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Topic: commBCHEncoder/commBCHDecoder
Replies: 35   Last Post: Oct 13, 2014 2:17 AM

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Ed MrTz

Posts: 3
Registered: 8/22/12
Re: commBCHEncoder/commBCHDecoder
Posted: Dec 29, 2012 11:18 AM
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Hi again!

After a while, I came back programming this code and with the "patch" told me before "decodedmsg = decode(dec, 1-2*codeword);" ran OKS but when I try to get BER curve of LDPC on AWGN channel and QPSK mod, comparing with QPSK no coded reference curve...... the LDPC curve appears over the theorical QPSK curve, instead of plot below.

Anybody knows why?

Extra: I use dvds2ldpc to generate the H matrix and fec.ldpcenc/dec to code.

Thanks for all,

Edgar

"Ethem Sozer" <esozer@mathworks.com> wrote in message <k12mok$784$1@newscl01ah.mathworks.com>...
> 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



Date Subject Author
12/18/10
Read commBCHEncoder/commBCHDecoder
Spiros
12/20/10
Read Re: commBCHEncoder/commBCHDecoder
Ethem
12/20/10
Read Re: commBCHEncoder/commBCHDecoder
Spiros
3/2/11
Read Re: commBCHEncoder/commBCHDecoder
Adam
3/4/11
Read Re: commBCHEncoder/commBCHDecoder
Spiros
4/12/11
Read Re: commBCHEncoder/commBCHDecoder
Bahman
4/15/11
Read Re: commBCHEncoder/commBCHDecoder
Spiros
6/2/11
Read Re: commBCHEncoder/commBCHDecoder
allice
5/22/11
Read Re: commBCHEncoder/commBCHDecoder
Ratty
4/12/11
Read Re: commBCHEncoder/commBCHDecoder
Bahman
6/23/12
Read Re: commBCHEncoder/commBCHDecoder
Fulus
6/23/12
Read Re: commBCHEncoder/commBCHDecoder
Fulus
6/24/12
Read Re: commBCHEncoder/commBCHDecoder
Bahman
6/25/12
Read Re: commBCHEncoder/commBCHDecoder
Fulus
7/2/12
Read Re: commBCHEncoder/commBCHDecoder
Fulus
7/3/12
Read Re: commBCHEncoder/commBCHDecoder
Bahman
7/15/12
Read Re: commBCHEncoder/commBCHDecoder
Fulus
7/16/12
Read Re: commBCHEncoder/commBCHDecoder
Bahman
7/16/12
Read Re: commBCHEncoder/commBCHDecoder
Fulus
7/17/12
Read Re: commBCHEncoder/commBCHDecoder
Bahman
8/14/12
Read Re: commBCHEncoder/commBCHDecoder
Fulus
8/14/12
Read Re: commBCHEncoder/commBCHDecoder
Bahman
8/15/12
Read Re: commBCHEncoder/commBCHDecoder
Fulus
8/16/12
Read Re: commBCHEncoder/commBCHDecoder
Bahman
8/22/12
Read Re: commBCHEncoder/commBCHDecoder
Ed MrTz
8/22/12
Read Re: commBCHEncoder/commBCHDecoder
Bahman
8/22/12
Read Re: commBCHEncoder/commBCHDecoder
Ethem Sozer
8/25/12
Read Re: commBCHEncoder/commBCHDecoder
Ed MrTz
12/29/12
Read Re: commBCHEncoder/commBCHDecoder
Ed MrTz
5/14/11
Read Re: commBCHEncoder/commBCHDecoder
Akilan
6/28/11
Read Re: commBCHEncoder/commBCHDecoder
Leonardo O. Iheme
7/4/11
Read Re: commBCHEncoder/commBCHDecoder
Leonardo O. Iheme
12/7/11
Read Re: commBCHEncoder/commBCHDecoder
Brian
12/7/11
Read Re: commBCHEncoder/commBCHDecoder
Brian
4/19/14
Read Re: commBCHEncoder/commBCHDecoder
ibrahemsami100@gmail.com
10/13/14
Read Re: commBCHEncoder/commBCHDecoder
sofiasankaran91@gmail.com

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