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

• US 7,245,671 B1
• Filed: 02/05/2002
• Issued: 07/17/2007
• Est. Priority Date: 04/27/2001
• Status: Expired due to Term

• Current Assignee: DIRECTV, LLC (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): Ghebretinsae; Temesghen
• Assistant Examiner(s): TORRES, JUAN A
• Application Number:
  US10/068,039
• Time in Patent Office: 1,988 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 comprised of a sum of a first layer signal and a second layer signal, the apparatus comprising:

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

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

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

a modulation map configured to modify the upper layer in-phase signal and the upper layer quadrature signal to account for transmission distortions of the layered modulation signal to produce an ideal upper layer in-phase signal and an ideal upper layer quadrature signal; and

a subtractor configured to subtract the ideal upper layer in-phase signal from the digitized layered in-phase signal to produce the lower layer in-phase signal and to subtract the ideal upper layer quadrature signal from the digitized layered quadrature signal to produce the lower layer quadrature signal;

a digital-to-analog converter 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 single layer signal.

2. The apparatus of claim 1, wherein the processor is adapted to produce the layered in-phase signal and the layered quadrature signal by match filtering the layered in-phase signal and the layered quadrature signal.

3. The apparatus of claim 1, wherein the lower layer signal is a legacy signal.

4. The apparatus of claim 1, wherein the processor is further configured to delay the digitized layered in-phase signal and the digitized layered quadrature signal to synchronize the subtraction of the ideal upper layer in-phase signal from the layered in-phase signal and the subtraction of the ideal upper layer in-phase signal from the layered in-phase signal.

5. The apparatus of claim 4, wherein the processor further comprises:

a first delay element configured to apply a first delay to the digitized layered in-phase signal and the digitized layered quadrature signal;

an amplitude and phase matching coefficient generator, configured to generate amplitude and phase matching coefficients from the digitized and first delayed layered in-phase signal, the digitized and first delayed quadrature signal, the modified upper layer in-phase signal and the modified upper layer quadrature signal;

an amplitude and phase matcher configured to apply the amplitude and phase matching coefficients to the modified upper layer in-phase signal and the modified upper layer quadrature signal to generate the ideal upper layer in-phase signal and the ideal upper layer quadrature signal; and

a second delay element, configured to apply a second delay to the digitized and first delayed layered in-phase signal and the digitized and first delayed layered quadrature signal to produce the delayed digitized layered in-phase signal and the delayed digitized layered quadrature signal.

6. A method of receiving a non-coherent layered modulation signal comprised of a sum of a first layer signal and a second layer signal, the method comprising the steps of:

receiving the layered modulation signal and producing a layered in-phase signal and a layered quadrature signal;

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

decoding the layered in-phase signal and the 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, comprising the steps of;

modifying the upper layer in-phase signal and the upper layer quadrature signal to account for transmission distortions of the layered modulation signal to produce an ideal upper layer in-phase signal and an ideal upper layer quadrature signal;

subtracting the ideal upper layer in-phase signal from the layered in-phase signal to produce the lower layer in-phase signal;

subtracting the ideal upper layer quadrature signal from the 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.

7. The method of claim 6, wherein the step of decoding further comprises delaying the digitized layered in-phase signal and the digitized layered quadrature signal to synchronize the subtraction of the ideal upper layer in-phase signal from the layered in-phase signal and the subtraction of the ideal upper layer in-phase signal from the layered in-phase signal.

8. The method of claim 7, wherein the step of decoding the layered in-phase signal and the layered quadrature signal comprises the steps of:

applying a first delay to the digitized layered in-phase signal and the digitized layered quadrature signal;

generating amplitude and phase matching coefficients from the digitized and first delayed layered in-phase signal, the digitized and first delayed quadrature signal, the modified upper layer in-phase signal and the modified upper layer quadrature signal;

applying the amplitude and phase matching coefficients to the modified upper layer in-phase signal and the modified upper layer quadrature signal to generate the ideal upper layer in-phase signal and the ideal upper layer quadrature signal;

applying a second delay to the digitized and first delayed layered in-phase signal and the digitized and first delayed layered quadrature signal to produce the delayed digitized layered in-phase signal and the delayed digitized layered quadrature signal.

9. The method of claim 6, wherein the lower layer signal is a legacy signal.