A radar level gauge (RLG) system and method for determining a filling level of a filling material in a tank is disclosed. The RLG system comprises a transmitter for generating and transmitting an electromagnetic transmitter pulse signal, a transmitter controller for controlling means for pulse width adjustment for adjusting the pulse width of the transmitter pulse signal in dependence of at least one application specific condition. Further, the system comprises a signal medium interface connectable to means for directing said transmitter pulse signal towards said filling material and for receiving a reception pulse signal reflected back from said filling material; a receiver for receiving said reception pulse signal from the tank; and processing circuitry for determining the filling level of the tank based on said reflection pulse signal received by said receiver. The application specific condition(s) is e.g. one or several of tank height, level of the filling material, type of filling material, presence of other tank structure providing reflecting surfaces and required accuracy of measurement.