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Sunday, June 8, 2008

Information on Convolutional Code

A convolutional code extends the concept of a block code to allow memory from block to block. Each encoded symbol is therefore a linear combination of information symbols in the current block and a selected number of preceding blocks. Therefore, for example, if the final output is a ‘1’ followed by a ‘0’, then these two digits could only have been arrived at by via a certain sequence of 0s and 1s preceding them. The longer the sequence, the easier it becomes for the receiver to detect where the received sequence deviates from a possible sequence and so correct one or more errors. Decoding of convolutional codes is based on the principle of the Viterbi decoding algorithm or sequential decoding.
Satellite communications systems commonly use a convolutional code to protect all data carried on the link.


hari said...

i need convolutional encoder,decoder programes plz help me