YSI SonTek RiverSurveyor, System Manual

Page: 129 / 194

SonTek/YSI Inc
RiverSurveyor System Manual (May 1, 2007)
117
Echo Sounder Settings
This dialog box (
Figure 7-29
) applies only
when an echo sounder is used to collect
depth information. Enter the depth of the
echo sounder’s transducer below the sur-
face and the results of the
Bar Check Cali-
bration
for the system. A bar check cali-
bration is a common technique used to ad-
just the echo-sounder depth readings
based on the site-specific water sound
speed. A more detailed explanation of this calibration procedure can be found in most echo
sounder user manuals.
Velocity Coordinate System
Lets you select the coordinate system (
Beam
,
XYZ
,
ENU
) in which to display velocity data. The
appropriate toolbar icon (
Table 7-2
) stays depressed for the selected coordinate system. For more
information about the velocity coordinate systems, see §
3.9
and §
6.6.8
.
SNR Threshold
Enter the minimum allowable signal-to-
noise ratio for acceptable velocity meas-
urements (
Figure 7-30
). This value indi-
rectly determines the number of valid cells
in a profile that will be used for discharge
calculations. The effects of this parameter
can be seen on the
Discharge Cutoff Depth
in the Contour Window . A default value of 3 is used. Values below 3 are not recommended and
could potentially cause the instrument to read inaccurate velocity values.
Velocity Reference
Lets you select the method in which velocity data will be referenced (
ADP
,
Bottom Track
,
GPS
).
The appropriate toolbar icon (
Table 7-2
) stays depressed for the selected velocity reference. For
more information about selecting a velocity reference see §
3.10
,
3.10.3
, and
3.10.4
.
User Specified Rotation
Lets you rotate all velocity profiles by a user-selectable angle between 0 and 360 degrees. The
User Specified Rotation
icon (
Table 7-2
) stays depressed as long as the rotation is in effect. This
feature is useful when analyzing current data along a channel. After entering the angle, place a
checkmark in the
Activate
box (
Figure 7-31
). Do not change this value after recording begins.
Lock Measurement
Selecting this option will lock a measurement and prevent
any changes to settings or parameters related to the locked
measurement from being saved. Typically, once analysis of
a measurement is complete the reviewer will lock the
measurement to prevent any further changes. Selecting this
option a second time will unlock the measurement.
Figure 7-29. Echo Sounder Settings dialog box
Figure 7-30. Set SNR Threshold dialog box
Figure 7-31. User Specified Rotation
dialog box