problem with fft

2011 5 19
3 个回答
回答已采纳
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0 个投票

hello i have this program that make ifft for some random vary maybe someone can help me with the fft? thanks
N=10;
fs=1e6;
T=1e-3;
% random signal
bit=randint(20,1); % 20 bits 0 or 1 1 x 20
% serial-to-parallel converter
par=reshape(bit,2,10); % 2 x 10 2 bits for sym
% mapper
sym=par'*[2;1]; % multiplay for mapper 00-0 01-1 10-2 11-3
phase=[-3*pi/4,3*pi/4,-pi/4,pi/4];
phase_sym=phase(sym+1); % every sym gets phase for example pi/4 will get '3'
% IFFT
for k=0:N-1
i=1;
for t=1/fs:1/fs:T
x(k+1,i)=cos((2*pi*k*t)/T+phase_sym(k+1))+j*sin((2*pi*k*t)/T+phase_sym(k+1));
i=i+1;
end
end

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 采纳的回答

0 个投票

Why don't you use MATLAB's fft and ifft functions directly?
EDIT
For example, if you want it to have a length of 1000, it is very easy:
% Suppose "x" is the signal you want
x_fft = fft(x, 1000);
x_mag = abs(x_fft); % Magnitude
x_pha = angle(x_fft); % Phase

更多回答（2 个）

itsik
itsik 2011-5-20

0 个投票

cause i need the length of the fft will be 1000 do u know how i make it? with fft?
itsik
itsik 2011-5-20

0 个投票

maybe someone's know? or how to replace all this code in ifft command?

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