Research on Improved Algorithm of Frequency Estimation Based on Complex Modulation

Achieving precision frequency estimation plays an important role in radar signal processing, especially on the aspects of target recognition, tracking and location. Applying Fast Fourier Transformation to analyze the spectrum is convenient whereas fence effect and spectrum leakage cannot be easily denied and the error is too much to satisfy practical engineering requirement. Zoom FFT algorithm, a complex modulation algorithm, provides advantages in spectrum analysis and frequency estimation while the magnification time is limited. A method utilizing Newton Interpolation is proposed to improve the precision of frequency estimation, which the requirement of magnification time is unessential. The corresponding frequency correction equations are derived and two scenarios are illustrated to depict the performance of the proposed method. The simulation results verified that the method had an awesome effect on frequency estimation and the error of frequency measurement decreased an average by 30% compared to Zoom FFT algorithm. The real ranging system also indicated that the proposed method could improve ranging precision.