OPTIMAL SIGNAL-PROCESSING OF FREQUENCY-STEPPED CW-RADAR DATA

An optimal signal processing algorithm is derived for estimating the t ime delay and amplitude of each scatterer reflection using a frequency -stepped CW system, The channel is assumed to be composed of abrupt ch anges in the reflection coefficient profile, The optimization techniqu e is intended to maximize the target range resolution achievable from any set of frequency-stepped CW radar measurements made in such an env ironment. The algorithm is composed of an iterative two-step procedure , First, the amplitudes of the echoes are optimized by solving an over determined least squares set of equations. Then, a nonlinear objective function is scanned in an organized fashion to find its global minimu m, The result is a set of echo strengths and time delay estimates, Alt hough this paper addresses the specific problem of resolving the time delay between the first two echoes, the derivation is general in the n umber of echoes. Performance of the optimization approach is illustrat ed using measured data obtained from an RP-8510 network analyzer, It i s demonstrated that the optimization approach offers a significant res olution enhancement over the standard processing approach that employs an IFFT. Degradation in the performance of the algorithm due to subop timal model order selection and the effects of additive white Gaussion noise are addressed.