SonTek – a Xylem brand
FlowTracker2 User’s Manual (January 2019)
85
Table 6-2 – SNR Data Types
All
Graphical
Raw Data
One second SNR data is displayed for each
beam and color codes based on the beam
Table 4:4
Moving
Average
Moving average is calculated of the one
second SNR data and is graphically displayed
with the raw SNR data.
Real Time
Raw Data
Instantaneous one second raw SNR data is
displayed with the graphical display.
Discharge
Measurement
Mean Point
SNR
The point measurement SNR is the mean of
beam 1 and 2 at the point measurement.
Receiver 3 (if installed) is not used in the mean
calculation because we assume the probe is
side-looking (either a 2D or 2D/3D probe), and
only Vx and Vy are of interest. Receiver 3,
which is only used for Vz, is irrelevant.
Review
Station
SNR
The station SNR is the mean of all point
measurements at a station.
Discharge
SNR
The discharge summary SNR is the mean of
all the station mean SNR within the section
General
Review Point
Measurement
Mean Beam
SNR at Point
Measurement
The point measurement SNR is the mean of
one second SNR data for each individual
beam (2 or 3 depending on probe type) at the
point measurement.
Review
Station
Mean Beam
SNR at
Station
The station SNR is the mean for each
individual beam (2 or 3 depending on probe
type) of all point measurements at a station.
General
Summary
Mean SNR
The general summary SNR is the mean of all
individual beam SNRs at all point
measurements.
SNR
Data
Evaluate
f) SNR is the most important quality control data provided by the FlowTracker2.
SNR is evaluated against number of quality control criteria and at the end of
each velocity point measurement, the following SNR checks are run in General
i). SNR from all beams must be greater than 4 dB for reliable data collection.
ii). Low SNR. If the SNR of any beam is below 4.0 dB, “Low SNR” alert will be
given at the end of point and section measurement.
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