| 摘要 |
PURPOSE:To make it possible to measure temperature regardless of the distance between wave transmitting and receiving devices, by transmitting ultrasonic waves having at least two kinds of frequencies in a gas to be measured in a pulse shape, obtaining the ratio between propagating times, and obtaining the temperature based on relationship between the temperature and a propagating speed, which is obtained beforehand. CONSTITUTION:An ultrasonic wave having a first frequency f1 is sent from a first wave transmitter 16 in a pulse shape aided by gate generating circuits 11 and 12. The wave is received with a first wave receiver 17. An ultrasonic wave having a second frequency f2 is sent from a second wave transmitter 26 in a pulse shape and received with a second wave receiver 27. The time from the transmitter 16 to the receiver 17 and the time from the transmitter 26 to the receiver 27 are obtained with frequency counters 20 and 30. The temperature data of a gas which is present between both wave transmitters 16 and 26 and both receivers 17 and 27 are obtained on the basis of the ratio between both times. The distance data between the transmitters and the receivers can be obtained from the results. An oscillating device 1 comprises an oscillator 1, a frequency synthesizer 3, a frequency divider 4 and the like. The oscillator 2 is, e.g., an original oscillator such as a crystal oscillator. The oscillator 2 oscillates a reference frequency signal and applies the signal to the frequency synthesizer 3.
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