Randy Boulter wrote:
> 
> Robert Rolf wrote :

>> We had an old 3-d digitizer that used
>>a pen that snapped (electric arc) and 3 mics with about a 0.5 meter
>>spacing, and it covered the 1/2 meter cube quite well.
>>
>>With 4 external sources, (to get better closure on the RMS position
>>error), and phase measurements, one could get very good accuracy,
>>if a continuos high sample rate was required.
>>
>>Sounds to me like you're looking to do performance art, so there is
>>no budget available to use the optimal technology.
>>
>>Robert
> 
> 
> This sounds like an excellent method, but how far apart would the
> microphones have to be if they were placed, say 20 feet away from the sound
> source (finger), and still maintain accuracy within a few millimeters?

First you say 1 meter (3 feet) and now you're asking for 20 feet.
BIG change in specifications here. Pointless for me to waste my time
suggesting solutions for a moving target.

The accuracy would be determined by noise levels, and how accurately
you measure the transit time.

Robert

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