SonTek/YSI Argonaut-XR Technical Manual - HydroScientific West

Section 7. Autonomous Deployment
7.1. Selecting Argonaut Operating Parameters
Argonaut Operation Manual Firmware Version 7.9 (May 1, 2001)
SonTek/YSI
The choice of Argonaut operating parameters depends on the nature of the deployment and the
goal of the study. Some guidelines for selecting the most important parameters are given below.
For more information about each parameter, see Section 3.
System parameters: output mode, output format, recorder, recorder mode
The settings of OutMode (Auto/Polled) and OutFormat (ASCII/Binary) are typically not important
for autonomous deployment, as they affect only the data output over the serial port and not
data stored to the internal recorder. The Recorder setting (ON/OFF) only affects data collection
initiated with the Start command; all autonomous deployments should be initiated with the
Deploy command, which will force the recorder ON. The RecMode setting (Normal/Buffer) is
typically Normal for autonomous deployments; the system stops recording data when the
recorder is full.
Buffer mode, where the oldest data are overwritten when the recorder is full, is typically used
when the recorder is acting as a data backup for real-time data installations.
**Note – buffer mode is not currently implemented in the Argonaut**
Sound speed: temperature, salinity, and temperature mode
For most Argonaut deployments, temperature mode is set to Measured and the user-specified
temperature has no effect on instrument operation. Salinity should be as accurate as is practical;
in regions with large variations, a mean value should be used. A salinity error of 12 ppt results in
a velocity error of 1%, so salinity variations typically have a minimal effect. If precise
temperature and salinity records are available, Argonaut velocity data can be easily corrected for
sound speed changes in post-processing (see Argonaut Principles of Operation).
Coordinate system
For most Argonaut MD and XR deployments, the ENU (East-North-Up) coordinate system
should be used. This allows the instrument to report velocity data in Earth coordinates regardless
of instrument orientation. For the Argonaut SL, the XYZ coordinate system is normally used
since instrument orientation is fixed based on the installation. BEAM coordinates are intended
for experienced users in specialized applications.
Measurement volume: cell begin and cell end
For the Argonaut MD, the measurement volume size and location is constant. For the Argonaut
XR and SL, the location of the measurement volume is set based on the environment and the
goals of the study. Normally, cell begin is set as close to the Argonaut as possible while still
avoiding flow interference from the mounting structure. Cell end is typically set at the maximum
range of the environment (e.g., if limited by surface, bottom, or underwater structures).
Timing parameters: averaging interval, sample interval, and burst sampling
As mentioned above, the choice of averaging interval is set based on the desired accuracy.
However, in many environments the required averaging time is not determined by the Argonaut,
but by real variations in the flow. Both of these factors should be taken into consideration when
determining the averaging interval for a given deployment. See Argonaut Principles of Operation
for calculating the expected accuracy based on the measurement volume and averaging interval.
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