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DATALOGR
An alternative way to collect data is to record data directly onto your PC using the
DATALOGR.exe program. This method is useful if your data card does not have
enough space or if you wish to bypass the download process. For more information
on using DATALOGR, see the DATALOGR User's Guide.
Position Mode/ALT Fix Mode
Because the GG Surveyor mixes two different constellation systems (GPS and
GLONASS) to determine position, and the clocks between these two systems are not
synchronized. The GG Surveyor initially needs to track a minimum of 5 satellites
(any combination of GPS and GLONASS satellites) to compute a 3D position, or four
satellites to compute a 2D position.
The GG Surveyor has three commands that control the position mode and fix the
altitude or time shift between system clocks. These commands enable the GG
Surveyor to compute a 3D position using only four satellites, or a 2D position using
only 3 satellites. The commands are PMD, GTM, and GTP.
The GG Surveyor performs a position computation in four different modes: 0, 1, 2, or
3. These modes determine the number of satellites required to compute a 3D or 2D
position, and depend upon the priority in which the altitude or time shift are held
fixed. The position modes are set with command $PASHS,PMD and depend upon the
setting of GTM (whether to compute time shift or hold it fixed), and GTP (set priority
to hold fixed time shift over altitude, or vice versa) when the number of used satellites
is fewer than 5. See "$PASHS,PMD,d" on page 97 for more information.
In mode 0 with GTM set to 0 (time shift not held fixed), at least 5 satellites with
elevation equal to or above the position elevation mask are required to compute a 3D
position. With GTM set to 1 (time shift held fixed if number of satellites fewer than
Advanced Operation
Table 4.3: GG Surveyor Recording Modes
Typical
Recording Mode
Application
0
Raw data, full code
and carrier phase
2
Position data only
File Types Created
B (GPS Raw Data)
E (GPS Ephemeris Data)
S (Session Info)
C (GPS Position Data)
S (Session Info)
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