Method to minimize compatibility error in hierarchical modulation using variable phase

a hierarchical modulation and compatibility error technology, applied in the field of digital data transmission, can solve the problems that the hierarchical modulation scheme has not been envisioned for use in the sdar system, and achieve the effects of increasing the amount of digital data, increasing the amount of data, and enhancing the performance of the receiver

Inactive Publication Date: 2005-05-26
DELPHI TECH INC
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  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

[0007] The present invention provides an apparatus and method for increasing the amount of digital data that may be transmitted from communication satellites to receivers in SDAR systems. In doing so, the present invention provides an advantage over the prior art. While hierarchical modulation schemes have been previously used in other data transmission applications (e.g., Digital Video-Broadcasting—Terrestrial [

Problems solved by technology

While hierarchical modulation schemes have been previously used in other data transmission applications (e.g., Digital Video-Broadcasting—Terrest

Method used

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  • Method to minimize compatibility error in hierarchical modulation using variable phase
  • Method to minimize compatibility error in hierarchical modulation using variable phase
  • Method to minimize compatibility error in hierarchical modulation using variable phase

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Embodiment Construction

[0021] The embodiments disclosed below are not intended to be exhaustive or limit the invention to the precise forms disclosed in the following detailed description. Rather, the embodiments are chosen and described so that others skilled in the art may utilize their teachings.

[0022] For the purposes of the present invention, certain terms shall be interpreted in accordance with the following definitions.

[0023] Baseband: A signal whose frequency content is in the vicinity of direct current (DC).

[0024] Carrier: A single frequency electromagnetic wave the modulations of which are used as communications signals.

[0025] Channel: A propagation medium for communication such as a path along which information in the form of an electrical signal passes (e.g., wire, air, water).

[0026] Data rate: The amount of data, or number of symbols, which may be transmitted on a signal per a unit of time.

[0027] Detector: A circuit that is capable of determining the content of a signal.

[0028] Downconv...

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Abstract

The present invention provides a method, receiver and transmitter for use in a SDAR system. The method involves generating a first modulated signal based on first input data. Additional modulation is superimposed on the first modulated signal based on additional input data, being spread across a plurality of symbols in the first modulated signal in a predetermined pattern to generate a modified signal which is then transmitted. The modified signal is decoded by performing a first demodulation of the first modulated signal then additional demodulation is performed to obtain additional input data. The superimposing step uses a plurality of offset sequence values to add the additional modulation to the first modulated signal. The offset sequence may appear as a pseudo-random distribution of offset sequence values, and may include at least one zero offset value. Alternatively, the additional modulated signal may be a fromed as a direct sequence spread spectrum modulation and the offset sequence appearing as a pseudo-noise distribution. A Hadamard matrix sequence may be used as the direct sequence code.

Description

[0001] This application claims the benefit of U.S. Provisional Patent Application No. 60 / 525,616 filed on Nov. 26, 2003.TECHNICAL BACKGROUND [0002] The present invention generally relates to the transmission of digital data, and more particularly, to the transmission of digital data in a satellite digital audio radio (“SDAR”) system. BACKGROUND OF THE INVENTION [0003] In October of 1997, the Federal Communications Commission (FCC) granted two national satellite radio broadcast licenses. In doing so, the FCC allocated twenty-five (25) megahertz (MHz) of the electromagnetic spectrum for satellite digital broadcasting, twelve and one-half (12.5) MHz of which are owned by XM Satellite Radio, Inc. of Washington, D.C. (XM), and 12.5 MHz of which are owned by Sirius Satellite Radio, Inc. of New York City, N.Y. (Sirius). Both companies provide subscription-based digital audio that is transmitted from communication satellites, and the services provided by these and other SDAR companies are c...

Claims

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Application Information

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IPC IPC(8): H04B7/185H04L27/18H04L27/34
CPCH04B7/18513H04L27/3488H04L27/183
Inventor WALKER, GLENN A.DIBIASO, ERIC A.HIATT, MICHAEL L. JR.
Owner DELPHI TECH INC
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