Method and apparatus for time synchronizing an in-vehicle network

• US 20040213295A1
• Filed: 04/28/2003
• Published: 10/28/2004
• Est. Priority Date: 04/28/2003
• Status: Active Grant

• Current Assignee: Continental Automotive Systems, Inc. (Continental AG)
• Original Assignee: Temic Automotive of North America, Incorporated (Continental AG)
• Inventors: Fehr, Walton L.
• Granted Patent: US 7,310,327 B2
• Time in Patent Office: Days
• US Class Current: 370/503
• CPC Class Codes: H04W 4/04 using association of physical positions and logical data in a dedicated environment, e.g. buildings or vehicles
• CPC Class Codes: H04W 4/48 for in-vehicle communication

Abstract

An independent, broadcast medium (32) is used to communicate an time reference to each element: switch element (36), active element (14-20) or passive element, of an in-vehicle network (30). Each element (36) in the network accepts the time information, i.e., a time reference from the source. The time reference is then used by each element (36) to adjust an internal clock of the element. Commands may then be sent to the elements to occur at a particular time.

Claims

1. A vehicle network comprising:

a plurality of network elements joined by communication links for the transmission of data there between;

each network element of the vehicle network including a local clock, a processor, and a memory, the memory adapted to store and retain an updatable time reference;

a receiver disposed within each network element, the receiver being adapted to receive a time reference signal from a time source within the vehicle and external to the node carried by a medium independent of the communication links and to communicate the absolute time reference signal to the processor; and

the processor being operable upon receipt of the absolute time reference signal to update the absolute time reference stored within the memory.

2. The vehicle network of claim 1, wherein each network element is coupled to a power distribution feed, and wherein the time reference is substantially simultaneously communicated via the power distribution feed to each network element.

3. The vehicle network of claim 2, wherein the time reference comprises an alteration of a characteristic of the power delivered via the power distribution feed.

4. The vehicle network of claim 1, wherein the medium comprises one of radio frequency, optical, and haptic transmission.

5. The vehicle network of claim 1, wherein the external time source comprises a Global Positioning System (GPS) receiver coupled to the node for receiving a GPS time reference signal.

6. The in-vehicle network of claim 1, wherein the external time source comprises a WWV time reference signal receiver coupled to the node for receiving a WWV time reference signal.

7. The in-vehicle network of claim 1, wherein the external time source comprises a cellular telephone receiver for receiving a time reference signal from a cellular telephone base station.

8. The in-vehicle network of claim 1, wherein the network comprises a switch fabric.

9. A vehicle network comprising:

a plurality of network elements joined by communication links for the transmission there between of data packets;

each network element of the in-vehicle network including a local clock, a processor and a memory, the memory adapted to store and retain an updatable absolute time reference;

a receiver coupled to the network at one of the network elements, the receiver being adapted to receive an absolute time reference signal from an time reference source external to the vehicle and to communicate the absolute time reference signal to the processor of the coupled network element;

the processor being operable upon receipt of the absolute time reference signal to update the absolute time reference stored within the memory of the network element and to communicate a time reference signal to each of the remaining network elements of the network; and

the processors of the remaining network elements of the network being operable upon receipt of the absolute time reference signal to update the absolute time reference stored within the memory of the network element.

10. The vehicle network of claim 9, wherein each network element is coupled to a power distribution feed, and wherein the absolute time reference is substantially simultaneously communicated via the power distribution feed to each network element.

11. The vehicle network of claim 9, wherein the absolute time reference comprises an alteration of a characteristic of the power delivered via the power distribution feed.

12. The in-vehicle network of claim 9, wherein the receiver comprises a Global Positioning System (GPS) receiver for receiving a GPS time reference signal, the absolute time reference signal being based upon the GPS time reference signal.

13. The in-vehicle network of claim 9, wherein the receiver comprises a WWV receiver for receiving a WWV time reference signal, the absolute time reference signal being based upon the WWV time reference signal.

14. The in-vehicle network of claim 9, wherein the receiver comprises a cellular telephone receiver for receiving a cellular telephone base station time reference signal, the absolute time reference signal being based upon the cellular telephone base station time reference signal.

15. The in-vehicle network of claim 9, wherein the network comprises a switch fabric.

16. In an in-vehicle network having a plurality of network elements joined by communication links for the transmission of data packets there between, a method of time synchronizing the network elements comprising the steps of:

receiving a time signal from a time signal source external to the network;

determining a time reference from the time signal; and

updating a time reference stored in each of the network elements based upon the absolute time reference.

17. The method of claim 16, wherein the step of receiving a time signal from a time signal source comprises receiving at each network element a time signal from a time signal source.

18. The method of claim 16, wherein the step of receiving a time signal from a time signal source comprises receiving via a power distribution feed at each network element a time signal from a time signal source.

19. The method of claim 16, wherein the step of receiving a time signal from a time signal source comprises receiving at a network element of the plurality of network elements an time signal from a time signal source;

and wherein the step of updating a time reference stored in each of the network elements based upon the time signal comprises communicating the time reference to the plurality of network elements.

20. The method of claim 19, wherein the step of receiving a time signal comprises receiving an absolute time signal.

21. The method of claim 19, wherein the step of receiving a time signal comprises a receiving a time signal from a source external to the vehicle.

22. The method of claim 16, wherein the step of receiving a time signal from a time signal source comprises receiving at least one of a global positioning system (GPS) time signal, a WWV time signal and a cellular base station time signal.