| 摘要 |
PROBLEM TO BE SOLVED: To limit the induced voltage generated in a wayside coil within a certain fixed range. SOLUTION: When the tank circuit 51 of a wayside coil 50 receives an induced wave WY transmitted from a vehicle, an induced voltage V1 is generated in the circuit 51 and becomes a detected voltage V2 when the voltage V1 is detected by means of a detector 53. The detected voltage V2 is changed to a DC voltage VDC by means of a regulator 54. When the DC voltage VDC is supplied, a CPU 55 outputs automatic maneuver information I1 which is changed to an automatic maneuver signal I2 by means of a modulator 56. The signal I2 is sent to the tank circuit 51 and transmitted as a transmission wave WS. On the vehicle side, the automatic maneuver information is received as the transmission wave WS. When the induced wave WY is intensified and the induced voltage V1 becomes higher, the control voltage VS amplified by means of the amplifier 62 of a voltage control circuit 60 also becomes higher. When the control voltage VS becomes higher, the junction capacitance of a varactor diode 61 becomes larger and the tuned frequency of the tank circuit 51 becomes lower. In addition, the value of the induced voltage V1 drops.
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