Doppler_Toolbox

Abstract

The Doppler Shift is defined as a change in pitch as a result of relative motion between a sound source and a receiver. As the source and receiver become closer together the sound waves arrive at closer intervals, and thus the receiver perceives a higher pitch than the original emitted frequency. As the source moves further away the receiver hears a lower frequency than what was emitted. The relative velocity also produces a change in magnitude (Nave 2012). The Doppler Shift occurs between ANY sound source and receiver when there is relative motion. It is most noticeable when a plane flies overhead or an ambulance drives passed, however the Doppler Shift is always occurring, giving important auditory cues that allow us to so accurately and usually subconsciously, localize sound. This principle forms the basis of many spatial related technologies, such as sonar, radar and acoustic mapping. Thus, it is of the utmost importance for anyone studying engineering, science, audio or acoustics to be aware of, and understand the Doppler Shift. The computer program Matlab is used extensively by university students and professionals in these fields for coding purposes. The software includes many in-built functions for performing calculations, but none of the in-built functions address the doppler shift. I believe the addition of a “Doppler Toolbox” would be a very effective and usable addition to the software for future releases. This submission includes four functions - POLICE_RADAR, DOPPLER_APPROACHING, DOPPLER_RECEDING & DOPPLER_PASSING. They can all be run using the script Doppler_Toolbox_script.