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Feature Descriptions
MDM9000 Satellite Modem
16.7.1 MODCODs in Satellite Communication
Data transferred via a satellite is modulated and coded at the sending side and demodulated and
decoded at the receiving end.
The used modulation and coding (FEC) is called the MODCOD. Each combination of a specific
modulation and coding has a certain spectral efficiency determining the data throughput. This
spectral efficiency refers to the amount of information that can be transmitted over satellite in a given
bandwidth, the larger the spectral efficiency, the more information can be send over the satellite link
in the same bandwidth.
• A high MODCOD is linked to a high data rate but requires a good signal-to-noise ratio at the
receivers end;
• A low MODCOD functions with a lower signal-to-noise ratio at receivers end but has a lower data
rate.
As an example: the MODCOD 32 APSK-9/10 has a spectral efficiency of 4.45 while MODCOD
QPSK-1/4 has a spectral efficiency of 0.49.
In the S2 extension mode there is an increased number of MODCODs added to have an even better
performance, also taken into account linear operation.
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