GPS Receiver Codephase Correction for Jamming Mitigation
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Solution Overview
Problem
Existing GPS receivers face accuracy issues due to local jamming from mobile device signals, which notch filters attempt to mitigate but can distort codephase measurements, affecting position estimates.
Innovation Solution
The method involves determining notch filter configurations, pseudorandom noise codes, and doppler frequencies to calculate a codephase correction value, using look-up-tables or interpolation functions, to improve range computations in GPS receivers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If notch filters are used to mitigate jamming signals, then anti-interference capability is improved, but codephase measurement accuracy deteriorates
Solution Approach 1:
The patent pre-calculates codephase correction values for various notch filter configurations, pseudorandom noise codes, and doppler frequencies before actual signal reception. These correction values are stored in lookup tables, allowing the receiver to quickly apply the appropriate correction without real-time computation, thus maintaining measurement accuracy while using notch filters for jamming mitigation
Solution Approach 2:
The patent implements a feedback mechanism where the receiver determines the actual codephase measurement, compares it with the expected value based on pseudorandom noise code and doppler frequency, calculates the correction value, and applies it to compensate for the notch filter-induced distortion. This closed-loop approach ensures accurate range computation despite the presence of notch filters
2Reliability
If notch filter configurations are applied to reduce jamming, then signal reliability is improved, but positioning accuracy deteriorates
Solution Approach 1:
The patent changes the parameter space by considering multiple notch filter configurations, pseudorandom noise codes, and doppler frequencies. For each combination, pre-calculated codephase correction values are determined and stored. During operation, the appropriate correction value is selected based on the actual signal conditions, allowing the system to maintain positioning accuracy while benefiting from notch filter-based jamming mitigation
Solution Approach 2:
The patent introduces codephase correction values as an intermediary element between the notch filter processing and the final range computation. These correction values act as a compensatory mechanism that bridges the gap between the filtered signal and the accurate position estimate, allowing the system to use notch filters for reliability improvement without sacrificing positioning accuracy
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
This approach enhances the accuracy of GPS position estimates by mitigating the impact of jamming signals on codephase measurements, leading to improved positioning accuracy.
Implementation Method 1
Notch filtering within the GNSS receiver may be used to reduce the impact of such jamming signals
Implementation Method 2
determining a pseudorandom noise code and a doppler frequency associated with the signal
Implementation Method 3
determining a pseudorandom noise code and a doppler frequency associated with the signal
Data Source
AI summary
Techniques are provided for utilizing notch filters to overcome narrowband jamming. An example method for determining a range to a satellite vehicle with a receiver includes receiving a signal from the satellite vehicle, determining one or more notch filter configurations, determining a pseudorandom noise code and a doppler frequency associated with the signal, determining a codephase correction value based at least on the one or more notch filter configurations, the pseudorandom noise code and the doppler frequency, and computing the range to the satellite vehicle based at least in part on the signal and the codephase correction value.