Find frequency from fourier transform
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I have the following code which generates a sine wave of frequency 30Hz:
num_sam =1000; %number of samples
sam_int = 0.001; %sample interval in seconds
time = sam_int*(1:num_sam); %sample times, in sec's
sin_freq = 30; %in hertz
y = exp(1i*sin_freq*time);
I'd like to perform a Fourier transform of this wave to find the frequency, but every graph I get isn't peaking (if at all) at 30Hz. How can I achieve this?
Thanks.
1 个评论
Adam
2017-1-17
Have you looked at
doc fft
? There are examples of how to do this.
回答（1 个）
Honglei Chen
2017-1-17
The signal should be defined as
exp(1i*2*pi*sin_freq*time)
Otherwise, your frequency is scaled by 2*pi.
HTH
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2017-1-17
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