GNSS Signal Snapshot Processing for Low-Power Delay and Doppler Tracking
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Solution Overview
Problem
GNSS receivers face challenges in reducing power consumption while maintaining accurate estimation of delays and Doppler shifts, as conventional tracking loops quickly deplete battery power.
Innovation Solution
A GNSS receiver operates in a power-saving mode with duty cycles, taking snapshots of GNSS signals, computing correlations and frequency spectra to estimate delays and Doppler shifts, and reducing power consumption during non-processing cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If closed tracking loops (DLL, PLL, FLL) are used to continuously track delays and frequencies of GNSS signals, then accurate estimation of delays and Doppler shifts is achieved, but power consumption increases quickly
Solution Approach 1:
The patent implements periodic action by operating the GNSS receiver in duty cycles with alternating active and sleep phases. During active phases, the receiver performs signal processing to estimate delays and Doppler shifts; during sleep phases, the receiver reduces power consumption by shutting down processing functions. This periodic operation maintains estimation accuracy while significantly reducing average power consumption compared to continuous tracking.
Solution Approach 2:
The patent applies preliminary action by performing signal acquisition and coarse estimation of delays and Doppler shifts before entering power-saving mode. This preliminary processing establishes initial parameter estimates that enable the receiver to resume accurate tracking quickly after wake-up from sleep mode, avoiding the need for continuous processing while maintaining estimation accuracy.
2Duration of action of moving object
If the GNSS receiver reduces power consumption by operating in duty cycles with snapshots, then battery life is extended, but continuous tracking capability is reduced
Solution Approach 1:
The receiver performs preliminary signal acquisition and coarse parameter estimation before entering sleep mode. These preliminary estimates of delays and Doppler shifts are stored and used to quickly resume tracking after wake-up, ensuring continuous tracking capability is maintained despite periodic sleep intervals. The preliminary action enables rapid re-acquisition without requiring continuous processing.
Solution Approach 2:
The system implements feedback by using the estimated delays and Doppler shifts from active phases to adjust and optimize subsequent duty cycle operations. The estimation results feed back into the tracking algorithm to maintain accuracy across duty cycle boundaries, ensuring reliable continuous tracking capability even with intermittent processing.
Data Source
AI summary
A method for receiving and processing GNSS signals is performed by a GNSS receiver featuring a power saving mode. The method comprises, in the power saving mode: receiving and taking a snapshot of a GNSS signal in a duty cycle, wherein the duty cycle is part of a cycle; computing, in the duty cycle, respective correlations between the snapshot and different delays of a PRN code sequence; computing, in the duty cycle, respective frequency spectra of the correlations; estimating, in the duty cycle, a delay and a Doppler shift of the GNSS signal based on the frequency spectra; and reducing power consumption for the rest of the cycle; wherein an accuracy of the estimated delay and the estimated Doppler shift is in a same order of magnitude as an accuracy of a delay and a Doppler shift estimated in a full power mode without reducing power consumption.