Real Time Low Pass Filtering
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Commented: tinkyminky93 on 31 Jan 2023
I am trying to apply the low pass filter to my data. My samples are like square wave and I want them to be smoother. In order to do that, I am using low pass filter. This works fine for offline operations, I mean, I have all the data and time vector, so it is easy to filter the data. But I want to do it real-time with minimum delay, like 1 sample delay. Here is my .mat files and graphs that I got.
temperature = load("C:\Users\User\Desktop\Samples.mat");
% Samples.mat have temperature data.
filtered_temperature = lowpass(temperature, 1, 1000);
% temperature.mat and filtered_temperature.mat attached.
Thanks for your help.
Benjamin Thompson on 31 Jan 2023
All digital filters working in real time must have some delay, this is a law of filtering in general. The amount of delay depends on the type of filter, how fast the passband falls off, etc. You can use the "fir" option of lowpass to ensure an FIR (finite impulse response) type filter which has constant delay in time. Then if you have a data file, your problem is not "real time", right? The delay of an FIR filter is equal to the order or number of coefficients in the filter. So just adjust the time values of the output so they line up with the original time values.
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