Robust, Efficient, Localization System

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.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a divisional of U.S. application Ser. No. 10 / 347,471, filed Jan. 17, 2003, now pending, which is a continuation of U.S. application Ser. No. 09 / 240,889, filed Feb. 1, 1999, now U.S. Pat. No. 6,546,256B1, issued Apr. 8, 2003, which is a divisional of U.S. application Ser. No. 08 / 855,589, filed May 13, 1997, now U.S. Pat. No. 6,047,192, issued Apr. 4, 2000, which claims the benefit of U.S. Provisional Application Nos. 60 / 017,269, filed May 13, 1996 and 60 / 035,691, filed Jan. 16, 1997, the contents of all of which are hereby incorporated by reference in their entireties.BACKGROUND OF THE INVENTION[0002]Determining the location of standard, wireless radio frequency (RF), communications transmitter / receivers (“transceivers”) based on their communications offers the potential for emergency response services (fire, rescue and police) to more rapidly respond to calls for help. Public safety and private security can all be aide...

AI Technical Summary

Benefits of technology

[0004]The present invention addresses these issues by providing robust and efficient means to extract parametric measurements from either or both of voice and control communications signals. These measurements can then be used to support the localization processing that is needed to locate wireless communications transceivers. Location data can be used to rapidly rout wireless calls to someone, or some agency, who is in a position to respond to the call.

[0013]The use in the present invention of correlation processing further enables extended processing integration times to facilitate the effective detection of desired communications-signal effects and enhanced measurement of their location-related parameters, even for the communications signals modulated to convey voice conversations or those weakened through propagation effects. When derivable from the received transmissions themselves, such as with sufficiently strong modulated signals representing digital information, or when otherwise available, such as with communications-control or other known-data contents in the received transmissions, the use in the present invention of reconstructed signal replicas in the correlation processing enables elimination of the inter-site communications of the signal representations that support the correlation analyses. The use in the present invention of reduced-data representations of the modulated signals for voiced conversation, or for the variable components of data communications, significantly reduces the inter-site communications that support the correlation analyses. Thus, the present invention significantly enhances the robustness, applicability, and efficiency, and reduces the cost of implementation, of correlation techniques for the detection and measurement of signal parameters to support the localization and tracking of the wireless communications transmitters used in cellularized or geographically subdivided communications systems.

Problems solved by technology

Cellular communications systems typically use control-data messages to “manage” the transmitted power level of a mobile unit to limit its transmitted level to only that needed for successful communications reception within the controlling local “cell.” This power management can limit the reception of the communications transmissions at multiple receiver sites and thus make more difficult the task of determining the transmitter's location.

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