Apparatus and method to synchronize multimedia playback over a network using out-of-band signaling

• US 7,206,367 B1
• Filed: 07/10/2001
• Issued: 04/17/2007
• Est. Priority Date: 07/10/2001
• Status: Expired due to Fees

• Current Assignee: Apple Inc.
• Original Assignee: SigmaTel Incorporated (NXP Semiconductors NV)
• Inventors: Moore, Daniel L
• Primary Examiner(s): Bayard; Emmanuel
• Assistant Examiner(s): WILLIAMS, LAWRENCE B
• Application Number:
  US09/903,040
• Time in Patent Office: 2,107 Days
• Field of Search: 375/354, 375/356, 375/366, 370/538, 709/249, 709/250, 713/500, 713/501, 713/502, 348/515
• US Class Current: 375/354
• CPC Class Codes: H04J 3/0658 Clock or time synchronisation among packet nodes
• CPC Class Codes: H04L 12/66 Arrangements for connecting between networks having differing types of switching systems, e.g. gateways
• CPC Class Codes: H04L 65/1101 Session protocols
• CPC Class Codes: H04L 65/612 for unicast
• CPC Class Codes: H04L 65/80 Responding to QoS
• CPC Class Codes: H04L 7/0008 Synchronisation information channels, e.g. clock distribution lines
• CPC Class Codes: H04L 7/08 the synchronisation signals recurring cyclically

Abstract

An apparatus and method to synchronize devices in a network to a sub-millisecond timing accuracy. In a first embodiment, the transmission of data is synchronized between a first source device and destination devices communicatively coupled to a network. In a second embodiment, data is deterministically transmitted between a first source device and destination devices communicatively coupled to a network. In a third embodiment, a deterministic network synchronizes the transmission of data between a first source device and destination devices coupled to a network.

Claims

1. A method to synchronize transmission of data, said method comprising:

receiving a plurality of data into a buffer at a destination device, wherein the plurality of data is transmitted by a first source device via a first network;

receiving a plurality of synchronization pulses at said destination device, wherein the plurality of synchronization pulse is transmitted by a second source device via a second network; and

receiving a sequence number at said destination device to determine when said destination device will access said plurality of data from said buffer.

2. The method of claim 1, further comprising extracting the sequence number from said plurality of synchronization pulses received by said destination device to determine when and in which order said destination device will access said plurality of data from said buffer.

3. The method of claim 1, wherein the first network is a power line network and the second network is a data network.

4. The method of claim 1, wherein said first source device and said second source device are the same device.

5. The method of claim 1, wherein said plurality of synchronization pulses adjusts a clock signal used by said destination device.

6. The method of claim 5, wherein said plurality of synchronization pulses adjusts a phase-locked-loop (PLL) in said destination device.

7. The method of claim 1, wherein said plurality of synchronization pulses is transmitted to said destination device by a transmission media selected from a group consisting of:

a pair of wires, a double pair of wires, a coaxial cable, radio transmission, infrared transmission, one optical fiber, and two optical fibers.

8. The method of claim 1, wherein said plurality of synchronization pulses and said plurality of data are transmitted using one modulation method.

9. The method of claim 8, wherein said plurality of synchronization pulses and said plurality of data are transmitted using orthogonal differential frequency (ODFM) modulation.

10. The method of claim 8, wherein said plurality of synchronization pulses and said plurality of data are transmitted using a modulation method selected from a group of modulation methods consisting of:

QAM, CODFM, DFM, PSK, BPSK, or QPSK.

11. The method of claim 1, wherein said plurality of synchronization pulses is transmitted with a different modulation from a modulation used to transmit said plurality of data.

12. The method of claim 1, wherein said plurality of synchronization pulses is transmitted without modulation.

13. The method of claim 1, wherein said plurality of data has an embedded sequence number.

14. The method of claim 1, further comprising receiving said plurality of synchronization pulses by a global positioning satellite (GPS) receiver in said destination device.

15. The method of claim 1, wherein said plurality of data includes audio data, video data, multimedia data, or a combination thereof.

48. The method of claim 1, wherein the first network is a wireless network and the second network is a power line network.

49. The method of claim 1, wherein said first source device and said second source device are physically separate devices.

50. The method of claim 3, wherein the data network is a wireless network.

16. A method to transmit data, said method comprising:

transmitting a plurality of data from a first source device into a buffer at a destination device via a first network;

wherein the destination device receives a plurality of synchronization pulses from a second source device via a second network;

wherein said plurality of synchronization pulses adjusts a local clock in said destination device; and

wherein the destination device extracts a sequence number from said plurality of synchronization pulses to determine when and in which order to access said plurality of data from said buffer.

17. The method of claim 16, wherein the first network is a power line network and the second network is a wireless network.

18. The method of claim 16, wherein said first source device and said second source device are the same device.

19. The method of claim 16, wherein said plurality of synchronization pulses and said plurality of data are transmitted using one modulation method.

20. The method of claim 16, wherein said plurality of synchronization pulses is transmitted with a different modulation from a modulation used to trait said plurality of data.

21. The method of claim 16, wherein said plurality of synchronization pulses is transmitted without modulation.

22. The method of claim 16, wherein said plurality of data has an embedded sequence number, which said destination device can extract to determine when to access said plurality of data from said buffer.

51. The method of claim 16, wherein the first network is a wireless network and the second network is a power line network.

23. A data system, comprising:

a destination device having a buffer and a controller, wherein the destination device receives a plurality of data from a first source device to be stored in the buffer and receives a plurality of synchronization pulses from a second source device that is physically separate from the first source device;

wherein the controller is configured to calculate a sequence number to determine when the controller accesses the plurality of data from the buffer;

wherein the destination device is configured to receive the plurality of data from the first source device via a first transmission medium of a first network; and

wherein the destination device is configured to receive the synchronization pulses from the second source device via a second transmission medium of a second network.

24. The system of claim 23, wherein said destination device determines said sequence number from said plurality of synchronization pulses.

25. The system of claim 23, wherein said first transmission medium and said second transmission medium are the same transmission medium.

26. The system of claim 23, wherein said first source device and said destination device are connected in a network by a power line.

27. The system of claim 23, wherein said first source device and said second source device are the same device.

28. The system of claim 23, wherein said plurality of synchronization pulses adjusts a clock signal used by said destination device.

29. The system of claim 28, wherein said plurality of synchronization pulses adjusts a phase-locked-loop (PLL) in said destination device.

30. The system of claim 23, wherein said plurality of synchronization pulses is transmitted to said destination device by a transmission media selected from a group consisting of:

a pair of wires, a double pair of wires, a coaxial cable, radio transmission, infrared transmission, one optical fiber, and two optical fibers.

31. The system of claim 23, wherein said plurality of synchronization pulses and said plurality of data are transmitted using the same modulation method.

32. The system of claim 31, wherein said plurality of synchronization pulses and said plurality of multimedia data are transmitted using orthogonal differential frequency (ODFM) modulation.

33. The system of claim 31, wherein said plurality of synchronization pulses and said plurality of multimedia data are transmitted using a modulation method selected from a group of modulation methods consisting of:

QAM, CODFM, DFM, PSK, BPSK, or QPSK.

34. The system of claim 23, wherein said plurality of synchronization pulses is transmitted with a different modulation from a modulation used to transmit said plurality of data.

35. The system of claim 23, wherein said plurality of synchronization pulses is transmitted without modulation.

36. The system of claim 23, wherein said plurality of data has an embedded sequence number.

37. The system of claim 23, wherein said destination device comprises a global positioning satellite (GPS) receiver receiving said plurality of synchronization pulses.

38. The system of claim 23, further comprising an error detection circuit in said destination device.

39. The system of claim 23, wherein said plurality of data includes audio data.

40. The system of claim 23, wherein said plurality of data includes video data.

41. The system of claim 23, wherein said first source device comprises a first audio controller and said second source device comprise a second audio controller, and said destination device comprises one or more speakers.

42. The system of claim 23, wherein said destination device further includes one or more demodulators demodulating said plurality of data and said plurality of synchronization pulses.

43. The system of claim 23, wherein said destination device further includes a detector extracting said sequence number from said plurality of synchronization pulses.

44. A computer-implemented method for synchronizing transmission of data, the method comprising:

receiving a plurality of data transmitted from a source device via a first network;

subsequently receiving a plurality of synchronization pulses transmitted from said source via a second network;

adjusting a clock local to each of one or more destination devices in response to said plurality of synchronization pulses;

extracting a sequence number from said plurality of synchronization pulses; and

invoking each of said one or more destination devices to access said plurality of data according to said sequence number.

45. A computer program product for synchronizing transmission of data, wherein said computer program product is stored on a computer readable medium and adapted to perform operations of:

receiving a plurality of data transmitted from a source device via a first network;

subsequently receiving a plurality of synchronization pulses transmitted from said source device via a second network;

adjusting a clock local to each of one or more destination devices in response to said plurality of synchronization pulses;

extracting a sequence number from said plurality of synchronization pulses; and

invoking each of said one or more destination devices to access said plurality of data according to said sequence number.

46. The computer program product of claim 45, wherein at least one of said one or more destination devices comprises a phase-locked-loop (PLL) and said plurality of synchronization pulses adjusts said PLL.

47. The computer program product of claim 45, wherein said plurality of data is selected from a group consisting of audio data, visual data, multimedia data, or a combination thereof.