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Acoustic Detection 
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Joined: 22 Mar 2008, 16:09
Posts: 26
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For a long time now I have been meaning to try out a method of acoustic detection with a Ping Pong (Table Tennis) Table.
I saw a demo at Casa Paganini in 2006 (is this the Tai Chi project?).

I have 4 piezo transducers linked up to Eyesweb through my sound card sampling at 96KHZ.
When the threshold of one rises above a certain level I take a timestamp.
In this way I can estimate position using Time Difference On Arrival.

My results seem very unpredictable though. Sometimes accurate, other times meaningless.

Is there anyone who has used this method who could give me some tips?

Am I wasting my time in the quest for (vaguely) reliable results?

Should I try to develop an interrupt based system?

Thanks,

Gavin
http://www.digitalfunfair.co.uk


21 Apr 2008, 09:56
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Joined: 21 Mar 2008, 22:35
Posts: 131
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gavspav wrote:
For a long time now I have been meaning to try out a method of acoustic detection with a Ping Pong (Table Tennis) Table.
I saw a demo at Casa Paganini in 2006 (is this the Tai Chi project?).


Yes, it was the TaiChi project.


gavspav wrote:
I have 4 piezo transducers linked up to Eyesweb through my sound card sampling at 96KHZ.
When the threshold of one rises above a certain level I take a timestamp.
In this way I can estimate position using Time Difference On Arrival.

My results seem very unpredictable though. Sometimes accurate, other times meaningless.

Is there anyone who has used this method who could give me some tips?

Am I wasting my time in the quest for (vaguely) reliable results?


Maybe TDoA is not the most reliable method (suffers for some drawbacks, such as the effects of reflections at the borders, or dispersion). However, we successfully used TDoA in real-world applications.

Are you using ASIO for audio input?

Paolo

gavspav wrote:
Should I try to develop an interrupt based system?

Thanks,

Gavin
http://www.digitalfunfair.co.uk


22 Apr 2008, 14:37
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Joined: 22 Mar 2008, 16:09
Posts: 26
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Yes I am using Asio drivers and an M - Audio Delta 66 soundcard (although without the breakout box):

http://www.maudio.co.uk/products/en_gb/Delta66-main.html

I've been having a few problems with Eyesweb freezing but this could well be nothing to do with Eyesweb as I am using a shuttle PC which has always seemed slow and now needs a fresh Windows install.

I am going to reapply myself to this project in the next couple of weeks. If anyone is willing to share advice/pitfalls/patches it'd be great ;) ,

Best,

Gavin


22 Apr 2008, 17:06
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