[SciPy-Dev] FIR filter design - patch attached to ticket #457

Charles R Harris charlesr.harris@gmail....
Sat Nov 13 20:53:16 CST 2010


On Sat, Nov 13, 2010 at 7:46 PM, Warren Weckesser <
warren.weckesser@enthought.com> wrote:

>
>
> On Sat, Nov 13, 2010 at 6:53 PM, Charles R Harris <
> charlesr.harris@gmail.com> wrote:
>
>>
>>
>> On Sat, Nov 13, 2010 at 5:29 PM, Charles R Harris <
>> charlesr.harris@gmail.com> wrote:
>>
>>>
>>>
>>> On Sat, Nov 13, 2010 at 4:22 PM, Warren Weckesser <
>>> warren.weckesser@enthought.com> wrote:
>>>
>>>> For any of you interested in FIR filter design, feedback on the patch in
>>>> ticket #457 (http://projects.scipy.org/scipy/ticket/457) would be
>>>> appreciated.
>>>>
>>>>
>>> What about negative frequencies? Do you want to limit yourself to real
>>> filters? I expect yes ;) But at some point I want to add my version of the
>>> Remez algorithm which I use to design complex filters and it would be nice
>>> to have a ready made template for the interface.
>>>
>>>
>> Also, I've always found it easier to design with actual frequencies rather
>> than setting the sampling frequency to 1. The conversion isn't difficult,
>> but it is repetitive and usually required which makes it something the
>> software  should do. Most filter specs are in frequency and it just makes
>> life easier.
>>
>
> That is what the `nyq` argument is for: specify the frequencies in whatever
> units you prefer (e.g. Hz, samples per year, scores of samples per
> fortnight, etc), and give the `nyq` keyword argument in the same units.
>
>
Ah, I didn't see that, it's in firwin2. Great.

Chuck
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