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




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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 
 
  http://www.jcl=
ahr.com/science/psn/mcclure/index.html
 
  I use WQFilter exclusively for WinQuake event file filtering. It=
 is=20
contained in seismic_dataq.zip, which can be downloaded from
 
  =
http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html
 
  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
 
   http://www.jclahr.com/science/psn/mcclure/filter_examples/index.html
 
  By the way, if anyone is presently using WQFilter.exe older than=
=20
version 2.0.15, please download the update. It is now rigorously accurate, a=
s=20
proven in
 
  http://=
www.jclahr.com/science/psn/mcclure/filter/index.html =20

 
 
Bob McClure
PSN Station=20
REM



See what's free at AOL.com.