| 摘要 |
<p>PURPOSE:To detect a mobile body without generating a dead zone by providing a transmitter and a receiver at the terminals of two open type coaxial cables, and detecting both the amplitude and phase of a reception signal by near-end coupling with the receiver. CONSTITUTION:A near-end coupling signal shown in the arrow of dotted line generated by transmission from the transmitter 3 at one terminal of the open type coaxial cables 1, 2 provided being separated a prescribed distance with each other is distributed with a distributor 8, and is inputted to an amplitude meter 8 and a phase meter 10. Also, a transmission signal is introduced to a branching filter 11 as shown in the arrow of continuous line to obtain in reference phase meter 10. Then, the amplitude meter 9 and the phase meter 10 are connected a deciding device 12. The deciding device 12 compares the amplitude meter 9 and the phase meter 10 with reference amplitude and the reference phase, and decides that the or not is within a prescribed range, and decides that the mobile body traverse or approaches the cables 1, 2 when it is judged that a result is outside the range. In such a way, since the mobile body can be detected based n the change of the amplitude and the phase, the mobile body can be detected at an arbitrary position along the length direction of the cable.</p> |
