A method includes receiving data identifying wireless signals including wireless signals reflected off a surface of material in a tank and detecting a plurality of reflection peaks associated with the wireless signals. The method also includes classifying at least some of the detected reflection peaks and tracking at least some of the classified reflection peaks. The method further includes identifying a level of the material using at least one of the tracked reflection peaks. The classified peaks could include main-mode and/or high-mode reflection peaks, where the material level is identified using the main-mode peak or using an estimated location of the main-mode peak based on the high-mode peak. The classified peaks could also include level, bottom, and obstruction peaks, where the material level is identified by using a known permittivity, the bottom peak, and a tank height to estimate a location of the level peak when the level peak is lost or obscured.