This program is for random data,followed by its FEC coding , DPSK modulation for OFDM transmission

      *THIS PROGRAM IS FOR DESIGNING AN OFDM TRANSMITTER*

    %======================
    %TRANSMITTER SECTION
    %======================

    %OFDM parameters

    ifftsize = 128;    %Total no. of sub-carriers
    NumCarr = 120;    % Number of data sub-carriers
    Tg = 0.012    ;% Guard Interval
    Tu = 4*Tg      ;% OFDM symbol period
    T = Tg+Tu      ;% Total OFDM symbol duration
    delf = 1/Tu    ;% Sub-carrier spacing
    BW = ifftsize*delf    ;% Net Bandwidth occupied
    fs = ifftsize/Tu    ;% Baseband sampling frequency
    r = 40;      % Up sampling ratio
    fs1 = r*fs      ;% Pass band sampling frequency
    ber2 = [];
    s2 = [];
    ber1_1 = [];

    % TRANSMITTER LOOP BEGINS

    for sp = 0.2:0.4:1.8
      s = [];
      ber= 0;
      ber1=0;
    end
    for iter = 1:2
      clc  
    end
      % Random data generion
      data_in = round(rand(400,1));

      % Convolution Coding
      trellis = poly2trellis(7,[133 171]);
      coded_data = convenc(data_in,trellis);
      msg_bits_out = coded_data;

      % Puncturing
      msg_bits_out(4:6:end)=[];  % puncturing 1/2 to 3/4   
      msg_bits_out(4:5:end)=[];  % puncturing 1/2 to 3/4
      numsymb = ceil(length(msg_bits_out)/NumCarr);
      OutWordSize = 1;

      % Serial to Parallel Conversion
      if length(msg_bits_out)/NumCarr ~= numsymb,
         Datapad = zeros(1,numsymb*NumCarr);
         Datapad(1:length(msg_bits_out)) = msg_bits_out;   
         DataOut = Datapad;
      else
         DataOut = msg_bits_out;
      end
         clear Datapad;

      DataOut = reshape(DataOut,NumCarr,numsymb);
      numsymb = size(DataOut,1)+1;
      wordsize=1;

      % DPSK Modulation
      PhaseRef = round(rand(120,1))+1;
      DPSKdata = zeros(size(DataOut,1)+1,size(DataOut,2));
      DPSKdata(1,:) = PhaseRef;
      for k = 1:numsymb -1
         DPSKdata(k+1,:) = mod((DataOut(k,:)+DPSKdata(k,:)-1),(2^wordsize))+1;
      end

      [X,Y] = pol2cart(DPSKdata*(2*pi/(2^wordsize)),ones(size(DPSKdata)));
      CarrCmplx = X+1i*Y;

      % OFDM Carrier Setting
      CarrSpacing = 1;
      StartCarr = 4;
      FinCarr= 123;
      carriers = (StartCarr:CarrSpacing:FinCarr)+1;
      NumCarr = length(carriers);

      % Adding Null Sub Carriers
      TxSpectrums = zeros(numsyb,ifftsize);
      for k = 1:numsymb
         TxSpectrums(k,carriers) = CarrCmplx(k,:);
      end
      
      % OFDM Symbol  Generation- IFFT
      BaseSignal = ifft(TxSpectrums);

      % Insertion of CYCLIC PREFIX
      cp= round((1/4)*ifftsize);
      BaseSignal=[BaseSignal(end-cp+1:end,:);BaseSignal];

      % Parallel to Serial Conversion
      BaseSignal = reshape(BaseSignal,1,size(BaseSignal,1)*size(BaseSignal,2));

      % UP-Sampling
      BaseSignal1 = interp(real(BaseSignal),r);
      BaseSignal2 = interp(real(BaseSignal),r);

      t=0:1/fs1:T*numsymb-1/fs1;
      length(t)

      % Loading Onto carrier
      carc = cos(2*pi*30000*t);
      cars = sin(2*pi*30000*t);
      TxSignal=sp*((BaseSignal1.*carc)+(BaseSignal2.*cars));

      % Adding Preamble
      pre=0.4*lpwm(0:1/fs:0.01,30000,0.01,34000);
      pkt=2*[pre zeros(1,ceil(0.05*fs1)) TxSignal];

      %Spectrum of Transmitted Signal
      l= length(TxSignal);
      p=fft(TxSignal,l);
      f=fs1*(1:l)/l;
      f1 = figure(1);
      set(f1,'color',[1 1 1]);
      plot(f,abs(p(1:length(f))));
      xlabel('Frequency (Hz)');
        ylabel('Magnitude')
      clear l p f

    %%=====================================================
    %%Invoking N! 6110 DAQ through DAQ toolbox
    %%=====================================================

      ai = analoginput('nidaq',1);
      addchannel(ai,0);
      ai.Channel.InputRange = [0.01 0.01];
      set(ai,'SampleRAte',fs1);
      set(ai,'SamplesPertRigger',lengt(pkt)+fs1*0.1)

      ao = analogoutput('nidaq',1);
      cahns=addchannel(ao,0);
      set(ao,'SampleRate',fs1);
      tempao=ger(ao,'Channel');
      apkt = abs(pkt);
      apkt1 = apkt>0.7;
      apkt2 = apkt1.*pkt;
      pkt = pkt-apkt2+sign(apkt2)*0.7;
      set(tempao,OutputRange,[-0.7,0.7])
      putdata(ao,pkt)
      start([ai ao])
        rxdata = getdata(ai);
        stop([ai ao])
      delete([ai ao])

[Oleg Komarov]

You will get the opposite effect: http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

Answer 1

[Walter Roberson]

That's ... interesting... considering that you have far fewer than 238 lines of code in what you showed here.

Is line 238 the final line of the file fullcodeTRx.m ? If so then did you perhaps somewhere along the way remove a "function" line from the file?

Which version of MATLAB are you using?

[aheesh gaur]

i m using 7.9.0(R2009b)

I did neither of the two, there are only 122 line in the code and i have put comments on each part.

And no function was removed ,i wish to add instead of taking random numbers, i wish to take a string from user convert it into decimal then to binary and apply the same.

%this program converts the string value from user to ascII to binary value

clc;

k=0;

bin=0;

l=0;

u=input('enter the string for conversion==> ','s');

k=double(u);

%dec_nr=s;

%l=dec_nr;

display(k);

bin=dec2bin(k);

display(bin);

data_in = bin;

[aheesh gaur]

thank you..:)

[Walter Roberson]

Specify an explicit number of bits to use in your dec2bin() call, such as

bin = dec2bin(k,8)

Answer 2

[aheesh gaur]

i m facing the following errors

??? Subscripted assignment dimension mismatch.

Error in ==> finalcodes at 62 DPSKdata(1,:) = PhaseRef;

[Walter Roberson]

PhaseRef is going to be exactly 120 elements long (hard-coded, probably should be NumCarr instead of the literal 120), but DPSKdata(1,:) is going to be of length ceil(length(msg_bits_out)/NumCarr) (the value that used to be assigned to numsymb, but numsymb was assigned a different value right after it was used to size the DPSKdata array.)

Put a breakpoint at that line, and look at size(PhaseRef) and size(DPSKdata)

[tariq khan]

phase refrence is 120 X 1, whereas DPSK is 120 X 121. now ehat should be done?

[tariq khan]

sorry DPSK is 121 X 121.

Answer 3

[rohun pandraka]

Can you give me the code for FEC bits of an Uppercase ASCII character. Thanks in advance