| 摘要 |
<p>PURPOSE:To lighten the limit of voltage directly induced to the receiving coil from the transmitting coil to simplify the circuit and make easy the receipt of the response signal from the resonance circuit and obtain the object discrimination device by using the phase equivalent device and the detector. CONSTITUTION:FM signal from the signal generator OSC is amplified 1 and supplied to the transmission coil Ls and when the resonance circuit approaches thereto, it is excited by the electromagnetic induction. The excited current of the resonance circuit further induces voltage to the receiver coil Lr. This induced signal separates the noise by PBF1, and thereafter the amplitude is limited by the limitter LiM2 and inputted to the phase detector PD. The receiver signal inputted into PD is taken out of the radio wave transformer CT. The phase of the signal in a fixed phase relationship with the transmitted signal is standardized the displacement of the phase due to SC, BPF1 or the like is compensated by the phase equivalent device EQ. The output signal of this EQ is inputted to the phase detector PD through the limitter LiM1, hence the receiver signal is phase detected. This signal is amplified 2, driving the relay RY, to obtain the response signal of the resonance circuit.</p> |
