6

Channel coding (forward error correction)

Once the source coding operations have been performed (including multiplexing and eventually scrambling), a transport stream made of 188 byte packets is available for transmission to the end users via a radiofrequency link (satellite, cable, terrestrial network).

We previously indicated that these transmission channels are, unfortunately, not error-free, but rather error-prone due to a lot of disturbances which can combine with the useful signal (noise, interference, echoes). However, a digital TV signal, especially when almost all its redundancy has been removed, requires a very low bit error rate (BER) for good performance (BER of the order of 10−10−10−12, corresponding to 0.1−10 erroneous ...

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