| 摘要 |
PURPOSE:To eliminate a maloperations and the troublesomeness of manual operations by using a detector for the level of an input wave, an indicating part which indicates the output of the detector via a level converter and a discriminator which discriminates whether the input wave is equal to a multi- value QAM wave or a carrier wave and short-circuits the level converter in the case of the multi-value QAM wave. CONSTITUTION:The wave detectors 11 and 12 fetch the envelope curve component (amplitude component) of a part of the fetched output wave of a a primary intermediate frequency amplifier 5. A capacitor 13 prevents the DC component of the output wave and applies this wave to a rectifier 14 and a capacitor 15 for the acquisition of the variance of the amplitude. Then a certain amount of DC voltage and the DC voltage of OV are obtained when the input wave of a terminal IN is equal to a multi-value GAM wave and a carrier wave respectively. Here the voltage is applied to a comparator 16 and a relay 17 works only with the multi-value QAM wave. Then a level converter 8 is short-circuited at the contact r1 of the relay 17. While the relay 17 is hardly actuated with the carrier wave. Thus the converter 8 is put into a meter 10. |
