An Ionospheric Pollution Correction Method Based on Parametric Time-Frequency Analysis of PCT

The ionosphere serves as the primary propagation medium for High-Frequency Sky-Surface Wave Radar (HFSSWR). However, its non-stationary and time-varying characteristics cause severe broadening of the first-order sea clutter spectrum in the combined sky-emitting and ground-receiving mode, hindering the detection of slow ship targets. To address this issue, this paper presents an ionospheric contamination correction method for HFSSWR based on the Polynomial Chirplet Transform (PCT) algorithm. Unlike the traditional Chirplet Transform (CT), which uses a sinusoidal kernel, this method employs a polynomial kernel for time-frequency analysis of the broadened echo spectrum. It extracts the phase contamination function by estimating the instantaneous frequency, thereby correcting the ionospheric phase path perturbation in the echo spectrum. This approach effectively suppresses sea clutter broadening caused by ionospheric perturbations. Simulation and experimental results demonstrate that, compared to conventional ionospheric decontamination methods, this method achieves superior suppression of broadened sea clutter spectra caused by both small- and large-amplitude ionospheric phase perturbations, improving the signal-to-noise ratio. This method effectively mitigates sea clutter broadening in HFSSWR.