YSI SonTek RiverSurveyor, Системное руководство

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SonTek/YSI Inc
RiverSurveyor System Manual (May 1, 2007)
147
Appendix A. Glossary
This appendix provides a description of the major terms and abbreviations used in discussing the
RiverSurveyor system, Acoustic Doppler Profilers, and current profiling in general.
Term Description
ADP Acoustic Doppler Profiler
ATMDS Automatic Transducer-Mounting Depth Sensor (§
3.6
)
averaging interval
or AI The period of time, in seconds, over which the ADP averages data to
compute a mean velocity profile. For most real-time applications, the
averaging interval and profiling interval are the same. This provides a
continuous measurement from start to finish. Commonly abbreviated as
AI.
blanking distance
or BD The region in front of the transducers where no measurements can be
made. This parameter is measured as the vertical distance (in meters or
feet) from the ADP transducers to the start of the first range cell (also re-
ferred to as depth cell). The blanking region is required to give time for
the transducers and electronics to recover from the transmit pulse. That
is to say, the transducers/electronics need time to switch from the trans-
mit mode to the receive mode. Commonly abbreviated as BD.
bottom-track Bottom-tracking is a feature used by an ADP to measure the speed of a
vessel (e.g., a boat, the RiverCat system) relative to the river bottom.
The vessel speed is then subtracted from the measured water velocity to
give the absolute water current profile independent of vessel motion.
More bottom-track specific terminology can be found in §
3.3.6
.
cell The area of water in which data is averaged and collected. Also referred
to as depth cells or range cells. The size of these data collection points is
determined by a user-selected
cell size .
cell location The data collected within a cell is averaged to the center of the cell. The
distance from the ADP to the center of each cell can be determined us-
ing the formula:
Distance to center of a cell = BD + N * CS
where:
BD = Blanking distance
N = Number of the cell (Cell 1 is the cell closest
to the ADP)
CS = Cell size
cell size or CS This defines the resolution of the velocity profile (in meters or feet).
Commonly abbreviated as CS. Keep in mind there are advantages and
disadvantages to selecting small or large cell sizes:
•
Small cells allow you to get higher-resolution profile data, especially
in shallow water. However, more small cells are needed to profile to
a specific range, which means that individually analyzing small-cell
data can be a time consuming process.
•
Large cells make data analysis of individual cells easier. However,
the resolution of the profile will be lower, which could make it more
difficult to analyze shallow water data.
depth cell See cell .