In our laboratory, we developed a simple estimation of the wall thickness by the UWB (Ultra Wide-Band) radar system. The described technique measures the wall thickness in the two steps. The first step is a measurement of the wall relative permittivity. The second step is a reflections localisation and estimation of the wall thickness. The borders of the wall could be detected by the envelope of the received signals. The described technique calculates the signal envelope by the Hilbert transform. Moreover, the relative permittivity of the wall is estimated by the technique developed in our department as well. The effective relative permittivity is calculated from the frequency dependency of relative permittivity. This technique was developed for the impulse radar system. The aim of this article is compare the results from impulse radar system with M-sequence radar system which operates in the time domain as well measuring wall relative permittivity and wall thickness estimation.