A Method of Nonlinearity Estimation and Correction Based on Difference Filtering

In the linear Frequency Modulation Continuous Waveform (FMCW) Radar system, due to the non-ideal characteristics of each instrument, the phase of the signal produces various distortions, which affects seriously the radar's ranging accuracy and imaging quality. It requires certain correction methods to obtain high-precision measurement results. In view of the characteristics of FMCW signal and deterministic nonlinear phase, this paper establishes a FMCW signal model subject to nonlinear interference, and proposes a new nonlinear estimation method based on difference filtering, which can simultaneously estimate periodic and non-periodic nonlinearities, and uses Matching Fourier Transform (MFT) method to correct the nonlinear phase. Simulation and comparative analysis show that this method has higher estimation accuracy than other methods, and it can also have a good correction effect when the nonlinearity is large. Finally, the actual measurement data of the radar is used to verify the effectiveness of the algorithm.