| 摘要 |
PROBLEM TO BE SOLVED: To eliminate influence of a raking device relating to a sludge interface monitor device monitoring the sludge interface of a sludge disposal device, which exhausts the sludge precipitated in a waste water disposal vessel from an exhaust port with the raking device, by the use of ultrasonic wave. SOLUTION: A storage circuit 17 storing first delay interface signal b and second delay interface signal c generated by delaying interface signal, at least in two steps, based on wave reception signal 22 wherein ultrasonic wave is reflected on a sludge interface 9 or a raking device 6, and the current interface signal a caused by the first delay interface signal b and the second delay interface signal c stored in the storage circuit 17 are compared with each other. At the same time, a comparator circuit 18 which compares absolute values of differences between the interface signal a and the interface signal b, and between the interface signal a and the interface signal c, with a specified value▵e, respectively, and outputs the interface signal a, b or c based on the relative size in the comparison result, is provided. |
