Impact of Phase Noise on Frequency Estimation of FM Signals

This paper examines the problem of instantaneous frequency estimation at the output of frequency-modulated continuous-wave (FMCW) synthesizer based on fractional-N phase-locked loop (PLL) in the presence of the phase noise (PN). Nowadays, FMCW synthesizers used in radar systems cover high operating frequency ranges and wide frequency bandwidths. Thus, it is important to investigate methods that are precise and fast enough to estimate instantaneous frequency despite a huge number of time-domain signal samples per linear frequency ramp. The paper presents an impact of PN, modeled as the Ornstein-Uhlenbeck (OU) process, on the instantaneous frequency estimation that is maintained using zero-crossing (ZC) with linear interpolation, ZC with cubic spline interpolation and Hilbert transform (HT).