Runway Zone Multipath Detection for Aircraft Ground Positioning
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Solution Overview
Problem
Satellite positioning systems, such as GPS, face accuracy and integrity issues on the ground due to local clock errors, receiver mobility, ionospheric variations, and multipath phenomena, which disrupt position measurements and confidence levels, especially in complex airport environments requiring high precision and safety.
Innovation Solution
A method to determine a rectangular runway zone with specific dimensions relative to the runway threshold, minimizing multipath electromagnetic illumination, and using this zone to ensure accurate and hybrid position information generation, combining GPS data with inertial data to achieve high integrity positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If GPS satellite positioning system is used for aircraft ground navigation, then position information can be obtained, but accuracy and integrity are compromised due to multipath phenomena and signal interference in airport environments
Solution Approach 1:
The patent segments the airport ground area into multiple zones based on multipath risk levels. A no-fly zone is defined around buildings and structures where multipath interference is severe, while safe zones are identified where GPS signals remain reliable. This spatial segmentation allows the system to selectively use GPS positioning only in areas where accuracy requirements can be met.
Solution Approach 2:
The patent introduces an intermediary ground-based reference system (such as ground stations or beacons) that works in conjunction with GPS satellite signals. This intermediary system provides additional positioning references that help compensate for GPS signal degradation caused by multipath effects, thereby improving overall position measurement accuracy in challenging airport environments.
2Duration of action of stationary object
If hybridization between GPS data and aircraft inertial data is used, then positioning continuity is improved, but integrity is reduced due to accumulation of inertial errors
Solution Approach 1:
The patent implements dynamic switching between different positioning modes based on real-time assessment of signal quality and aircraft location. When GPS signals are reliable (in safe zones), the system uses GPS primary positioning. When GPS signals degrade (in no-fly zones or during multipath events), the system dynamically transitions to inertial navigation or ground-based reference systems, thereby maintaining positioning continuity while managing error accumulation through periodic re-synchronization.
3Reliability
If banks of sub-filters with FDE type satellite failure detection are employed, then integrity is improved, but device complexity increases
Solution Approach 1:
The patent applies local quality by implementing integrity monitoring and FDE (Fault Detection and Exclusion) selectively in regions and conditions where it is most needed. Rather than deploying complex filter banks uniformly across all operations, the system activates enhanced integrity monitoring primarily in no-fly zones, during critical phases of ground operations, or when GPS signal quality deteriorates. This targeted approach maintains high reliability where required while avoiding unnecessary complexity in benign operating conditions.
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 provides accurate and reliable position information with a confidence level of 10^-7, reducing the impact of multipath interference and ensuring safe navigation and positioning on the ground, even in complex airport conditions.
Implementation Method 1
multipath phenomena, which disrupt the accuracy of the position measurement... electromagnetic fields diffracted by obstacles in the vicinity of the receiver antenna, such as for instance buildings, are transformed into echo signals called multipath signals
Implementation Method 2
the message is superimposed on a code that contains the time reference. The synchronization of signals is obtained through atomic clocks on board of each satellite. The receiver compares the shift between the received signal and the locally generated signal in the receiver and measures in this way the distance of the corresponding satellite
Data Source
AI summary
An assist device for ensuring the accuracy and integrity of position information of an aircraft on the ground includes a processing unit for determining in the airport (AE) a zone (ZP) of insensitivity to multipath GPS signals, the zone (ZP) having a rectangular shape, which is determined relative to the threshold (O) of the runway, and which has a length (L1) equal to the length of the runway and a width (L2) depending on a maximum illumination distance (D). The device further includes a unit for verifying, while the aircraft is moving in the airport (AE), whether the position relative to position information of the aircraft is inside said runway zone (ZP). A method for ensuring the accuracy and integrity of position information of an aircraft on the ground is also disclosed herein.