Carrier Replica Phase Adjustment for GNSS Tracking Continuity
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing GNSS receivers using CapTune switching-based VCOs in their PLLs are prone to phase shifts due to temperature changes, leading to potential loss of satellite signals during down-conversion and disruption of navigation.
Innovation Solution
A method involving a tracking loop that blanks the phase control of the carrier replica signal upon detecting a phase shift, uses a constant value to adjust the phase, determines the magnitude of the shift, and then resumes normal phase control, thereby preventing phase jumps from propagating to the carrier replica signal.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If CapTune switching is used to tune the VCO to desired frequency, then frequency tuning capability is improved, but phase shifts occur causing loss of satellite signal
Solution Approach 1:
The system performs preliminary detection of phase shifts in the digital baseband signal before they propagate to the carrier replica signal. By detecting the phase shift early and preemptively adjusting the carrier replica phase, the system prevents signal loss rather than reacting after the problem occurs.
Solution Approach 2:
The patent introduces an intermediary mechanism (the phase detection and adjustment system) between the CapTune switching and the carrier replica signal generation. This intermediary detects phase shifts and compensates for them, isolating the carrier replica from the harmful phase variations caused by CapTune switching.
2Measurement precision
If PLL with charge pump is used to regulate VCO phase and frequency, then frequency regulation precision is improved, but phase jumps occur due to current mismatch
Solution Approach 1:
The system continuously monitors the phase of the digital baseband signal and uses this feedback to detect phase shifts. When a phase shift is detected, the system adjusts the carrier replica phase accordingly, creating a closed-loop feedback mechanism that maintains phase stability despite PLL operations.
Solution Approach 2:
The patent dynamically changes the phase parameter of the carrier replica signal based on detected phase shifts in the baseband signal. By adjusting the phase parameter in response to detected changes, the system compensates for phase instability caused by charge pump current mismatches.
3Temperature
If temperature changes occur in the environment, then operational adaptability is improved, but phase shifts in baseband signal occur leading to navigation disruption
Solution Approach 1:
The system performs self-diagnosis by continuously monitoring its own baseband signal for phase shifts. When temperature changes cause phase shifts, the system automatically detects these changes and compensates for them without external intervention, maintaining navigation continuity through self-correcting behavior.
Data Source
AI summary
In an example embodiment, a method for adjusting a phase of a carrier replica signal includes receiving, by a tracking loop, a digital baseband signal, generating within the tracking loop the carrier replica signal, generating within the tracking loop a sequence of samples from the digital baseband signal and the carrier replica signal, and controlling a phase of the carrier replica signal depending on the sequence of samples. The example method further includes receiving a trigger signal indicating an upcoming phase shift of the digital baseband signal, blanking the tracking loop and controlling the phase of the carrier replica signal using a constant value, determining a magnitude of the phase shift, adjusting the phase of the carrier replica signal using the determined magnitude of the phase shift, and un-blanking the tracking loop and controlling the phase of the carrier replica signal depending on the sequence of samples.