GNSS Signal Calibration via Phase Amplitude Compensation
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Solution Overview
Problem
Existing Global Navigation Satellite System (GNSS) receivers 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 positioning accuracy.
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 closest to the true value through comparison of compensated correlation signals, enabling longer coherent integration times and improved signal discrimination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If standard correlation procedure is used in GNSS receivers, then the system can operate with simple processing, but positioning accuracy deteriorates in low signal-to-noise ratio environments due to noise and multi-path effects
Solution Approach 1:
The system performs preliminary phase and amplitude compensation of the received signal using multiple estimates of system parameters (such as Doppler shift, frequency offset, and clock error) before correlation. This pre-processing step prepares the signal in advance to counteract expected distortions, enabling more accurate correlation in challenging environments with low signal-to-noise ratios and multi-path effects
Solution Approach 2:
The system changes multiple parameters simultaneously (phase, amplitude, frequency offset, Doppler shift compensation) to optimize the correlation process. By adjusting these parameters based on multiple estimates and selecting the combination that maximizes correlation output, the system achieves improved positioning accuracy in noisy environments
2Measurement precision
If longer coherent integration times are used to improve signal-to-noise ratio, then positioning accuracy improves, but computational load increases
Solution Approach 1:
Phase and amplitude compensation is performed in advance before correlation, preparing the signal to maintain coherence over longer integration periods. This preliminary preparation reduces the need for repeated computational adjustments during the correlation process itself, enabling longer coherent integration times with manageable computational load
Solution Approach 2:
The system uses periodic correlation with longer coherent integration times to accumulate signal energy over extended periods. By combining this periodic integration with pre-computed phase and amplitude compensation, the system achieves improved signal-to-noise ratio while the computational burden is distributed and optimized across multiple processing cycles
3Measurement precision
If multiple estimates of system parameters are tested with different compensations, then the estimate nearest to true value can be selected improving accuracy, but device complexity increases
Solution Approach 1:
The system segments the parameter estimation process by testing multiple discrete estimates of system parameters (such as multiple Doppler shift values, frequency offsets, and clock error estimates) independently. Each estimate is tested with its corresponding compensation, and the results are compared to select the nearest true value, breaking down the complex estimation problem into manageable segments
Solution Approach 2:
The system uses feedback from the correlation output to determine which parameter estimate is nearest to the true value. By comparing correlation results from multiple compensated signals, the system selects the estimate that produces the maximum correlation output, creating a feedback loop that refines parameter estimation accuracy while managing processing complexity through selective testing
Data Source
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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.