MATLAB: Interpolate/Adjust to new Sampling Rate

fftinterpolationsampling ratetime stamps

Hello,

i have data received from a accelerometer with a sampling frequency of 10Hz.

But the time stamps in the data file are not equidistant, the sampling time interval is changin.

How can i "fix" the time stamps with my corresponding acceleration values?

So far i have just calculated the mean value for the sampling time interval (for further fft calculations) -> t_s = mean(diff(t))

Is there a better way to do that? maybe by interpolation?

Best Answer

Use the Signal Processing Toolbox resample function. The advantage it offers over simply interpolating is that it uses an anti-aliasing filter to keep the resamples signal free of extraneous frequencies.

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MATLAB: Downsampling of RPM traces

I assume that the signal is sampled regularly, and a fixed sampling interval.

Use the Signal Processing Toolbox resample function. It will do exactly what you want.

A prototype call to it would be:

RPMrs = resample(RPM, 52, 260);

so the output will be sampled at 5.2/26 of the original rate.

To calculate a new time vector for it, use the linspace function.

Note that if it is not uniformly sampled, first follow the procedure in Resample a Nonuniformly Sampled Data Set, then do the rate resampling.

MATLAB: How to resample 50Hz signal to 30Hz

It’s always best to upsample rather than downsample because it’s easier to design filters for them.

If you must, use the Signal Processing Toolbox resample funciton:

S50 = ...;                                                  % Signal Sampled At 50 Hz
S30 = resample(S50, 3, 5);                                  % Resampled Signal At 30 Hz

Use resample rather than interp. The resample function incorporates a FIR anti-aliasing filter.

Best Answer

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MATLAB: Downsampling of RPM traces

MATLAB: How to resample 50Hz signal to 30Hz

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