrambler Mode Operation
The operation is the same as the IESS-308 option with the exception that with just RS enabled, the
self-synchronizing Intelsat scrambler is used.
3.7.3.3.
Fixed Scrambler Mode Operation
The V.35 and Intelsat scrambler modes use the V.35 and Intelsat self-synchronizing scramblers
respectively in all modes.
3.7.3.4.
Alternate Scrambler Mode Operation
The alternate V.35 and alternate Intelsat scrambler mode performs a data inversion required by some
legacy
“Comstream” modems.
Содержание M7 Series
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