SonTek ADP - Integrated GPS Data; Considerations When Collecting GPS Data

SonTek
ADP Software Manual Version 6.42 (November 1, 2000)
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To stop data acquisition, the user must press the ALT and F10 keys simultaneously. After this is
done, the user is presented with a prompt (a Yes/No multiple-choice window) to confirm the
intention to stop the program. Data collection/recording proceeds normally until the confirmation
is given. Upon selecting “Yes”, the program returns to the setup screen. If the program was run
with the automatic start option (“ADPSA -g”), confirmation after ALT-F10 returns to the DOS
prompt.
F1 – Change Vel Reference: (Multiple-choice)
This allows the user to select how ADP velocity data are displayed. “Relative to ADP” gives the
raw velocity relative to the instrument. “Relative to GPS” uses the GPS calculated vessel speed
and the magnetic variation (from the setup menu) to determine the absolute water velocity,
independent of vessel motion.
If ADPSA has been run with the –p option for integrated GPS data, there will be several minor
changes in the data acquisition screen. Several additional fields will be present in the status
portion of the screen, and one additional active key is enabled. Each of these is described below.
2.4.4. Integrated GPS Data
If ADPSA has been run with the –p option for integrated GPS data, there will be several minor
changes in the data acquisition screen. Several additional fields will be present in the status
portion of the screen, and one additional active key is enabled. Each of these is described below.
Latitude / Longitude
These fields display the most-recent position information from the incoming GPS data.
Vessel Speed (knots)
These fields give the north-south and east-west vessel speed from the last profile, calculated
based upon GPS position data.
F1 – Change Vel Reference: (Multiple-choice)
This allows the user to select how ADP velocity data are displayed.
“Relative to ADP” gives the raw velocity relative to the instrument.
“Relative to GPS (if present)” uses the GPS calculated vessel speed and the magnetic variation
(from the setup menu) to determine the absolute water velocity, independent of vessel motion.
“Relative to Bottom (if enabled)” uses the Bottom Track speed and the magnetic variation (from
the setup menu) to determine the absolute water velocity, independent of vessel motion.
2.5. Considerations When Collecting GPS Data
Integration of GPS position with ADP velocity data allows the instrument to measure absolute
current profiles from a moving vessel. This is a very powerful capability, particularly for
performing rapid current surveys over a wide area. However, the user must be aware that
collecting data from a moving vessel is inherently more complex than from a stationary system.
Extra precautions are required to ensure good quality data. Several areas of concern are described
below.