Digital PLL Jerk Correction for Accurate Phase Estimation
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Solution Overview
Problem
Conventional methods for estimating non-energy signal parameters using Phase Locked Loops (PLLs) are not adaptive to jerking motion and cannot completely eliminate dynamic measurement errors, especially in navigation systems like GPS and GLONASS.
Innovation Solution
A digital Phase Locked Loop system that includes a phase discriminator, loop filter, numerically controlled oscillator, full phase calculation block, low-pass filter, preliminary estimation of signal parameters block, and jerk-corrections block, which adjusts the algorithm to compensate for dynamic errors during jerking motion by correcting preliminary estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional PLL methods are used for estimating non-energy signal parameters, then the system structure is simple, but dynamic measurement errors cannot be completely eliminated during jerking motion
Solution Approach 1:
The system segments the estimation process into distinct functional blocks: a preliminary estimation block that generates initial phase and frequency estimates, and a jerk-corrections block that processes these estimates separately. This segmentation allows each block to be optimized for its specific function while maintaining overall system manageability and accuracy during dynamic motion.
Solution Approach 2:
The preliminary estimation block performs preliminary calculations of phase and frequency estimates before the final correction stage. By pre-computing these values and preparing correction terms in advance, the system reduces computational complexity during real-time operation while maintaining high measurement precision during jerking motion.
2Adaptability or versatility
If the PLL bandwidth is expanded to adapt to jerking motion, then the system becomes adaptive to dynamic conditions, but measurement noise increases
Solution Approach 1:
The system dynamically adjusts its estimation behavior based on detected jerking conditions. The jerk-corrections block activates specific correction algorithms only when jerking motion is detected, allowing the system to adapt to dynamic conditions without permanently expanding bandwidth. This dynamic adaptation maintains precision by applying corrections selectively rather than continuously.
Solution Approach 2:
The system changes estimation parameters dynamically by switching between different correction algorithms based on motion conditions. The jerk-corrections block modifies estimation parameters (such as filter coefficients or correction factors) according to the detected jerking state, enabling adaptability to varying motion conditions while maintaining optimal measurement precision through parameter optimization rather than bandwidth expansion.
Data Source
AI summary
A digital system of measuring parameters of the signal (phase, frequency and frequency derivative) received in additive mixture with Gaussian noise. The system is based on the use of variables of a PLL for calculating preliminary estimates of parameters and calculating the corrections for these estimates when there is a spurt frequency caused by a receiver motion with a jerk. A jerk is determined if the low pass filtered signal of the discriminator exceeds a certain threshold. The jerk-correction decreases the dynamic errors. Another embodiment includes a tracking filter for obtaining preliminary estimates of parameters to reduce the fluctuation errors. Estimates are taken from the tracking filter when there is no jerk and from the block of jerk-corrections when there is a jerk.