ABSTRACT
The first error correction coding layer, called outer coding, is used with all Digital Video Broadcasting specified transmission media; a second complementary layer, called inner coding, is used only in satellite and terrestrial transmissions. The inner coding is a convolutional coding and is an efficient complement to the ReedSolomon coding and Forney interleaving, as it corrects other kinds of errors. In order to be able to correct most errors introduced by the physical transmission channel, it is necessary to introduce some form of redundancy allowing the detection and correction of transmission errors to obtain a quasi-error-free channel. The terms inner coding and outer coding are seen from the point of view of virtual channel. The virtual channel thus created between the input of the 'forward error correction' (FEC) encoder on the transmission side and the output of the FEC decoder on the receiver side is quasi-error-free and is sometimes referred to as a super channel.
