| 摘要 |
PURPOSE:To correct transmission distortion effectively with a simple constitution, by extracting a pilot signal and its higher harmonic in the base band signal of the demodulation output and by performing a required operation processing so that this higher harmonic may be eliminated. CONSTITUTION:The signal from demodulation base band signal input terminal 1 is squared and cubed by multipliers 2 and 3 respectively, and the original signal and signals squared and cubed are applied to adder 17 through phase shifters 4, 5 and 7 and nultipliers 9 and 11, and further, respective outputs squared and cubed are applied to adder 17 through phase shifters 6 and 8, which have difference pi/2 of the phase shift quantity for phase shifters 5 and 7, and multipliers 10 and 12. The output of this adder 17 is used as a distortion correction output, and the pilot signal in the correction output is applied to pilot extracting filter 19 and the second and the third higher harmonic extracting filters 20 and 21 for pilot, and higher- degree higher harmonic components included in the correction signal output corresponding to respective degrees are subjected to phase detection in phase detectors 28-31, and inputs or outputs of multipliers 9-12 are controlled, thus correcting transmission distortion effectively. |
