Guralp Systems CMG-3TB - Manual (Page 54)

CMG-3TB
You should see an ok prompt, indicating that the digitizer is
ready to receive commands.
2. Type
0 rotation AZIMUTH
where rotation is the angle of deviation from true North that
you measured earlier, as a whole number of tenths of a degree.
This is the same angle (with the same sign) as that given by the
orientation program.
The 0 tells the digitizer to apply the rotation to instrument
number 0 (the first, or only instrument.)
Thus in the example above, you would type 0 -903 AZIMUTH
to make the digitizer rotate signals by –90.3 degrees.
3. Reboot the digitizer with the command re-boot.
4. Collect some more data with the transformation active, and
carry out another orientation calculation. The data from the
downhole instrument should now have a maximum coherence
with the reference sensor at 0 °. Check in particular that the sign
of the rotation you have applied is correct.
54 Issue C