Flowtracker2 Data; Basic Sampling Strategy; Velocity Data; Accuracy Of Velocity Data - Xylem SonTek FlowTracker2 User Manual

13.8. FlowTracker2 Data

13.8.1

Basic Sampling Strategy

The FlowTracker2 collects a burst of velocity data at each measurement location. The
sampling strategy for the FlowTracker2 instruments is summarized in
Original FlowTracker sampling strategy is included for comparison.
Category
Sampling
Rate
2 Hz
Field
a) An individual measurement of the 2D or 3D velocity is referred to as a ping.
b) Sample refers to the mean of 20 pings to produce a measurement of the 2D or
3D water velocity.
c) Two samples are recorded per second during the user specified averaging time.
d) The averaging time at each location is user-specified (10 to 1000 seconds).
e) The system collects a time-series of velocity at each measurement location over
the user specified averaging interval.
13.8.2

Velocity Data

The FlowTracker2 provides several important performance advantages.
a) It can measure 2D or 3D water velocities from 0.001 to 4.0 m/s (0.003 to 13 ft/s).
b) Velocity data are accurate to 1% of the measured velocity in a one-second
sample.
c) Velocity data can be used immediately without any post processing corrections.
d) True 2D or 3D velocity data are output in Cartesian coordinates (XYZ) relative to
probe orientation.
e) The FlowTracker2 calibration will not change unless the probe is physically
damaged. No periodic calibration is required.
f) Diagnostic software is included to evaluate system performance periodically.
13.8.3

Accuracy of Velocity Data

13.8.3.1

Optimizing of FlowTracker2

The FlowTracker2 has been optimized to provide the best possible velocity data.
a) Velocity data are accurate to 1% of measured velocity for each one-second
sample.
b) Variations in velocity data are dominated by true variations in water velocity.
c) Instrument noise does not normally have an impact on velocity data.
FlowTracker2 User's Manual (January 2019)
Table 13-1- Sampling Strategy
FlowTracker2
Pings per
Ping Rate
Sample
20 40 Hz
SonTek – a Xylem brand
Table
Original FlowTracker
Sampling Pings per
Rate Sample
1 Hz 10
13:1. The
Ping Rate
10 Hz
230