We are famous!!

Sami AldalahmehDecember 8, 20102 comments

Today one of my supervisor said to me that the IEEE Signal Processing eNewsletter mentioned me, well sort of:) It actually talked about Social media resources for DSP and pointed to this website's blog section. You check it out here http://tinyurl.com/36dga4n


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Comments:

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Comment by ahmsa474December 16, 2010
Hi I need to know output of convolutional encoder for K = 7 means (6 memory elements), output with corresponding (transition) states. I could found this for K = 3 (means 2 memory elements) with 4 states and 4 different outputs and in other way 8 possible outputs which are written on arrows leading from one stage of trellis to another trellis stage. Its dimension should be 64 x 2 which means 64 rows and 2 columns. In other words, I want to see/create one complete trellis stage (64 states) with corresponding outputs. I need to know this because I want to calculate Euclidean distance of these outputs and received values. By using polynomial description, I know its possible to calculate output or next states etc but it's a very lengthy process. I have seen Matlab's function "poly2trellis" but "trellis.outputs" is also not useful for me. Please help me if anyone can. Thank you in advance.
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Comment by December 27, 2010
Sorry for the late response. Fortunately, the convolutional encoder is relatively simple. The basic idea is to have a number of states, which are basically a shift register, and the output are simply the "XORing" of those states. The output is usually represented by a polynomial. The powers of this polynomial dictates which state, or memory location, is used by the output, i.e. it'll be the input of the XOR gate. Now I got a bit confused with your question here, do you mean that you have 7 or 64 states, and does the columns represent? The matlab function you mentioned is useful when you like to see the trellis representation of you encoder, which I don't think you need in your case to calculate the output and the new state.

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