A Novel Approach to Signal Processing in FMCW Radar
Andrzej Wojtkiewicz, Marek Nałęcz, Krzysztof Kulpa, Rafał Rytel-Andrianik · Bulletin of the Polish Academy of Sciences Technical Sciences · 2002
New possibilities of Digital Signal Processing (DSP) in Frequency Modulated Continuous Wave (FMCW) radar are presented. By the use of a transform belonging to the class of higher-order bilinear time-frequency transforms (such as Polynomial Phase Transform PPT, Generalized Ambiguity Function GAF or Generalized Wigner-Ville Distribution GWVD) one can estimate coefficients of polynomial phase of the intermediate frequency (IF) signal. Two practical cases with non-negligible higher order coefficients are considered: compensation of nonlinear modulator and estimation of moving target acceleration, velocity and range. In the latter case, target velocity introduces to the processed signal a linear phase shift that can be measured using Fourier Transform. Similarly, target acceleration introduces parabolic shift to the signal phase, which in turn enables the estimation of the acceleration. The article includes the description of a relationship between quadratic coefficient and object acceleration as well as estimation methods for this coefficient. Examples based on recorded signals from working FMCW radar prove usefulness of proposed methods.