Object location

• US 6,587,079 B1
• Filed: 02/11/2002
• Issued: 07/01/2003
• Est. Priority Date: 05/14/1999
• Status: Expired due to Term

• Current Assignee: ROKE Manor Research Limited (Chemring Group PLC)
• Original Assignee: ROKE Manor Research Limited (Chemring Group PLC)
• Inventors: Rickard, David Charles, Horne, James William
• Primary Examiner(s): Phan, Dao
• Application Number:
  US09/979,008
• Time in Patent Office: 505 Days
• Field of Search: 342/357.01, 342/357.06, 342/387, 342/450, 342/457, 342/459
• US Class Current: 342/387
• CPC Class Codes: G01S 5/0081 Transmission between base stations
• CPC Class Codes: G01S 5/14 Determining absolute distances from a plurality of spaced points of known location

Abstract

A system for locating an object that produces identifying signals comprises a plurality of receiver sites arranged in an array for receiving signals from the object and for receiving a common time reference in the form signals received from a global navigation system. The array comprises a reference receiver site and three auxiliary receiver sites that are connected to the reference site by data links. Each receiver site receives signals from the object and timing control signals from a global navigation system. Each site determines a time difference between the receipt of the object signals and the timing signals, the auxiliary sites providing data signals on data links to the reference site where the location of the object is determined.

Claims

1. A method of locating the position of an object which provides identifying signals, using a receiver array comprising a reference receiver site and at least three auxiliary receiver sites which are not on a line of sight with the reference receiver site, the method comprising the steps of:

receiving the identifying signals from the object at each receiver site;

receiving global navigation system signals from a global navigation system at each receiver site, and each receiver site using the received global navigation system signals for providing timing signals;

providing a clock at each receiver site for providing clock signals;

combining the timing signals with the clock signals to provide a timing reference signal at each receiver site;

determining a time difference between receiving the identifying signals and the timing reference signal at each receiver site;

transmitting data signals to the reference receiver site which are indicative of the determined time differences at each auxiliary receiver site; and

calculating the position of the object using the transmitted data signals and a time difference determined at the reference receiver site.

2. Apparatus for locating an object producing identifying signals, the apparatus comprising:

a receiver array comprising a reference receiver site and at least three auxiliary receiver sites which are not on a line of sight with the reference receiver site;

a first receiver means at each receiver site for receiving the identifying signals from the object;

a second receiver means at each receiver site for receiving timing signals from a global navigation system;

clock means at each receiver site for generating clock signals;

combining means at each receiver site for combining the timing signals and clock signals to provide a timing reference signal;

processing means at each receiver site for receiving signals from the first receiver means and the combining means and for providing a time difference measurement from the received signals; and

control means at the reference receiver site for receiving data signals from the auxiliary receiver sites indicative of the time difference measurement signals determined thereat, and for processing the data signals together with a time difference measurement from the reference receiver site, to provide a determination of the location of the object.

3. Apparatus according to claim 2, wherein the identifying signals from the object comprise secondary surveillance radar signals and the first receiver means comprises a secondary surveillance radar receiver.

4. Apparatus according to claim 2, wherein the clock means comprises a high precision clock oscillator.

5. Apparatus according to claim 2, wherein the processing means comprises, a time interval counter and a measurement control system.

6. Apparatus according to claim 2, wherein the processing means includes a communications interface for interfacing between each auxiliary receiver site and the reference receiver site.