Hi Geoff,
 
  I have a home-built 5 second period vertical sensor that I paid a  friend 
to build for $500. See
 
_http://www.jclahr.com/science/psn/mcclure/vert2.html_ 
(http://www.jclahr.com/science/psn/mcclure/vert2.html) 
 
  I extend its natural period to 16 seconds or more with my special  digital 
filter, implemented in "WQFilter.exe", 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.exe" operates on WinQuake files, and its long period  filter will 
extend the bandwidth of any open loop sensor by a factor of 5 or  more.
 
  I run a 3-axis station, and I agree that the vertical  sensor is the most 
important one to have, (but the hardest to build).
 
Regards,
 
Bob McClure
PSN Station REM
 





Hi Geoff,
 
  I have a home-built 5 second period vertical sensor that I paid=20=
a=20
friend to build for $500. See
 
http://www.jcl=
ahr.com/science/psn/mcclure/vert2.html
 
  I extend its natural period to 16 seconds or more with my specia=
l=20
digital filter, implemented in "WQFilter.exe", which can be downloaded=20
from
 
=
http://www.jclahr.com/science/psn/mcclure/wdq_utilities/index.html
 
  "WQFilter.exe" operates on WinQuake files, and its long period=20
filter will extend the bandwidth of any open loop sensor by a factor of 5 or=
=20
more.
 
  I run a 3-axis station, and I agree that the vertical=20
sensor is the most important one to have, (but the hardest to build).
 
Regards,
 
Bob McClure
PSN Station REM