67
GSM19 Series Magnetometers - Version 7
GEM Systems, Inc. Advanced Magnetometers
For more technical information, visit www.gemsys.ca
An alternative method involves using only one unit and a special type of readings called Tie Point
Reading. The Tie Point method is not as effective since it implies interpolating readings with a
large time interval and it is very seldom used. It was a standard feature on previous models but has
not been implemented in our version 6 magnetometers. If you are interested in using Tie Point
Corrections with a version 5 or earlier magnetometer, please refer to our web site that has a
technical note on this subject.
When using two units, the Diurnal Correction can be performed unit to unit by sharing the contents
of their memory, or File-to-File after dumping the files to a PC and using GEMLinkW's Diurnal
correction Utility.
5.9.1 Mag-to-Mag Diurnal Correction
When performing Diurnal Correction by connecting two units, the Base readings are transferred to
the Mobile file and stored in it. This permanently modifies the original Mobile file and memory.
NOTE:
Because the flash memory chips cannot be overwritten, DO NOT perform a
second diurnal correction on a file that has been already corrected or the file
may be corrupted.
After a Mobile file has been merged with a Base file, the corrected data is available for file review
either in text or graph mode (see section VII) or data transfer (see section 6.2.2).
The actual correction is not performed during the transfer but while dumping or reviewing a Mobile
file that has been merged with the base readings. This allows you to perform many corrections or
files review, all with different values of Datum if needed. To change the Datum before dumping or
reviewing the file press
C-info
from the
Main menu
and then
0-datum
.
NOTE:
You require a reduction cable (6-pin to 6-pin cable) to connect the two units.
NOTE:
The same cable is used for time synchronization. This is why sometimes it is
called Reduction Cable and sometimes Synch cable. Please contact GEM
Systems if you need to order one.