A robust and precise centroid positioning method for the weak beacon spot in long-distance inter-satellite optical...

Area of Science:

• Optical Wireless Communication
• Satellite Systems Engineering
• Signal Processing

Background:

• Accurate centroid estimation is vital for the pointing, acquisition, and tracking (PAT) subsystem in inter-satellite optical wireless communication (IsOWC).
• Weak beacon signals, often resulting from long link distances, pose a significant challenge to traditional centroid estimation methods.
• Low peak signal-to-noise ratio (SNR) further complicates precise beacon spot localization.

Purpose of the Study:

• To develop an accurate centroid positioning method for weak beacon spots with low SNR.
• To enhance the robustness and precision of centroid estimation in IsOWC PAT systems.
• To provide a superior alternative to existing methods for beacon-based tracking applications.

Main Methods:

• A novel centroid positioning method utilizing the normalized amplitude of the gray gradient is proposed.
• This method enhances the weighting of pixels near the beacon spot's center.
• Comparative numerical simulations and experimental verifications were conducted to validate the method's performance.

Main Results:

• The proposed method demonstrates superior accuracy and robustness compared to the gray centroid, interpolation-based, Hough transform, and Gaussian fitting methods.
• Numerical simulations confirmed the method's effectiveness in handling weak beacon signals.
• Experimental results validated the practical feasibility and performance gains of the proposed technique.

Conclusions:

• The developed centroid estimation method effectively addresses the challenges of weak beacon signals in IsOWC.
• The method offers significant improvements in accuracy and robustness for IsOWC PAT systems.
• This technique is highly applicable to IsOWC and other beacon-based pointing and tracking systems.