ACCOUSTICAL APPARATUS AND METHOD FOR MEASURING WATER LEVEL IN A GROUND WATER WELL

摘要

An acoustic distance measuring device adapted to measure the level of water in a ground water well by first emitting a sonic low frequency acoustic pulse and measuring the time-of-flight for each reflected pulse from the surface of the water in the well. Each reflected pulse must have an amplitude greater than a threshold amplitude or it will be rejected. Based on time-of-flight measurements from the first low frequency sonic pulse reception windows are established for a second higher frequency sonic pulse. To refine the time-of- flight measurements for the second pulse only those reflected pulses whose reception times fall within the reception windows are accepted. A more accurate calculation of the distance from the sonic pulse emitter to the surface of the water is accomplished by using the refined time-of-flight measurements from the second higher frequency pulse.