How do Gill Ultrasonic Anemometers Work?
A Gill Ultrasonic Anemometer measures the time taken for an ultrasonic pulse of sound to travel from the North transducer to the South transducer, and compares it with the time for a pulse to travel from S to N transducer. Likewise
times are compared between West and East, and East and West transducers.
If, for example, a North wind is blowing, then the time taken for the pulse to travel from N to S will be less than from S to N, whereas the W to E, and E to W times will be the same. The wind speed and direction can then be calculated from the differences in the times of flight on each axis. This calculation is independent of factors such as temperature.
The animation below provides a simplified time of flight visualisation using the Gill WindObserver Ultrasonic Anemometer.