Plotting amplitude spectrum of a signal

Question

prodeje 2020-4-23

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/520083-plotting-amplitude-spectrum-of-a-signal

回答： Sady 2023-10-25

So I need to generate a segment of 95 Hz sine wave for the duration of 35 ms, with 3.5 kHz sampling rate and display it in 2 graphs, time domain and amplitude spectrum.

I am struggling with amplitude spectrum, I imagine function fft is required, but how should it be used in this case?

Thanks in advance!

Here is my code below for representation in time domain:

   Fs = 3500;                   % samples per second
   dt = 1/Fs;                   % seconds per sample
   StopTime = 0.35;             % seconds
   t = (0:dt:StopTime-dt)';     % seconds
   %%Sine wave:
   Fc = 95;                     % hertz
   x = cos(2*pi*Fc*t);
   % Plot the signal versus time:
   plot(t,x);
   xlabel('Time(S)');
   title('Signal versus Time');

0 个评论
显示 -2更早的评论隐藏 -2更早的评论

请先登录，再进行评论。

请先登录，再回答此问题。

Answer 1

Ameer Hamza 2020-4-23

2
链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/520083-plotting-amplitude-spectrum-of-a-signal#answer_427864

编辑：Ameer Hamza 2020-4-23

在 MATLAB Online 中打开

Try the following code. Also see the first example on the documentation page of ff() for more details.

Fs = 3500;                   % samples per second
dt = 1/Fs;                   % seconds per sample
StopTime = 0.35;             % seconds
t = (0:dt:StopTime-dt)';     % seconds
%%Sine wave:
Fc = 95;                     % hertz
x = cos(2*pi*Fc*t);
% Plot the signal versus time:
subplot(2,1,1);
plot(t,x);
xlabel('Time(S)');
title('Signal versus Time');
subplot(2,1,2);
f = Fs*linspace(0, 1/2, floor(numel(x)/2));
fr = fft(x);
fr = abs(fr)/numel(x);
fr = fr(1:floor(end/2));
fr(2:end-1) = 2*fr(2:end-1);
plot(f, fr);
xlabel('Time(S)');
title('Frequency Response');