Use the filtfilt function for the actual filtering, since unlike filter, filtfilt does not introduce any phase distortion. PROCESSING with MATLAB: Filter Implementation with GUI ToolsOctober 2016.Use the trapz function (be sure to give it your sampling frequency, ‘Fs’, to make the output understandable) in order to check the filter performance to be sure it is stable and does what you intend it to do.Use the tf2sos function to create a second-order-section representation for stability.
Use the output of buttord to design a transfer function (b,a) realization of your filter with the butter function, (I usually use 1 dB for Rp and 10 dB for Rs, but these are not relevant for Butterworth designs).If dsp.LowpassFilter is called with default properties, the following are some default values by which the input signal will be filtered by the low pass filter: passband frequency will be 8 kHz. To determine the order, start with the buttord function Description: LowPass dsp.LowpassFilter will return a low pass filter of minimum order and default filter properties.Electric filters, ActiveDesign and construction. That’s simply my personal bias, because my signals usually have baseline drift.) The MathWorks Publisher Logo identifies books that contain MATLAB content. (I usually prefer a bandpass with a very low cutoff, in the event that I want to filter out baseline drift. You have already decided on a lowpass design, the default for all of them, so you don’t have to specify a filter type. Filter Designer enables you to quickly design digital FIR or IIR filters by setting filter performance specifications, by importing filters from your MATLAB workspace or by adding, moving, or deleting poles and zeros.
You are always free to experiment with other designs, but the scheme I’m outlining for the Butterworth design is a prototype for all of them. Filter Designer is a powerful user interface for designing and analyzing filters. From your description, a Butterworth design is likely the best. Since you have Fs, the Signal Processing Toolbox makes the rest easy. You need to know the passband of the filter you want to design (the frequencies you want to either keep or filter out), and the sampling frequency (Fs) at the very least.