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>> 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>
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 list
Tinyos-help@millennium.berkeley.edu
https://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 list
Tinyos-help@millennium.berkeley.edu
https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
_______________________________________________
Tinyos-help mailing list
Tinyos-help@millennium.berkeley.edu
https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
