In practice, it is not always possible to position your sensor with a clean, unobstructed view of the water surface you would like to measure. Additionally you may find that over time grass, weeds, or floating debris can impede the sensors view of the water. All of these situations can result in sporadic interference with ultrasonic measurements and transmission of erroneous data. To help combat this situation we have added a configurable "delta based" filtering system to our sensors.