Patent ID: 7178396

Claim:
An acoustic distance measuring device adapted to measure the level of water in a ground water well having obstructions, said ground water well having an axis, wherein said level of water is measured as a function of the distance (D) from said device to the surface of the water level, the device comprising: a. an electrical circuit adapted to generate an electrical signal having a frequency (f); b. a sonic pulse emitter coupled to said electric circuit and adapted to convert said electric signal into a single emitted sonic pulse having a frequency (f) and an initial amplitude A i , said sonic pulse emitter co-axial with the ground water well, the sonic pulse emitter adapted and oriented to emit said single emitted sonic pulse down said axis of the ground water well so that the single emitted sonic pulse is reflected up and down the groundwater well to form a series of successive reflected cycles comprising a series of reflected sonic pulses R 1 to R N having amplitudes A R1 to A RN to be received by; c. a sonic pulse receiver installed proximate to the sonic pulse emitter and internal to the ground water well, said sonic pulse receiver adapted and oriented to receive said series of reflected sonic pulses R 1 to R N from the surface of the water, the sonic pulse receiver further adapted to generate electrical signals having strengths relative to said amplitude A R1 to A RN ; d. a comparator connected to the sonic pulse receiver for comparing amplitudes A R1 to A RN with a predetermined and variable threshold value A LIM , said comparator adapted to reject any reflected pulse having any of A R1 to A RN below A LIM ; said comparator adapted to send accepted signals to; e. a microprocessor connected to said comparator and connected between the comparator and the electrical circuit, said microprocessor programmed to calculate the average time-of-flight (t fAVG ) of said series of successive reflected cycles having A R1 to A RN greater than A LIM and times-of-flight t 1 to t N from the sonic pulse emitter to the surface of the water in the ground water well and back to the sonic pulse receiver, the microprocessor further adapted to calculate said distance (D) according to the relationship D=S(t fAVG )/2 where S is the speed of sound and wherein t fAVG =(Σ t1 tN /N); f. a programmable memory device connected to the microprocessor for storing microprocessor operating and application software; g. means for remotely triggering the device from a remote location; and, h. a display for displaying the level of water in a ground water well remotely.