Desinging both IIR and FIR bandpass filter

Hello,

Can someone help me out in designing a IIR bandpass filter and FIR bandpass filter with the needed parameters of sampling rate=500Hz and frequencies to be passed are between 0.5 Hz to 2.4Hz.

Thanks.

Answer 1

[Jan]

What about a sixth order Butterworth for the IIR filter:

Wn     = [0.5, 2.4] / 250;
[B, A] = butter(3, Wn)

And as a FIR filter:

[B, A] = fir1(3, Wn)

But there are a lot of other possible choices of parameters. Do you have any further details to consider?

[Gova ReDDy]

The signal I want to filter is being acquired through serial port into matlab and this signal is the output of the analog board that is sampled on microcontroller at 500Hz.

The analog board has a analog bandpass filter that allows only freq in 0.5 to 2.4Hz.

So,I want to be sure that the signal acquired into matlab doesn't contain any other freq except the freq's in the range of 0.5 to 2.4Hz for the post processing of signal.

[Gova ReDDy]

can I know how to design the filter with above requirements.

[Jan]

The posted details are not useful to specify filter conditions.

A filter cannot crop "everything" outside the band while keeping "all" frequencies inside the band. The are always effects on the edges of the band. It is impossible to keep all frequencies with 2.39999999999999999Hz and removing all signals with 2.40000000000000001Hz. The filter parameters, e.g. the order of the Butterworth filter define the slope of the damping at the edges.

[Gova ReDDy]

Then can I know how to design the filter that can allow minimum frequencies in addition to the required 0.5Hz frequency for the lower limit and other highest frequency in addition to the required 2.4Hz frequency and required filter order as I don't have better knowledge on the filter order.