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Sound Localization using Sound Amplitude

Started by jigajigajoo July 8, 2011

"Eric Jacobsen"  wrote in message 
news:4e1b9db6.38140731@www.eternal-september.org...

On Mon, 11 Jul 2011 20:34:11 -0400, "Phil Martel"
<pomartel@comcast.net> wrote:

> > >"Fred Marshall" wrote in message >news:50ISp.87892$fD6.45795@en-nntp-02.dc1.easynews.com... > >On 7/11/2011 7:15 AM, Clay wrote: > >> >> >> Hello Fred, >> >> >> You can take 2 different sets of data for the same signal where the >> only essential difference is the time delay and frequency offset and >> then do a frequency domain approach to the TDOA. For example find the >> DFT of each signal. Then conjugate one of the signals and then form a >> sample by sample inner product between the two. The find the argument >> of each resulting sample. When plotted (argument vs sample(frequency >> bin) you will get a straight line whose slope is the time offset and >> intercept is the frequency offset. Notice how the TDOA and the >> frequency offset get separated out in the analysis - I found this >> quite useful in RF applications when I didn't have to worry about >> carrier and doppler frequency offsets. You can even weight the >> samples by their spectral power before doing the regression fit. >> >> This is basically doing TDOA autocorrelation via FFT except for the >> converting back to the time domain and peak search. >> >> >> Clay >> >> >> > >Ah! OK. Thanks Clay. > >Fred > >Hi, > >The approach we used was somewhat different, but probably isomorphic. >We FFTed each channel, summed the magnitude squared then selected peak >frequencies, >then took the phase difference at a given peak between one channel and each >of the others. >From that information and the geometry of the array, we were able to >determine the DOA of the signal at that frequency. > > Best wishes, > --Phil >
How well did that work? I've been thinking of using a very similar technique for a slightly different application. Eric Jacobsen http://www.ericjacobsen.org http://www.dsprelated.com/blogs-1//Eric_Jacobsen.php Reasonably well. We were getting about 3 degrees RMS error with good S/N, in-an-open-field sorts of situations.