GNSS Receiver Multipath Error Detection Using Code-Minus-Carrier Delta Range
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Solution Overview
Problem
Current GNSS receivers face challenges in accurately detecting multipath errors, especially in urban areas where high house facades block satellite signals, leading to position inaccuracies, and existing methods require a minimum number of satellite signals or introduce complexity, which is not feasible for moving receivers like those in motor vehicles.
Innovation Solution
The method generates a 'Code-Minus-Carrier Delta Range' (CMCD) evaluation variable by taking the difference of the time derivative of run-time and Doppler distances, allowing for multipath error detection using a single satellite signal without reference infrastructure, and is robust against cycle slips and dynamic changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If existing multipath error detection methods are used, then position accuracy can be improved, but the device complexity increases due to requiring multiple satellite signals and reference infrastructure
Solution Approach 1:
The patent extracts and utilizes only the necessary components (run-time gap and carrier-phase gap from a single satellite signal) to detect multipath errors, eliminating the need for complex reference infrastructure and multiple satellite signals required by traditional methods
Solution Approach 2:
The evaluation variable serves multiple functions: it detects multipath errors, operates with a single satellite signal, and works in dynamic situations without requiring reference infrastructure, making the system versatile and applicable in urban environments
2Measurement precision
If existing multipath error detection methods are used, then position accuracy can be improved, but the number of required satellite signals increases
Solution Approach 1:
The patent extracts and utilizes only the necessary components (run-time gap and carrier-phase gap from a single satellite signal) to detect multipath errors, eliminating the need for multiple satellite signals required by traditional methods
Solution Approach 2:
The patent achieves full multipath error detection capability with a single satellite signal, which is fewer than the multiple signals traditionally required, demonstrating that partial action (single signal) can achieve the same effect as excessive action (multiple signals)
3Measurement precision
If carrier-phase measurement is used for distance measurement, then measurement precision can be improved, but reliability decreases due to loss of lock and cycle slips
Solution Approach 1:
The patent merges run-time measurement and carrier-phase measurement into a combined evaluation variable, leveraging the precision of carrier-phase while the run-time component provides robustness against cycle slips and loss of lock
Solution Approach 2:
The patent prepares for potential cycle slips by designing an evaluation variable that is insensitive to them, cushioning against future reliability issues before they occur
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 enables reliable multipath error detection in dynamic situations, reducing complexity and the need for multiple satellite signals, and is independent of reference data, providing robustness against ionosphere and troposphere errors, thus improving positioning accuracy in urban environments.
Implementation Method 1
carrier-phase measurement, which uses Doppler measurements in which the carrier frequency phase and its change is analyzed
Data Source
AI summary
A method is disclosed for evaluating a satellite signal in a global navigation satellite system with regard to a multipath error, wherein a receiver determines a run-time gap between the receiver and a satellite based on a run-time measurement from the satellite signals of several satellites and a carrier-phase gap based on the carrier-phase measurement between the receiver and the satellite or a reference point, wherein a difference of the time derivative of the run-time gap and of the carrier-phase gap is formed in the receiver as an evaluation variable, which is evaluated using at least one multipath criterion for the presence of a multipath error.