System Parameter Calibration Via Compensated Signal Correlation
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Solution Overview
Problem
Existing positioning, navigation, and timing systems face challenges in accurately correlating local and received signals due to noise and phase changes, particularly in environments with low signal-to-noise ratios and multi-path effects, which degrade the accuracy of system parameter estimation.
Innovation Solution
A method involving phase and amplitude compensation of local and received signals based on multiple estimates of system parameters, allowing for the selection of the estimate closer to the true value by comparing compensated correlation signals, enabling longer coherent integration times and improved signal-to-noise ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard correlation procedures are used in low signal-to-noise ratio environments, then the system can operate without additional complexity, but correlation accuracy deteriorates due to noise and phase changes
Solution Approach 1:
The system performs preliminary phase and amplitude compensation on the received signal before correlation using multiple estimates of system parameters (such as Doppler shifts, clock offsets, and frequency errors). This preliminary action prepares the signal in advance to withstand the harsh correlation environment, improving accuracy without requiring complex post-processing
Solution Approach 2:
The system changes multiple parameters simultaneously including phase compensation values, amplitude scaling factors, and frequency corrections based on different estimates of system parameters. By varying these parameters across multiple hypotheses and selecting the best match, the system achieves higher correlation accuracy in noisy environments
2Reliability
If longer coherent integration times are used, then signal-to-noise ratio improves, but the system becomes more sensitive to phase changes and frequency errors
Solution Approach 1:
The system applies preliminary phase compensation and frequency correction to the received signal before performing long coherent integration. This preliminary action removes the accumulation of phase errors that would otherwise occur during extended integration periods, enabling the system to achieve high signal-to-noise ratio without sacrificing phase estimation accuracy
Solution Approach 2:
The system uses feedback from multiple parameter estimates (Doppler shifts, clock offsets, frequency errors) to continuously adjust phase compensation and amplitude scaling during the integration process. This feedback mechanism corrects for phase changes that occur during long integration, maintaining measurement precision while achieving improved signal-to-noise ratio
3Measurement precision
If multiple parameter estimates are tested with different compensations, then the true system parameter can be identified, but computational complexity increases
Solution Approach 1:
The system tests a limited number of discrete parameter estimates (such as a few Doppler shift hypotheses and clock offset values) rather than exhaustively searching all possible parameter combinations. This partial action approach finds the true parameter with sufficient accuracy while significantly reducing computational energy requirements compared to exhaustive search methods
Data Source
AI summary
A method for performing in a positioning, navigation, tracking, frequency-measuring, or timing system is provided. The method comprises: providing first and second estimates of at least one system parameter during a first time period, wherein the at least one system parameter has a true value and/or true evolution over time during the first time period; providing a local signal; receiving, at a receiver, a signal from a remote source; providing a correlation signal by correlating the local signal with the received signal; providing amplitude and/or phase compensation of at least one of the local signal, the received signal and the correlation signal based on each of the first and second estimates so as to provide first and second amplitude-compensated and/or phase-compensated correlation signals corresponding to the first and second estimates of the at least one system parameter during the first time period, and; determining which of the first and second estimates is nearer the true value and/or true evolution over time of the at least one system parameter during the first time period, based on a comparison between the first and second amplitude-compensated and/or phase-compensated correlation signals. A computer readable medium and system are also disclosed.