Enhanced COSTAS Loop Implementation for Phase-Locked Loop (PLL) in High-Dynamic Digital Receivers

This paper introduces an enhanced Phase-Locked Loop (PLL) implementation using a modified COSTAS loop architecture, specifically designed for high-dynamic digital receiving systems. The improved COSTAS loop incorporates advanced phase detection algorithms and adaptive filtering techniques, achieving faster lock acquisition speeds and lower lock thresholds compared to conventional implementations. The implementation typically involves digital signal processing components including I/Q demodulators, phase error detectors, and loop filters programmed with adaptive bandwidth control. Key algorithmic enhancements include: - Modified phase detector logic that reduces false lock conditions - Adaptive loop filter coefficients that dynamically adjust to signal dynamics - Digital implementation allowing precise control of loop parameters through programmable gain stages Through comprehensive MATLAB/Simulink simulations and experimental validation, results demonstrate that this enhanced COSTAS-based PLL significantly improves both performance metrics and stability in digital receiving systems. The implementation provides robust carrier synchronization under high-dynamic conditions, offering substantial support for practical applications in modern communication systems. Code implementation typically involves digital down-conversion, error signal generation, and numerically controlled oscillator (NCO) adjustment routines.