Xylem SonTek FlowTracker2, User Manual

Page: 63 / 308

SonTek – a Xylem brand
FlowTracker2 User’s Manual (January 2019)
62
SNR Raw Data 4.4.2
The SNR variable displays the individual Beam SNR measurements from the one
second measured raw data.
a) SNR is primarily a function of the amount of particulate matter in the water. For
good conditions, SNR should be at least 10 dB. The system can operate
effectively with SNR as low as 2-3 dB, although the noise in individual velocity
measurements will increase,
b) The SNR data is updated once per second,
c) The display options for individual or all beam SNR values are listed in
Table 4:4 .
The shortcut key on the keypad determines which beam SNR will be displayed,
Table 4-4 - Beam SNR Display
Beam SNR Line Color Keypad Key
Beam1 SNR1 Red 1
Beam2 SNR2 Blue 2
Beam3 SNR3 Green 3
All Beams All SNR All 4
d) The continuous lines displayed in the graphics are defined under the following
categories,
i). Thin continuous line represents the one second raw SNR data,
ii). Thick continuous line represents moving average of the one second raw SNR
data.
e) The SNR values displayed in the rectangular boxes for each beam below the
graphical display are defined under the following categories,
i). Thin box outline, instantaneous one second raw SNR data,
ii). Thick box outline, represents moving average of the one second raw SNR
data.
Temperature Raw Data 4.4.3
The Temperature variable displays the temperature measurements from the one second
measured raw data.
a) Temperature data are used for sound speed calculations and can affect velocity
data.
b) Check temperature data to be sure the values are reasonable for the
environment.
c) The Temperature data are updated once per second.