A Passive Signal Focusing Algorithm Based on Synthetic Aperture Technique for Multiple Radiation Source Localization

The Doppler dispersion of the received signal is very severe when the beamwidth of the antenna is wide, resulting in a decrease in localization accuracy for multiple radiation source localization. To resolve the problem, we propose a passive signal focusing algorithm (PSFA) for multiple radiation sources localization based on a full-aperture model. The full-aperture model overcomes the resolution degradation in conventional subaperture processing. In the PSFA, the residual frequency correction (RFC) eliminates the localization bias in the azimuth domain and the instantaneous Doppler compensation (IDC) resolves the Doppler dispersion in the range domain, improving localization accuracy. The matched filtering is used to complete precise azimuthal focusing and the locations are obtained according to the focusing results. Moreover, the Cramer–Rao lower bound (CRLB) for synthetic aperture localization is derived. The CRLB is essential for evaluating algorithms in theoretical studies and designing system parameters in practical applications. Finally, the CRLB, simulation, and acquired data are used to evaluate the localization performance.