Abstract: A method for processing a time domain reflectometry (TDR) signal used to determine at least one process variable for a material in a tank, wherein said TDR signal has been generated by a radar level gauge system comprising a pulse generator, a probe extending into the tank for guiding the pulse, and a receiver for receiving said TDR signal, and wherein the TDR signal comprises at least a surface reflection pulse caused by an interface between different materials in the tank, and an interfering pulse caused by a transition between the pulse generator and the probe.