The Solent Wind Sensors measure 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 E and W transducer.
If, for example, a North wind is blowing, then the time taken for the
pulse to travel from N to S will be faster 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 WindObserver UltraSonic anemometer.
