Ultrasonic sensors come in a variety of sensing ranges, which are directly related to the frequency of the sound wave. Generally speaking lower frequency suffers less attenuation due to factors such as humidity, dust, and air turbulence. Low frequency will therefore travel further than higher frequency sound waves.
On the other hand, higher frequency allow for higher resolution, a shorter minimum sensing range and better accuracy - all due to the shorter wavelength of the sound wave.
In order to select an ultrasonic sensor with the right sensing range, it is necessary to consider the characteristics of the application. Simply choosing a sensor based on matching the maximum sensing range with the required range of the application is often a recipe for failure.
Another often-overlooked characteristic associated with sensing range is the width of the detection area, or beam spread. Increasing the gain settings of a sensor in order to achieve maximum range also widens the beam spread, which can result in amplified electrical noise and detecting unwanted targets.
Most sensor specifications are based on targets with good reflective characteristics, precise alignment to the target surface, and a clear/calm atmosphere at ambient temperature. This is usually not the case in real life applications. It is often beneficial to choose a sensor with a maximum range that far exceeds the requirements of the application, which allows the sensor to be run at a lower gain setting, narrow the detection area, and perform better in less than ideal circumstances.
Let us know what you think of this article, and if you have any questions regarding ultrasonic sensor range and frequency.