All,

I found a pretty good book called Analog and Digital Filter Design by Les
Thede. I got mine at Amazon.com. The description of the book at Amazon said
it comes with a disk. Actually you need to download it from here
www.onu.edu/user/FS/lthede/.

Using this book and the "C" code he supplies, I was able to add time domain
filtering to WinQuake. The user will be able to do high or low pass
filtering directly to the data set without having to do a FFT first. This
and supporting the new PSN format will be the main new features in the next
release.

-Larry Cochrane
Redwood City, PSN


At 08:37 PM 8/1/00 -0400, you wrote:
>
>John,
>
>The idea had already crossed my mind that it might be interesting to build
>some sort of a software digital filter.  I am a retired
>electrical-turned-software engineer but don't know much about digital
>filtering.  I'd be very interested in any information you could provide me.
>I have experimented a little with the filtering capabilities in Winquake on
>some of my event files.  A high pass with a 30 second cut-off (ie. .033 hz)
>is very effective in cleaning up my data.
>
>Larry
>
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