System and method for tracking vehicles and containers

• US 7,755,541 B2
• Filed: 02/11/2008
• Issued: 07/13/2010
• Est. Priority Date: 02/13/2007
• Status: Active Grant

• Current Assignee: Zebra Technologies Corporation
• Original Assignee: Wherenet Corporation (Zebra Technologies Corporation)
• Inventors: Richardson, Tom, Wohl, Michael A., Romero, Santiago, Boyd, Robert W., Wisherd, David S.
• Primary Examiner(s): Tarcza; Thomas H.
• Assistant Examiner(s): LIU, HARRY K
• Application Number:
  US12/028,894
• Publication Number:
  US 20080191937A1
• Time in Patent Office: 883 Days
• Field of Search: 342/357.03, 455/412.1
• US Class Current: 342/357.24
• CPC Class Codes: G01S 19/073 involving a network of fixed stations
• CPC Class Codes: G01S 19/09 providing processing capability normally carried out by the receiver

Abstract

A location system for tracking assets within a terminal includes a Differential Global Positioning System (DGPS) reference receiver within the terminal that receives GPS signals and generates DGPS correction data. In one aspect, a roving receiver unit is carried by an asset to be tracked within the terminal. It includes a GPS receiver that receives GPS signals and the DGPS correction data from the DGPS reference receiver. A tag transmitter transmits a wireless RF signal containing GPS location data based on received GPS signals and DGPS correction data. At least one access point is positioned within the terminal for receiving the wireless RF signal from the tag transmitter. A processor is operatively connected to the at least one access point for receiving GPS location data and determining a location of the asset to be tracked.

Claims

1. A location system for tracking assets within a terminal, comprising:

a differential global positioning system (DGPS) reference receiver within the terminal that receives GPS signals and generates DGPS correction data;

a roving receiver unit carried by an asset to be tracked within the terminal, and comprising a GPS receiver that receives GPS signals and the DGPS correction data from the DGPS reference receiver and a tag transmitter operative for transmitting a wireless RF signal containing GPS location data based on received GPS signals and DGPS correction data;

at least one access point positioned within the terminal for receiving the wireless RF signal from the tag transmitter; and

a location processor operatively connected to the at least one access point for receiving GPS location data and determining a location of the asset to be tracked.

2. The location system according to claim 1, and further comprising a plurality of spaced apart access points positioned at known locations within the terminal and operative with the roving receiver unit and the location processor as a Real Time Location System (RTLS) for augmenting any positioning determination based on GPS.

3. The location system according to claim 2, wherein said processor is operative for determining which signals are first-to-arrive signals and conducting differentiation of the first-to-arrive signals relative to the access points to locate the tag transmitter.

4. The location system according to claim 1, wherein said RF signal comprises a pseudo random spread spectrum RF signal.

5. The location system according to claim 1, wherein said at least one roving receiver unit, at least one access point and location processor comprise a wireless local area network (WLAN).

6. The location system according to claim 1, wherein said roving receiver unit further comprises a receiver processor for caching GPS data relating to a number of sensed locations and compiling said data into a single data packet for transmission.

7. The location system according to claim 1, wherein said processor is operative for processing real time algorithm output data as differential or kinematic baseline vectors for GPS differential processing.

8. The location system according to claim 7, wherein said processor is operative for processing the algorithm output data within a North-East-Down (NED) system.

9. The location system according to claim 1, wherein said asset to be tracked comprises container handling equipment or a container.

10. The location system according to claim 9, wherein said RF signal is transmitted from the tag transmitter based on an event affecting the location of a container handled by container handling equipment.

11. The location system according to claim 1, wherein said GPS receiver generates GPS data and further comprising a RF transmitter operative for transmitting a wireless RF signal containing GPS data and at least one access point positioned within the terminal for receiving the wireless RF signal from the RF transmitter.

12. A location system for tracking assets within a terminal, comprising:

a differential global positioning system (DGPS) reference receiver within the terminal that receives GPS signals and generates DGPS correction data;

a plurality of assets to be tracked within the terminal, each asset having a roving receiver unit carried by the asset and comprising a GPS receiver that receives GPS signals and the DGPS correction data from the DGPS reference receiver and a tag transmitter operative for transmitting a wireless RF signal containing GPS location data based on received GPS signals and DGPS correction data, wherein said RF signals transmitted from each tag transmitter are transmitted randomly in time;

a plurality of access points positioned at known locations within the terminal for receiving wireless RF signals from the tag transmitters; and

a location processor operatively connected to the plurality of access points for receiving GPS location data and determining a location of the assets to be tracked, wherein said plurality of spaced apart access points are operative with the roving receiver units and the processor as a Real Time Location System (RTLS) and communicate as a wireless local area network (WLAN) for augmenting any positioning determination based on GPS.

13. The location system according to claim 12, wherein said processor is operative for determining which signals are first-to-arrive signals and conducting differentiation of the first-to-arrive signals relative to the access points to locate the tag transmitter.

14. The location system according to claim 12, wherein said RF signal comprises a pseudo random spread spectrum RF signals.

15. The location system according to claim 12, wherein each roving receiver unit further comprises a receiver processor for caching GPS data relating to a number of sensed locations and compiling said data into a single data packet for transmission.

16. The location system according to claim 12, wherein said processor is operative for processing real time algorithm output data as differential or kinematic baseline vectors for GPS differential processing.

17. The location system according to claim 16, wherein said location processor is operative for processing the algorithm output data within a North-East-Down (NED) system.

18. The location system according to claim 12, wherein said assets to be tracked each comprise container handling equipment or a container.

19. The location system according to claim 12, wherein each GPS receiver generates GPS range records and further comprising a RF transceiver operative for transmitting a wireless RF signal containing GPS data and a plurality of access points for receiving the wireless RF signals.

20. A method for tracking assets within a terminal, comprising:

generating differential global positioning system (DGPS) correction data from a reference receiver located within the terminal;

transmitting a wireless RF signal from a tag transmitter containing GPS location data based on GPS signals received within a roving receiver unit carried by an asset to be tracked within the terminal and DGPS correction data received from the DGPS reference receiver;

receiving the wireless RF signal from the tag transmitter within at least one access point positioned within the terminal; and

processing the data received within that at least one access point using a location processor operatively connected to the at least one access point to determine a location of the asset to be tracked.

21. The method according to claim 20, which further comprises augmenting the processing using a Real Time Location System (RTLS).

22. The method according to claim 20, which further comprises determining which signals are first-to-arrive signals and conducting differentiation of the first-to-arrive signals relative to a location of a plurality of access points to locate a tag transmitter.

23. The method according to claim 20, which further comprises caching GPS data relating to a number of sensed locations and compiling said data into a single data packet for transmission.

24. The method according to claim 20, which further comprises processing real time algorithm output data as differential or kinematic baseline vectors for GPS differential processing.

25. The method according to claim 20, which further comprises generating GPS data and transmitting wireless RF signals containing the GPS range records at a plurality of access points.