BERtool showing "Too many input arguements"

here is the code.On running this fuction code in BERTool/BER Analysis i get some error(read title for the error msg)

function [ber, bits]=WNproj(EbNo, maxNumErrs, maxNumBits)
%% Constants
FRM=2048;
Trellis=poly2trellis(4, [13 15], 13);
Indices=randperm(FRM);
M=4;k=log2(M);
R= FRM/(3* FRM + 4*3);
snr = EbNo + 10*log10(k) + 10*log10(R);
noise_var = 10.^(-snr/10);
%% Initializations
persistent Modulator AWGN DeModulator BitError TurboEncoder TurboDecoder
if isempty(Modulator)
    Modulator = comm.QPSKModulator('BitInput',true);
    AWGN = comm.AWGNChannel;
    DeModulator = comm.QPSKDemodulator('BitOutput',true);
    BitError = comm.ErrorRate;
    TurboEncoder=comm.TurboEncoder('TrellisStructure',Trellis,'InterleaverIndices',Indices);
    TurboDecoder=comm.TurboDecoder('TrellisStructure',Trellis,'InterleaverIndices',Indices,'NumIterations',6);
end
%% Processsing loop modeling transmitter, channel model and receiver
AWGN.EbNo=snr;
numErrs = 0; numBits = 0;results=zeros(3,1);
while ((numErrs < maxNumErrs) && (numBits < maxNumBits))
% Transmitter
    u = randi([0 1], FRM,1); % Random bits generator
    encoded = TurboEncoder.step(u); % Turbo Encoder
    mod_sig = Modulator.step(encoded); % QPSK Modulator
    % Channel
    rx_sig = AWGN.step(mod_sig); % AWGN channel
    % Receiver
    demod = DeModulator.step(rx_sig, noise_var); % Soft-decision QPSK Demodulator
    decoded = TurboDecoder.step(-demod); % Turbo Decoder
    y = decoded(1:FRM); % Compute output bits
    results = BitError.step(u, y); % Update BER
    numErrs = results(2);
    numBits = results(3);
end
%% Clean up & collect results
ber = results(1); bits= results(3);
reset(BitError);

Answer 1

[Shiva Kalyan Diwakaruni]

Hi,

demod = DeModulator.step(rx_sig, noise_var); uses soft decision demodulation and noise variance VAR. This syntax applies when you set the BitOutput property to true, the DecisionMethod property to Approximate log-likelihood ratio or Log-likelihood ratio, and the VarianceSource property to Input port. The data type of input VAR must be double or single precision.

Hence in your code BitOutput property is set to true but the DecisionMethod property also should be set to Approximate log-likelihood ratio or Log-likelihood ratio, and the VarianceSource property should be set to Input port

Hope it helps.