| 摘要 |
PURPOSE:To eliminate the nonlinear distortion of a digital modulation input by controlling a nonlinear correcting circuit by providing a phase rotation detector and an amplitude error detector. CONSTITUTION:The output of a nonlinear correcting circuit 1 is supplied to a phase rotation detector 2 and an amplitude error detector 3. Then, both the detectors 2 and 3 detect a phase rotation and amplitude variation due to nonlinear distortion from a difference between an input and an output signal to and from a discriminator 20 which estimates a transmitted code. The output of the detector 2 is supplied as a control signal to the variable attenuator 12 of the correcting circuit 1 via a polarity inverting circuit 24 and an integrator 25. The detection output of the detector 3, on the other hand, is supplied to the phase shifter 11 of the correcting circuit 1 via an LPF33 to exercise phase control. Thus, the nonlinear distortion of a digital modulation input is eliminated. |
