A Sonic Velometer

Wind-velocity measurement at remote winter mountain sites is hampered by icing of the moving parts of the measuring device and by restrictions on the amount of electrical power which is available. A sonic velometer which determines the wind velocity by measuring the transit times of sound pulses in air and has no moving parts has been developed. The sound pulse transit times are measured accurately through the use of phase-locking techniques. Circuit construction is exclusively solid state, with integrated circuits used for several functions. The device exhibits an uncertainty of 0.05 percent in the determination of the pulse-transit times yielding a wind-velocity resolution capability of 0.13 m/s. The velometer has been tested over a dynamic range of 5 m/s.