Larson Davis 831, User Manual

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19-12 Location Measurement Using 831-INT Model 831 Manual
The GPS will turn on automatically at the beginning of
every measurement run to acquire the current position
information. The Live GPS display will show the data from
previous acquisitions instead of clearing the data when the
GPS is off. They will be cleared on if there is a GPS connect/
disconnect error.
GPS Time-Sync
The time-sync is made from the average of thirty readings
from the satellite (thirty second average) as long as there are
four or more satellites detected. The time-sync can be
performed manually or automatically when the Daily
Autostore mode is active.
Manual
Note that the manual time sync can
only be performed while the
instrument is stopped. A time-sync can be triggered manually by pressing the
5
(ENTER) key from the GPS display, shown in FIGURE 19-
14.
Daily Autostore
A time-sync will be performed along with a Daily Autostore
if the time is found to be more than one second off. In this
case, the GPS is turned on two minutes prior to the autostore
time in order to gather the time and create the time
correction value that will be utilized.
Datum
The GPS uses WGS 84 as its default datum. The user can
change the datum as described in the Ho lux manual.