I want to mirror my signal over the y axis and make 4 repetitions of it

Question

Iztok Grof 2021-1-15

0
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https://ww2.mathworks.cn/matlabcentral/answers/717750-i-want-to-mirror-my-signal-over-the-y-axis-and-make-4-repetitions-of-it

回答： Prudhvi Peddagoni 2021-1-18

Hello

I am trying to show that the frequency specter of a signal repeats itself. I wrote a code which samples a signal and plots its frequency specter, but it only shows the specter from 0 onwards (half the signal), and only 1 repetition.

I wish for it to be symetric over the y axis and repeat itself, something in this style:(pardon my symplisti drawing)

this is my code:

Fs=1e6; %%%% frequency of sampling
t=0:1/Fs:0.001;
f=10000;
x=0.5*(square(2*pi*f*t)+1);
nfft=1024;
X=fft(x,nfft);
X=X(1:nfft/2);
mx=abs(X);
f=(0:nfft/2-1)*Fs/nfft;
subplot(212)
plot(f,mx), title('Freq. Spekter, Fs = 1MHz'), xlabel('frekvenca (Hz)'), ylabel('moč')
grid on