I have remodeled my old 2 year old Lehman by going =
from
3" wide aluminum bars to 2.5" wide bars and using the same =
coil and same
Chris Chapman magnets. At the same time I built a second Lehman that =
will be my
NS seismometer. At the present time I have both lined up as EW and I =
want calibrate
so that I see the same response on both before I position the second =
unit to
NS. The coil on the second is 1850 turns vs. 1650 turns for the first =
and the
second unit has a 27 second period vs. 23 second for the first. I'm =
adjusting
the gain on Larry's analog board to get the same response. I have the =
same
filtering (WinSDR) on both units. What I'm seeing is that the first unit =
seems
to have more background noise and higher frequency content. And the FFT
confirms that. Is the longer period and or larger number of turns in the =
coil
related to this?
Any thoughts are most welcome.
Gary
Gary Lindgren
585 Lincoln Ave
Palo Alto CA 94301
650-326-0655<=
/span>
www.blue-eagle-technologies.com &nbs=
p;
Check out Lastest Seismometer =
Reading
cymonsplace.blogspot.com =
sites.google.com/site/seismicsensorinfo/Home<=
/a>
Design Details for New Vertical Seismometer