How do I find the period or frequency of a signal?

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Phillip C
Phillip C 2018-3-7
编辑： Dmitry Grigoryev 2020-10-14
I currently have an array of data points which is clearly periodic and i can see the period just by lopoking at the graph, however how would i go about getting matlab to give me a readout of the period. One problem with finding the distance between peaks is that they are faily noisey so was thinking of finding distance between the dips, but i am having trouble workiing out how i would go about doing that.

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Star Strider
Star Strider 2018-3-7
I would first detrend (link) your data, then use findpeaks (link) to identify the peaks and their locations. Use the location information to calculate the period and from that, frequency.
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jb4earth
jb4earth 2019-9-19
@Xu you are correct
PEAK period should be calculated as:
peak_wave_period = max(diff(your_time_vector(peaks)))
DoubleO7
DoubleO7 2019-10-15
I was wondering if anyone could expand upon this answer. What do you mean by time vector? Would an example of a time vector be:
tv = 1:100;
Is writing the following code correct for displaying the period?
[pks,locs] = findpeaks(data,tv)
period = max(diff(locs))
I appreciate your input.

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Dmitry Grigoryev
Dmitry Grigoryev 2020-10-14
编辑：Dmitry Grigoryev 2020-10-14
Start by substracting the sliding average from the raw signal.
Then shift the signal by rougly 1 period and use autocorrelation to find the exact period value.

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