error with 8psk modulation

Hi, I'am trying to test a code of the 8PSK modulation,this is the code:

custMap = [0 2 4 6 7 5 3 1];

hMod = comm.PSKModulator(8,'BitInput',true,'SymbolMapping','Custom','CustomSymbolMapping',custMap);
hDemod = comm.PSKDemodulator(8,'BitOutput',true,'SymbolMapping','Custom','CustomSymbolMapping',custMap);

% Display the modulator constellation.
constellation(hMod)
hChan = comm.AWGNChannel('BitsPerSymbol',log2(8));
hErr = comm.ErrorRate;

% Initialize the simulation vectors. The Eb/No is varied from 0 to 10 dB in
% 1 dB steps.
ebnoVec = 0:10;
ber = zeros(size(ebnoVec));

for k = 1:length(ebnoVec)

      % Reset the error counter for each Eb/No value
      reset(hErr)
      % Reset the array used to collect the error statistics
      errVec = [0 0 0];
      % Set the channel Eb/No
      hChan.EbNo = ebnoVec(k);

      while errVec(2) < 200 && errVec(3) < 1e7
          % Generate a 1000-symbol frame
          data = randi([0 1],4000,1);
          % Modulate the binary data
          modData = step(hMod,data);
          % Pass the modulated data through the AWGN channel
          rxSig = step(hChan,modData);
          % Demodulate the received signal
          rxData = step(hDemod,rxSig);
          % Collect the error statistics
          errVec = step(hErr,data,rxData);
      end

      % Save the BER data
      ber(k) = errVec(1);
  end
  berTheory = berawgn(ebnoVec,'psk',8,'nondiff');
  figure
  semilogy(ebnoVec,[ber; berTheory])
  xlabel('Eb/No (dB)')
  ylabel('BER')
  grid
  legend('Simulation','Theory','location','ne')

but I have a problem at this line

modData = step(hMod,data);

this is the error:

how can I solve the problem pleaze and thanks

Answer 1

[Rick Rosson]

Instead of

    data = randi([0 1],4000,1);

please try

    data = randi([0 1],3000,1);