Method and system for synchronizing a quadrature amplitude...

Details Method and system for synchronizing a quadrature amplitude... Method and system for synchronizing a quadrature amplitude...

2002-05-01

2004-04-27

Callahan, Timothy P. (Department: 2816)

Modulators

Phase shift keying modulator or quadrature amplitude modulator

C329S307000, C375S261000, C375S264000, C375S287000

Reexamination Certificate

active

06727772

ABSTRACT:

BACKGROUND OF THE INVENTION
QAM modulators and demodulators are well known and may be used as part of numerous communication applications and links, for example telephone and cable modems. Telephone and cable modems are usually connected to a telephone line or a coaxial cable either through a telephone jack connector or a coaxial connector, respectively. In general, a QAM modulator may convert a set of bits into a symbol which may be represented by a point on a complex plane. Each symbol and its associated point may be identified either by its i and q coordinates (using a rectangular coordinate system) or by its angle and magnitude (using a rotational coordinate system). The set of all points on a complex plane associated with a QAM modulator's full set of symbols may be referred to as a constellation or “known” constellation.
FIG. 2A
shows a “known” constellation associated with a QAM 25 modulator, having 25 symbols, and thus having 25 points on a complex plane.


REFERENCES:
patent: 5544328 (1996-08-01), Seshadri
patent: 5793818 (1998-08-01), Claydon et al.
patent: 5838734 (1998-11-01), Wright
patent: 6005897 (1999-12-01), McCallister et al.
patent: 6268767 (2001-07-01), Maalej et al.
patent: 6282168 (2001-08-01), Vijayan et al.

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