ULTRASONIC LEVEL SENSOR

摘要

PROBLEM TO BE SOLVED: To predict the water level in a tank installed in a tunnel at a prescribed accuracy or more and prevent error detection caused by a substance stuck to a cylinder attached in the adjacent to an ultrasonic transmitting/ receiving part. SOLUTION: A judgment timing prediction means 8 predicts an abnormality judgment timing in a timing prediction preparation mode based on distance data 12 from a distance operation means and writes the position of the level measured according to each timing in a judgment liquid surface position memory means 10. An abnormality judgment means 9 compares the distance data 12 from a distance operation means 6 with a judgment liquid level data 15 from the judgment liquid surface positions storage means 10 to judge it abnormal or not. If it is judged abnormal, the distance data 12 is registered in an abnormal data memory means 11 and the judgment liquid surface position data 15 is outputted as an outputted signal 19 substitute for the present distance data 12.