A GPS Phase-Locked Loop Performance Metric Based on the Phase Discriminator Output.

Area of Science:

• Electrical Engineering
• Signal Processing
• Navigation Systems

Background:

• Global Positioning System (GPS) receivers rely on phase-lock loops (PLLs) for accurate signal tracking.
• Traditional performance metrics like phase jitter may not fully capture PLL robustness under challenging conditions.
• Existing linear models for GPS PLLs have limitations in accurately predicting performance, especially with additive white Gaussian noise (AWGN).

Purpose of the Study:

• To propose a novel performance metric for GPS phase-lock loop (PLL) systems: the standard deviation of tracking error.
• To demonstrate the superiority of this new metric over the conventional phase jitter metric, particularly under interference.
• To develop an augmented linear model for more accurate PLL performance prediction.

Main Methods:

• Derivation of an augmented GPS PLL linear model incorporating coherent averaging.
• Theoretical analysis, numerical simulations, and experimental validation of the proposed tracking error metric.
• Comparison of the standard deviation of tracking error with phase jitter under various noise and interference conditions.

Main Results:

• The standard deviation of tracking error is shown to be a more reliable and robust performance indicator than phase jitter.
• The augmented linear model accurately predicts tracking error standard deviation up to a specific threshold, improving prediction efficiency.
• The proposed metric and model remain valid under interference, offering better insights into PLL behavior.

Conclusions:

• The standard deviation of tracking error provides a superior metric for GPS PLL performance evaluation.
• The augmented linear model enhances the accuracy and efficiency of PLL performance prediction, reducing the need for extensive simulations and testing.
• The findings facilitate the design of more robust GPS receivers, especially in environments prone to interference.