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1answer
10 views

lower-rate LDPC codes

Currently I am using (128, 64) LDPC codes to error correct messages wirelessly sent in Arduino using the SoftwareSerial library. I was advised to use a lower-rate ldpc code and see if that improves my ...
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0answers
26 views

A forward error correction method to reduce the error rate in transmssion over a lossy channel?

I am working on a project where I have to transmit binary data over a lossy channel. Currently, my data is only students' ID number (10 characters) along with their mobile number (10 characters) and ...
0
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0answers
20 views

Checking a convolutional enocder/decoder implementation

I've created a convolutional encoder and Viterbi decoder implementation in Python, and I'm trying to confirm that everything works properly. I'm finding a discrepancy in my testing, and I'm not sure ...
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0answers
13 views

How to implement Gilbert Eliot Packet loss Model

I am using JM reference software to encode H.264 video with RTP header. I am trying to apply packet loss in video and want to see its impact on different video sequences. By looking at the Rtp_loss ...
0
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0answers
12 views

What are the distinguishing features between tree codes and convolutional codes?

Are convolutional codes special case of tree codes? I understand convolutional codes. But have no clear idea of tree codes.
0
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1answer
25 views

Does Reed-Muller codes exist when $r = 0$ and $m = 0$?

Does Reed-Muller codes $\mathrm{RM}(r,m)$ exist for $r = 0$ and $m = 0$? Namely, does $\mathrm{RM}(0,0)$ exist? Some books mention that $m$ should be a natural number whereas some books mention that ...
0
votes
1answer
39 views

Block code error control with $d \ge c+u+1$

This is about error control coding formula $$ d \ge c+u+1$$ of a block code, with $c$ being the number of correctable errors, $u$ being the number of uncorrectable errors, and $d$ being the ...
1
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0answers
26 views

Is there a way to see video after applying packet loss

I have encoded a video stream using JM using RTP. Then i have applied rtp_loss on it but after that i am unable to decode video. Like in this example a video with different packet loss percentages are ...
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0answers
24 views

Binary Orthogonal Sequences

The set shown below is a biorthogonal signal set. $\{|0000|,|0101|,|0011|,|0110|,|1111|,|1010|,|1100|,|1001| \}$ Any two codewords or signals can be checked for orthogonality using the equation ...
1
vote
1answer
136 views

How to compute bit level soft decisions from an M-ary symbol?

When working with a decoder such as LDPC that can take in soft-decision inputs (or channel posterior probabilities as I've seen them called as well), how are these soft-decision values calculated for ...
0
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1answer
136 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
68 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
1k 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
vote
1answer
115 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) ...
3
votes
3answers
1k 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
190 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 ...
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votes
2answers
828 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 ...