GNSS Receiver Parameter Change Detection for Multipath Error Correction
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Solution Overview
Problem
Global Navigation Satellite System (GNSS) receivers face inaccuracies in position determination due to multipath effects, particularly in heavily multipath areas where signals from low-elevation satellites are affected, leading to erroneous pseudorange measurements and incorrect altitude calculations.
Innovation Solution
A receiver apparatus and method that includes a parameter change detector and error determiner to identify sudden changes in parameters such as altitude and clock offset, using environmental information to determine if changes are erroneous, and taking corrective actions like modifying pseudorange measurements or searching for direct line-of-sight signals to mitigate errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If signals from low-elevation satellites are used for positioning, then the receiver can maintain position estimation in multipath areas, but the pseudorange measurements become erroneous due to multipath effects
Solution Approach 1:
The system continuously monitors receiver parameters (altitude, clock offset) and compares changes against thresholds to detect multipath conditions. When multipath is detected, the system feeds back by adjusting or rejecting affected satellite signals, thereby maintaining position estimation continuity while improving measurement precision through selective signal rejection.
Solution Approach 2:
The patent replaces direct reliance on signal strength-based multipath rejection with a parameter-change detection mechanism. Instead of using traditional signal processing methods to filter multipath, the system substitutes a monitoring approach that detects parameter anomalies (sudden altitude changes, clock offset shifts) and uses these detections to identify and correct multipath errors, achieving both continuity and precision.
2Measurement precision
If parameter changes are detected and corrected, then measurement precision improves, but device complexity increases due to additional detection and determination circuits
Solution Approach 1:
The parameter change detector and parameter error determiner are designed to handle multiple types of errors (altitude errors, clock offset errors, multipath effects) using a unified approach. The same detection mechanism works for different satellite configurations and error types, making the added complexity worthwhile by providing comprehensive error correction across multiple scenarios rather than requiring separate correction systems for each error type.
Solution Approach 2:
The system changes the approach from modifying signal processing algorithms to monitoring parameter changes. By detecting changes in receiver parameters (altitude, clock offset) and using these parameter changes as indicators of multipath conditions, the system achieves error correction through parameter monitoring rather than complex signal manipulation, thereby limiting the increase in device complexity.
Data Source
AI summary
A receiver receiving global positioning data from one or more satellites above the Earth's surface detects a change in at least one parameter associated with the receiver and determines if the change is to be treated as erroneous. As a result of determining if the change in the at least one parameter is to be treated as erroneous, a further action may be performed. Determining if the change is to be treated as erroneous may include, for example, detecting changes in more than one parameter and determining if the changes are coincident. Detecting the change may also enable the receiver to predict the presence and magnitude of multipath components of signals, predict changes in an environment local to the receiver, predict large errors in position estimates determined by the receiver and modify an acquisition and tracking strategy used by the receiver.