Please rectify the error in the code

clc;
clear all;
close all;
SNR=[0:1:14];
snr=10.^(SNR/10);
BER1=zeros(length(SNR),1);
BER2=BER1;
BER3=BER1;
Nmax=1000;
Nerr=100;
for k=1:length(SNR)
    for l=1:Nmax
        Ns=100;
        data=2*round(rand(Ns,1))-1;
        if l==1 && k==1
            plot(data);title('data');axis([0 Ns -1.1 1.1]);
            pause
        end
        bpsk=data;
        n=1/sqrt(2)*(randn(Ns,1)+j*randn(Ns,1));
        if l==1 && k==1
            var_n=norm(n)^2;
        end
        bpsk=sqrt(snr(k))*data+n;
        if l==1 && k==1
            plot([real(bpsk) data]);
            legend('real part of signal','data');
            title('BPSK signal in noise');
            pause
        end
        taps=1/sqrt(2)*(randn(Ns,1)+j*randn(Ns,1));
        bpsk_r=sqrt(snr(k))*abs(taps).*data+n;
        if l==1 && k==1
            plot([real(bpsk_r) data])
            legend('real part of signal','data');
            title('BPSK signal in noise & fading channel');
            pause
        end
        if l==1 && k==1
            plot(abs([bpsk bpsk_r]))
            legend('AWGN','RAYLEIGH');
            title('BPSK in AWGN & Rayleigh fading channel');
            pause
        end
        r1=real(bpsk);
        r2=real(bpsk_r);
        if l==1 && k==1
            plot([r1 r2])
            legend('AWGN','Rayleigh');
            title('demodulated symbols');
            pause;
        end
        d1=find(r1>=0);d2=find(r1<0);
        r1(d1)=1;r1(d2)=-1;
        d1=find(r2>=0);d2=find(r2<0);
        r2(d1)=1;r2(d2)=-1;
        if l==1 && k==1
            plot([r1 r2])
            legend('AWGN','Rayleigh');
            axis([0 Ns -1.1 1.1]);
            title('demodulated symbols after hard decisions');
            pause;
        end
        Ber1=length(find((data-r1)~=0));
        Ber2=length(find((data-r2)~=0));
        if k==1 && l==1
            errors=[Ber1 Ber2];
        end
        BER1(k)=BER1(k)+Ber1;
        BER2(k)=BER2(k)+Ber2;
        if BER1(k)>Nerr && BER2(k)>Nerr
            break
        end
    end
    BER1(k)=BER1(k)/Ns/l;
    BER2(k)=BER2(k)/Ns/l;
end
BER=[SNR BER1(k) BER2(k)];
The_awgn=.5*erfc(sqrt(2*snr)/sqrt(2));
The_rayl=.5*(1-sqrt(snr./(1+snr)));
semilogy(SNR,[The_awgn The_rayl BER1(k) BER2(k)]);
xlabel('SNR [dB]');
ylabel('BER');
axis([0 SNR(length(SNR)) 1e-4 .5]);
grid on;
legend('Theor AWGN','Theor Rayl.','AWGN','Rayl.');

[Supratik Das]

at the end their is an error in using semilogy

"Vectors must be of same length"

[Supratik Das]

please help......

Answer 1

[Star Strider]

Try this instead:

semilogy(SNR,[The_awgn; The_rayl; BER1'; BER2']);

[Supratik Das]

Thank you....

could you please explain what changes you have performed it will be helpfull for me....

[Star Strider]

As always, my pleasure.

Sure.

You were trying to plot a matrix of two row vectors and two scalars as a function of a row vector. My changes created your dependent variables as a (4x15) matrix by changing them all to row vectors (eliminating the subscripts of the last two and transposing them) and then concatenating them.

[Supratik Das]

Thank you for your explanation...it helped me a lot

[Star Strider]

As always, my pleasure.