OPTIMAL WINDOWS FOR STEP FREQUENCY RADAR

The Step Frequency Radar is an alternative technique to the impulse Gr ound Penetrating Radar. This technique consists in measuring the groun d transfer function in the frequency domain and then translating to th e time domain. It requires a specific signal processing to increase ra dar performances, that means investigation depth and resolution. Howev er, the necessity to apply a processing in real time does not allow to develop methods which demand large computational time and obliges us to use the inverse Fourier transform (IFT) to go back to the time doma in. In this paper, we study the transformation from the measurement in the frequency domain to the ground response in the time domain and we propose the optimisation of the window applied before the inverse Fou rier transform. A modelling of the received signal shows that one must use the window with the non-null phase. So we propose two kinds of co mplex windows: the phase maximal window which can be calculated analyt ically and the optimal window which is better but which should be calc ulated numerically. The complex windows are applied to synthetical dat a to show their performances. (C) 1997 Elsevier Science B.V.