Dear fellows,i have generated OOK(on off keying signal).Then i have taken FFT of OOK signal and then i have removed some part of frequecny from 50-150HZ.Then again i have taken IFFT so that i can see signal in time domain.This code is working perfectly now by collaboration of you guys.Now my next step is calculate BER(bit error rate).I have write code for it but it is not working well even when i simulate it ,it is giving errorsThere should be no errors when BODE=10,and when we increase it it gives errors.I am Pastin my both codes.
clc,close all,clear all
codn=100;
fs=360;
bode=10;
code=round(rand(1,codn));
code_len=round(1/bode/(1/fs))
for ii=1:codn
x((ii-1)*code_len+1:code_len*ii)=code(ii)
end
x2 = x-(1/2)
length(x)
u = length(x)
N = 2^nextpow2(u)
delt = 1/fs;
delf = fs/N;
delf1=fs/u
figure(1)
tvec2=(1:length(x2))*delt;
plot(tvec2,x2(1,:)+0.5)
title('orignal baseband')
xlabel('time');
ylabel('amplitude')
ylim([-1 1.5]);
y = fftshift(fft(x2)/N);
z=abs(y);
figure(2)
fvec2=(-length(x2)/2:length(x2)/2-1)*delf1;
plot(fvec2,z)
title('FFT')
xlabel('frequency')
ylabel('amplitude')
figure(3)
z=y;
z(abs(fvec2)>50 & abs(fvec2)<=150)=0
plot(fvec2,abs(z))
xlabel('frequency removed from 50 to 150 HZ');
ylabel('amplitude')
figure(4)
zf=fftshift(z)*N;
zifft=ifft(zf)+0.5;
plot(tvec2,abs(zifft))
ylim([-1 1.5])
title('recovered signal')
xlabel('time');
ylabel('amplitude')
The above code is ok.
Problem is in the code below.Please anyone can remove erros.i tried but not succcedded.I have set fs=360 and bode=10.At these parameters there should be no BER,but if i increase bode then there should be errors,because if you run above code and change bode>10 then in last figure(4) you can see there are bit which are distorted.
clc,close all,clear all
codn=100;
max_run=20;
Eb=1;
SNRdB=0:1:9;
SNR=10.^(SNRdB/10);
fs=360;
bode=10;
code=round(rand(1,codn));
code_len=round(1/bode/(1/fs))
for iii=1:length(SNR)
avgError=0;
No=Eb/SNR(iii);
for ii=1:codn
x((ii-1)*code_len+1:code_len*ii)=code(ii);
Error=0;
data=randint(1,codn);
N=sqrt(No/2)*randn(1,codn);
Y=N;
u = length(x);
N = 2^nextpow2(u);
delt = 1/fs;
delf1=fs/u;
figure(1)
tvec2=(1:length(x))*delt;
plot(tvec2,x(1,:)+0.5)
title('orignal baseband')
xlabel('time');
ylabel('amplitude')
ylim([-1 1.5]);
y = fftshift(fft(x)/N);
z=abs(y);
figure(2)
fvec2=(-length(x)/2:length(x)/2-1)*delf1;
plot(fvec2,z)
title('FFT')
xlabel('frequency')
ylabel('amplitude')
figure(3)
z=y;
z(abs(fvec2)>120 & abs(fvec2)<=150)=0;
plot(fvec2,abs(z))
xlabel('frequency removed from 50 to 150 HZ');
ylabel('amplitude')
figure(4)
zf=fftshift(z)*N;
zifft=ifft(zf)+0.5;
for k=1:codn
if ((Y(k)>0 && data(k)==0)||(Y(k)<0 && data(k)==1))
Error=Error+1;
end
end
Error=Error/codn;
avgError=avgError+Error;
end
BER_sim(codn)=avgError/max_run;
end
BER_th=(1/2)*erfc(sqrt(SNR));
plot(tvec2,abs(zifft))
ylim([-1 1.5])
title('recovered signal')
xlabel('time');
ylabel('amplitude')
figure; semilogy(SNRdB,BER_sim,'k*');
xlabel('Eb/N0,db');
ylabel('Bit Error Rate');
grid on
title('Bit error probability curve for OOK ');
legend('simulation','theory');
