Table-Based Adaptive Digital Phase-Locked Loop for GNSS Receivers Operating in Moon Exploration Missions

Area of Science:

• Electrical Engineering
• Signal Processing
• Aerospace Engineering

Background:

• Adaptive digital phase-locked loops (DPLLs) are crucial for Global Navigation Satellite System (GNSS) receivers to track signals.
• Conventional adaptive DPLLs exhibit high computational complexity, limiting their application in resource-constrained environments.
• Harsh operational conditions, such as those in space missions, pose significant challenges for signal tracking stability.

Purpose of the Study:

• To propose a computationally efficient table-based adaptive DPLL for GNSS receivers.
• To optimize the noise bandwidth adjustment for improved stability and performance in challenging environments.
• To reduce the computational complexity of adaptive DPLLs while maintaining signal tracking accuracy.

Main Methods:

• A table-based adaptive DPLL approach was developed, utilizing pre-computed noise bandwidth values.
• Noise bandwidth table values were optimized considering thermal noise, oscillator phase noise, and dynamic stress.
• A method for calculating optimal integration time was presented to ensure loop filter stability.
• Simulations were conducted using trajectory data from a Moon exploration mission.

Main Results:

• The proposed table-based adaptive DPLL demonstrated stable operation in simulated harsh environments where conventional fixed-bandwidth loops failed.
• The algorithm achieved phase jitter performance comparable to existing adaptive DPLLs.
• Execution time was significantly reduced, being 2.4-5.4 times faster than conventional adaptive DPLLs.
• Computational efficiency was verified without sacrificing jitter performance.

Conclusions:

• The table-based adaptive DPLL offers a computationally efficient solution for GNSS signal tracking.
• The algorithm provides robust performance in challenging environments, crucial for applications like space exploration.
• This approach represents a significant advancement in adaptive DPLL design for GNSS receivers.