| 摘要 |
PURPOSE:To send a high quality microwave signal by equalizing a nonlinear distortion caused by temperature change, secular change and replacement of components automatically so as to correct the nonlinear distortion. CONSTITUTION:An inputted intermediate frequency IF signal receives linearity by a resonance circuit a discriminating circuit 5 applies FM detection with the best linearity and the result is inputted to an amplifier 6 and a hybrid circuit 7. One signal from the circuit 7 is outputted from an output terminal 8 and the other signal is inputted to a band pass filter 9. A noise produced by nonlinear distortion from a transmission line is extracted by the filter 9 and its level is detected by a level detector 10, where the signal is converted into a DC voltage and amplified by a DC amplifier 11 and then fed to a varactor diode 13. In changing the resonance frequency by the detected voltage, the frequency response is changed to a curve having a prescribed linearity. The polarity of the DC amplifier 11 is matched to decrease the detected voltage to change the linearity of the demodulator thereby correcting the nonlinearity.
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