Talk:Convolutional code

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Re the recent change to say that code rates could be equal to 1, I don't know of any such codes ever being used in practice, and it certainly doesn't seem very useful...

There *are* codes that when combined with M-ary modulation schemes produce one output symbol per input bit, but the output symbols are non-binary. But I don't think that's what you meant. Can you clarify?? User: Karn

From BrettE: This page doesn't descripte the ENCODING at all. Perhaps I'll add some of that later...

Josh Rubin: I second BrettE. The page for Reed-Solomon codes gives a rough but accurate definition; this page manages to talk about convolutional codes without defining them. A definition of "convolution" as used in mathematics and signal processing is in order too.

[edit] Sequential decoding

I notice there is some confusion on sequential decoding and algorithms. The Fano algorithm (which doesn't currently seem to have a page on Wikipedia) is a low-memory sequential decoding algorithm. Shannon-Fano coding is a data compression technique and AFAIK is just related by having the same inventer. Perhaps we need a page on sequential decoding? Edratzer 22:46, 12 February 2007 (UTC)

[edit] Wrong picture?

The Img. 2 is said to have a constraint length of 4, but I can only see a length of 3, since reg3 has no effect on any output (it is used twice for output 1 (which cancels out in xor)). Am I wrong?