8. Operation
The SnowVUE 10 bases every measurement on several readings and applies an algorithm to
improve measurement reliability. The distance-to-target readings that are obtained from the
sensor are referenced from the metal mesh on the face of the transducer. The SnowVUE 10
transmits an ultrasonic beam that detects objects within a 30-degree field of view (see
The SnowVUE 10 completes a measurement and outputs the data typically in 10 to 15 seconds,
depending on the target distance, target type, and noise in the environment.
The SnowVUE 10 may reject readings from a moving target. If the SnowVUE 10 rejects a reading
or detects no target, 0 will be output for the distance to target and for the quality number.
8.1 Quality numbers
The following table describes the measurement quality numbers provided in the output data.
These numbers indicate the measurement certainty. The quality number is calculated as the
standard deviation of multiple readings used to return one distance value. A 0 indicates that the
reading was not obtained. Numbers greater than 300 indicate a degree of uncertainty in the
measurement. Causes of high numbers include:
l
sensor is not perpendicular to the target surface
l
target is small and reflects little sound
l
target surface is rough or uneven
l
target surface is a poor reflector of sound (for example, extremely low-density snow)
Table 8-1: Quality number description
Quality number range
Quality range description
0
Unable to read distance
1 to 100
Good measurement quality numbers
100 to 300
Reduced echo signal strength
300 to 600
High measurement uncertainty
Although not necessary, quality numbers provide useful information such as surface density in
snow monitoring applications. Please note that quality number values may increase during
snowfall events consisting of low-density snow.
SnowVUE 10 Sonic Ranging Sensor
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