Robust, Efficient, Localization System

• US 20080161015A1
• Filed: 01/02/2008
• Published: 07/03/2008
• Est. Priority Date: 05/13/1996
• Status: Abandoned Application

• Current Assignee: TruePosition Incorporated
• Original Assignee: TruePosition Incorporated
• Inventors: Maloney, John E., Stevenson, James O.
• Application Number:
  US11/968,592
• Publication Number:
  US 20080161015A1
• Time in Patent Office: Days
• US Class Current: 455/456.1
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial

Abstract

Replica correlation processing, and associated representative signal-data reduction and reconstruction techniques, are used to detect signals of interest and obtain robust measures of received-signal parameters, such as time differences of signal arrival and directional angles of arrival, that can be used to estimate the location of a cellularized-communications signal source. The new use in the present invention of signal-correlation processing for locating communications transmitters. This enables accurate and efficient extraction of parameters for a particular signal even in a frequency band that contains multiple received transmissions, such as occurs with code-division-multiple-access (CDMA) communications. Correlation processing as disclosed herein further enables extended processing integration times to facilitate the effective detection of desired communications-signal effects and replication measurement of their location-related parameters, even for the communications signals modulated to convey voice conversations or those weakened through propagation effects. Using prior, constructed, signal replicas in the correlation processing enables elimination of the inter-site communications of the signal representations that support the correlation analyses. Reduced-data representations of the modulated signals for voiced conversation, or for the variable components of data communications, are used to significantly reduce the inter-site communications that support the correlation analyses.

Claims

1. A method for locating a standard, mobile-communications, radio transmitter in a cellularized communications system, comprising:

at first, second and third sensor stations, receiving a signal carrying voice/traffic-related data from the mobile radio transmitter;

at the first sensor station, generating replicated signal data and generating a reduced form of the replicated signal data, said replicated signal data comprising voice/traffic-related signal data received at the first sensor station;

communicating the reduced form of the replicated signal data to the second and third sensor stations;

at the second and third sensor stations, reconstructing the replicated signal data from the reduced form of the replicated signal data, whereby voice/traffic-related signal data received at the first sensor station is recovered at the second and third sensor stations, and performing correlation processing with the voice/traffic-related signal data received at the second and third sensor stations and the replicated signal data communicated by the first sensor station to produce location-related signal parameters;

communicating the location-related signal parameters from the second and third sensor stations to a central site; and

estimating the position of the mobile transmitter from the location-related signal parameters.

2. The method of claim 1, further comprising demodulating said signal carrying voice-related data from the mobile radio transmitter at the first sensor station to generate said reduced form of the replicated signal data.

3. The method of claim 2, wherein said signal carrying voice-related data is communicated in at least one of CDMA, TDMA, GSM and CDPD systems.

4. The method of claim 1, the sensor stations having an antenna comprising at least two elements and one of said location-related signal parameters being an angle of arrival determined in accordance with:

$\sin <br><br>\left(\mathrm{AOA}-\mathrm{bisector}\right)\approx <br><br>\frac{1}{\mathrm{kb}}<br><br>\arg <br><br>\left[\frac{1}{S}<br><br>\int <br><br>R_{01}*\left(t_{\max }<br><br>\left(s\right)|s,T\right)<br><br>R_{02}<br><br>\left(t_{\max }<br><br>\left(s\right)|s,T\right)<br><br><br><br>s\right]$

wherein k is the wavenumber of the signal, b is the (baseline) inter-element separation, and the “

arg”

function extracts a phase of the correlation of the correlation coefficients themselves.

5. The method of claim 1, one of said location-related signal parameters being a time difference of arrival between the sensor stations determined in accordance with:

$\mathrm{TDOA}\approx <br><br>t_{\max }|<br><br>R_{12}<br><br>\left(t_{\max }\right)<br><br>=\underset{t}{\max }<br><br><br><br>\frac{1}{T}<br><br>\int <br><br>x_1*\left(s\right)<br><br>x_2<br><br>\left(s+t\right)<br><br><br><br>s<br><br>$

where t_max is the relative time delay (lag) value for which the magnitude of the correlation of the signals achieves a local maximum.

6. A method of locating a standard, mobile-communications, radio transmitter in a cellular communications system, comprising:

receiving a signal from the mobile radio transmitter at first and second sensor stations;

time-tagging an identified, representative instant of the received signal to produce time-tagged received signal data;

generating replicated signal data at the first and second sensor stations;

performing matched-replica correlation processing with the time-tagged received signal data and the replicated signal data to produce location-related signal parameters;

communicating the location-related signal parameters from the first and second sensor stations to a central site;

estimating the position of the mobile transmitter from the location-related signal parameters; and

indicating the estimated position of the mobile transmitter;

wherein the step of generating replicated signal data at the first and second sensor stations further comprises the step of reconstructing the replica of the received signal data derived from a prior known form of the received signal content.

7. A method according to claim 6, wherein the location-related signal parameters comprise angle-of-arrival information.

8. A method according to claim 6, wherein the location-related signal parameters comprise time difference of arrival information.

9. A method according to claim 6, wherein the replicated signal data comprise voice related data.

10. A method according to claim 6, wherein the replicated signal data comprise voice/traffic channel overhead data.

11. A system for locating a mobile radio transmitter, comprising:

at least first and second sensor stations, each sensor station having an antenna for receiving a signal from the mobile radio transmitter and a timing mechanism to time-tag an identified, representative instant of the received signal to produce time-tagged received signal data;

at least first and second signal replica units at the first and second sensor stations, respectively, each signal replica unit providing replicated signal data,

at least first and second signal correlation and measurement extraction processing units at the first and second sensor stations, respectively, each correlation and measurement extraction processing unit performing matched-replica correlation processing with the time tagged received signal data and the replicated signal data to produce location-related signal parameters;

a communications system for communicating the location-related signal parameters from the sensor stations to a central site;

means for estimating the position of the mobile transmitter from the location-related signal parameters; and

an output for indicating the estimated position of the mobile transmitter,

wherein

the signal replica unit at the first and second sensor stations reconstructs the replica of the received signal data using a prior, known form of the received signal content.

12. A system according to claim 11, wherein the location-related signal parameters comprise angle-of-arrival information.

13. A system according to claim 11, wherein the replicated signal data comprise voice related data.

14. A system according to claim 11, wherein the replicated signal data comprise voice/traffic channel overhead data.

15. A system according to claim 11, wherein the location-related signal parameters comprise time-of-arrival information.

16. A system according to claim 11, wherein the location-related signal parameters comprise time-difference-of-arrival parameters.