Geometrics, Inc. G-824A Magnetometer Manual
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Here is an example on how to turn on the 1 pps phase locking function. From the main
configuration menu select T to get to the triggering submenu. The following submenu items
will need to be set:
If triggering is enabled, when the edge on the trigger
input occurs, the current field value in memory
is captured and sent to the digital output.
Phase locking is used to precisely align the sample timing
and prevent sample frequency drift. Typically it is used
with a GPS's 1PPS signal.
An edge on the trigger input also causes the "Status"
number to become an odd number for one sample.
You can enable the display of the "Status" number
in the "Format" menu, if desired.
Trigger/PLL input :
(0=Normal 1=Aux1 2=Aux2 3=Aux3 4=Aux4 5=RS-232 ):1
Trigger/PLL input sense :
(0=Rising 1=Falling ):0
Enable external triggering :
(0=No 1=Yes ):0
Enable phase locking :
(0=No 1=Yes ):1
Concatenation/Trigger character :$
ASCII mode concatenation termination character :\r
XS3 mode concatenation termination character :*
Be sure to save the configuration before powering down or all changes will be lost.
7.3.10 Magnetometer Operational Status
This same status byte decribed in the section 7.3.9 will be changed to a “2” when the
counter's output is outside the range of the earth's field (as is the case when the unit is first
turned on and warming up), or there has been a change in the magnetometers settings while
Select Aux1 by changing this to a 1 (if not already)
Set to 0 or 1 depending on which PPS edge is desired
Set to 0 since we are not externally triggering the magnetometer
Set to 1 to enable phase locking the cycle time to GPS
1 here in the status column indicates that this reading is
synchronized to a PPS event as seen by the G-824A’s
PPS input.
