Multi-satellite signal detection and isolation method for starlink satellites’ signals of opportunity

Currently, utilizing wide-beam and low-gain antennas to receive starlink satellites signals of opportunity (SOP) enables the simultaneous tracking of multiple satellites, which contributes to reducing positioning convergence time and enhancing positioning accuracy. In this scenario, the detection of high-dynamic, weak signals typically relies on the compensation and stripping of Doppler shift and its rate of change. However, existing methods inadequately account for the bias in Doppler rate estimation introduced by satellite ephemeris errors. This limitation results in insufficient coherent integration gain for signals and the inability to detect certain tone signals, consequently reducing the number of valid observations obtainable in a single measurement epoch. Furthermore, current multi-satellite tracking methods for starlink lack a robust mechanism for satellite signal differentiation and isolation. To address these issues, this paper proposes an optimized Doppler rate search strategy implemented after stripping the Doppler shift and Doppler rate. This approach effectively mitigates the degradation of integration gain caused by ephemeris errors, significantly improving the detection capability for tone signals. Simultaneously, we design a single-epoch signal preliminary screening method based on the starlink signal structure, combined with a multi-epoch joint decision strategy leveraging the characteristic Doppler rates of individual satellites. This dual approach achieves reliable differentiation and isolation of signals from multiple satellites. Experimental results demonstrate that the proposed optimized Doppler rate search method increases the number of detected tone signals by approximately 35.88%. Within a 5 min observation window, the system successfully identifies and distinguishes signals from 15 satellites. In terms of positioning accuracy, it achieves a 2D positioning accuracy better than 10 m and a 3D positioning accuracy better than 15 m.