Method and apparatus for receiving a digital audio broadcasting signal

• US 7,221,688 B2
• Filed: 07/31/2002
• Issued: 05/22/2007
• Est. Priority Date: 07/31/2002
• Status: Active Grant

• Current Assignee: iBiquity Digital Corporation (Xperi Inc.)
• Original Assignee: iBiquity Digital Corporation (Xperi Inc.)
• Inventors: Vanness, Philip H.
• Primary Examiner(s): Pezzlo, John
• Application Number:
  US10/210,143
• Publication Number:
  US 20040022229A1
• Time in Patent Office: 1,756 Days
• Field of Search: 370/529, 370/430, 370/419, 370/463, 370/486, 370/487, 455/266, 455/552, 455/61, 375/216, 375/350, 375/316, 708/316
• US Class Current: 370/529
• CPC Class Codes: H04H 20/30 by a single channel
• CPC Class Codes: H04H 2201/183 FM digital or hybrid
• CPC Class Codes: H04H 2201/20 digital audio broadcasting [DAB]
• CPC Class Codes: H04L 1/0036 arrangements specific to the receiver
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01
• CPC Class Codes: H04L 5/0005 Time-frequency

Abstract

A method for processing a composite digital audio broadcasting signal including an analog modulated portion in a central frequency band and digitally modulated portions in upper and lower sidebands with respect to the central frequency band, the method comprises the steps of wideband filtering the composite digital audio broadcasting signal to produce a first intermediate frequency signal, narrowband filtering the composite digital audio broadcasting signal to produce a second intermediate frequency signal, simultaneously processing the first intermediate frequency signal to retrieve a digitally modulated version of program material from the first intermediate frequency signal, and processing the second intermediate frequency signal to retrieve an analog modulated version of the program material from the second intermediate frequency signal, making a determination of the quality of the digitally modulated version of the program material, and using the quality determination to select the analog modulated version of the program material, the digitally modulated version of the program material, or a combination of the analog modulated version of the program material and the digitally modulated version of the program material as an output signal. Receivers that process a digital audio broadcasting signal using the method are also disclosed.

Claims

1. A method for processing a composite digital audio broadcasting signal including an analog modulated portion in a central frequency band and digitally modulated portions in upper and lower sidebands with respect to the central frequency band, the method comprising the steps of:

wideband filtering the composite digital audio broadcasting signal to produce a first intermediate frequency signal;

narrowband filtering the composite digital audio broadcasting signal to produce a second intermediate frequency signal;

simultaneously processing the first intermediate frequency signal to retrieve a digitally modulated version of program material from the first intermediate frequency signal, and processing the second intermediate frequency signal to retrieve an analog modulated version of the program material from the second intermediate frequency signal;

making a determination of the quality of the digitally modulated version of the program material; and

using the quality determination to select the analog modulated version of the program material, the digitally modulated version of the program material, or a combination of the analog modulated version of the program material and the digitally modulated version of the program material as an output signal.

2. The method of claim 1, wherein the step of wideband filtering the composite digital audio broadcasting signal to produce a first intermediate frequency signal produces a first filtered signal, and wherein the step of narrowband filtering the composite digital audio broadcasting signal to produce a second intermediate frequency signal filters the first filtered signal to produce the second intermediate frequency signal.

3. The method of claim 1, wherein the step of simultaneously processing the first intermediate frequency signal to retrieve a digitally modulated version of the program material from the first intermediate frequency signal, and processing the second intermediate frequency signal to retrieve an analog modulated version of the program material from the second intermediate frequency signal, processes the first and second intermediate frequency signals in independent signal paths.

4. The method of claim 1, wherein the step of making a determination of the quality of the digitally modulated version of the program material comprises the step of:

determining the bit error rate of the digitally modulated version of the program material.

5. The method of claim 1, wherein the step of making a determination of the quality of the digitally modulated version of the program material comprises the step of:

making a channel quality estimate of the digitally modulated portions of the digital audio broadcasting signal.

6. A receiver for processing a composite digital audio broadcasting signal, the receiver comprising:

a first filter for wideband filtering the composite digital audio broadcasting signal to produce a first intermediate frequency signal;

a second filter for narrowband filtering the composite digital audio broadcasting signal to produce a second intermediate frequency signal; and

processing means for retrieving a digitally modulated version of program material from the first intermediate frequency signal, retrieving an analog modulated version of the program material from the second intermediate frequency signal, making a determination of the quality of the digitally modulated version of the program material, and using the quality determination to select the analog modulated version of the program material, the digitally modulated version of the program material, or a combination of the analog modulated version of the program material and the digitally modulated version of the program material as an output signal.

7. A receiver according to claim 6, wherein the first and second filters are electrically connected in series with each other.

8. A receiver according to claim 6, wherein the processing means includes:

a first analog to digital converter for converting the first intermediate frequency signal from the wideband filter into a first digital signal, and a second analog to digital converter for converting the second intermediate frequency signal from the narrowband filter into a sampled audio signal.

9. A receiver according to claim 8, wherein the processing means further includes:

a chip set for processing the first digital signal and for making the determination of the quality of the digitally modulated version of the program material.

10. A receiver according to claim 9, wherein the chip set further includes means for producing a blend control signal.

11. A receiver for processing a composite digital audio broadcasting signal including an analog modulated portion in a central frequency band and digitally modulated portions in upper and lower sidebands with respect to the central frequency band, the receiver comprising:

means for wideband filtering the composite digital audio broadcasting signal to produce a first intermediate frequency signal;

means for narrowband filtering the composite digital audio broadcasting signal to produce a second intermediate frequency signal; and

means for retrieving a digitally modulated version of program material from the first intermediate frequency signal, retrieving an analog modulated version of the program material from the second intermediate frequency signal, making a determination of the quality of the digitally modulated version of the program material, and using the quality determination to select the analog modulated version of the program material, the digitally modulated version of the program material, or a combination of the analog modulated version of the program material and the digitally modulated version of the program material as an output signal.