GNSS Snapshot Delay and Doppler Estimation Without Tracking Loops
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Solution Overview
Problem
Conventional GNSS receivers struggle to achieve accurate estimation of delays and Doppler shifts when snapshots are not continuous, as tracking loops cannot effectively operate without continuous snapshots, particularly in power-saving scenarios.
Innovation Solution
A method that processes individual snapshots of GNSS signals to estimate delays and Doppler shifts by converting correlations to frequency spectra, using discrete Fourier transforms and matrix analysis to interpolate values, eliminating the need for conventional tracking loops.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional tracking loops (DLL, PLL, FLL) are used to continuously update fine estimation of delays and Doppler shifts, then accurate positioning and navigation can be achieved, but continuous snapshots are required which increases power consumption
Solution Approach 1:
The patent applies periodic action by taking snapshots at specific intervals rather than continuously. The receiver captures snapshots at predetermined time points (e.g., every few seconds) and processes them to estimate delays and Doppler shifts. This periodic sampling approach maintains adequate positioning accuracy while significantly reducing power consumption compared to continuous snapshot acquisition required by conventional tracking loops.
Solution Approach 2:
The patent extracts only the essential information needed for positioning from snapshots taken at intervals, rather than continuously processing all signal parameters. By extracting delay and Doppler shift estimates from periodic snapshots and using these for positioning calculations, the system achieves acceptable accuracy with reduced energy expenditure.
2Measurement precision
If snapshots are taken continuously to enable tracking loops to output accurate estimation of delays and Doppler shifts, then fine estimation accuracy is improved, but device complexity and processing load increase
Solution Approach 1:
The system replaces continuous tracking loop operations with periodic snapshot processing. Instead of maintaining continuous feedback loops that require constant signal processing, the receiver takes snapshots at intervals and performs batch processing to estimate delays and Doppler shifts. This reduces computational complexity and processing load while maintaining adequate estimation accuracy for positioning purposes.
Solution Approach 2:
The patent uses short-duration snapshots as disposable data samples for estimation rather than maintaining persistent tracking states. Each snapshot is processed independently to extract delay and Doppler information, then discarded, eliminating the need for complex continuous tracking loop structures and reducing overall system complexity.
3Use of energy by moving object
If snapshots are not taken continuously to save power, then power consumption is reduced, but tracking loops cannot effectively track phase and frequency of GNSS signal
Solution Approach 1:
The patent implements periodic snapshot acquisition at optimized intervals that balance power savings with positioning reliability. By carefully selecting the snapshot interval duration, the system ensures adequate tracking of signal phase and frequency changes while minimizing power consumption. The periodic processing updates delay and Doppler estimates sufficiently for reliable positioning without requiring continuous operation.
Solution Approach 2:
The system performs preliminary coarse acquisition of signal parameters before positioning calculations, allowing it to operate with intermittent snapshots rather than continuous tracking. This preliminary estimation approach enables the receiver to maintain reliable positioning functionality with reduced snapshot frequency, improving power efficiency while preserving adequate tracking reliability.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Accurate estimation of delays and Doppler shifts is achieved, allowing for precise pseudorange calculation and navigation, even with non-continuous snapshots, while reducing power consumption and computational cost.
Implementation Method 1
obtaining a frequency spectrum by computing a K-point discrete Fourier transform, DFT, of the output sequence
Data Source
AI summary
A method for estimating delays and Doppler shifts of GNSS signals comprises obtaining respective output sequences from N correlators for a snapshot of a received GNSS signal, wherein each sequence has K values, the N correlators correspond to N different delays of a pseudorandom noise, PRN, code sequence, the K values are correlation values at K sampling time points in each sequence, N and K are positive integers. The method further comprises, for each output sequence, obtaining a frequency spectrum by computing a K-point discrete Fourier transform, DFT, of the output sequence; obtaining a N×K matrix using the N frequency spectra; determining at least one peak value in the N×K matrix; and estimating a delay and a Doppler shift of the received GNSS signal using indices of the at least one peak value in the N×K matrix.