Multilateration system and method

• US 8,138,967 B2
• Filed: 04/24/2009
• Issued: 03/20/2012
• Est. Priority Date: 04/26/2008
• Status: Expired due to Fees

• Current Assignee: ROKE Manor Research Limited (Chemring Group PLC)
• Original Assignee: ROKE Manor Research Limited (Chemring Group PLC)
• Inventors: Weedon, Robert J.
• Primary Examiner(s): GREGORY, BERNARR E
• Application Number:
  US12/429,564
• Publication Number:
  US 20090303102A1
• Time in Patent Office: 1,061 Days
• Field of Search: 342 29- 51, 342/118, 342/126, 342/175, 342/195, 342450-465, 342/27, 342/28, 342/59, 342/125, 342/123, 342/145, 342385-416, 73/73, 367/118, 375/259
• US Class Current: 342/126
• CPC Class Codes: G01S 13/723 by using numerical data
• CPC Class Codes: G01S 13/781 Secondary Surveillance Radar [SSR] in general

Abstract

A multilateration system and method includes a plurality of receiver stations for receiving signals from an aircraft, and a controller that derives the position of the aircraft by applying a multilateration process to outputs from the receiver stations. For this purpose, the controller determines the altitude of the aircraft and selects a multilateration process that is to be used for position determination, based on the determined altitude.

Claims

1. A multilateration system comprising:

a plurality of receiver stations for receiving a signal from an aircraft; and

a controller that derives the position of the aircraft by applying a multilateration process to outputs of the receiver stations, which outputs indicate receipt of said signal, wherein the controller determines

i) determines an altitude of the aircraft;

ii) chooses a multilateration process based on the determined altitude; and

iii) performs the chosen multilateration process to provide a position of the aircraft.

2. The system as claimed in claim 1, wherein the controller performs the multilateration process using said outputs of the stations and the altitude of the aircraft.

3. The system as claimed in claim 1, wherein:

the controller uses said outputs to create a track for the aircraft; and

said track is stored in a memory.

4. The system as claimed in claim 3, wherein the track comprises at least one of a mode type indicator, a mode code, and a position.

5. Currently Amended) The system as claimed in claim 3, wherein:

the controller comprises a locator having logic for comparing i) a currently determined position provided by the chosen multilateration process with ii) a predicted position extrapolated from a track; and

if comparison is within a certain threshold, the logic concludes that there is a match and updates the track with the currently determined position.

6. The system as claimed in claim 1, wherein:

the controller comprises a locator having control logic for i) determining the number of receiver stations providing usable outputs, ii) determining from the outputs the geometry of the receiver stations making the outputs and whether the geometry will support a three dimensional multilateration, and iii) carrying out such a multilateration; and

in the absence of such a determination the control logic carries out a two dimensional or two dimensional augmented multilateration.

7. An air-traffic control system for monitoring air-traffic, said air-traffic control system comprising:

a multilateration system that includes a plurality of receiver stations for receiving a signal from an aircraft; and

a controller that derives the position of the aircraft by applying a multilateration process to outputs of the receiver stations, which outputs indicate receipt of said signal, wherein the controller i) determines an altitude of the aircraft;

ii) chooses a multilateration process based on the determined altitude; and

iii) performs a chosen multilateration process to provide a position of the aircraft;

means for displaying at least some of track information provided by the chosen multilateration system to a system operator.

8. A multilateration method of determining the position of an aircraft emitting a code, said method comprising:

receiving the code at a plurality of receiver stations; and

deriving a position of the aircraft by applying a multilateration process to outputs of the receiver stations;

wherein said step of deriving a position of the aircraft comprises,

determining an altitude of the aircraft;

choosing a multilateration process based on the determined altitude; and

performing the chosen multilateration process to provide the position of the aircraft.

9. The method as claimed in claim 8, wherein the altitude is a barometric altitude obtained from a received code.

10. A method as claimed in claim 8, wherein said step of choosing a multilateration process comprises comparing the determined altitude with threshold values to determine the multilateration process.

11. A method as claimed in claim 8, wherein data contained in said outputs of said receiver stations are stored as tracks.

12. The method as claimed in claim 11, further comprising:

comparing a current position provided by the chosen multilateration process with extrapolated positions from the tracks to determine a match; and

in the event of a match, updating the track with the current position.

13. The air-traffic control method comprising determining aircraft positions using a method as claimed in claim 8, and displaying the aircraft positions to an operator.