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Redirecting the sound
The sonic beam can be redirected via a reverberant, smooth reflecting surface without significant losses. Accessories are
available to deflect the sound through 90°.
These can be used to advantage in certain confined installations.
Accuracy
The (absolute) accuracy is the discrepancy between the real distance between sensor and object and the distance as measured
by the sensor. The accuracy obtainable depends on the reflective properties of the object and the physical influences affecting
the velocity of sound in air.
Objects with poor reflective properties or a surface roughness greater than the wavelength of the ultrasonic frequency have
an adverse effect on the accuracy achievable. It is not possible to quantify this exactly but as a rule of thumb we can assume
an inaccuracy of several wavelengths of the ultrasonic frequency employed.
Air temperature
The biggest influence on the velocity of sound and hence on the accuracy is the temperature of the air (0.17%/K). Therefore,
the majority of ultrasonic sensors from microsonic contain temperature compensation circuitry. Even better is to carry out a
comparative measurement over a known distance to determine the influence of temperature. The pico column sensor is, for
example, designed for such comparative measurements. With temperature-compensated sensors, an accuracy of ≤ ±1 % can
be achieved.
Air pressure
The velocity of sound over a wide range does not depend on the pressure of the air. microsonic has special sensors for
measuring distances in up to 4 bar overpressure.
Relative humidity
In comparison to the influence of temperature, the effect of the humidity of the air on the accuracy can be ignored.
Repeat accuracy R
The repeat accuracy, or reproducibility, describes the deviation in the measured distances under the same conditions over a
defined period.
The repeat accuracy of microsonic sensors is better than ±0.15%.
::: Installation notes :::