SonTek/YSI Argonaut-XR Technical Manual - HydroScientific West

SonTek/YSI
When looking at the ARGCHECK output, keep in mind that individual samples will vary
significantly from ping to ping. Look for features that are consistent over a number of pings. It is
often helpful to record a number of pings and plot the mean profile to look for consistent features
in the data.
Noise level
The system noise level for each beam can be directly measured by running ARGCHECK with the
transducers out of the water. The output will show a spike close to the transducers, which should
immediately decay to a constant noise level throughout the remainder of the profile. You can
read the system noise level from the data at the top of the screen.
For the Argonaut XR and SL, the noise level is typically 35-55 counts. For the standard Argonaut
MD (3000 kHz), the noise level is typically 50-70 counts. For the deep-water titanium Argonaut
MD (1500 kHz), the noise level is typically 35-55 counts. The noise will vary slightly among
different beams. If the noise level of any on beam is outside this range, this can be an indicator of
a noisy environment or of problems with the system. Try moving the system away from any
motors or electronics to see if the noise level changes. If problems persist, contact SonTek.
Boundary reflection
If the Argonaut has some type of boundary within the measurement range (surface, bottom or
underwater structure), this boundary should be seen as a strong spike in the return signal profile.
One example is illustrated in Figure 17. In most cases, all beams will see a reflection of
approximately the same magnitude at the same range. In certain locations, the magnitude and
location of the boundary reflection will vary between beams due to the different beam mounting
angles and the nature of the boundary reflection. If the system is tested in very shallow water, it
may show multiple boundary reflections with increasing range.
Sine/cosine data
The lower two plots in ARGCHECK show the sine and cosine velocity channels using internal units
called vel-counts. These data have no direct interpretation and are provided for basic diagnostic
purposes only. They will typically show a mean level through the profile of about 125 counts,
with a small amount of variation around that level. The amount and nature of the variations
depends upon the environment.
The only reason to be concerned is if they show a flat line with no variations. This indicates that
something in the electronics is not functioning properly; contact SonTek if you see this when
running ARGCHECK (with the transducer either in or out of the water).
Argonaut Software Manual (March 1, 2001) 63