Re: Designing a first-order IIR filter

[Shaun Jackman]

On 11/6/06, Paul Kienzle <address@hidden> wrote:
> On Nov 6, 2006, at 7:32 PM, Shaun Jackman wrote:
>
> > I can use the `freqz' function to find the cutoff
> > (-20 dB) frequency for a given filter, specified
> > by its IIR coefficients and sampling period. However,
> > if I have a desired cutoff frequency and given
> > sampling period, how do I find the IIR coefficients
> > that give the desired first-order filter?
>
> octave-forge has butter, cheby1, cheby2 and ellip
> for designing IIR filters.

Thank you. These are all very good suggestions.

I am particularly interested in designing a first-order filter. I
believe the above filters are exclusively higher-order -- please
correct me if I'm wrong. Or can one (all?) of the above be used to
design a first-order filter?

Thanks,
Shaun