CENTER OF GRAVITY CONTROL FOR HIERARCHICAL QAM TRANSMISSION SYSTEMS

摘要

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.