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 McClureHi 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 fromThe 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.htmlTo 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