High quality, low power, wireless audio system

• US 7,542,784 B2
• Filed: 02/25/2005
• Issued: 06/02/2009
• Est. Priority Date: 02/25/2005
• Status: Active Grant

• Current Assignee: Smsc Holdings Sarl (Microchip Technology Incorporated)
• Original Assignee: Kleer Semiconductor Corporation
• Inventors: Mason, Ralph, Allen, Brent, Passier, Chris
• Primary Examiner(s): Corsaro; Nick
• Assistant Examiner(s): BROOKS, SHANNON
• Application Number:
  US11/065,995
• Publication Number:
  US 20060193273A1
• Time in Patent Office: 1,558 Days
• Field of Search: 455/41.1, 455/41.2, 455/41.3, 455/575.2, 455/556.1, 455/557, 381/2, 381/11, 381/311, 381/334, 381/77, 381/74, 709/94
• US Class Current: 455/557
• CPC Class Codes: G08C 17/02 using a radio link
• CPC Class Codes: G08C 23/04 using light waves, e.g. infrared
• CPC Class Codes: H04L 1/0007 by modifying the frame length
• CPC Class Codes: H04L 1/1607 Details of the supervisory signal
• CPC Class Codes: H04N 21/41265 having a remote control device for bidirectional communication between the remote control device and client device unidirectional remote control device H04N21/42204
• CPC Class Codes: H04N 21/43637 involving a wireless protocol, e.g. Bluetooth, RF or wireless LAN [IEEE 802.11] arrangements for wireless networking or broadcasting of information in indoor or near-field type systems H04B10/114
• CPC Class Codes: H04N 21/8106 involving special audio data, e.g. different tracks for different languages

Abstract

The invention relates to the field of wireless communications and more specifically to an high quality, low power wireless audio system. More specifically, the invention comprises an audio source for receiving audio signals (e.g. music) and audio status information (e.g. song title) from a first external device (e.g. an MP3 player) and transmitting the audio signals and the audio status information over a wireless connection; and at least one audio sink for receiving the audio signals and said audio status information from the audio source and communicating the audio signals and the audio status information to a second external device (e.g. headphones), wherein a specified one of the at least one audio sink receives audio control information (e.g. pause) from the second external device and transmits said audio control information to said audio source via said wireless connection. Among other features, the wireless audio system of the present invention incorporates dynamic channel selection as well as dynamic adjustment of the transmission interval to ensure enhanced audio quality using the lowest possible power.

Claims

1. A wireless audio system comprising:

an audio source for receiving audio signals and audio status information from a first external device and transmitting said audio signals and said audio status information over a wireless connection; and

at least one audio sink for receiving said audio signals and said audio status information from said audio source and communicating said audio signals and said audio status information to a second external device, wherein a specified one of said at least one audio sink receives audio control information from said second external device and transmits said audio control information to said audio source via said wireless connection,

wherein said wireless connection uses a specified one of a plurality of available channels, and wherein said audio source comprises;

a source packet formatter and buffer communicating with said first external devices, wherein said source packet formatter creates a plurality of source transmit packets containing said audio signals and said audio status information, and wherein said source buffer stores said plurality of source transmit packets prior to transmission to said audio sink;

a source transmitter communicating with said source packet formatter and buffer for receiving said plurality of source transmit packets from said source buffer and transmitting said plurality of source transmit packets to said audio sink every defined unit of time;

a source audio synchronizer communicating with said source transmitter for defining said unit of time for said source transmitter;

a source receiver for receiving said audio control information from said audio sink, wherein said audio control information is in the form of a plurality of sink transmit packets, and wherein said source receiver communicates with said source transmitter to coordinate said receiving and transmitting within respective ones of said defined units of time;

a source packet de-formatter communicating with said source receiver for receiving said plurality of sink transmit packets and extracting said audio control information; and

a source channel quality monitor communicating with said source packet de-formatter and source transmitter for monitoring said specified in use one of said plurality of available channels.

2. The wireless audio system of claim 1 wherein said audio signals are taken from the group comprising digital and analog.

3. The wireless audio system of claim 2 wherein said first external device is taken from the group comprising compact disc (CD) player, MP3 player and mini-disk player.

4. The wireless audio system of claim 2 wherein the second external device is taken from the group comprising headphones and a remote control.

5. The wireless audio system of claim 1 wherein said audio status information is taken from the group comprising song title, song artist and song number.

6. The wireless audio system of claim 1 wherein said audio control information comprises a command taken from the group comprising play, stop, rewind, fast forward, skip and pause.

7. The wireless audio system of claim 1 wherein said wireless connection is a radio frequency connection.

8. The wireless audio system of claim 1 wherein said wireless connection is an infra-red connection.

9. The wireless audio system of claim 7 wherein said radio frequency connection is a time division duplex radio frequency connection.

10. The wireless audio system of claim 9 wherein said audio sink comprises:

a sink receiver for receiving said plurality of source transmit packets from said audio source every defined unit of time;

a sink packet de-formatter and buffer communicating with said sink receiver, wherein said sink packet de-formatter extracts said audio signals and said audio status information from said source transmit packets, and wherein said sink buffer stores said extracted audio signals and said audio status information;

a sink audio synchronizer communicating with said sink receiver for defining said unit of time for said sink receiver;

a sink packet formatter communicating with said second external device for creating said plurality of sink transmit packets containing said audio control information;

a sink transmitter communicating with said sink packet formatter for transmitting said plurality of sink transmit packets, wherein said sink receiver communicates with said sink transmitter to coordinate said receiving and transmitting within specified ones of said defined units of time; and

a sink channel quality monitor communicating with said sink packet de-formatter and buffer and said sink receiver for monitoring said specified in use one of said plurality of available channels.

11. The wireless audio system of claim 10 wherein, if an analog audio signal is delivered from said first external device said wireless audio system further comprises an analogue-to-digital converter (ADC) communicating with said first external device, and wherein a source audio sampling clock signal generated by said source audio synchronizer is fed to said ADC.

12. The wireless audio system of claim 11 wherein, if an analog audio signal is required by said second external device, said wireless audio system further comprises a digital-to-analogue converter (DAC), and wherein a sink audio sampling clock signal generated by said sink audio synchronizer is fed to said DAC.

13. The wireless audio system of claim 12 further comprising a compression module communicating with said ADC for compressing digital audio signals outputted by said ADC.

14. The wireless audio system of claim 13 further comprising a decompression module communicating with said sink packet de-formatter and buffer for decompressing said digital audio signals received from said sink buffer.

15. The wireless audio system of claim 10 wherein said defined unit of time is a transport super frame interval (TSF_Interval).

16. The wireless audio system of claim 15 wherein specified ones of said plurality of source and sink transmit packets are contained within a specified TSF_Interval, and wherein said TSF_Interval further comprises and idle period.

17. The wireless audio system of claim 10 wherein a specified one of said plurality of sink transmit packets also comprises an acknowledgement that a specified one of said plurality of source transmit packets has been received by said source receiver, and wherein said acknowledgement comprises a data sequence number (DSN), and wherein said DSN is contained in an overhead portion associated with said specified one of said plurality of sink transmit packets.

18. The wireless audio system of claim 17 wherein said source packet formatter and buffer sends a next one of said plurality of source transmit packets when a sequential DSN number has been received by said source receiver.

19. The wireless audio system of claim 18 wherein, if a specified one of said plurality of source transmit packets is not received by said sink receiver, said specified one of said plurality of source transmit packets is retransmitted upon receipt of a non-sequential DSN by said source receiver.

20. The wireless audio system of claim 15 wherein said TSF_Interval is 4 m/sec, and wherein said plurality of source and sink transmit packets are received at a bit rate of 2.4 Mb/s, and wherein said audio sampling clock signal is 44.1 KHz.

21. The wireless audio system of claim 15 wherein, upon receiving an indication at said source channel quality monitor that said specified in use one of said plurality of available channels is deteriorating, said source audio synchronizer is instructed by said source channel quality monitor to shorten said TSF_Interval and wherein said shortened TSF_Interval is communicated to said audio sink in an overhead portion associated with a specified one of said plurality of source transmit packets.

22. The wireless audio system of claim 12 wherein a frequency reference synchronous to said source audio sampling clock signal is contained within a specified one of said plurality of source transmit packets, and wherein, upon receipt of said specified one of said plurality of source transmit packets by said sink receiver, said frequency reference is forwarded to said sink audio synchronizer to generate said sink audio sampling clock signal.

23. The wireless audio system of claim 14 wherein said compression module associated with said audio source and said decompression module associated with said sink are lossy compression modules.

24. The wireless audio system of claim 14 wherein said compression module associated with said audio source and said decompression module associated with said sink are lossless compression modules.

25. The wireless audio system of claim 21 wherein said source channel quality monitor maintains a preferred channel sequence (PCS) comprising a list of said plurality of available channels, and wherein, if a quality measurement associated with said specified in use one of said plurality of available channels falls below a pre-defined threshold, then said source channel quality monitor switches to a subsequent channel in said PCS.

26. The wireless audio system of claim 25 wherein said quality measurement is a pre-defined signal energy level associated with said specified in use one of said plurality of available channels.

27. The wireless audio system of claim 25 wherein said quality measurement is a pre-defined level associated with said source buffer.

28. The wireless audio system of claim 25 wherein a specified one of said plurality of sink transmit packets also comprises an acknowledgement that a specified one of said plurality of source transmit packets has been received by said source receiver, and wherein said quality measurement is a pre-defined number of missed ones of said acknowledgements.

29. The wireless audio system of claim 25 wherein, prior to establishing a wireless connection from said audio source to said audio sink, said source channel quality monitor scans said PCS and determines a preferred one of said plurality of available channels.

30. The wireless audio system of claim 25 wherein, once a wireless connection from said audio source to said audio sink is established, said audio source periodically re-scans said list of said plurality of available channels to determine if an updated list is required.

31. The wireless audio system of claim 25 wherein said quality measurement is a combination of a pre-defined signal energy level associated with said specified in use one of said plurality of available channels, and a pre-defined level associated with said source buffer.

32. The wireless audio system of claim 31 wherein, if said pre-defined signal energy level is high and said pre-defined source buffer level is deteriorating, then said TSF_Interval is shortened, and wherein if said specified in use one of said plurality of available channels continues to deteriorate said subsequent channel in said PCS is selected.

33. The wireless audio system of claim 10 wherein, if a quality measurement associated with said specified in use one of said plurality of available channels is above a pre-defined threshold, a power output associated with said source transmitter is reduced.

34. In a wireless audio system, an audio source comprising:

a source packet formatter and buffer communicating with a first external device, wherein said source packet formatter creates a plurality of source transmit packets containing audio signals and audio status information, and wherein said source buffer stores said plurality of source transmit packets prior to transmission to an audio sink;

a source transmitter communicating with said source packet formatter and buffer for receiving said plurality of source transmit packets from said source buffer and transmitting said plurality of source transmit packets to said audio sink every defined unit of time;

a source audio synchronizer communicating with said source transmitter for defining said unit of time for said source transmitter;

a source receiver for receiving audio control information from said audio sink, wherein said audio control information is in the form of a plurality of sink transmit packets, and wherein said source receiver communicates with said source transmitter to coordinate said receiving and transmitting within respective ones of said defined units of time;

a source packet de-formatter communicating with said source receiver for receiving said plurality of sink transmit packets and extracting said audio control information; and

a source channel quality monitor communicating with said source packet de-formatter and source transmitter for monitoring a specified one of a plurality of available channels.

36. The wireless audio system of claim 34 wherein said first external device is taken from the group comprising compact disc (CD) player, MP3 player and mini-disk player.

38. The wireless audio system of claim 36 wherein, if an analog audio signal is delivered from said first external device said wireless audio system further comprises an analogue-to-digital converter (ADC) communicating with said first external device, and wherein a source audio sampling clock signal generated by said source audio synchronizer is fed to said ADC.

40. The wireless audio system of claim 38 further comprising a compression module communicating with said ADC for compressing digital audio signals outputted by said ADC.

35. In a wireless audio system, an audio sink comprising:

a sink receiver for receiving a plurality of source transmit packets from an audio source every defined unit of time, wherein said plurality of source transmit packets comprise audio signals and audio status information;

a sink packet de-formatter and buffer communicating with said sink receiver, wherein said sink packet de-formatter extracts said audio signals and said audio status information from said source transmit packets, and wherein said sink buffer stores said extracted audio signals and said audio status information;

a sink audio synchronizer communicating with said sink receiver for defining said unit of time for said sink receiver;

a sink packet formatter communicating with a second external device for creating a plurality of sink transmit packets containing audio control information;

a sink transmitter communicating with said sink packet formatter for transmitting said plurality of sink transmit packets, wherein said sink receiver communicates with said sink transmitter to coordinate said receiving and transmitting within specified ones of said defined units of time; and

a sink channel quality monitor communicating with said sink packet de-formatter and buffer and said sink receiver for monitoring a specified one of a plurality of available channels.

37. The wireless audio system of claim 35 wherein the second external device is taken from the group comprising headphones and a remote control.

39. The wireless audio system of claim 37 wherein, if an analog audio signal is required by said second external device, said wireless audio system further comprises a digital-to-analogue converter (DAC), and wherein a sink audio sampling clock signal generated by said sink audio synchronizer is fed to said DAC.

41. The wireless audio system of claim 39 further comprising a decompression module communicating with said sink packet de-formatter and buffer for decompressing said digital audio signals received from said sink buffer.

42. A bi-directional wireless audio system comprising:

a packet formatter and buffer communicating with an external device, wherein said source packet formatter creates a plurality of transmit packets containing transmit audio signals and audio status information, and wherein said buffer stores said plurality of source transmit packets prior to transmission;

a transmitter communicating with said packet formatter and buffer for receiving said plurality of transmit packets from said buffer and transmitting said plurality of transmit packets every defined unit of time;

an audio synchronizer communicating with said transmitter for defining said unit of time for said transmitter;

a receiver for receiving receive audio signals and audio status information, wherein said receive audio signals and audio status information are in the form of a plurality of receive packets, and wherein said receiver communicates with said transmitter to coordinate said receiving and transmitting within respective ones of said defined units of time;

a packet de-formatter and buffer communicating with said receiver and said external device for receiving said plurality of receive packets and extracting said receive audio signals and audio status information; and

a channel quality monitor communicating with said packet de-formatter and buffer and said transmitter, for monitoring a specified one of a plurality of available channels,

wherein, if an analog audio signal is delivered from said external device, said bi-directional wireless audio system further comprises an analogue-to-digital converter (ADC) communicating with said external device, and wherein an audio sampling clock signal generated by said audio synchronizer is fed to said ADC,

and wherein, if an analog audio signal is required by said external device, said wireless audio system further comprises a digital-to-analogue converter (DAC) communicating with said packet de-formatter and buffer, and wherein said audio sampling clock signal is fed to said DAC.

43. The bi-directional wireless audio system of claim 42 wherein said external device is a cellular phone.

44. The bi-directional wireless audio system of claim 42 wherein said external device is a wireless headset.