| 摘要 |
PURPOSE:To enable a distance between a transmitter and a receiver to be lengthened in the transmission of signals between the transmitter and the receiver by pulse-modulating a frequency outputted from an oscillator and conducting radio transmission and reception with the pulse-modulated frequency. CONSTITUTION:A frequency signal is transmitted from an oscillator 11 using a vibrator that resonates at a frequency in accordance with a temperature to be detected. The frequency signal is amplified 12 up to a level at which a pulse modulation is possible. The frequency signal outputted from the oscillator 11 is frequency-divided 16, therefrom a gate signal being generated in a gate generating circuit 17. The frequency signal from an amplifier 12 is pulse- modulated 13 by the gate signal. A resultant modulated signal is amplified 14 up to a prescribed level and radio-transmitted from a transmitting antenna 15. On the other hand, a receiver 2 receives the transmitted signal by a receiving antenna 21 to amplify 22 the received signal up to a prescribed level. Part of the frequencies of the amplified signal corresponding to a change in a temperature to be detected is detected by frequency detecting means 3 and the temperature to be detected is obtained from a detected value by a microcomputer 24. A detected result is displayed on a temperature display 25.
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