Preprocessing signal layers in a layered modulation digital signal system to use legacy receivers

• US 7,426,243 B2
• Filed: 01/02/2007
• Issued: 09/16/2008
• Est. Priority Date: 04/27/2001
• Status: Expired due to Fees

• Current Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Original Assignee: The DIRECTV Group, Inc. (AT&T, Inc.)
• Inventors: Santoru, Joseph, Chen, Ernest C., Hilmes, Philip R., Furuya, Tiffany S.
• Primary Examiner(s): Ghayour; Mohammad
• Assistant Examiner(s): Torres; Juan A.
• Application Number:
  US11/619,173
• Publication Number:
  US 20070147547A1
• Time in Patent Office: 623 Days
• Field of Search: 375/316, 375/320, 375/343, 375/261, 375/235, 375/298, 375/349, 375/308, 375/377, 375/279, 375/281, 342/152, 332/103, 329/304, 329/308, 370/206, 455/17
• US Class Current: 375/316
• CPC Class Codes: H04L 27/3488 Multiresolution systems

Abstract

Systems and methods for receiving non-coherent layered modulation signals are presented. An exemplary apparatus comprises a tuner for receiving a layered signal and producing a layered in-phase signal and a layered quadrature signal therefrom, an analog-to-digital converter for digitizing the layered in-phase signal and the layered quadrature signal, a processor for decoding the layered in-phase signal and the layered quadrature signal to produce a single layer in-phase signal and a single layer quadrature signal, a digital-to-analog encoder for converting the single layer in-phase signal and the single layer quadrature signal to a single layer in-phase analog signal and a single layer quadrature analog signal and a modulator for modulating the single layer in-phase analog signal and the single layer quadrature analog signal to produce a single layer signal.

Claims

1. An apparatus for receiving a non-coherent layered modulation signal comprising the sum of a first layer signal and a second layer signal, comprising:

a tuner for receiving the non-coherent layered signal and producing a layered in-phase signal and a layered quadrature signal therefrom;

an analog-to-digital converter for digitizing the layered in-phase signal and the layered quadrature signal;

a digital processor for processing the digitized layered in-phase signal and the digitized layered quadrature signal to produce a lower layer in-phase signal, a lower layer quadrature signal, an upper layer in-phase signal and an upper layer quadrature signal, the processor comprising a subtractor configured to subtract an ideal upper layer in-phase signal from the digitized layered in-phase signal to produce the lower layer in-phase signal and to subtract an ideal upper layer quadrature signal from the digitized layered quadrature signal to produce the lower layer quadrature signal;

a digital-to-analog encoder for converting the lower layer in-phase signal and the lower layer quadrature signal to a lower layer in-phase analog signal and a lower layer quadrature analog signal; and

a modulator for modulating the lower layer in-phase analog signal and the lower layer quadrature analog signal to produce a lower layer signal.

2. The apparatus of claim 1, wherein the non-coherent layered signal is compatible with a legacy receiver such that at least one signal layer is decodeable directly from the layered signal with the legacy receiver.

3. The apparatus of claim 1, wherein the processor comprises a logic circuit.

4. The apparatus of claim 1, wherein processing by the processor comprises match filtering the digitized layered in-phase signal and the digitized layered quadrature signal.

5. The apparatus of claim 1, wherein the digitized layered in-phase signal and the digitized layered quadrature signal are delayed to synchronize the subtraction.

6. The apparatus of claim 1, wherein the processor applies a signal map to the ideal upper layer in-phase signal and the ideal upper layer quadrature signal, the signal map accounting for transmission distortions of the non-coherent layered signal.

7. The apparatus of claim 1, wherein the processor amplitude and phase matches the ideal upper layer in-phase signal and the ideal upper layer quadrature signal with the digitized layered in-phase signal and the digitized layered quadrature signal, respectively.

8. A digital processor for decoding a non-coherent layered signal to produce a single layer signal, comprising:

a demodulator and decoder for decoding an upper layer signal from the non-coherent

layered signal;

an encoder for generating an ideal upper layer signal from the decoded upper layer signal;

a signal processor for modifying the ideal upper layer signal to characterize transmission and processing effects; and

a subtractor for subtracting the modified ideal upper layer signal from the layered signal to produce the single layer signal.

9. The digital processor of claim 8, further comprising a delay function correlated to an output of the signal processor to appropriately delay the layered signal to synchronize amplitude and phase matching of the modified ideal upper layer signal and the layered signal.

10. The digital processor of claim 8, further comprising a delay function correlated to an output of the signal processor to appropriately delay the layered signal to synchronize subtraction of the modified ideal upper layer signal and the layered signal.

11. The digital processor of claim 8, wherein the signal processor amplitude and phase matches the ideal upper layer signal with the layered signal.

12. The digital processor of claim 9, wherein the signal processor applies a signal map to the ideal upper layer signal.

13. The digital processor of claim 9, wherein the signal processor performs finite impulse response matched filtering on the ideal upper layer signal.

14. A method of receiving a non-coherent layered modulation signal, comprising the steps of:

receiving the non-coherent layered signal and producing a layered in-phase signal and a layered quadrature signal therefrom;

digitizing the layered in-phase signal and the layered quadrature signal;

processing the digitized layered in-phase signal and the digitized layered quadrature signal to produce a lower layer in-phase signal, a lower layer quadrature signal, an upper layer in-phase signal, and an upper layer quadrature signal;

subtracting an ideal upper layer in-phase signal from the digitized layered in-phase signal to produce the lower layer in-phase signal and subtracting an ideal upper layer quadrature signal from the digitized layered quadrature signal to produce the lower layer quadrature signal;

converting the lower layer in-phase signal and the lower layer quadrature signal to a lower layer in-phase analog signal and a lower layer quadrature analog signal; and

modulating the lower layer in-phase analog signal and the lower layer quadrature analog signal to produce a single layer signal.

15. The method of claim 14, wherein the non-coherent layered signal is compatible with a legacy receiver such that at least one signal layer is decodeable directly from the layered signal with the legacy receiver.

16. The method of claim 14, wherein the lower layer signal from the modulator is decodeable with a legacy receiver.

17. The method of claim 14, wherein the steps of processing and subtracting are performed by a logic circuit.

18. The method of claim 14, wherein the step of processing comprises match filtering the digitized layered in-phase signal and the digitized layered quadrature signal.

19. The method of claim 15, wherein the step of processing further comprises delaying the digitized layered in-phase signal and the digitized layered quadrature signal to synchronize the subtraction.

20. The method of claim 15, further comprising the step of applying a signal map to the ideal upper layer in-phase signal and the ideal upper layer quadrature signal, the signal map accounting for transmission distortions of the non-coherent layered signal.

21. The method of claim 15, further comprising the step of amplitude and phase matching the ideal upper layer in-phase signal and the ideal upper layer quadrature signal with the digitized layered in-phase signal and the digitized layered quadrature signal, respectively.