
Re: commBCHEncoder/commBCHDecoder
Posted:
Aug 22, 2012 9:27 AM


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, 12*codeword);
You should see zero errors. A more realistic simulation would be
rcvd = awgn(12*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(decodedmsgmsg))]); >> >> THANXXXX > DEAR WHERE IS YOUR TRANSMISSION CHANNEL?????? > BAHMAN

