PURPOSE: To set constellation of a QAM modulation system to reduce a data error rate.
CONSTITUTION: A high-order 3-bit signal and a low-order 3-bit signal fed from a serial parallel converter 2 via an arrangement converter 3 are given respectively to nonlinear converters 15, 16, in which the signal is converted into a nonlinear 4-bit signal, D/A converters 4, 5 convert the signal into an analog signal, which is subject to quadrature modulation by multipliers 8, 9. In the constellation of QAM modulation for an obtained quadrature modulating wave depending on a nonlinear input output characteristic of the nonlinear converters 15, 16, 2-bit signals are arranged at positions of in point symmetry with respect to the origin, interval of signals between quadrants is increased and a bit error rate among the signals is decreased.
NODA TSUTOMU
MURATA TOSHINORI
NAKAGAWA HIMIO
