Doppler Effects

doppler.m MATLAB code / view online

The most difficult aspect of this project was applying the doppler shift to a frequency-varying source; this required the use of frequency modulation, which follows this expression for a sinusoidal baseband signal:

Where indicates the modulation depth and indicates the modulation rate. More information about frequency modulation at Wikipedia.

Problem 1

Sound source producing a tone of 440 hz passes through the observer.

Audio example:

Problem 2

Sound source producing a tone of 440 hz passes 10 m in front of the observer.

Audio example:

Problem 3

Sound source producing a frequency-varying tone passes 10 m in front of the observer.

Audio example:

Problem 4

A binaural representation of the scenario in Problem 1 and Problem 2.

NOTE: For problem 4, the inter-aural distance of 17 cm didn't result in a very audible difference in the stereo signal. For these examples, the inter-aural distance has been deliberately exaggerated by a factor of 4, to a distance of 68 cm.

Audio example (P1):

Audio example (P2):

One ResponseLeave a Reply

  1. Thanks for sharing the doppler effects lesson. I'll share it with my school friends.

    Rohan

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