Method and apparatus for detecting and locating noise sources whether correlated or not

• US 20050137804A1
• Filed: 12/17/2003
• Published: 06/23/2005
• Est. Priority Date: 12/17/2003
• Status: Active Grant

• Current Assignee: 01 DB - METRAVIB
• Original Assignee: Metravib R.D.S.
• Inventors: Millet, Joel, Permuy, Alfred
• Granted Patent: US 6,999,881 B2
• Time in Patent Office: Days
• US Class Current: 702/14
• CPC Class Codes: G01V 1/362 Effecting static or dynamic corrections; Stacking

Abstract

The invention relates to a method of detecting and locating noise sources each emitting respective signals S_j with j=1 to M, detection being provided by means of sound wave or vibration sensors each delivering a respective time-varying electrical signal s_i with i in the range 1 to N. According to the invention, the method 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 a functional; and
  • in minimizing the functional relative to the vectors n_j for j=1 to M so as to determine the directions vector n_j of the noise sources.

Claims

1. A method of detecting and locating noise sources each emitting a respective signal S_j with 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 lying in the range 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 time-varying electrical signals as taken;

in digitizing the electrical signals;

in calculating the functional f, such that;

$f<br><br>\left(n_1,\mathrm{\dots <br><br>}<br><br>\text{\hspace{1em}<br><br>},n_j,\mathrm{\dots <br><br>}<br><br>\text{\hspace{1em}<br><br>},n_M\right)=\frac{\det <br><br>\left(<<br><br>T_k<br><br>\left(\mathrm{\omega <br><br>}\right),T_1^{*}<br><br>\left(\mathrm{\omega <br><br>}\right)><br><br>k,1=0<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{to}<br><br>\text{\hspace{1em}<br><br>}<br><br>M\right)}{\det <br><br>\left(<<br><br>T_k<br><br>\left(\mathrm{\omega <br><br>}\right),T_1^{*}<br><br>\left(\mathrm{\omega <br><br>}\right)><br><br>k,1=1<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{to}<br><br>\text{\hspace{1em}<br><br>}<br><br>M\right)}$

with

${\left(T_k<br><br>\left(\mathrm{\omega <br><br>}\right)\right)}_i={\mathrm{e<br><br>}}^{J<br><br>\text{\hspace{1em}<br><br>}<br><br>\mathrm{\omega <br><br>}<br><br>\frac{<<br><br>n_k,c_i><br><br>}{c}}$

<

.,.>

being the scalar product;

.. c_i being the vector constructed between the center of gravity of the sensors and the position of sensor i;

.. n_j being the unit vector in the direction defined by the center of gravity of the senors and source j;

.. with T₀=s; and

.. with c=the speed of sound; and

in minimizing the functional f relative to the vectors n_j for j=1 to M 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 when the noise sources are narrow band sources, the method consists:

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

in using the expressions for the determinants of the matrices of general term;

<

T_k(ω

),T_l*(ω

)>

to calculate the functional;

$f_1=\underset{k}{\sum <br><br>}<br><br>{<br><br>{B<br><br>\left(\mathrm{\omega <br><br>}\right)}_k<br><br>}^2$

and after selecting a determined number of noise sources, in minimizing the functional f₁ 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 when the noise sources are broad band, the method consists:

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

in using the expressions of the determinants of the matrices of general term;

<

T_k(ω

),T_l*(ω

)>

to calculate the functional;

f₂=∫

∥

B(ω

)∥

²dω

and after selecting a determined number of noise sources, in minimizing the functional f₂ to determine the directions n_j of the selected noise sources.

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

in simplify the expression for the functional f to minimize the following functional f₃;

f₃=∫

det(<

T_k,T_l*, >

k, l=0 to M)dω

in calculating the cross-correlation functions γ

_ij of the signals s_i and s_j; and

after selecting a determined number of noise sources, in minimizing the functional f₃.

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

S(ω

)=(^tT*·

T)<sup>−

1</sup>·

^tT*·

s(ω

)

in order to discover the characteristics of the noise sources.