Matlab代码，将时域信号转换成频域信号，附带汇报PPT

clc,clear; Fs = 1000; % 采样频率 f1=10*105; f2=100*105; amp=1 T = 1/Fs; % 采样周期 L = 790; % 信号长度 t = (0:L-0.001)*(pi); % 时间向量 phase=0; S = amp*cos((2*pi*f1*t)+phase) X = amp*cos((2*pi*f2*t)+phase) Y=S+X; Z=S.*X; figure %时域图 subplot(2,2,1) plot(t,S,"R","linewidth",1);xlabel("S(t)");ylabel("Amplitude") title("Signal_1)") % plot(1000*t(1:50),X(1:50),"R","linewidth",1);xlabel('t (milliseconds)') % ylabel('X(t)') % title('Signal Corrupted with Zero-Mean Random Noise') subplot(2,2,2) plot(t,X,"Blue","linewidth",1);xlabel("X(t)");ylabel("Amplitude") title("Signal_1)") subplot(2,2,3) plot(t,Y,"Black","linewidth",1);xlabel("Y(t)");ylabel("Ampltitude") title("Adding the two Signals") subplot(2,2,4) plot(t,Z,"Green","linewidth",1);xlabel("Z(t)");ylabel("Ampltitude") title("Multiplying the two Signals") % subplot(2,2,2) % plot(1000*t(1:5),S(1:50),"Blue","linewidth",1) % title("Secend Signal") % xlabel("t (millisecond") % ylabel("S(t)") figure %频域图 a = fftshift(fft(X)); P2 = abs(a/L); P1 = P2(1:L/2+1); P1(2:end-1) = 2*P1(2:end-1); f = Fs*(0:(L/2))/L; subplot(2,2,1) plot(f,P1,"Black","linewidth",1);xlabel('f (Hz)');ylabel('Amp') title('Frequency Spectrum of Signal_1') b = fftshift(fft(S)); P2 = abs(b/L); P1 = P2(1:L/2+1); P1(2:end-1) = 2*P1(2:end-1); subplot(2,2,2) plot(f,P1,"Green","Linewidth",1);xlabel('f (Hz)');ylabel('Amp') title('Frequency Spectrum of Signal_2') c = fftshift(fft(Y)); P2 = abs(c/L); P1 = P2(1:L/2+1); P1(2:end-1) = 2*P1(2:end-1); f = Fs*(0:(L/2))/L; subplot(2,2,3) plot(f,P1,"Blue","linewidth",1);xlabel('f (Hz)');ylabel('|P1(f)|') title('Frequency Spectrum of Adding two Signals') d = fftshift(fft(Z)); P2 = abs(d/L); P1 = P2(1:L/2+1); P1(2:end-1) = 2*P1(2:end-1); f = Fs*(0:(L/2))/L; subplot(2,2,4) plot(f,P1,"Red","linewidth",1);xlabel('f (Hz)');ylabel('|P1(f)|') title('Frequency Spectrum of Multiplication')