Method for Tracking a Transmitter by Means of a Synthetic Sparse Antenna Network

• US 20070216577A1
• Filed: 04/25/2005
• Published: 09/20/2007
• Est. Priority Date: 05/14/2004
• Status: Active Grant

• Current Assignee: Thales SA
• Original Assignee: Thales SA
• Inventors: Ferreol, Anne, Heurguier, Domininique
• Granted Patent: US 7,907,089 B2
• Time in Patent Office: Days
• US Class Current: 342/465
• CPC Class Codes: G01S 2205/03 Airborne
• CPC Class Codes: G01S 3/46 using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
• CPC Class Codes: G01S 3/74 Multi-channel systems specially adapted for direction-finding, i.e. having a single antenna system capable of giving simultaneous indications of the directions of different signals systems in which the directions of different signals are determined sequentially and displayed simultaneously G01S3/04, G01S3/14
• CPC Class Codes: G01S 3/8006 Multi-channel systems specially adapted for direction-finding, i.e. having a single aerial system capable of giving simultaneous indications of the directions of different signals
• CPC Class Codes: G01S 5/0249 Determining position using measurements made by a non-stationary device other than the device whose position is being determined

Abstract

Method of locating one or more transmitters on the basis of an array of sensors moving with respect to the transmitters comprising at least the following steps:

• • determining the direction vectors â_k corresponding to the response of the array of sensors to a source with incidence (θ, Δ) as a function of the incidence parameters θ, Δ, and of the parameter p related to the distortion of the phases on the sensors,
  • transforming this vector â_k so as to eliminate the unknown parameter p, into a vector Ĉ_km, Ĉ′_km, using the transformed vector to obtain the position of the transmitter using a maximized locating criterion.

Claims

1. A method of locating one or more transmitters on the basis of an array of sensors moving with respect to the transmitters the method of comprising the following steps:

determining Direction vectors â

_k corresponding to a response of the array of sensors to a source with incidence (θ

, Δ

) as a function of incidence parameters θ

, Δ

, and of parameter ρ

related to the distortion of the phases on the sensors,

transforming the vector â

_k so as to eliminate the unknown parameter ρ

, into a transformed vector ĉ

_km, ĉ

′

_km, and

using the transformed vector to obtain the position of the transmitter using a maximized locating criterion.

2. The method as claimed in claim 1, wherein the transformation step comprises the following steps:

choosing a reference channel or sensor and constructing a vector b(t_k,x_m,y_m,z_m, ρ

) whose components correspond to the ratio of 2 channels,

$\left[\begin{array}{c}\left({\mathrm{\rho <br><br>}}_2<br><br>v_2<br><br>\left({\mathrm{\theta <br><br>}}_k,{\mathrm{\Delta <br><br>}}_k\right)\right)/\left({\mathrm{\rho <br><br>}}_1<br><br>v_1<br><br>\left({\mathrm{\theta <br><br>}}_k,{\mathrm{\Delta <br><br>}}_k\right)\right)\\ M\\ \left({\mathrm{\rho <br><br>}}_N<br><br>v_N<br><br>\left({\mathrm{\theta <br><br>}}_k,{\mathrm{\Delta <br><br>}}_k\right)\right)/\left({\mathrm{\rho <br><br>}}_1<br><br>v_1<br><br>\left({\mathrm{\theta <br><br>}}_k,{\mathrm{\Delta <br><br>}}_k\right)\right)\end{array}\right]\hspace{1em}<br><br>$

o choosing a reference instant and constructing on the basis of the vector b(t_k,x_m,y_m,z_m,ρ

) a vector whose components are;

${\hat{c}}_{k<br><br>\text{\hspace{1em}<br><br>}<br><br>m}=\left[\begin{array}{c}{\hat{b}}_{k<br><br>\text{\hspace{1em}<br><br>}<br><br>m}<br><br>\left(1\right)/{\hat{b}}_{\mathrm{im}}<br><br>\left(1\right)\\ M\\ {\hat{b}}_{k<br><br>\text{\hspace{1em}<br><br>}<br><br>m}<br><br>\left(n\right)/{\hat{b}}_{\mathrm{im}}<br><br>\left(n\right)\\ M\\ {\hat{b}}_{k<br><br>\text{\hspace{1em}<br><br>}<br><br>m}<br><br>\left(N-1\right)/{\hat{b}}_{\mathrm{im}}<br><br>\left(N-1\right)\end{array}\right]$

3. The method as claimed in claim 2, wherein the locating criterion is a normalized vector correlation criterion L_k(x, y, z) in the position space (x, y, z) of a transmitter with:

4. The method as claimed in one of claim 3, wherein it comprises the following iterative steps:

identifying the vectors c_(K+1)m at the instant t_k+1.

calculating the criterion L_K+1(x,y,z) in an iterative manner and minimizing L_K+1(x,y,z) to obtain a new position estimation (x_m,y_m,z_m) for the transmitter and possible loopback to the preceding step I1.

5. The method as claimed in claim 1, wherein the transformation step comprises the following steps:

choosing a reference instant i, and

constructing a vector Ĉ

′

_km whose components correspond to the ratio of the components between the given instant k and the instant i.

${\hat{c}}_{k<br><br>\text{\hspace{1em}<br><br>}<br><br>m}^{\mathrm{\prime <br><br>}}=\left[\begin{array}{c}{\hat{a}}_{k<br><br>\text{\hspace{1em}<br><br>}<br><br>m}<br><br>\left(1\right)/{\hat{a}}_{\mathrm{im}}<br><br>\left(1\right)\\ M\\ {\hat{a}}_{k<br><br>\text{\hspace{1em}<br><br>}<br><br>m}<br><br>\left(n\right)/{\hat{a}}_{\mathrm{im}}<br><br>\left(n\right)\\ M\\ {\hat{a}}_{k<br><br>\text{\hspace{1em}<br><br>}<br><br>m}<br><br>\left(N\right)/{\hat{a}}_{\mathrm{im}}<br><br>\left(N\right)\end{array}\right]$

6. The method as claimed in claim 5, wherein the locating criterion is equal to:

7. The method as claimed in claim 5, wherein it comprises the following iterative steps:

identification of the vectors c′

_(K+1)m at the instant t_K+1.

calculation of the criterion L_K+1(x,y,z) in an iterative manner and minimization of L_K+1(x,y,z) to obtain a new position estimation (x_m,y_m,z_m) for the transmitter.

8. The method as claimed in claim 5, wherein a phase tracking is performed for the vectors ĉ

′

_km.

9. The method as claimed in claim 1, wherein it comprises a step of filtering the direction vectors â

_k.

10. The method as claimed in claim 1, wherein a sliding time window is used by taking i=k−

1 or i=k−

L.

11. The method as claimed in claim 6, wherein it comprises the following iterative steps:

identification of the vectors c′

_K+1)m at the instant t_K+1.

calculation of the criterion L_K+1(x,y,z) in an iterative manner and minimization of L_K+1(x,y,z) to obtain a new position estimation (x_m,y_m,z_m) for the transmitter.