Determination of State Vector, Timing, and Navigation Quality Metrics from Reception of ADS-B Transmissions

• US 20140302775A1
• Filed: 06/20/2014
• Published: 10/09/2014
• Est. Priority Date: 04/15/2011
• Status: Active Grant

• Current Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Original Assignee: Exelis Incorporated (L3Harris Technologies, Inc.)
• Inventors: Garcia, Michael A., Mueller, Robert, Lambert, John W., Dolan, John M.
• Granted Patent: US 9,255,804 B2
• Time in Patent Office: Days
• US Class Current: 455/3.06
• CPC Class Codes: G01C 21/20 Instruments for performing navigational calculations G01C21/24, G01C21/26 take precedence
• CPC Class Codes: G01S 13/781 Secondary Surveillance Radar [SSR] in general
• CPC Class Codes: G01S 5/10 Position of receiver fixed by co-ordinating a plurality of position lines defined by path-difference measurements , e.g. omega or decca systemsG01S5/12 takes precedence ; beacons and receivers cooperating therewith G01S1/306, G01S1/308
• CPC Class Codes: H04H 20/55 for traffic information
• CPC Class Codes: H04H 20/57 for mobile receivers
• CPC Class Codes: H04H 40/27 specially adapted for broadcast systems covered by groups H04H20/53 - H04H20/95

Abstract

A technique for determining the position of a mobile device includes receiving messages from respective mobile reference devices. Each of the messages is broadcast beginning at one of several predetermined message start opportunity (MSO) times that have known timings relative to a reference time. Each of the messages contains a MSO value identifying the MSO time at which transmission of the message started. The MSO value is used to determine the time of transmission of each of the messages received at the mobile device, and the position of the mobile device is determined via multi-lateration. According to another approach, the mobile device receives a set of ADS-B messages from a respective set of mobile reference devices. The time of transmission of each of the ADS-B messages is supplied in the ADS-B message itself or in a subsequent message and used to determine the position of the mobile device.

Claims

1. A method of synchronizing a local clock with the timing of a mobile reference device, the method comprising:

receiving, from the mobile reference device, an Automatic Dependent Surveillance-Broadcast (ADS-B) message at an ADS-B receiver co-located with the local clock;

determining a time of reception of the ADS-B message received at the ADS-B receiver;

determining a time of transmission of the ADS-B message from information contained in the ADS-B message or information contained in a subsequent message; and

synchronizing the local clock with the timing of the mobile reference device based on the time of transmission and time of reception of the ADS-B message.

2. The method claim 1, wherein the ADS-B message is received from an airborne aircraft.

3. The method of claim 1, wherein the ADS-B message is broadcast beginning at one of a plurality of ADS-B message start opportunity (MSO) times having known timings relative to a reference time, wherein the ADS-B message is an ADS-B message containing an MSO value indicating the MSO time at which transmission of the message started, and wherein the time of transmission of the ADS-B message is determined from the MSO value.

4. The method of claim 3, wherein the time of transmission is determined relative to a Coordinated Universal Time (UTC) epoch.

5. The method of claim 1, wherein the ADS-B message is transmitted under the 1090ES protocol.

6. The method of claim 1, wherein the time of transmission of the ADS-B message is received in the subsequent message, wherein the subsequent message comprises an aircraft ID &

category (ACID) message reconfigured to contain the time of transmission of the ADS-B message.

7. The method of claim 1, wherein the time of transmission of the ADS-B message received at the ADS-B receiver is randomized.

8. An apparatus, comprising:

a receiver co-located with a local clock and configured to receive an Automatic Dependent Surveillance-Broadcast (ADS-B) message from a mobile reference device; and

a processor configured to;

determine a time of transmission of the ADS-B message from information contained in the ADS-B message or information contained in a subsequent message; and

synchronize the local clock with a timing of the mobile reference device based on the time of transmission and a time of reception of the ADS-B message.

9. The apparatus of claim 8, wherein the receiver is configured to receive the ADS-B message from an airborne aircraft.

10. The apparatus of claim 8, wherein the ADS-B message is broadcast beginning at one of a plurality of ADS-B message start opportunity (MSO) times having known timings relative to a reference time, wherein the ADS-B message is an ADS-B message containing an MSO value indicating the MSO time at which transmission of the message started, and wherein the processor is configured to determine the time of transmission of the ADS-B message from the MSO value.

11. The apparatus of claim 10, wherein the processor is configured to determine the time of transmission relative to a Coordinated Universal Time (UTC) epoch.

12. The apparatus of claim 8, wherein the receiver is configured to receive the ADS-B message transmitted under the 1090ES protocol.

13. The apparatus of claim 8, wherein the receiver is configure to receive the time of transmission of the ADS-B message in the subsequent message, wherein the subsequent message comprises an aircraft ID &

category (ACID) message reconfigured to contain the time of transmission of the ADS-B message.

14. The apparatus of claim 8, wherein the receiver is configured to receive ADS-B messages whose time of transmission has been randomized.

15. One or more non-transitory computer readable storage media encoded with software comprising computer executable instructions and, when the software is executed, operable to:

determine a time of transmission of an Automatic Dependent Surveillance-Broadcast (ADS-B) message received from a mobile reference device based on information contained in the ADS-B message or information contained in a subsequent message; and

synchronize a local clock with a timing of the mobile reference device based on the time of transmission and a time of reception of the ADS-B message.

16. The computer readable storage media of claim 15, wherein the ADS-B message is received from an airborne aircraft.

17. The computer readable storage media of claim 15, wherein:

the ADS-B message is broadcast beginning at one of a plurality of ADS-B message start opportunity (MSO) times having known timings relative to a reference time;

wherein the ADS-B message is an ADS-B message containing an MSO value indicating the MSO time at which transmission of the message started; and

the instructions that are operable to determine the time of transmission comprise instructions that are operable to determine the time of transmission of the ADS-B message from the MSO value.

18. The computer readable storage media of claim 17, wherein the instructions that are operable to determine the time of transmission comprise instructions that are operable to determine the time of transmission relative to a Coordinated Universal Time (UTC) epoch.

19. The computer readable storage media of claim 15, wherein the ADS-B message is transmitted under the 1090ES protocol.

20. The computer readable storage media of claim 15, wherein the time of transmission of the ADS-B message is received in the subsequent message, wherein the subsequent message comprises an aircraft ID &

category (ACID) message reconfigured to contain the time of transmission of the ADS-B message.