SonTek/YSI
ADVField Software Manual (September 1, 2001) 19
Some specific notes for the conversion programs are given below. For additional information
about the different types of data, see the ADVField Principles of Operation.
•
GETAMP
- Retrieves signal strength from each of the three receivers in units of counts. One
count is equal to 0.43 dB. If you are using signal strength data to estimate suspended sedi-
ment concentration, the signal amplitude should be used instead of SNR because changes in
the electronic noise level may affect SNR data.
•
GETCOR
- Correlation is a data quality parameter that can be used to monitor the quality of ve-
locity data and to edit data in post processing.
•
GETSNR
- Retrieves signal strength data from each of the three receivers as a signal-to-noise
ratio (SNR) in dB. SNR is calculated from signal amplitude by subtracting the noise level and
converting to units of dB. For high-frequency velocity measurements (i.e.; sampling at
25 Hz), SNR should be above 15 dB; and for mean velocity measurements (i.e.; sampling at
1 Hz), SNR should be above 5 dB.
•
GETVEL
- Velocity data are output in either the XYZ or ENU coordinate system, depending on
the setting used during data collection. See the ADVField Operations Manual for more de-
tails about the ADV coordinate system. Velocity data are output in either cm/s or ft/s, de-
pending on the selection specified in the data acquisition setup menu. See Section 2 for de-
tails about parameter settings during data collection.
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