Acoustic Position Measuring Device

[Stefan Strahl]

Hi Openmoko list :)

Cool idea :) As already mentioned you won't get a real validated
measurement system, but it should be fun enough :)

I would suggest using a
http://en.wikipedia.org/wiki/Maximum_length_sequence (MLS) instead of
a sweep or alike. As its spectrum is flat you will hear only a white
noise like sound. From the measured impulse response we can then get
the direct speaker-microphone path and the distances to the reflecting
surfaces as Rusty explained.

Once I got my freerunner (should have arrived at pulster.eu last
friday and any day at my doorstep :) ) I will test the speaker/mic
quality. If someone needs a MLS of length 2^n just let me know and I
can mail the sequence.

:) stefan