SHAPING THE FUTURE OF SATELLITE COMMUNICATIONS
9.1.1.1 ModCods in Satellite Communication
Figure 70 – Data Transmission via Satellite
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.
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