| 摘要 |
PURPOSE:To detect the position of a moving body continuously at a period P by laying a folded conductor of the period P and a straight conductor along the travelling course of the moving body, mounting two groups of three antennas on the moving body at an interval of P/3 and using inductive radio. CONSTITUTION:An inductive radio line 22 consisting of the folded conductor of the period P and the straight conductor 21 is laid along the travelling course of the moving body and high frequency current is supplied from a transmitter 24 to both the conductors. The three antennas 23-1a-23-3a having the interval of P/3 and the three antennas 23-1b-23-3b having the interval of P/3 and separated from the former antennas by 3P/2 are mounted on the moving body. Induced voltages of respective antennas are straight detected 27-1a-27-3a, 27-1b-27-3b to obtain envelope voltages, the differences between antennas separated by 2P/3 respectively are found out by subtractors 28-1-28-3 and a carrier from an oscillator 31 is modulated by modulators 29-1-29-3 on the basis of the outputs of the subtractors 28-1-28-3. Signals obtained by phase-shifting the outputs of the modulators 29-2, 29-3 by -120 deg., 120 deg. are added to the output of the modulator 29-1 by an adder 32 and the phase difference between the added output and a reference phase signal from the oscillator 31 is indicated by a phase shifter 33 to detect the position of the moving body. |
