PSN-L Email List Message

Subject: Re: New WinQuake Beta Release
From: "Larry Cochrane" cochrane@..............
Date: Sun, 26 Jan 2003 15:13:37 -0800

Hi John,

> At 02:17 PM 1/26/2003, you wrote:
> >WinQuake uses 1 second and 20 seconds for the default P and S waves
> Hi Larry,
> Thanks for the added info.  I guess the other thing one can do with
AmaSeis is
> save the file in .sac format.  If it is then read by WinQuake, can it be
> saved in Type 4 format?

Yes, you can read in a SAC file and then save it as a PSN Type 4 file. The
problem is the SAC format does not have all of the fields like the new data
structure I just added to WinQuake and WinSDR. Since the new fields are not
part of the SAC format they can not be transferred to the PSN file from the
datalogger. They would have to be manually entered in WinQuake after loading
the SAC file.

> On the magnitudes, do you allow for just one gain for the system?  That
> only work for very broad band systems.  Most would need to use a different
> for 1 s and 20 s periods.

There is only one gain (or what I call sensor sensitivity number) field in
the PSN 4 file. As far as I know, this is also the case for both the PEPP
and SAC formats. I think the proper way of handling this is to include the
frequency response of the sensor as a list of poles and zeros. This way a
program like WinQuake can calculate the actual ground motion based on the
frequency of the P or S wave. As you point out WinQuake assumes the sensor
is broadband and has the same sensitivity at 1 or 20 seconds. Adding a list
of poles and zeros to the PSN format is easy, it's just another variable
data structure. Coming up with the correct list of poles and zeros
describing the sensor channel and then using them in WinQuake is a lot more

-Larry Cochrane
Redwood City, PSN


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