hi all
i'd like to create a patch, that measures the distance between the speaker and the microphone. my first problem is, that i don't know which kind of signal would be suitable for that purpose. the simplest is to use a dirac impulse. but on the receiver-side it's hard to separate unwanted artefacts from the impulse itself. also it would be nice, if it would be possible to detect the signal reliably at different amplitudes, since the amplitude heavily changes when moving the mic closer to and farer from the speaker. i am looking for a method, that allows higher precision than the usual block-size (which introduces a grid of ~0.5m @ 44100Hz, which is not very accurate). also should it be possible to detect the signal correctly, when there was reverberation added from a room. i know, there are ultrasonic-bases devices to measure a distance to a wall, but i don't have clue how they work, but it makes me hope, that something similar is possible with pd. any hints are much appreciated.
roman
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Roman Haefeli a écrit :
hi all
i'd like to create a patch, that measures the distance between the speaker and the microphone. my first problem is, that i don't know which kind of signal would be suitable for that purpose. the simplest is to use a dirac impulse. but on the receiver-side it's hard to separate unwanted artefacts from the impulse itself. also it would be nice, if it would be possible to detect the signal reliably at different amplitudes, since the amplitude heavily changes when moving the mic closer to and farer from the speaker. i am looking for a method, that allows higher precision than the usual block-size (which introduces a grid of ~0.5m @ 44100Hz, which is not very accurate). also should it be possible to detect the signal correctly, when there was reverberation added from a room. i know, there are ultrasonic-bases devices to measure a distance to a wall, but i don't have clue how they work, but it makes me hope, that something similar is possible with pd. any hints are much appreciated.
roman
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hello, you could use the patch you've made last month for am-radio and use it to measure latency...
[message bang( | [t b b] | | [modulator] | | | [am-radio] | | | [dac~] | | [adc~ 1] | | | [demodulator] | | | [route message] | | | [timer ] | [nbx]
obviously the message is translated into voltage levels by a modulator and a demodulator. In the equation, you will need to substract the latency of the soundcard. hope you get what I mean, and find something in this way, best, patco.
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On Wed, 2007-02-14 at 14:32 +0100, Patco wrote:
hello, you could use the patch you've made last month for am-radio and use it to measure latency...
[message bang( | [t b b] | | [modulator] | | | [am-radio] | | | [dac~] | | [adc~ 1] | | | [demodulator] | | | [route message] | | | [timer ] | [nbx]
obviously the message is translated into voltage levels by a modulator and a demodulator. In the equation, you will need to substract the latency of the soundcard. hope you get what I mean, and find something in this way, best, patco.
hi patco
thank you for your thoughts. the problem is, that some time is needed to detect, whether the amplitude changes or not. that means to point of the change is not definable very precisely, which makes the measurements inaccurate. also i cannot send the sound produced by the [pd am-radio] to the speakers, because it uses a very high internal samplingrate (~1.5MHz or the like).
roman
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Patco -
Roman Haefeli