Nanometrics TC120-PH1, Руководство пользователя

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Chapter 2
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Performing a Posthole Installation
Trillium Compact User Guide
16889R5

2014-03-04
12
2.2.2 Using a Surface Seismometer
You can use a seismometer installed at the surface to determine the orientation of the
horizontal (X and Y) components of the Trillium Compact Posthole once installed in the
hole. This method involves comparing the recorded output of both seismometers and
computing the relative direction of seismic wave motion to determine the relative azimuth
of the down-hole Trillium Compact Posthole compared to the surface seismometer.
When you install the reference seismometer on the surface, ensure that you align it
carefully in a known orientation. After both seismometers have been installed, leave the
installations undisturbed for at least one hour while collecting data from both. When you
are ready to perform your data analysis, ensure that your post-processing software is
equipped to apply a rotation transformation, allowing it to measure and correct the
relative azimuth.
One advantage of this method of alignment is that it allows you to verify the performance
of the down-hole instrument: it should be quieter than the surface instrument.
Contact Nanometrics (see Contacting Nanometrics on page 81) for more information on
using this method of alignment.