| 摘要 |
PURPOSE:To prevent transmission efficiency from deteriorating by detecting the edge of square wave output of a waveform changing circuit, inputting the timing pulse of the edge to an FF circuit, and switching the frequency at the zero cross point nearest from the arrival of a switching signal. CONSTITUTION:When a mark signal M in a switching signal A is given to a switching input terminal 16, an FF10 generates output Q. At that time the operating current runs from a current switching circuit 6 to a resistance 8A side, and a VCO 2 oscillates the frequency f1 determined by a capacitor 4 and resistance 8A and it is converted into square wave B by a waveform changing circuit 14. An edge detecting circuit 20 detects the edge, generates the timing pulse C and adds it to the clock input CK of an FF10. When a space signal S of A is given to a terminal 16, the VCO 2 oscillates frequency f2. And the pulse C corresponding to the f2 is added to the FF10. In this frequency switching operation, the frequency is changed at the timing pulse arrival closest to the point when the switching signal A is changed from M to S, i.e. at the arrival of the closest zero cross point of the waveform oscillated by the VCO 2. |
