AVR-Chat

Do a Google search on Infinite Impulse Response filters.  

I first learned about them in the book "The scientist and Engineers guide to
digital signal processing", Steven Smith.  Chapter 19, 20, ...

You can make pretty fancy filters by feeding forward and backwards several
discrete time values (inputs and outputs).

I have never used anything more than a simple single order filter.


-----------
Larry Barello
www.barello.net


| -----Original Message-----
| From: AVR-Chat@yahoogroups.com [mailto:AVR-Chat@yahoogroups.com] On Behalf
| Of Mark Jordan
| Sent: Monday, September 19, 2005 8:30 PM
| To: AVR-Chat@yahoogroups.com
| Subject: RE: [AVR-Chat] Sensor filtering
| 
| On 11 Sep 2005 at 14:15, Larry Barello wrote:
| 
| > The weighted average filter is the digital version of a single
| > stage RC filter. A weighted average filter looks something like
| > this:
| >
| > Output = (prev_output - input)* K1 + input
| >
| > Where K1 is equal to e^-(dt/tau).  Dt = the sampling period and Tau is
| the
| > rise time desired (in seconds).  The frequency response is 1/2*PI*tau.
| > Or, tau = 1/2*pi*frequency.
| >
| 
| 	Is there an 'easy to implement' second-order IIR filter formula?
| 
| 	Thanks.
| 	Mark Jordan
| 
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| Yahoo! Groups Links
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