Dear fellows i am working on visible light communication and i removed frequency in the range of 3-200 HZ becuase of noise .Will you please do some modification in my code so that in last figure in time domain i use filter which does not remove noi

clc,close all,clear all

codn=70;

% fc=6e+3;

fs=3600;

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) % get rid of most of the dc peak

% set up time and frequency arrays

N = length(x);

delt = 1/fs;

delf = fs/N

tvec = (1:N)*delt

fvec = (-N/2:N/2-1)*delf ; % shifted frequency array

figure(1)

plot(tvec,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)

plot(fvec,abs(y))

title('FFT')

xlabel('frequency')

ylabel('amplitude')

figure(3)

z=y;

z(abs(fvec)>=3 & abs(fvec)<=200)=0

plot(fvec,abs(z))

xlabel('frequency removed from 3 to 200 HZ');

ylabel('amplitude')

figure(4)

zf=fftshift(z)*N;

zifft=ifft(zf)+0.5

plot(tvec,abs(zifft))

ylim([-1 1.5])

title('recovered signal')

xlabel('time');

ylabel('amplitude')

figure(5)

x2 = medfilt1(abs(zifft),70); % Filter with median filter

plot(tvec,x2)

title('Filtered Signal with median filter ')

xlabel('time ');

ylabel('amplitude ')

ylim([-1 1.5]);

[darova]

The question is unclear. YOu want you remove something? What?

[imran khan]

Dearf darva,

I mean i want to remove noise from signal which i filtered out in time domain using median filter.

and i want to transmitt this OOK signal which i am pasting below

I think now it is clear,if it is still not clear then you can ask any question without hesitation.

Best Regards,

Imran Khan.

[imran khan]

Please keep in mind after filtering signal shoul lies between 0 and 1 because we cant send signal in visible light communcation having negative amplitude.

[Daniel M]

No it's not clear. You're saying you want to remove noise from the signal in the plot "Filtered signal with median filter"? Can you indicate what you consider the noise to be in this signal? Looks pretty clean to me.

Also, and I've told you this before, it should be

zf=ifftshift(z)*N;

I've also asked you this before, but what do you want to do with the values of x outside of [0 1] range? Some suggestions: 1) clip values to the value at the boundary 2) take the reflection of the values about the boundary (like an absolute value) 3) normalize x to be within 0 and 1

And please post code using the "code" button so it is easier to read as well as copy/paste.

[imran khan]

Dear i will tell you complete detail on tuesday