PSN-L Email List Message
Subject: Re: Size of a lehman type sensor?
From: Bobhelenmcclure@.......
Date: Mon, 30 Apr 2007 18:59:58 EDT
In a message dated 2007/04/29, jonfr@......... writes:
> Next month I finally can start building a lehman type sensor. But I need
> to know what size / height I need to use for the sensor.
Hi Jon,
You do not have to build a big clunker Lehman to have a useful sensor. I
use compact horizontal sensors set to 6 to 13 seconds period. I extend the
long period response using my utility program WQFilter.exe. If you use either a
long period Lehman or a period-extended medium period Lehman, your site will
have a lot to do with your results. The sensor must rest on firm ground, and
you must not walk anywhere near it. (Long period horizontal sensors are very
sensitive to tilt.) Ground tilt induced by wind gusts is a big problem for
me. My sensors are on the basement floor of my home. They were placed where
walking around on the floor above produces the least response.
Information about my sensors and software can be found at
_http://www.jclahr.com/science/psn/mcclure/index.html_
(http://www.jclahr.com/science/psn/mcclure/index.html)
I use WQFilter exclusively for WinQuake event file filtering. It is
contained in seismic_dataq.zip, which can be downloaded from
_http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html_
(http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html)
WQFilter has a selection of lowpass and highpass filters, and my special
period extending filter. This filter can make the period either shorter or
longer than the physical period of the pendulum. It can also correct for
under-or-overdamping. For examples of the benefits of using WQFilter, see
_http://www.jclahr.com/science/psn/mcclure/filter_examples/index.html_
(http://www.jclahr.com/science/psn/mcclure/filter_examples/index.html)
By the way, if anyone is presently using WQFilter.exe older than version
2.0.15, please download the update. It is now rigorously accurate, as proven in
_http://www.jclahr.com/science/psn/mcclure/filter/index.html_
(http://www.jclahr.com/science/psn/mcclure/filter/index.html)
Bob McClure
PSN Station REM
************************************** See what's free at http://www.aol.com.
In a message dated 2007/04/29, jonfr@......... writes:
> Next month I finally can start building a lehman type sensor. But=20=
I=20
need
> to know what size / height I need to use for the sensor.
Hi Jon,
You do not have to build a big clunker Lehman to have a useful=20
sensor. I use compact horizontal sensors set to 6 to 13 seconds period. I ex=
tend=20
the long period response using my utility program WQFilter.exe. If you use=20
either a long period Lehman or a period-extended medium period Lehman, your=20=
site=20
will have a lot to do with your results. The sensor must rest on firm=20
ground, and you must not walk anywhere near it. (Long period horizontal sens=
ors=20
are very sensitive to tilt.) Ground tilt induced by wind gusts is a big prob=
lem=20
for me. My sensors are on the basement floor of my home. They were placed wh=
ere=20
walking around on the floor above produces the least response.
Information about my sensors and software can be found at
I use WQFilter exclusively for WinQuake event file filtering. It=
is=20
contained in seismic_dataq.zip, which can be downloaded from
WQFilter has a selection of lowpass and highpass filters, and my=
=20
special period extending filter. This filter can make the period either shor=
ter=20
or longer than the physical period of the pendulum. It can also correct for=20
under-or-overdamping. For examples of the benefits of using WQFilter, see
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