Talk:Acoustic Tape Measure

Some ideas:

Measure velocity using doppler?

For something like the "dance revolution graph" activity - maybe you could take some shortcuts.

idea 1: Have one computer broadcast an intermittent square wave at a given frequency. I understand that the result would lack some high harmonics necessary for a true square wave - but I bet it would be good enough to make the calculation of when the thing starts pretty simple. Certainly less robust than full-spectrum white noise, but probably good enough after an initial calibration against white noise.

idea 2: Have one computer broadcast a continuous square wave, and the other one just count beats (using some reasonable assumptions about possible accelerations to throw away bad data). This would tend to get progressively out-of-sync, but it would be fully real-time. Maybe have an intermittent transient to resync...

The point is, doing a whole deconvolve or whatever to match a known sound is computationally much heavier than just binning against a known frequency - sine or square, either way it's even easier than an FFT.

I actually imagine that maybe you could find some good algorithms in use in GPS recievers for electromagnetic stuff - the problem is similar.

(I know - everyone can kibbutz, few will code.)

--Homunq 16:46, 5 October 2007 (EDT)

ps. speed of sound depends on altitude as well as temperature. I think that asking people to guess the temperature is more accurate AND educational than just guessing it using time/location.