System and method for an improved device for measuring water levels

Abstract

A method and apparatus for determining the surface level of a given body using acoustic ranging that incorporates processes natural to human beings to improve identification of the echo from the water surface when spurious echoes might otherwise overshadow it. An acoustic beam is transmitted toward the surface where it is reflected. The beam also reflects off various interferences creating spurious reflections or echoes. The echoes from the surface as well as the spurious echoes are then received. Each echo is then evaluated according to several criteria, in order to determine which echo is associated with the surface. In one embodiment, a set of candidate echoes is identified, the one most likely to represent the surface is selected by using multiple different criteria for evaluating the echo, assigning each criteria a sensible quality factor, computing an overall quality factor by mathematically combining the individual quality factors, and identifying the surface peak as the peak with the highest overall quality factor. In one embodiment, an evaluation technique involves measuring the amplitude, signal to noise ratio, and width of a received echo. In another embodiment, a first echo is compared to subsequent echoes to determine if the subsequent echoes are multiple bounces of the first echo. In still another embodiment, an independent input device, such as a pressure sensor, is used to make a rough measurement of the surface level. In another embodiment, measurement history is used to analyze the received echoes in order to aid in determining which echo corresponds to the surface.