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Re: commBCHEncoder/commBCHDecoder
Posted:
Aug 22, 2012 9:27 AM
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The input of decode method should be a bipolar soft signal where a 0 is
represented by a real number greater than zero, and a 1 is represented by a
real number less than 0. If you try:
>> decodedmsg = decode(dec, 1-2*codeword);
You should see zero errors. A more realistic simulation would be
rcvd = awgn(1-2*codeword, SNR); % chose an SNR value
decodedmsg = decode(dec, rcvd);
Hth,
Ethem
"Bahman " <bahmanazarbad@yahoo.com> wrote in message
news:k12hvh$ihk$1@newscl01ah.mathworks.com...
> "Ed MrTz" wrote in message <k12c08$sbt$1@newscl01ah.mathworks.com>...
>> "Bahman " <bahmanazarbad@yahoo.com> wrote in message
>> <k0hsbu$1kd$1@newscl01ah.mathworks.com>...
>> > "Fulus " <case28@gmail.com> wrote in message
>> > <k0g2j4$ar5$1@newscl01ah.mathworks.com>...
>> > > > Hi dear
>> > > >
>> > > > is your bbframe a row vector?
>> > > > because error indicates that it is a column vector,try it inverted
>> > > > (BBframe')
>> > >
>> > > Hello, yeah you right, I nverted it and it runs without errors now
>> > > however, it still isnt function as it suppose to because as I go
>> > > higher in Eb/No my BER isnt going lower but is actually increasing by
>> > > a tiny amount. That is the Decoder is still introducing errors.
>> >
>> > Hi dear
>> > you need to be careful about the noise you are introducing to awgn as
>> > well as noise variance you need to set in demodulator
>>
>> Hi Everyone!
>>
>> I hope that someone could help me, even.
>>
>> I had the sames problems with BCH and LDPC Enc/Dec to make it
>> run......but at the end I can solved.
>>
>> Now, my problem is that when I use (without add a AWGN channel and
>> modulation) encoder and decoder of BCH (in raw)......its returns 0 errors
>> between the original msg and received/decoded msg. But its not so when I
>> use LDPC (in raw) because I get to many errors (original msg - decoded
>> msg).
>>
>> Do you know why? I attach the code that I use:
>> H=dvbs2ldpc(1/4);
>> enc = fec.ldpcenc(H); dec = fec.ldpcdec(H);
>> dec.DecisionType = 'Hard decision';
>> dec.OutputFormat = 'Information part';
>> dec.NumIterations = 50;
>>
>> msg = randi([0 1],1,enc.NumInfoBits);
>> codeword = encode(enc,msg);
>>
>> decodedmsg = decode(dec, codeword);
>
>
>>
>> % Compare with original message
>> disp(['Number of bits incorrectly decoded = ' ...
>> num2str(nnz(decodedmsg-msg))]);
>>
>> THANXXXX
> DEAR WHERE IS YOUR TRANSMISSION CHANNEL??????
> BAHMAN
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