[SciPy-User] Signal processing and filtering functions

Warren Weckesser warren.weckesser@enthought....
Wed Mar 9 12:01:51 CST 2011


On Wed, Mar 9, 2011 at 10:33 AM, Joe Kington <jkington@wisc.edu> wrote:

>
> The SAE filtering operation performs two-pass, zero phase
>
> shift, second-order Butterworth filtering.
>
>
> You may already be aware of it, but that sounds suspiciously like this
> cookbook example... http://www.scipy.org/Cookbook/FiltFilt
>


That cookbook code was added to scipy in r4391 and r5195.  scipy.signal has
the filtfilt and lfilter_zi function.  The basic idea is to apply an IIR
(e.g. Butterworth) filter to the signal twice, first forward and then
backward.

There is a lot of room for improvement in that code.  I've been working on
rewriting it, and implementing the true Gustafsson algorithm; despite the
comment in the code, lfilter_zi does not implement Gustafsson's method.
Once the change to github is made, I'll start a branch containing this work.

Warren



> I'm not sure if that helps any, but I hope it does!
> -Joe
>
> <http://www.scipy.org/Cookbook/FiltFilt>
>
> On Wed, Mar 9, 2011 at 9:53 AM, Nils Wagner <nwagner@iam.uni-stuttgart.de>wrote:
>
>> On Wed, 09 Mar 2011 14:10:43 +0100
>>  "Nils Wagner" <nwagner@iam.uni-stuttgart.de> wrote:
>> > Hi all,
>> >
>> > I am looking for the so-called SAE (Society of
>> >Automotive
>> > Engineers) Filter functions which are available in
>> >abaqus
>> > python.
>> >
>> > The Abaqus CAE User's manual points to
>> >
>> >
>> http://www.nhtsa.gov/Research/Databases+and+Software/Signal+Analysis+Software+for+Windows
>> >
>> > Has someone implemented those filter functions ?
>> >
>> > Any pointer would be appreciated.
>> >
>> > Thanks in advance.
>> >
>> >    Nils
>> >
>> >
>> I should add the following information
>>
>> The SAE filtering operation performs two-pass, zero phase
>> shift, second-order Butterworth filtering.
>>
>> Is it possible to reproduce such an operation with
>> scipy.signal ?
>>
>> Nils
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>
>
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