H - Electricity – 03 – D
Patent
H - Electricity
03
D
H03D 1/02 (2006.01) H03G 3/20 (2006.01) H04L 27/38 (2006.01)
Patent
CA 2061928
In a QAM (quadrature amplitude modulation) demodulator, gain-controlled amplifiers are provided respectively for the in-phase and quadrature channel baseband components of the signal, and a set of data and error signals is recovered from the output of each gain-controlled amplifier. To determine the location of the signal point of each channel component, the QAM signal constellation is divided along the axis of the channel into two outermost regions A, an innermost region B and two intermediate regions C, and further divided along the axis of the channel into two outer regions E and an inner region D therebetween. In response to each set of data and error signals, the location of the signal point of each baseband component is determined with respect to the regions A, B and C to produce a first logical output signal and with respect to the regions D and E to produce a second logical output signal. Each of the gain- controlled amplifiers is controlled in response to the first logical output signal derived from one channel and the second logical output signal derived from the other channel.
Corporation Nec
Smart & Biggar
LandOfFree
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