Brett,
    My two channel instrument (orthogonal pendulum pair) is operating at 24=
 bits on each channel.  The upload setting (for gif transmission) to Larry'=
s server is the value 100 for each of channel 1 (E-W) and channel 2 (N-S). =
 The integrated output from each of these is using the value 500.   The int=
egrated channels are being bandpass filtered (single pole, each corner freq=
uency)-range 10 mHz (period 100 s) to 500 mHz (period 2 s).  If you look on
http://www.seismicnet.com/currentseismicity.html at the Macon signals corre=
sponding to the raw data for E-W and N-S, you will see that there is no hig=
h pass filtering acting on them.  These show the present tilt offset (un-ze=
roed to d.c. output) of -23000 capacitance to digital converter (CDC) count=
s in E-W and 4500 CDC counts in N-S.  In other words, for the calibration c=
onstant of 2.5 billion CDC counts per radian, the E-W pendulum is offset by=
 -9 micro-radians and the N-S pendulum offset is 2 microradians.  It is dif=
ficult to set up these pendulums to better than one microradian offset.  Wi=
th the high-pass filter this is of no consequence.  But I want to look for =
displacements with characteristic periods of hours, days and months.    The=
 VolksMeter does this nicely in the mode I'm using --functioning as a tiltm=
eter with no low frequency limitations other than the stability of the pier=
 on which it stands.  The pier is a monolithic 4 ft x 4 ft x 2 ft rectangul=
ar parallelipiped with a bottom cylindrical piece (dia. 20 in) that goes 20=
 ft into the ground.  The structure is high-strength concrete in a reasonab=
ly isothermal enclosure, and isolated from the building slab vibrations (su=
ch as from air conditioning).  Only with a decent pier can thermal-induced,=
 diurnal cyclic tilt changes of aggravating type be avoided.
Brett,
    My two channel instrument (ort=
hogonal pendulum pair) is operating at 24 bits on each channel.  The u=
pload setting (for gif transmission) to Larry’s server is the value 1=
00 for each of channel 1 (E-W) and channel 2 (N-S).  The integrated ou=
tput from each of these is using the value 500.   The integrated =
channels are being bandpass filtered (single pole, each corner frequency)&#=
8212;range 10 mHz (period 100 s) to 500 mHz (period 2 s).  If you look=
 on
http://www.seismicnet.com/currentseismicity.html at the Macon signals corresponding to the raw data for E-W and N-S, you =
will see that there is no high pass filtering acting on them.  These s=
how the present tilt offset (un-zeroed to d.c. output) of -23000 capacitanc=
e to digital converter (CDC) counts in E-W and 4500 CDC counts in N-S. =
; In other words, for the calibration constant of 2.5 billion CDC counts pe=
r radian, the E-W pendulum is offset by -9 micro-radians and the N-S pendul=
um offset is 2 microradians.  It is difficult to set up these pendulum=
s to better than one microradian offset.  With the high-pass filter th=
is is of no consequence.  But I want to look for displacements with ch=
aracteristic periods of hours, days and months.    The Volks=
Meter does this nicely in the mode I’m using --functioning as a tiltm=
eter with no low frequency limitations other than the stability of the pier=
 on which it stands.  The pier is a monolithic 4 ft x 4 ft x 2 ft rect=
angular parallelipiped with a bottom cylindrical piece (dia. 20 in) that go=
es 20 ft into the ground.  The structure is high-strength concrete in =
a reasonably isothermal enclosure, and isolated from the building slab vibr=
ations (such as from air conditioning).  Only with a decent pier can t=
hermal-induced, diurnal cyclic tilt changes of aggravating type be avoided.=
  
=