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1answer
53 views

Important differences between BCJR and SOVA algorithms?

BCJR algorithm needs noise variance for Gamma (branch metrices) calculation. So I am wondering does SOVA (soft output Viterbi algorithm) needs noise variance?
1
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0answers
47 views

QC-LDPC Decoder - Is it a codeword?

I'm designing a QC-LDPC decoder in VHDL. It uses a layered decoding method - only a single block row of parity equations is evaluated each iteration (the bit values are still updated every iteration). ...
3
votes
1answer
932 views

QPSK soft decoding

I'm trying to decode a Hamming Block Code transmitted using a QPSK modulation. For the moment I can sucessfully decode it using hard decision but in order to improve performance I'd like to use soft ...
1
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1answer
93 views

extended hamming code

for the (7,4) Hamming code, I know how to decode a codeword using the syndrome decoding method, by just using the 3 parity bits, and it is correctable if there is just 1 error. However, for the (8,4) ...
2
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3answers
885 views

Why is an interleaver often placed between an outer block code and an inner convolution code?

It seems that when doing FEC with a concatenated-code, an interleaver is often placed between the outer block code and the inner convolution code. The explanations I've seen say that this is because ...
1
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1answer
2k views

How to compute generator matrix from a parity check matrix?

I have a parity matrix ("H") that is not in canonical form (the identity matrix is not on the right side). I'm trying to programatically calculate the generator matrix ("G") from it. The Wikipedia ...
0
votes
1answer
142 views

Viterbi Decoder - Decoding Continuously Encoded Stream Partially

I am in trouble with Viterbi decoder for a while. I have some questions. I need to decode messages from a continuous stream which is encoded without resetting the state metrics. Each message starts ...
7
votes
2answers
500 views

Deep space communications BER and FEC?

What kind of bit error rate do they get from deep space communications (Pioneer, Voyager, et.al.), and what kind of modulation and FEC allows them to recover messages with that microscopic level of ...