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- clc;cla;clf;clear;
- NP = 1;
- N = 128;
- DC = 0;
- A = 10;
- fsig = 5;
- Tsig = 1/fsig;
- fvz = 1/(NP*Tsig/N)
- k=0:N-1;
- y = DC + A*cos(2*pi*fsig*k*1/fvz);
- figure(1);
- stem(k,y);
- xlabel('Vzorky [-]');
- ylabel('Amplituda [V]');
- title('Originální signál');
- FFT = fftshift(fft(y)/length(y));
- DFT = zeros(1,N);
- for k = 0 : N - 1
- s = 0;
- for t = 0 : N - 1
- s = s + y(t + 1) * exp(-2i * pi * t * k / N);
- end
- DFT(k + 1) = s;
- end
- % Porovnání mojí DFT a zabudované FFT
- DFT = fftshift(DFT)/length(DFT);
- f = fvz/2*linspace(-1,1,N);
- figure(2);
- hold on;
- subplot(2, 1, 1);
- stem(f,FFT);
- xlabel('Frekvence [Hz]');
- ylabel('Amplituda [V]');
- title('FFT');
- subplot(2, 1, 2);
- stem(f,DFT);
- xlabel('Frekvence [Hz]');
- ylabel('Amplituda [V]');
- title('DTF');
- % Amplitudové spektrum
- amp = abs(FFT);
- f = fvz/2*linspace(-1,1,N);
- figure(3);
- subplot(2, 1, 1);
- stem(f(N/2+1:N),2*amp(N/2+1:N));
- xlabel('Frekvence [Hz]');
- ylabel('Amplituda [V]');
- title('Jednostranné amplitudové spektrum');
- subplot(2, 1, 2);
- stem(f,amp);
- xlabel('Frekvence [Hz]');
- ylabel('Amplituda [V]');
- title('Oboustranné amplitudové spektrum');
- % Fázové spektrum
- faz = 180/pi*angle(FFT);
- figure(4);
- subplot(2, 1, 1);
- stem(f(N/2+1:N),faz(N/2+1:N));
- xlabel('Frekvence [Hz]');
- ylabel('DEG [°]');
- title('Jednostranné fázové spektrum');
- subplot(2, 1, 2);
- stem(f,faz);
- xlabel('Frekvence [Hz]');
- ylabel('DEG [°]');
- title('Oboustranné fázové spektrum');
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