High quality wireless audio speakers

• US 6,466,832 B1
• Filed: 08/24/1998
• Issued: 10/15/2002
• Est. Priority Date: 08/24/1998
• Status: Expired due to Fees

• Current Assignee: Alst Technical Excellecnce Center Corporation
• Original Assignee: Altec Lansing R & D Center Israel
• Inventors: Tirosh, Oren, Rephaeli, Dan, Zuqert, Benjamin, Sussman, Giora
• Primary Examiner(s): Harvey, Minsun Oh
• Application Number:
  US09/138,606
• Time in Patent Office: 1,513 Days
• Field of Search: 370/328, 370/329, 370/330, 370/343, 370/345, 375/219, 375/221, 375/225, 375/227, 375/240, 375/259, 375/267, 455/59, 455/132-135, 381/2, 381/3, 381/14, 700/94
• US Class Current: 700/94
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04R 2420/07 Applications of wireless loudspeakers or wireless microphones
• CPC Class Codes: H04R 3/14 Cross-over networks
• CPC Class Codes: H04R 5/04 Circuit arrangements, e.g. for selective connection of amplifier inputs/outputs to loudspeakers, for loudspeaker detection, or for adaptation of settings to personal preferences or hearing impairments combinations of amplifiers H03F3/68; stereophonic systems H04S

Abstract

A wireless transmission system for transmitting audio data. The system includes a transmitter which re-frames the audio data into a plurality of packets and wirelessly transmits at least two copies of each packet during substantially non-overlapping periods, and one or more receivers which receive the plurality of packets and assess a quality level of at least one of the copies thereof, so as to extract the audio data from one of the copies having a desired quality level. Preferably, the receivers include respective back-transmitters, which transmit control commands back to the transmitter, responsive to the data.

Claims

1. A wireless transmission system for transmitting stereophonic audio data, comprising:

a transmitter which re-frames and compresses the stereophonic audio data into a plurality of packets, in which each stereophonic frame is re-framed as a pair of compressed monaural data frames, and wirelessly transmits at least two copies of each packet during substantially non-overlapping periods; and

one or more receivers which receive the plurality of packets and assess a quality level of at least one of the copies thereof, so as to extract the audio data from one of the copies having a desired quality level.

2. A system according to claim 1, wherein the transmitter compresses the data using a standard compression method.

3. A system according to claim 1, wherein the transmitter re-frames the data by adding a correction code to audio data.

4. A system according to claim 1, wherein each packet comprises audio signals belonging to only one of the pair of mono signals.

5. A system according to claim 1, wherein the transmitter adds a volume level indication to at least some of the packets, so that the audio data has a generally constant magnitude irrespective of the volume level.

6. A system according to claim 1, wherein the transmitter transmits the at least two copies on at least two respective, distinct carrier frequencies.

7. A system according to claim 6, wherein the distinct frequencies are mutually separated by least 10 MHz.

8. A system according to claim 6, wherein re-framing the data comprises adding an indication of the frequency at which the packets are transmitted.

9. A system according to claims 6, wherein a user initiates a change of the frequencies by inputting a user signal to the transmitter.

10. A system according to claim 6, wherein the receivers automatically tune in to the distinct frequencies.

11. A system according to claim 6, wherein the transmitter transmits an indication of the distinct frequencies along with the signals.

12. A system according to claim 6, wherein the frequencies are in the 902-928 MHz band.

13. A system according to claim 1, wherein the plurality of packets are transmitted in a signal having a bandwidth narrower than 1 MHz.

14. A system according to claim 1, wherein the receiver assesses the quality of a second copy of the at least one copies if a first copy of the at least one copies has an undesired quality.

15. A system according to claim 1, wherein each receiver assesses the quality of the at least two copies of the packets and extracts the audio data from the copy which is of better quality.

16. A system according to claim 1, wherein when the quality level of substantially all of the copies of a packet is beneath a predetermined quality threshold, the audio data in the packet is discarded by the receiver.

17. A system according to claim 16, wherein the receiver plays silence instead of the discarded audio data.

18. A system according to claim 16, wherein a copy is beneath the predetermined quality threshold when an error is detected in the copy.

19. A system according to claim 1, wherein the transmitter adds an ID to the packets, and the receivers ignore packets which do not carry the correct ID.

20. A system according to claim 1, wherein the receivers comprise back-transmitters which transmit control commands back to the transmitter.

21. A wireless speaker system for audio data, comprising:

a transmitter which re-frames the audio data in a packet including tuning information and wirelessly transmits the audio data on at least one carrier frequency in accordance with the tuning information; and

at least one speaker, which automatically tunes in to the carrier frequency using the tuning information and plays the audio data.

22. A system according to claim 21, wherein the tuning information comprises an identification of the carrier frequency.

23. A system according to claim 21, wherein the tuning information comprises an identification code of the at least one speaker.

24. A system according to any of claims 21, wherein the tuning information comprises an error detection code.

25. A method of wirelessly transmitting digital stereophonic audio data, comprising:

re-framing and compressing the stereophonic audio data such that each stereophonic frame is re-framed as a pair of compressed monaural data frames;

transmitting at least two copies of the re-framed audio data during substantially non-overlapping periods;

receiving the at least two copies;

assessing a quality level of one or more of the at least two copies; and

extracting the audio data from one of the copies.

26. A method according to claim 25, wherein transmitting the at least two copies comprises transmitting the at least two copies on at least two respective, distinct carrier frequencies.

27. A method according to claim 26, wherein transmitting on the at least two respective, distinct carrier frequencies comprises transmitting on at least two distinct frequencies which are mutually separated by at least 10 MHz.

28. A method according to claim 26, wherein re-framing the data comprises adding an indication of the frequency at which the copies are transmitted.

29. A method according to claim 26, wherein receiving the at least two copies comprises automatically tuning the receivers in to the distinct frequencies.

30. A method according to claim 25, wherein assessing the quality comprises determining an error rate and an AGC level of the received copies.

31. A method according to claim 25, wherein assessing the quality comprises determining whether errors have occurred in the at least two copies, and extracting the data comprises discarding the at least two copies when errors have occurred in substantially all of the at least two copies.

32. A method according to claim 25, wherein re-framing the audio data comprises a volume indication to the re-framed audio data.

33. A method according to claim 25, wherein re-framing, transmitting, receiving, assessing and extracting the audio data introduce a delay of less than 50 msec.

34. A wireless transmission system for transmitting data, comprising:

a transmitter which re-frames the audio data into a plurality of packets and wirelessly transmits the packets; and

one or more receivers which receive the plurality of packets, determine whether the transmitted packets are defective, and convey non-defective packets to be played by a speaker, wherein after receiving a first predefined number of defective packets, the one or more receivers discard a second predefined number of non-defective packets before resuming conveying non-defective packets to the speaker.

35. A system according to claim 34, wherein the transmitter transmits at least two copies of each of the packets, and wherein defective packets comprise packets of which substantially all copies are defective.

36. A system according to claim 34, wherein the first predefined number is between 1 and 3.

37. A system according to claim 34, wherein the second predefined number is between 25 and 32.

38. A system according to claim 34, wherein a third predefined number of packets received after the second predefined number of packets are played at a gradually increasing volume.