Estimation of Linear Chirp Signals with Time-Varying Amplitudes

For linear chirp signals with time-varying amplitudes, we propose using their spectrum to estimate parameters. First, we extend the spectrum phase unwrapping algorithm developed in our previous work to estimate phase parameters. Then, we develop a method utilizing spectrum amplitude to estimate instantaneous amplitude parameters, augmented by a refinement technique to improve accuracy. Additionally, this study identifies and analyzes inherent phase errors in the O'Shea refinement algorithm when applied to signals with time-varying amplitudes. Compared to existing methods, our approach significantly reduces computational complexity, as it requires only a single spectrum calculation. Simulation results demonstrate the superiority of the proposed method in terms of both SNR threshold and computational efficiency.