Method and apparatus for sensing fuel levels in tanks

An apparatus and method are described that utilize longitudinal guided waves propagated along a rod placed in a vehicle fuel tank, or the like, to identify the level of the fuel contained within the tank. The system includes a magnetostrictive sensor (MsS) positioned adjacent to one end of the rod that extends out from the tank. The MsS both generates the guided waves in the rod and detects the reverberating reflected waves within the rod. A permanent magnet may be positioned adjacent the MsS to establish a bias magnetic field in association with the MsS. The system and method detect the waves reverberating in the rod and from the detected signals, measure a degree of wave attenuation. A correlation is made between the measured attenuation change and the actual fuel level within the tank.