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1. (WO2001039453) CENTER OF GRAVITY CONTROL FOR HIERARCHICAL QAM TRANSMISSION SYSTEMS

Pub. No.:    WO/2001/039453    International Application No.:    PCT/US2000/032008
Publication Date: Fri Jun 01 01:59:59 CEST 2001 International Filing Date: Thu Nov 23 00:59:59 CET 2000
IPC: H04L 25/06
H04L 27/34
H04L 27/38
Applicants: THOMSON LICENSING S.A.
SETTLE, Timothy, Forrest
KRAUSS, Thomas, Peter
RAMASWAMY, Kumar
Inventors: SETTLE, Timothy, Forrest
KRAUSS, Thomas, Peter
RAMASWAMY, Kumar
Title: CENTER OF GRAVITY CONTROL FOR HIERARCHICAL QAM TRANSMISSION SYSTEMS
Abstract:
A QAM receiver calculates the location of the center-of-gravity of successive received data points in a quadrant. A level 1 decoder detects the quadrant in the I-Q plane of a received data point. Further circuitry translates the received data point in the I-Q plane such that the center-of-gravity of the detected quadrant is translated to the origin of the I-A plane. A level 2 decoder is then responsive to the translated data point for detecting the quadrant of the translated data point. A hierarchical QAM system allows the transmission of different sources by embedding the relative constellation points. In the hierarchical QAM receiver, a calculating circuitry determines the center of gravity of successive received data points in a quadrant. The displacement of the center of gravity is used in the decoding process when determining the single data streams pertaining to the different sources.