Tags: audio, code, demod, fsk, matlab, mod, ne1, programming, signal

Code for FSK mod and Demod of an Audio signal

On Programmer » Matlab

2,789 words with 2 Comments; publish: Sat, 26 Apr 2008 21:34:00 GMT; (20031.25, « »)

please could ne1 help me

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  • 2 Comments
    • In article <ef549d0.0.matlab.todaysummary.com.webcrossing.raydaftYaTP>,

      Matlab novice <arian_dame.matlab.todaysummary.com.yahoo.co.in> wrote:

      >please could ne1 help me

      Which was a follow up to the earlier question,

      >Can any one help me with the code of FSk modulation and demodulation

      >of an audio signal. I need it urgently.

      Answer: if you describe -specific- problems with your attempt at

      the FSK code, we may be able to assist you with it. However, people

      are unlikely to supply completed code for what sounds like a class

      assignment.

      --

      All is vanity. -- Ecclesiastes

      #1; Sat, 26 Apr 2008 21:35:00 GMT
    • The following code may be useful to you:

      %FSK Modulation

      bit = round(rand(1,10)); % bit stream of random 1's and 0's

      bitperiod = 0.01; %bit period

      fs = 15000; %sampling frequency

      fc = [3000 5000]; % carrier frequency

      % create the FSK signal

      L=length(0:(bitperiod/1500):bitperiod);

      transmitted = zeros(1,L);

      for k = 1:length(bit)

      f = fc(bit(k) + 1);

      transmitted((k-1)*L+1: k*L) =

      cos(2*pi*f*(0:(bitperiod/1500):bitperiod));

      %transmitted()=transmitted()+2*randn(siz

      e(0.01));

      %stem(transmitted);%fsk verified

      %y = filter(b,a,transmitted);

      end

      plot(transmitted);

      %FSK Demodulation

      demod_output=zeros(1,10);

      A=zeros(L,1);

      %B=zeros(L,1);

      Decision=0;

      %Logic_0=0;

      A=transpose(cos(2*pi*5000*(0:(bitperiod/1500):bitperiod))-cos(2*pi*300

      0*(0:(bitperiod/1500):bitperiod)));

      %B=transpose(cos(2*pi*5000*(0:(bitperiod

      /1500):bitperiod)));

      for x = 1:length(bit)

      Decision= transmitted((x-1)*L+1: x*L)*A;

      %Logic_0= transmitted((x-1)*L+1: x*L)*A;

      if Decision>0

      demod_output(x)=1;

      else

      demod_output(x)=0;

      end

      stem(demod_output);

      end

      I have one problem, if anyone couls solce it...

      I want to implement the FSK demodulator of the above code in FPGA.

      But how to implement the generation of mark 5kHz and space 3kHz

      frequenies in the FPGA(corresponding to the expression

      cos(2*pi*5000*(0:(bitperiod/1500):bitperiod))-cos(2*pi*3000*(0:(bitper

      iod/1500):bitperiod))))'

      Krishan.

      Walter Roberson wrote:

      >

      > In article <ef549d0.0.matlab.todaysummary.com.webcrossing.raydaftYaTP>,

      > Matlab novice <arian_dame.matlab.todaysummary.com.yahoo.co.in> wrote:

      > Which was a follow up to the earlier question,

      >

      > demodulation

      >

      > Answer: if you describe -specific- problems with your attempt at

      > the FSK code, we may be able to assist you with it. However, people

      > are unlikely to supply completed code for what sounds like a class

      > assignment.

      > --

      > All is vanity. --

      > Ecclesiastes

      >

      #2; Sat, 26 Apr 2008 21:36:00 GMT