| 摘要 |
PURPOSE:To transmit the high-quality signal to the receiving side, by providing a small-scale additional circuit to a multiphase/multivalue modulator and as a result pre-compensating the deterioration of properties of the signal which is caused by the nonlinearity at the stage of a base band. CONSTITUTION:The signals of base band 4 series given from input terminals 1-4 are applied to a code converting circuit 5 and a signal detecting circuit 6. Then the signal array receives a code conversion into the signal pulse through the circuit 5. At the same time, the combination of the signals that receive a nonlinear distortion is detected by the circuit 6 to deliver the control signal. The signal pulse train given from the circuit 5 and the control signal from the circuit 6 are applied to pulse amplifiers 7 and 8 respectively. The outputs of the amplifiers 7 and 8 are applied to mixers 10 and 11. The carrier wave produced from an oscillator 12 is branched into two waves. One of these two waves is applied to the mixer 10 via a 90 deg. phase shifter 9, and the other wave is applied directly to the mixer 11. The outputs of both mixers are added together through an adder circuit 13 to deliver the carrier signal to an output terminal 14. Thus the deterioration of the signal properties caused by the nonlinearity is compensated at the stage of a base band. |
