Digitexx vs Mt Whitney
Outline
this page compares data recorded from Millikan Library during the recent M5.4 Big Bear Earthquake, at a distance of 120km.
Data is recorded from 36 channels of FBA on 2 seperate datalogging systems, a 16-bit Digitexx Datalogger, and a 19-bit Mt. Whitney system run by USGS.
We compare data recorded on the EW channels from the 1st floor and the roof.
Link to a better resolution pdf file.
This first plot contains the acceleration timeseries. Note DXX has more of
the p-wave, so either has more pre-trigger buffer or lower trigger, or
combinations of both. DXX records a longer length of time. Due to the
nature of the beating at Millikan Library, it may be useful to change the
settings of the USGS system to also get a longer record section.
The next plot is a comparison of FFT of the records (all same length
as USGS records, 51s long) from roof and 1st floor between 2s and
15Hz. In this frequency range, we see almost no difference between the
DXX and USGS data for either floor.
Link to a better resolution pdf file.
Next we plot a wider bandwith, from 100s to 100Hz, for each floor
independently. Above 15Hz, the DXX and USGS channels deviate.
Link to a better resolution pdf file.
Link to a better resolution pdf file.
John Clinton
Last modified: Tue Apr 22 18:24:08 PDT 2003