Multilateration System and Method

• US 20090303102A1
• Filed: 04/24/2009
• Published: 12/10/2009
• Est. Priority Date: 04/26/2008
• Status: Active Grant

• Current Assignee: ROKE Manor Research Limited (Chemring Group PLC)
• Original Assignee: ROKE Manor Research Limited (Chemring Group PLC)
• Inventors: WEEDON, Robert J.
• Granted Patent: US 8,138,967 B2
• Time in Patent Office: Days
• US Class Current: 342/38
• CPC Class Codes: G01S 13/723 by using numerical data
• CPC Class Codes: G01S 13/781 Secondary Surveillance Radar [SSR] in general

Abstract

In the described system the multilateration process to be applied to determine an aircraft'"'"'s position is chosen on the basis of the available returns, receiver geometry and the height of the aircraft.

Claims

1. A multilateration system comprising a plurality of receiver stations for receiving signals from aircraft and a controller to apply a multilateration process to outputs of the receiver stations, which outputs indicating receipt of the signal, to derive a position of the aircraft characterized in that the controller determines the number of active receiver stations receiving the code, determines the type of code and performs a multilateration process in accordance with the determination to provide a position of the aircraft.

2. A system as claimed in claim 1 wherein the controller performs a multilateration process using outputs of the receivers and the height of the aircraft.

3. A system as claimed in claim 1 wherein the multilateration process applied is chosen with reference to a determined height for the aircraft.

4. A system as claimed in claim 1 wherein the outputs are used to create a track for the aircraft held in memory.

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

6. A system as claimed in claim 1 comprising control logic for determining the number of receivers providing usable returns, determining from the returns the geometry of the receivers making the returns and whether the geometry will support a three dimensional multilateration and instructing such a multilateration to be carried out, and in the absence of such a determination instructing a two dimensional or two dimensional augmented multilateration to be carried out.

7. A system as claimed in claim 4, comprising logic for comparing a currently determined position provided by the multilateration process carried out with a predicted position extrapolated from a track and in the event of the comparison being within a certain threshold concluding that there is a match and updating the track with the currently determined position.

8. An air-traffic control system for monitoring air-traffic comprising a multilateration system as claimed in claim 1 and means to display at least some of the track information provided by the multilateration system to an operator.

12. A method as claimed in claim 1 wherein the height is compared with threshold values to determine the multilateration process to be used.

13. A method as claimed in claim 1 wherein the data is stored as a track.

14. A method as claimed in claim 13 wherein a current position provided by the used multilateration process is compared with extrapolated positions from the tracks to determine a match and in the event of a match updating the track with the current position.

15. An air-traffic control method comprising determining aircraft positions using a method as claimed in claim 1 and displaying the aircraft positions to an operator.

9. A multilateration method of determining the position of an aircraft emitting a code which method comprising:

receiving the code at a plurality of receivers;

determining time of arrival data for arrival of the code at the receivers; and

applying one of a three, a two dimensional or a two dimensional, assisted by height data, multilateration process.

10. A method as claimed in claim 9 wherein the choice of multilateration process is also dependent upon a value for the height of the aircraft.

11. A method as claimed in claim 10 wherein the height is a barometric height obtained from a received code.

16. (canceled)