| 摘要 |
PURPOSE:To acquire the phase error characteristics corresponding to all signal points of at least outermost shell of a multilevel QAM. CONSTITUTION:Each of comparators 14 and 16 outputs a gate control signal '1' when the absolute value of the signals Ia and Qa are larger than or equal to the threshold value th and outputs a gate control signal '0' when those absolute value are smaller than the value th respectively. Then, the gates 8 and 12 receive the control signal '1' and supply the signals double as much as the signals Ib and Qb to the adders 6 and 10 respectively. Thus, the adders 6 and 10 output the signals Ic and Qc triple as much as the signals Ib and Qb respectively. Then, a subtractor 18 outputs the signal obtained by subtracting the signal Qc from the signal Ic as a phase error signal. |
