| 摘要 |
PURPOSE:To attain the operation of a transmitter without connecting the transmitter to a vehicle-use battery by rectifying an AC output caused in an on- vehicle antenna through the electromagnetic induction from a vehicle sensing loop coil burried under a road and applying the rectified output to the on-vehicle transmitter. CONSTITUTION:A high frequency signal in a frequency f1 from an oscillator 14 is amplified (15) and the amplified signal is fed to a vehicle sensing loop coil 1 burried in a road at a terminal device side via a switch means 13. The AC output in the frequency f1 is induced in the antenna 2 of the on-vehicle transmitter A through the electromagnetic induction with the coil 1. The AC output is converted into a DC by an AC/DC converting means 3 and a DC power supply is fed to an output means 6. The means 6 inputs the vehicle data, a signal in a frequency f2 is generated from a VCO 8 by using a voltage from a shift register 9 controlled by a clock pulse 10, which is sent to a mixer 11. The mixer 11mixes the induced output in the frequency f1 from the antenna 2 with a signal from the VCO 8 to output a frequency f1+ or -f2, an LPF 1 selects f3=f1-f2 and the result is sent to the terminal device side via a loop coil 7 and the antenna 2.
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