Hi Paul Can you tell me what might be the different between the microphone implementation in MicrophoneC inside SoundLocalizer Vs the MicP inside mts300 ?
Thanks a lot Akankshu On Thu, Nov 12, 2009 at 4:44 PM, Paul Johnson <oewyn...@gmail.com> wrote: > CVS under /tinyos-2.x-contrib/tinyos-programming/ > > -Paul > > > Martin Osterloh wrote: > > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > Hi all, > > sorry for interfering this thread. But, where can I find the > sourcecode to the soundlocalizer demo? > > Best, > Martin > > Akankshu Dhawan wrote: > > > Hi Michael and Zainul > > Thanks a lot for your response. I am grateful to be hearing from you. > > I will look into the corrected mean solution before I suggest some > hardware changes to my team. > > Although, my bigger question was why direct sampling by calling > getData->dataReady on a free running ADC (this is what is used in > the SoundLocalizer example in Tinyos-2.x described in the book also) > responds better ? if I try to do threshold detection of every sample > using the same interface and direct sampling I get values which are > very responsive and high rate of sampling. I know I am loosing on > some precision by sampling at a rate other than the default > ATM128_ADC_PRESCALE but since I am mainly using it for thresholding > I think my application can handle it. > > Can you tell me some comparison between the microphone setup used by > the MicP and MicStream compared to the SoundLocalizer direct > sampling setup ? > > Thanks a lot once again > > Sincerely > Akankshu Dhawan > > On Thu, Nov 12, 2009 at 1:30 PM, Michael Schippling > <sc...@santafe.edu <mailto:sc...@santafe.edu> <sc...@santafe.edu>> wrote: > > I suspect that the straight averaging thing is not what you want. > > I haven't looked at the mic data, but it's sampling an AC > signal (sound wave pressure alternates between compression > and rarefaction at the frequency you perceive) and is probably > biased so a no-pressure signal is pretty much in the middle of > the ADC range. Averaging that AC signal over a number of high-low > pressure waves will just give you the middle again. > > If that is the case, what you want to do is rectify the signal -- > half-wave would just chop off the samples below the mid-value, > full-wave would invert them around the mid-value -- before > trying to average to get a "loudness". If you are trying > to get the "Sound Pressure Level" -- how loud the sound is at > any particular time -- it's called "Envelope Following" in the > good old days of signal processing. If you know any electronics, > what you want to build is a diode or diode bridge, to rectify > the signal, and a capacitor to filter, or average, it to a slowly > varying DC value. > > MS > > Akankshu Dhawan wrote: > > Hi All > I am using two mechanisms for high sampling. > 1. Using MicStreamC and changing the prescalar value inside > MicP to ATM128_ADC_PRESCALE_32 and the gain value is set to > 64. I create a buffer of 1000 samples and every time the > buffer gets full I take the average and print it out. The > problem is that the microphone does not seem to be > responding or is not showing me sufficiently precise values. > The average when I dont make a noise is around 500 ADC.. and > even if I am clapping shouting (for long durations) it still > shows me slightly */lower values /like 497 etc. So I am not > sure why this is so ?* > > 2. When I created the low level interfaces on my own using > the sample SoundLocalizer example in Tinyos programming > book, I am giving the microphone ADC a free run at the same > prescale setup (there is a difference of some parameter > being passed through getData as FALSE in that example which > is suppose to cater to LEFT_ADJUSTMENT ) but when I compare > the values that I am getting inside dataReady they respond > well to sounds. This would work for me but I am just curious > why the MicStream does not work. This way I would not have > to recreate all the buffer code. > > If anyone can please tell me what setting inside MicSetting > or MicP have I done wrong that it is not responding. > > Thanks a lot. > > SIncerely > Akankshu Dhawan > > -- > First they ignore you, then they laugh at you, then they > fight you, then you win. > - Mahatma Gandhi > > > > > > ------------------------------------------------------------------------ > > > _______________________________________________ > Tinyos-help mailing list > Tinyos-help@millennium.berkeley.edu > <mailto:Tinyos-help@millennium.berkeley.edu> > <Tinyos-help@millennium.berkeley.edu> > > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > -- > First they ignore you, then they laugh at you, then they fight you, > then you win. > - Mahatma Gandhi > > ---------------------------------------------------------------------- > > _______________________________________________ > Tinyos-help mailing > listtinyos-h...@millennium.berkeley.eduhttps://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.9 (GNU/Linux) > Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ > > iEYEARECAAYFAkr8e2AACgkQa1gn+vovozNg8ACfaJLQVdQFUlNJWg6GDBsQSqAj > q+8An38HnQsg1iyeSx8odAGKFG5d3EFj > =BE0Q > -----END PGP SIGNATURE----- > > _______________________________________________ > Tinyos-help mailing > listtinyos-h...@millennium.berkeley.eduhttps://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > > -- First they ignore you, then they laugh at you, then they fight you, then you win. - Mahatma Gandhi
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