## PSN-L Email List Message

Subject: Re: WinQuake Filtering Advice and/or Tutorial
From: Bobhelenmcclure@.......
Date: Fri, 21 Jul 2006 17:46:28 EDT

```Hi Jerry,

I design and code my own seismic digital filters, and I have yet to  find
any reference that follows the "KISS" principle. The subject is highly
mathematical. I got the most help on Butterworth filter design from

_http://kwon3d.com/theory/filtering/lpass.html_
(http://kwon3d.com/theory/filtering/lpass.html)

The information there is drawn from the bible of signal  processing:

Oppenheim, A.V., & Schafer, R.W. (1989). Discrete-time signal  processing.
Englewood Cliffs, NJ: Prentice Hall.

You will find my program "WQFilter" for filtering WinQuake files  in the
file "seismic_dataq.zip" at
_http://www.jclahr.com/science/psn/mcclure/index.html_ (http://www.jclahr.com/science/psn/mcclure/index.html)

To explore the impulse response and bandpass properties of any  filter in
WinQuake or WQFilter, use "Impulse.psn" as the source file. After  filtering
it, you will see the impulse response of the filter. Use WinQuake's  FFT to
reveal the corresponding spectral response of the filter. This is a very  useful
exercise, even if you decide not to dig deeper.

Bob McClure

Hi Jerry,

I design and code my own seismic digital filters, and I have yet=
to=20
find any reference that follows the "KISS" principle. The subject is highly=20
mathematical. I got the most help on Butterworth filter design from

http://kwon3d.com/the=
ory/filtering/lpass.html

The information there is drawn from the bible of signal=20
processing:

Oppenheim, A.V., & Schafer, R.W. (1989). Discrete-time signal=20
processing. Englewood Cliffs, NJ: Prentice Hall.

You will find my program "WQFilter" for filtering WinQuake f=
iles=20
in the file "seismic_dataq.zip" at http://www.jcl=
ahr.com/science/psn/mcclure/index.html

To explore the impulse response and bandpass properties of any=20
filter in WinQuake or WQFilter, use "Impulse.psn" as the source file. After=20
filtering it, you will see the impulse response of the filter. Use WinQuake'=
s=20
FFT to reveal the corresponding spectral response of the filter. This is a v=
ery=20
useful exercise, even if you decide not to dig deeper.

Bob McClure
```