Error in coding

The following code taken from

http://www.mathworks.com/products/commblockset/demos.html?file=/products/demos/shipping/commblks/commLLRvsHD_m.html

is not workign , plese some one help me to make it work. Two errors were displayed.

EbNo           = 2:0.5:8;    % information rate Eb/No in dB
codeRate       = 1/2;        % code rate of convolutional encoder
nBits          = 4;          % number of bits in a 16-QAM symbol
Pavg           = 10;         % average signal power of a 16-QAM modulated si
gnal
snr            = EbNo - 10*log10(1/codeRate) + 10*log10(nBits); % SNR in dB
noiseVarVector = Pavg ./ (10.^(snr./10)); % noise variance

    % Initialize variables for storing the BER results
  ber_HD      = zeros(1, length(EbNo));
  ber_SD      = zeros(1, length(EbNo));
  ber_LLR     = zeros(1, length(EbNo));

    % Loop over all noiseVarVector values
  for idx=1:length(noiseVarVector)
      noiseVar = noiseVarVector(idx);
      sim(modelName);
      % Collect BER results
      ber_HD(idx)  = BER_HD(1);
      ber_SD(idx)  = BER_SD(1);
      ber_LLR(idx) = BER_LLR(1);
  end

    % Perform curve fitting and plot the results
  fitBER_HD  = real(berfit(EbNo, ber_HD));
  fitBER_SD  = real(berfit(EbNo, ber_SD));
  fitBER_LLR = real(berfit(EbNo, ber_LLR));
  semilogy(EbNo, ber_HD, 'r*', ...
           EbNo, ber_SD, 'g*', ...
           EbNo, ber_LLR, 'b*', ...
           EbNo, fitBER_HD, 'r', ...
           EbNo, fitBER_SD, 'g', ...
           EbNo, fitBER_LLR, 'b');
  legend('Hard Decision Decoding','Soft Decision Decoding','Unquantized Decodi
  ng');
  xlabel('Eb/No (dB)'); ylabel('BER');
  title('LLR vs. Hard Decision Demodulation with Viterbi Decoding');
  grid on;

[Matt Fig]

It is always helpful to give more information rather than less. For example, what did the error messages say? Copy and paste the error messages.

Answer 1

[Matt Fig]

Do have the correct toolboxes? Did you format the code correctly? It looks like there is some wrapping going on even on the page you got it from. Try this:

EbNo           = 2:0.5:8;    
codeRate       = 1/2;        
nBits          = 4;          
Pavg           = 10;         
snr            = EbNo - 10*log10(1/codeRate) + 10*log10(nBits); 
noiseVarVector = Pavg ./ (10.^(snr./10)); % noise variance

% Initialize variables for storing the BER results
ber_HD      = zeros(1, length(EbNo));
ber_SD      = zeros(1, length(EbNo));
ber_LLR     = zeros(1, length(EbNo));

% Loop over all noiseVarVector values
for idx=1:length(noiseVarVector)
    noiseVar = noiseVarVector(idx);
    sim(modelName);
    % Collect BER results
    ber_HD(idx)  = BER_HD(1);
    ber_SD(idx)  = BER_SD(1);
    ber_LLR(idx) = BER_LLR(1);
end

% Perform curve fitting and plot the results
fitBER_HD  = real(berfit(EbNo, ber_HD));
fitBER_SD  = real(berfit(EbNo, ber_SD));
fitBER_LLR = real(berfit(EbNo, ber_LLR));
semilogy(EbNo, ber_HD, 'r*', ...
         EbNo, ber_SD, 'g*', ...
         EbNo, ber_LLR, 'b*', ...
         EbNo, fitBER_HD, 'r', ...
         EbNo, fitBER_SD, 'g', ...
         EbNo, fitBER_LLR, 'b');
legend('Hard Decision','Soft Decision','Unquantized Decoding');
xlabel('Eb/No (dB)'); ylabel('BER');
title('LLR vs. Hard Decision Demodulation with Viterbi Decoding');
grid on;

Answer 2

[Sherif]

that coding was also not working, following error message has occoured.

??? Undefined function or variable 'modelName'.

Error in ==> Untitled4 at 16 sim(modelName);

can you please correct it ..?

Answer 3

[Walter Roberson]

You appear to have missed the part before the diagram on that page:

modelName = 'commLLRvsHD';
open_system(modelName);