Method and apparatus for transmission and reception of compressed audio frames with prioritized messages for digital audio broadcasting

• US 6,721,337 B1
• Filed: 08/24/1999
• Issued: 04/13/2004
• Est. Priority Date: 08/24/1999
• Status: Expired due to Term

• Current Assignee: iBiquity Digital Corporation (Xperi Inc.)
• Original Assignee: iBiquity Digital Corporation (Xperi Inc.)
• Inventors: Kroeger, Brian William, Mattson, Stephen Douglas
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Fox, Jamal A.
• Application Number:
  US09/382,716
• Time in Patent Office: 1,694 Days
• Field of Search: 379/101.01, 375/222, 381/15, 381/2, 381/22, 381/23, 704/229, 714/784, 714/795
• US Class Current: 370/477
• CPC Class Codes: H04H 20/30 by a single channel
• CPC Class Codes: H04H 2201/20 digital audio broadcasting [DAB]

Abstract

A method for transmission of compressed data for a digital audio broadcasting system comprises the steps of producing digital information representative of an audio signal; estimating the number of bits to be allocated to the digital information in a modem frame; encoding the digital information within the estimated number of bits to produce encoded data; removing selected bits from the encoded data; adding bits corresponding to digital messages to the encoded information to form a composite modem frame; formatting the composite modem frame bits to produce formatted composite modem frame bits; and transmitting the formatted composite modem frame bits. The invention also encompasses transmitters that perform the method.

Claims

1. A method for transmission of compressed data for a digital audio broadcasting system comprising the steps of:

receiving digital information representative of an audio signal;

estimating a number of bits to be allocated to said digital information in a modem frame;

encoding said digital information within the estimated number of bits to produce encoded data;

adding bits corresponding to digital messages to said encoded information to form a composite modem frame;

formatting said composite modem frame bits to produce formatted composite modem frame bits; and

transmitting the formatted composite modem frame bits.

2. The method of claim 1, wherein the step of estimating the number of bits to be allocated to encode said digital information in a modem frame, comprises the steps of:

storing said digital information in a buffer; and

estimating the entropy of said digital information.

3. The method of claim 1, further comprising the step of:

removing selected overhead bits from said encoded data.

4. The method of claim 1, wherein the step of adding bits corresponding to digital messages to said encoded information to form a composite modem frame, comprises the steps of:

prioritizing a plurality of said digital messages; and

selecting bits of said digital messages having the highest priority to be added to available bits in said modem frame.

5. The method of claim 1, wherein the step of formatting said composite modem frame bits to produce formatted composite modem frame bits, comprises the step of:

inserting redundant frame overhead data into said composite modem frame.

6. The method of claim 1, further comprising the step of:

multiplexing said digital messages and inserting the multiplexed digital messages into said composite frame data.

7. The method of claim 1, wherein said modem frame includes a fixed number of audio frames, said audio frames having variable lengths.

8. The method of claim 1, wherein the step of encoding said digital information within the estimated number of bits to produce encoded data comprises the step of:

arranging the bits of digital information into a plurality of backup frames and an enhanced audio frame.

9. The method of claim 8, wherein the bits of digital information in said backup frames and said enhanced audio frame are arranged to be subsequently code combined.

29. The method of claim 1, wherein the steps of estimating a number of bits to be allocated to said digital information in a modem frame, encoding said digital information within the estimated number of bits to produce encoded data, and receiving digital messages, adding bits corresponding to digital messages to said encoded information to form a composite modem frame, and formatting said composite modem frame bits to produce formatted composite modem frame bits, are performed by a digital signal processor.

30. The method of claim 29, wherein the digital signal processor is a software programmable digital signal processor.

10. A transmitter for a digital audio broadcasting system comprising:

means for receiving digital information representative of an audio signal;

means for estimating the number of bits to be allocated to said digital information in a modem frame;

means for encoding said digital information within the estimated number of bits to produce encoded data;

means for adding bits corresponding to digital messages to said encoded information to form a composite modem frame;

means for formatting said composite modem frame bits to produce formatted composite modem frame bits; and

means for transmitting the formatted composite modem frame bits.

11. The transmitter of claim 10, wherein the means for estimating the number of bits to be allocated to encode said digital information in a modem frame, comprises:

means for storing said digital information in a buffer; and

means for estimating the entropy of said digital information.

12. The transmitter of claim 10, further comprising:

means for removing selected bits from said encoded data.

13. The transmitter of claim 10, wherein the means for adding bits corresponding to digital messages to said encoded information to form a composite modem frame, comprises:

means for prioritizing a plurality of said digital messages; and

means for selecting bits of said digital messages having the highest priority to be added to available bits in said modem frame.

14. The transmitter of claim 10, wherein the means for formatting said composite modem frame bits to produce formatted composite modem frame bits, comprises:

means for inserting redundant frame overhead data into said composite modem frame.

15. The transmitter of claim 10, further comprising:

means for multiplexing said digital messages and inserting the multiplexed digital messages into said composite frame data.

16. The transmitter of claim 10, wherein said modem frame includes a fixed number of audio frames, said audio frames having variable lengths.

17. The transmitter of claim 10, wherein the means for encoding said digital information within the estimated number of bits to produce encoded data comprises:

means for arranging backup frames of said digital information for transmission within said composite modem frame.

18. The transmitter of claim 17, wherein the bits of digital information in said backup frames and said enhanced audio frame are arranged to be subsequently code combined.

19. A transmitter for a digital audio broadcasting system comprising:

an input for receiving digital information representative of an audio signal;

a processor for estimating the number of bits to be allocated to said digital information in a modem frame, for encoding said digital information within the estimated number of bits to produce encoded data, for adding bits corresponding to digital messages to said encoded information to form a composite modem frame, and for formatting said composite modem frame bits to produce formatted composite modem frame bits; and

an antenna for transmitting the formatted composite modem frame bits.

20. The transmitter of claim 19, wherein the processor estimates the entropy of said digital information.

21. The transmitter of claim 19, wherein the processor removes selected bits from said encoded data.

22. The transmitter of claim 19, wherein the processor prioritizes a plurality of said digital messages and selects bits of said digital messages having the highest priority to be added to available bits in said modem frame.

23. The transmitter of claim 19, wherein the processor inserts redundant frame overhead data into said composite modem frame.

24. The transmitter of claim 19, further comprising:

a multiplexer for multiplexing said digital messages and inserting the multiplexed digital messages into said composite frame data.

25. The transmitter of claim 19, wherein said modem frame includes a fixed number of audio frames, said audio frames having variable lengths.

26. The transmitter of claim 19, wherein the processor arranges backup frames of said digital information for transmission within said composite modem frame.

27. The transmitter of claim 26, wherein the bits of digital information in said backup frames and said enhanced audio frame are arranged to be subsequently code combined.

28. The transmitter of claim 19, wherein the processor is a programmable digital signal processor.

31. A method for transmitting and receiving compressed data for a digital audio broadcasting system comprising the steps of:

receiving digital information representative of an audio signal;

estimating a number of bits to be allocated to said digital information in a modem frame;

encoding said digital information within the estimated number of bits to produce encoded data, and receiving digital messages;

adding bits corresponding to digital messages to said encoded information to form a composite modem frame;

formatting said composite modem frame bits to produce formatted composite modem frame bits;

transmitting the formatted composite modem frame bits;

receiving the modem frame bits; and

producing an output in response to the modem frame bits.

32. The method of claim 31, wherein the step of estimating the number of bits to be allocated to encode said digital information in a modem frame, comprises the step of:

estimating the entropy of said digital information.

33. The method of claim 31, further comprising the step of:

removing selected overhead bits from said encoded data.

34. The method of claim 31, wherein the step of adding bits corresponding to digital messages to said encoded information to form a composite modem frame, comprises the steps of:

prioritizing a plurality of said digital messages; and

selecting bits of said digital messages having the highest priority to be added to available bits in said modem frame.

35. The method of claim 31, wherein the step of formatting said composite modem frame bits to produce formatted composite modem frame bits, comprises the step of:

inserting redundant frame overhead data into said composite modem frame.

36. The method of claim 31, further comprising the step of:

multiplexing said digital messages and inserting the multiplexed digital messages into said composite frame data.

37. The method of claim 31, wherein said modem frame includes a fixed number of audio frames, said audio frames having variable lengths.

38. The method of claim 31, wherein the step of encoding said digital information within the estimated number of bits to produce encoded data comprises the step of:

arranging the bits of digital information into a plurality of backup frames and an enhanced audio frame.

39. The method of claim 38, wherein the bits of digital information in said backup frames and said enhanced audio frame are arranged to be subsequently code combined.