Method and apparatus for locating a wireless device

• US 7,050,786 B2
• Filed: 10/30/2003
• Issued: 05/23/2006
• Est. Priority Date: 10/30/2002
• Status: Active Grant

• Current Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Original Assignee: Lockheed Martin Corporation (Martin Marietta Corporation)
• Inventors: Caci, J. Claude
• Primary Examiner(s): Trost, William
• Assistant Examiner(s): Ewart, James D
• Application Number:
  US10/695,894
• Publication Number:
  US 20040087316A1
• Time in Patent Office: 936 Days
• Field of Search: 455/414.2, 455/440, 4554561-4566, 455/457, 455/521, 455/404.1, 455/404.2, 342/357.01, 342/357.02, 342450-452, 342/457, 342/458, 701/214, 340/993, 340/995.19, 340/995.25
• US Class Current: 455/404.2
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01S 2205/06 Emergency
• CPC Class Codes: G01S 5/02 using radio waves using satellite radio beacon systems for determining position G01S19/00
• CPC Class Codes: G01S 5/02213 Receivers arranged in a network for determining the position of a transmitter
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

Disclosed is a method and apparatus for locating a wireless device especially useful for locating a cellular telephone making a call from an unknown location. The call may be a request for emergency assistance, or for location-based commercial services, for example. Various embodiments may optionally include a mobile location component, a cellular telephone enabled to chirp-on-demand, and/or an interferometer link. A mobile location component may include a directional antenna. The directional antenna may be mounted on an antenna boom on top of an emergency vehicle, for example. The mobile location component may alternately or additionally comprise a hand-held unit. System elements may cooperate to generate a situation awareness map or other display. The mobile location component may be moved in the general direction of a first location calculation associated with a first circular error of probability. After being moved in the general direction, the mobile location component may cooperate with other elements to determine a second location calculation associated with a second circular error of probability. Second and subsequent location calculations are of increasing precision, enabling an emergency vehicle or attendant to zero in on a cellular telephone.

Claims

1. A wireless radio communications system that includes at least one communications tower and a mobile unit, the system comprising:

a mobile unit configured to emit signals representing a plurality of three-digit codes, a first one of the plurality indicating a request for emergency services and a second one of the plurality indicating a request for location-based non-emergency commercial services;

a communications tower receiver associated with a communications tower, the communications tower receiver configured to receive the signals and decode the plurality of three-digit codes, including both the first one indicating a request for emergency services and the second one indicating a request for location-based non-emergency commercial services, the communications tower receiver further configured to perform a location measurement responsive to receipt of any one of the first and second codes, the location measurement including issuing a wireless chirp-on-demand command to the mobile unit, the wireless chirp-on-demand command instructing the mobile unit to transmit a chirp signal;

a location receiver operatively connected to the at least one communication tower configured to receive the chirp signal from the mobile unit and determine a location calculation of the mobile unit, the system taking different action with said determined location calculation depending on which one of the first and second codes was transmitted from the mobile unit.

2. A wireless radio communications system that includes at least one communications tower and a mobile unit, the system comprising:

a mobile unit configured to emit signals representing a plurality of codes, a first one of the plurality indicating a request for emergency services and a second one of the plurality indicating a request for location-based non-emergency commercial services;

a communications tower receiver associated with a communications tower, the communications tower receiver configured to receive the signals and decode the plurality of codes, including both the first one indicating a request for emergency services and the second one indicating a request for location-based non-emergency commercial services, the communications tower receiver further configured to perform a location measurement responsive to receipt of one of the first and second codes, the location measurement including issuing a wireless chirp-on-demand command to the mobile unit, the wireless chirp-on-demand command instructing the mobile unit to transmit a chirp signal comprising a pattern of frequency, amplitude, and timing;

a location receiver operatively connected to the at least one communication tower configured to receive the chirp signal from the mobile unit and decode the signal according to its pattern of frequency, amplitude, and timing for determining a location calculation of the mobile unit.

3. A method comprising the steps of:

receiving at a single communications tower a wireless signal from a cellular telephone, the signal representing a dialed three-digit code;

decoding at the communications tower the three-digit code;

determining at the single communications tower that the decoded three-digit code represents a request for location-based non-emergency services;

in response to said receiving, sending to the cellular telephone a chirp-on-demand signal causing the cellular telephone to emit a chirp signal;

receiving the emitted chirp signal at the single communications tower from the cellular telephone;

performing an approximate location calculation based solely on signals received wirelessly at the single communications tower; and

wirelessly providing location-based non-emergency information services to the cellular telephone based on the approximate location calculation.