代码:
x = [1, 1, 1, 1]; N = 4; X_DFT = dft(x,N); % DFT of x(n) magX_DFT = abs(X_DFT), phaX_DFT = angle(X_DFT)*180/pi; realX_DFT = real(X_DFT); imagX_DFT = imag(X_DFT); angX_DFT = angle(X_DFT); n = 0:(N - 1); k = 0:1000; w = (pi/500)*k; % [0,2pi] axis divided into 501 points. %k = 0:500; w = (pi/500)*k; % [0,pi] axis divided into 501 points. X_DTFT = x * (exp(-j*pi/500)) .^ (n‘*k); % DTFT of x(n) magX_DTFT = abs(X_DTFT); angX_DTFT = angle(X_DTFT); realX_DTFT = real(X_DTFT); imagX_DTFT = imag(X_DTFT); figure(‘NumberTitle‘, ‘off‘, ‘Name‘, ‘Exameple5.6 x sequence‘) set(gcf,‘Color‘,‘white‘); stem(n,x); title(‘x sequence‘); axis([0,4,-0.5,1.5]); xlabel(‘n‘); ylabel(‘x(n)‘); grid on; %% -------------------------------------------------------------- %% START X_DTFT‘s mag ang real imag %% -------------------------------------------------------------- figure(‘NumberTitle‘, ‘off‘, ‘Name‘, ‘X_DTFT its Magnitude and Angle, Real and Imaginary Part‘); set(gcf,‘Color‘,‘white‘); subplot(2,2,1); plot(w/pi,magX_DTFT); grid on; % axis([-2,2,0,15]); title(‘Magnitude Part‘); xlabel(‘frequency in \pi units‘); ylabel(‘Magnitude |X\_DTFT|‘); subplot(2,2,3); plot(w/pi, angX_DTFT*180/pi); grid on; % axis([-2,2,-1,1]); title(‘Angle Part‘); xlabel(‘frequency in \pi units‘); ylabel(‘Degrees‘); %axis([-200,200,0,2]); subplot(‘2,2,2‘); plot(w/pi, realX_DTFT); grid on; title(‘Real Part‘); xlabel(‘frequency in \pi units‘); ylabel(‘Real‘); subplot(‘2,2,4‘); plot(w/pi, imagX_DTFT); grid on; title(‘Imaginary Part‘); xlabel(‘frequency in \pi units‘); ylabel(‘Imaginary‘); %% -------------------------------------------------------------- %% END X_DTFT‘s mag ang real imag %% -------------------------------------------------------------- %% -------------------------------------------------------------- %% START X_DFT‘s mag ang real imag %% -------------------------------------------------------------- figure(‘NumberTitle‘, ‘off‘, ‘Name‘, ‘Example5.6 X_DFT its Magnitude and Angle‘); set(gcf,‘Color‘,‘white‘); subplot(2,1,1); stem(n,magX_DFT); hold on; plot(2*w/pi,magX_DTFT,‘--‘); hold off; grid on; axis([-0.5,4.2,-1,5]); title(‘Magnitude Part of the DFT: N = 4‘); xlabel(‘k‘); ylabel(‘Magnitude |X\_DFT|‘); subplot(2,1,2); stem(n, phaX_DFT); hold on; plot(2*w/pi,angX_DTFT*180/pi,‘--‘); hold off; grid on; axis([-0.5,4.2,-200,200]); title(‘Angle Part of the DFT: N = 4‘); xlabel(‘k‘); ylabel(‘Degrees‘); %axis([-200,200,0,2]); %subplot(‘2,2,2‘); stem(n, realX_DFT); grid on; %title(‘Real Part‘); %xlabel(‘frequency in \pi units‘); ylabel(‘Real‘); %subplot(‘2,2,4‘); stem(n, imagX_DFT); grid on; %title(‘Imaginary Part‘); %xlabel(‘frequency in \pi units‘); ylabel(‘Imaginary‘); %% -------------------------------------------------------------- %% END X_DFT‘s mag ang real imag %% --------------------------------------------------------------
运行结果:
时间: 2024-11-05 16:02:51