Estimation and compensation of frequency sweep nonlinearity in FMCW radar

One of the main issues limiting the range resolution of linear frequency-modulated continuous-wave (FMCW) radars is nonlinearity of frequency sweep, which results in degradation of contrast and range resolution, especially at long ranges. Two novel, slightly different, methods to correct for nonlinearities in the frequency sweep by digital post-processing of the deramped signal were introduced independently by Burgos-Garcia et al. (Burgos-Garcia, Castillo et al. 2003) and Meta et al. (Meta, Hoogeboom et al. 2006). In these publications, however, no formal proof of the techniques was given, and no limitations were described. In this thesis, we prove that the algorithm of Meta is exact for temporally infinite chirps, and remains valid for finite chirps with large time-bandwidth products provided the maximum frequency component of the phase error function is sufficiently low. It is also shown that the algorithm of Meta reduces to that of Burgos-Garcia in this limit. A digital implementation of both methods described. We also propose a novel method to measure the systematic phase errors which are required as input to the compensation algorithm.