Abstract: A method includes lowering a sensor unit in a tank, where the tank is capable of receiving a material. The method also includes determining a first distance between the material and the sensor unit and determining a second distance between the sensor unit and a main unit that lowers the sensor unit. In addition, the method includes determining a level of the material in the tank using the first and second distances. The method could further include calibrating the sensor unit to compensate for variations in a medium within the tank, where the sensor unit transmits wireless signals through the medium to determine the first distance. Determining the first distance could include using an ultrasonic measurement technique, and determining the second distance could include using a non-contact servo measurement technique.