DATA QUALITY CHECKS - one of the advantages of the 2-axis USA-2
Wind Horizon and the 3-axis USA-1 Wind Professional /
Wind Research ultrasonic anemometers.
These sensors perform real-time
data quality checks which means that you can
have the utmost confidence in your measurements.
Each instantaneous measurement is checked and the result
recorded in the output data string as a percentage of reliability (i.e. 100% would
indicate that you can have total confidence in the measurement whereas 80% would suggest
that an external or environmental influence is affecting measurement accuracy and you
should be aware of this).
The validity of each measurement is checked on 3 levels:
Sonic Temperature check
The sensors make measurements on three non-orthogonal paths including the sonic
temperature of each path. These sonic temperature path lengths are known and the
electronics perform a data quality check by comparing the known length to the measured
length. The sonic temperature should not deviate more than a certain percentage on any
single path and if a deviation is recorded above the tolerance it is output to the user so
corrective action can be taken (ie a recalibration).
Sonic data check
The sensor electronics measure the amount of sonic pulses that are received and compare
those to the transmitted pulses. A ratio is derived from this and the percentage output
for the user to see. This allows the user to understand how well the sensor is
performing in any given condition and take appropriate actions (ie switch heating on,
perform instrument checks etc).
Standard deviation check
The sensor electronics perform continuous data quality evaluations on the measured
parameters and have a user definable threshold for the standard deviation tolerance that
is allowable. For example if you are measuring a 5 m/s wind and have set a standard
deviation tolerance of 10% and the sensor suddenly starts to measure 15 m/s then the
sensor will output the data as erroneous saving you post processing time while giving you
confidence in the data that has been collected.
These are the only ultrasonic anemometers which provide
these data quality checks.
The other advantages . . .
..... time and date stamped
..... field calibration kit
..... protected transducers
......heating technology
..... robustness
.... sonic
temperature
..... customized
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