Complex carrier signal generator for determining cyclic wave...

Coded data generation or conversion – Analog to or from digital conversion – Differential encoder and/or decoder

Reexamination Certificate

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Details

C332S101000, C348S724000

Reexamination Certificate

active

06313772

ABSTRACT:

BACKGROUND
1. Field of the Invention
The present invention relates to various approaches for processing an ongoing stream of digital samples which, when employed together, are suitable for use in a vestigial-sideband (VSB) digital modulator that derives a 6 MHz bandwidth input signal selectively centered either at 63 MHz (Channel 3), 69 MHz (Channel 4) or 5.38 MHz IF (baseband) for a television receiver and, more particularly, for a compressed digital television receiver or set top box. Related applications filed concurrently herewith are SIN(X)/X COMPENSATION CIRCUITRY Ser. No. (09/382,235); VSB DIGITAL MODULATOR Ser. No. (09/382,231); and A PULSE CODE MODULATED TO DC CENTERED VSB CONVERTER Ser. No. 09/382,232.
2. Description of the Prior Art
Reference is made to the article “ATSC Re-modulator System” by Hauge et al., IEEE Transactions on Consumer Electronics, Vol. 44, No. 3, August, 1998. This article discloses a VSB digital re-modulator implementation to interconnect between various digital products (e.g., terrestrial digital broadcasting, satellites, digital cable set top boxes, cable modems, DVD, DVCR, PC's, etc.) and digital TV receivers. Such a VSB digital re-modulator is the digital equivalent to current analog re-modulators found in VCR's and video games.
There is a need for a simple inexpensive approach to generating digital representations of a plurality of carrier signals for application to, for example, TV signal remodulators, and which approach is conducive to an integrated-circuit (IC) implementation.
SUMMARY OF THE INVENTION
The present invention is directed to a system and method for generating a carrier signal for application to a digital modulator. An exemplary embodiment of the method includes providing a first repeating sequence of complex values occurring at a given sample rate and upsampling these values to a higher sample rate. A second repeating sequence of complex values is provided, wherein respective complex values in the second repeating sequence occur at the higher sample rate. The second sequence of complex values is employed to modulate the upsampled first sequence of complex values and thereby provide the complex carrier signal.


REFERENCES:
patent: 5021872 (1991-06-01), Shiratsuchi
patent: 5349549 (1994-09-01), Tsutsui
patent: 5694419 (1997-12-01), Lawrence et al.
Corden et al, “Digital Group Demodulation Systems for Multiple QPSK Carriers,” IEEE, 377-381, Sep. 1990.*
Ray Hauge et al.,ATSC VSB Re-Modulator System, IEEE Transactions on Consumer Electronics, vol. 44, No. 3, Aug., 1998, pp. 823-826.

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