Which of the following describes an ultrasonic level transmitter?

An ultrasonic level transmitter operates by emitting high-frequency sound waves that travel through a medium (such as air or liquid) and reflect off the surface of the material whose level is being measured. The transmitter sends out these sound waves, and when they hit the surface, they are reflected back to the sensor. The time it takes for the sound waves to return is measured and used to calculate the distance to the surface, which directly correlates to the level of the material.

This method is non-invasive and works well in various applications, making it a widely used technology for level measurement in tanks, silos, and open channels. The technique’s reliance on sound waves (which are inaudible to humans when at the frequencies used) allows for accurate level detection without physical contact with the material.

In contrast, the other options describe different technologies or devices that do not align with the principles of ultrasonic measurement.