Method and apparatus for detecting and locating noise sources not correlated

• US 20050135632A1
• Filed: 12/17/2003
• Published: 06/23/2005
• Est. Priority Date: 12/17/2003
• Status: Abandoned Application

• Current Assignee: 01 DB - METRAVIB
• Original Assignee: Metravib R.D.S.
• Inventors: Permuy, Alfred, Millet, Joel
• Application Number:
  US10/736,895
• Publication Number:
  US 20050135632A1
• Time in Patent Office: Days
• US Class Current: 381/71.200
• CPC Class Codes: G01H 3/125 for representing acoustic field distribution using optical means G01H9/002; sonar systems for imaging G01S7/56, G01S15/89; acoustic holography G03H3/00
• CPC Class Codes: G10K 11/346 using phase variation

Abstract

According to the invention, the method of detecting and locating sources of noise each emitting respective signals S_j with j=1 to M, detection being performed using sensors each delivering a respective time-varying electrical signal s_i with i varying from 1 to N, consists in taking the time-varying electrical signals delivered by the sensors, each signal s_i(t) delivered by a sensor being the sum of the signals S_j emitted by the noise sources, in amplifying and filtering the time-varying electrical signals as taken, in digitizing the electrical signals, in calculating the functional $f\left(n_1,\dots ,n_j,\dots ,n_N\right)=\sum _{k\ne 1}^{}{R}_{\mathrm{k1}}$
with coefficients R_kl being a function of the vectors n_j giving the directions of the noise sources, and in minimizing the functional f in such a manner as to determine the directions n_j of the noise sources.

Claims

1. A method of detecting and locating noise sources each emitting respective signals S_j where j=1 to M, detection being provided by means of acoustic wave or vibration sensors each delivering a respective time-varying electrical signal s_i with i varying from 1 to N, the method consisting:

in taking the time-varying electrical signals delivered by the sensors, each signal s_i(t) delivered by a sensor being the sum of the signals S_j emitted by the noise sources;

in amplifying and filtering the taken time-varying electrical signals;

in digitizing the electrical signals;

in calculating the functional

$f<br><br>\left(n_1,\mathrm{\dots <br><br>}<br><br>\text{\hspace{1em}<br><br>},n_j,\mathrm{\dots <br><br>}<br><br>\text{\hspace{1em}<br><br>},n_N\right)=\underset{k\ne <br><br>1}{\overset{\text{\hspace{1em}<br><br>}}{\sum <br><br>}}<br><br>\text{\hspace{1em}<br><br>}<br><br>R_{\mathrm{k1}}$

with the coefficients R_kl being a function of the vectors n_j giving the directions of the noise sources; and

in minimizing the functional f in such a manner as to determine the directions n_j of the noise sources.

2. A method according to claim 1, wherein, in order to minimize the functional f, the method consists in:

calculating the Fourier transforms of the signals s_i(t) delivered by the sensors;

formally calculating the coefficients R_ij;

$R_{\mathrm{ij}}=\frac{{\int <br><br>}_{-\mathrm{\infty <br><br>}}^{+\mathrm{\infty <br><br>}}<br><br>{<br><br>{\hat{S}}_i<br><br>\left(\mathrm{\omega <br><br>}\right)<br><br>}^2·<br><br>{<br><br>{\hat{S}}_i<br><br>\left(\mathrm{\omega <br><br>}\right)<br><br>}^2<br><br>\text{\hspace{1em}<br><br>}<br><br>d<br><br>\mathrm{\omega <br><br>}}{{\int <br><br>}_{-\mathrm{\infty <br><br>}}^{+\mathrm{\infty <br><br>}}<br><br>{<br><br>{\hat{S}}_i<br><br>\left(\mathrm{\omega <br><br>}\right)<br><br>}^2<br><br>\text{\hspace{1em}<br><br>}<br><br>d<br><br>\mathrm{\omega <br><br>}·<br><br>{\int <br><br>}_{-\mathrm{\infty <br><br>}}^{+\mathrm{\infty <br><br>}}<br><br>{<br><br>{\hat{S}}_j<br><br>\left(\mathrm{\omega <br><br>}\right)<br><br>}^2<br><br>d<br><br>\mathrm{\omega <br><br>}}$

and minimizing the functional f in order to determine the directions n_j of the selected noise sources.

3. A detection method according to claim 1, wherein, in order to minimize the functional f, the method consists:

in formally calculating the correlation coefficient R_ij;

$R_{\mathrm{ij}}=\frac{{\int <br><br>}_{-\mathrm{\infty <br><br>}}^{+\mathrm{\infty <br><br>}}<br><br>{\mathrm{\Gamma <br><br>}}_{\mathrm{ij}}^2<br><br>\left(\mathrm{\tau <br><br>}\right)<br><br>\text{\hspace{1em}<br><br>}<br><br>d<br><br>\mathrm{\tau <br><br>}}{{\mathrm{\Gamma <br><br>}}_{\mathrm{ii}}<br><br>\left(0\right)·<br><br>{\mathrm{\Gamma <br><br>}}_{\mathrm{jj}}<br><br>\left(0\right)}$

where Γ

_ij is the cross-correlation function between the signals S_i and S_j.

4. A detection method according to claim 1, wherein, after performing the minimization operation, the method consists in calculating the source vector:

S(w)=(^tT*·

T)<sup>−

1</sup>·

^tT*·

s(ω

)

in order to find the characteristics of the noise sources.