Method and apparatus for source device synchronization in a communication system

• US 20040179510A1
• Filed: 03/11/2003
• Published: 09/16/2004
• Est. Priority Date: 03/11/2003
• Status: Active Grant

• Current Assignee: Motorola Solutions, Inc.
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Gurney, David P., Collins, Timothy, Kuffner, Stephen, Rachwalski, Richard S.
• Granted Patent: US 7,023,817 B2
• Time in Patent Office: Days
• US Class Current: 370/350
• CPC Class Codes: G06K 7/0008 General problems related to the reading of electronic memory record carriers, independent of its reading method, e.g. power transfer
• CPC Class Codes: G06K 7/10039 interrogator driven, i.e. synchronous
• CPC Class Codes: H04J 3/0638 Clock or time synchronisation among nodes; Internode synchronisation synchronization for ring networks H04L12/422; data switching networks with synchronous transmission H04L12/43
• CPC Class Codes: H04W 56/00 Synchronisation arrangements

Abstract

A communications method including the steps of: activating a plurality of signal sources, and transmitting a synchronization event to the plurality of signal sources to cause the plurality of signal sources to simultaneously transmit data in response to the synchronization event.

Claims

1. A communications method comprising the steps of:

activating a plurality of signal sources; and

transmitting a synchronization event to said plurality of signal sources to cause said plurality of signal sources to simultaneously transmit data in response to said synchronization event.

2. The method of claim 1, wherein said synchronizing event is an absence of transmission of a carrier signal for a predetermined duration.

3. The method of claim 2, wherein each signal source in said plurality of signal sources is passively powered.

4. The method of claim 2, wherein said synchronizing event commences and terminates at a predetermined phase of the carrier signal.

5. The method of claim 4, wherein said predetermined phase of the carrier signal is a positive-going zero crossing.

6. The method of claim 1, wherein said plurality of signal sources transmit data in accordance with a multiple pass transmission algorithm having at least one transmission pass.

7. The method of claim 1, wherein said plurality of signal sources transmit data upon detecting that the synchronizing event has completed.

8. The method of claim 1, wherein said synchronization event further causes said plurality of signal sources to change their power-on range.

9. The method of claim 1, wherein said synchronizing event is a presence of a carrier signal for a predetermined duration.

10. The method of claim 9, wherein each signal source in said plurality of signal sources is self-powered.

11. The method of claim 1, wherein the step of transmitting said synchronization event is performed using pulse width modulation.

12. The method of claim 11, wherein said pulse width modulation conveys information in addition to said synchronization event to said plurality of signal sources.

13. The method of claim 1, wherein said plurality of signal sources simultaneously transmit using a symbol clock derived from a carrier signal.

14. The method of claim 1, wherein each signal source in said plurality of signal sources simultaneously transmits using a locally generated symbol clock.

15. The method of claim 14, wherein said locally generated symbol clock commences at a predetermined phase based on said synchronization event.

16. The method of claim 14, wherein said locally generated symbol clock is derived from a carrier signal.

17. A communications system comprising:

a plurality of source devices each adapted for transmitting data; and

at least one destination device adapted for activating said plurality of source devices, and transmitting a synchronization event to said plurality of source devices to cause said plurality of source devices to simultaneously transmit data in response to said synchronization event.

18. The system of claim 17, wherein each said source device in said plurality of source devices is passively powered.

19. The system of claim 17, wherein said plurality of source devices are further adapted for transmitting data in accordance with a multiple pass transmission algorithm having at least one transmission pass.

20. The system of claim 17, wherein said plurality of source devices are further adapted for transmitting data upon detecting that the synchronization event has completed.

21. The system of claim 17, wherein each said source device in said plurality of source devices is self-powered.

22. The system of claim 17, wherein said at least one destination device is further adapted for transmitting said synchronization event using pulse width modulation.

23. The system of claim 17, wherein said plurality of source devices are further adapted for simultaneously transmitting data using a symbol clock derived from a carrier signal.

24. The system of claim 17, wherein said plurality of source devices are further adapted for simultaneously transmitting data using a locally generated symbol clock.

25. The system of claim 24, wherein said locally generated symbol clock commences at a predetermined phase based on said synchronization event.

26. The system of claim 24, wherein said locally generated symbol clock is derived from a carrier signal.