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Installation
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.
2.9.1.1 IBS Multiplexer and Reed-Solomon Selection
The PSM-500 Modem contains on-board circuitry implementing either an IBS Multiplexer or a
Reed-Solomon concatenated FEC capability independently.
The IBS Multiplexer and Reed-Solomon functions are independent and each can be enabled and
disabled as required. The Modulator (Transmit) and Demodulator (Receive) functions of each
option are also independent and can be enabled and disabled as required.
For additional information on the configuration of the IBS Multiplexer/Reed-Solomon capabilities
refer to Appendix RS.
2.9.1.2 Using the Proper Scrambler
The PSM-500 modems now have had 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" auto modes used in the PSM-4900. There is no IESS Standard covering the Turbo
Product Codes FEC. The Auto mode is highly recommended. Following is the setting 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 IBS 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.
IESS-308 Scrambler Mode Operation
•
With no mux or RS then the self-synchronizing Intelsat scrambler is enabled.
•
With just the IBS mux enabled then the IBS synchronous scrambler is used
•
With just the R-S enabled then the R-S synchronous scrambler is used
•
With both IBS Mux and R-S enabled then the IBS synchronous scrambler is used.
IESS-309 Scrambler Mode Operation
The operation is the same as the IESS-308 option with the exception that
•
With just R-S enabled then the self-synchronizing Intelsat scrambler is used.
Fixed Scrambler Mode Operation
The V.35 and Intelsat scrambler modes use the V.35 and Intelsat self-synchronizing scramblers
respectively in all modes.
Alternate Scrambler Mode Operation
The alternate V.35 and alternate Intelsat scrambler mode performs a data inversion required by
some "Comstream" modems.
2.9.1.3 Using The L-Band PSM-500L Transmit RF Frequency Feature
The PSM-500L can cover the entire satellite's receive range from it's transmit output. This output
can be tuned to any frequency on 1 Hz increments in the 950 to 1750 MHz range. The coverage
can be "projected" to the actual satellite RF frequency being transmitted at the BUC output. To
Page 2-16
PSM-500/500L/500LT SCPC Satellite Modem
PSM-500/500L/500L T- Rev. 0.91
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