To low pass filter the data in Matlab, you can use the lowpass
function from the Signal Processing Toolbox. The following code snippet shows how to apply the low pass filter to the precipitation data.
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In the code above, we first load the data from a text file and extract the datetime and precipitation values. We then define the sampling frequency Fs
as the inverse of the sampling interval (which is 3600 seconds in this case). We also define the cutoff frequency Fc
as 0.1 Hz, which means we are removing any content in the signal above 0.1 Hz. We choose a filter order of 4, which is a good trade-off between filter complexity and performance.
We then design the low pass filter using the butter
function, which returns the filter coefficients B
and A
. Finally, we apply the filter to the precipitation data using the filtfilt
function, which applies the filter twice (once forward and once backward) to ensure zero phase distortion.
Note that in practice, you may need to adjust the filter parameters (i.e., Fc
and N
) to achieve the desired filtering performance.
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