Doppler frequency shift of sound apparatus

Abstract

A large 1-m diameter rotary table with a semicircular waveguide along its periphery is the basis of the Doppler frequency shift of sound apparatus. A “button” speaker is attached to the outer edge of the rotary table and a microphone pickup is positioned on the wall of the waveguide at its midpoint. At approximate speeds of 25 mph (11 m/s), the velocity measured from the frequency shift between the approaching and receding speaker compared to the velocity measured from the repeat sound pattern agree to within 1%. The microphone output is fed successively to our 10 computer stations.