Convolutional code: Difference between revisions

Revision as of 01:23, 9 May 2006

Revision as of 15:09, 13 May 2006

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[[Image:Convolutional_encoder_recursive.png|left|thumb|340px|none|Img.2. Rate 1/2 recursive, systematic convolutional encoder with constraint length 4]]

One can see that a data sequence being encoded is here a part of the output (encoded) sequence too (look at the output 2). Such codes are referred to as ''systematic'', otherand others are called ''non-systematic''.

Recursive codes are almost always systematic, and, on the contraryconversely, non-recursive codes are non-systematic. It isn't a strict requirement, but a common practicepractise.

===Impulse response, transfer function and constraint length===