matlab怎样对时域信号进行频谱分析

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  370026575susu 2017-11-03 00:00:00

  在命令窗口输入doc fft回车后，可看到例子。 %构造出信号（如已有信号，此步可省略） Fs = 1000; % Sampling frequency T = 1/Fs; % Sample time L = 1000; % Length of signal t = (0:L-1)*T; % Time vector % Sum of a 50 Hz sinusoid and a 120 Hz sinusoid x = 0.7*sin(2*pi*50*t) + sin(2*pi*120*t); y = x + 2*randn(size(t)); % Sinusoids plus noise plot(Fs*t(1:50)，y(1:50)) title('Signal Corrupted with Zero-Mean Random Noise') xlabel('time (milliseconds)') NFFT = 2^nextpow2(L); % Next power of 2 from length of y Y = fft(y，NFFT)/L; f = Fs/2*linspace(0，1，NFFT/2+1); %FFT分析 % Plot single-sided amplitude spectrum. plot(f，2*abs(Y(1:NFFT/2+1))) title('Single-Sided Amplitude Spectrum of y(t)') xlabel('Frequency (Hz)') ylabel('|Y(f)|')

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