| 摘要 |
PROBLEM TO BE SOLVED: To prevent error detection of reflected echoes due to the previous transmission of ultrasonic waves by changing a transmission period each time and performing arithmetic processing when ultrasonic waves are transmitted by a plurality of times in an ultrasonic level meter. SOLUTION: The ultrasonic level meter transmits ultrasonic waves as changing the transmission period of an ultrasonic sensor, in such a way that the occurrence timing of reflected waves of ultrasonic waves transmitted at a previous time may be different each time when ultrasonic waves are transmitted by a plurality of times at a transmission period shorter than the interval, between the time when the ultrasonic waves are transmitted from the ultrasonic sensor and the time when their reflected waves are attenuated to a prescribed level or lower (S6 and S7), and acquires waveform data on the reflected waves according to the transmitted ultrasonic waves each time. The ultrasonic level meter creates statistical waveform data by performing arithmetic processing on a plurality of times of acquired waveform data (S8), selects the echo timing of the reflected waves of a predetermined wave height level or higher from among reflected waves included in the statistical waveform data, and detects the position of a liquid level on the basis of the echo timing. COPYRIGHT: (C)2005,JPO&NCIPI |
