Hybrid FM-polynomial phase signal modeling: Parameter estimation and Cramer-Rao bounds

Parameter estimation for a class of nonstationary signal models is addresse d. The class contains combination of a polynomial-phase signal (PPS) and a frequency-modulated (FM) component of the sinusoidal or hyperbolic type, Su ch signals appear in radar and sonar applications involving moving targets with vibrating or rotating components, A novel approach is proposed that al lows us to decouple estimation of the FM parameters from those of the PPS, relying on properties of the multilag high-order ambiguity function (mI-HAF ), The accuracy achievable by any unbiased estimator of the hybrid FM-PPS p arameters is investigated by means of the Cramer-Rao lower bounds (CRLB's), Both exact and large sample approximate expressions of the bounds are deri ved and compared with the performance of the proposed methods based on Mont e Carlo simulations.