[PD] Ultrasonic 'theremin' patch

[Luigi Rensinghoff]

http://nm-archives.electro-music.com/010_NordModular/ 
014_Interesting_Threads/Folder/ModularAsMotionSensor/ 
ModularAsMotionSensor.htm


here i found it ... maybe it can be helpful for you

luigi

Am 07.08.2008 um 22:57 schrieb Luigi Rensinghoff:

> Thats very cool...
>
> i heard of someone implementing that with a nord-modular....
>
> If you browse the forums maybe you can find it...
>
> Its a cool thing to have for Sound-Installations...
>
> Best
>
> Luigi
>
> Am 07.08.2008 um 21:16 schrieb Ico Doornekamp:
>
>>
>> Hi all,
>>
>> Yesterday I found out that modern audio cards can do much higher
>> sample
>> rates then 48000, which allows for entertaining experiments with
>> ultrasound.
>>
>> I'm not sure if this has been done before, but I'm pretty happy
>> with the
>> results so far.
>>
>> I've created a patch running on a samplerate of 88200 Hz, which sends
>> out high-frequency chirps over two laptop speakers. The chirps are
>> reflected back to the bultin mic using both hands. The reflection is
>> correlated with the outgoing chirps to calculate the time the sound
>> waves needed to return to the mic, thus measuring the distance to the
>> hands or any objects hovering above the laptop.
>>
>> This particular patch just drives two tone generators whose
>> frequencies
>> depend on the measured distances, which are played back over the same
>> speakers as the high-frequency chirps. The result is a
>> two-tone-polyphonic theremin-like instrument.
>>
>> If only I could play this thing in tune...
>>
>> A simple demonstration video and the patch can be found at
>>
>>   http://zevv.nl/play/code/ultrasonic-theremin/
>>
>> This patch just a first test using ultrasound, I'm sure much more
>> interesting things can be done using this technique.
>>
>> The patch is not very well documented at this time, and I think
>> getting
>> things to work needs a fair amount of tweaking for each different
>> setup.
>> Things that need to be setup properly are output level of the
>> soundcard,
>> a magic gain factor after the correlation, and the range that
>> should be
>> inspected for echo peaks to avoid detecing of reflections from the
>> ceiling.  I think it would be possible to make the patch do some
>> auto-detection of some of the paremeters like ceiling height and gain
>> factors, which would make a nice addition for future versions.
>>
>> Enjoy,
>>
>> Ico
>>
>> -- 
>> :wq
>> ^X^Cy^K^X^C^C^C^C
>>
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>
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