Re: filtering decimation of a signal

MooseFET wrote:

That is an IIR filter. If you put a spike into it, it basically never
returns to the zero point.

This depends on alpha and the resolution. E.g. if you use 8 bit words, even
for low alpha values like 0.1, after a pulse of 255 the filtered variable
will be down to 0 after 19 steps, but I think this is ok for a spike. A FIR
lowpass filter with 19 taps can show the same behavior.

It depends on the application. The main disadvantage of IIR filters are
different phase delay times for different frequencies, so it is nothing you
want to use for audio filtering, but it is much faster to calculate than
FIR filters and good for doing some noise filtering for sensor measurement.

--
Frank Buss, fb@xxxxxxxxxxxxx
http://www.frank-buss.de, http://www.it4-systems.de
.

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