Antenna Positioning by Transponder Ranging Under GNSS Jamming
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Solution Overview
Problem
The challenge in accurately calculating the position of an antenna on a moving vehicle, such as a VTOL aircraft, during landing on a moving platform like a vessel is exacerbated by susceptibility to jamming and interference, particularly when GNSS signals are unreliable, necessitating a robust and reliable navigation system.
Innovation Solution
A method involving range measurements between the antenna and at least three transponders with known positions, using a first coordinate to predict and optimize the antenna's position through an optimization process, which includes calculating and subtracting predicted ranges to minimize a figure of merit, thereby enhancing the robustness of position calculation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If GNSS receivers are used for navigation, then positioning capability is provided, but susceptibility to jamming and interference increases
Solution Approach 1:
The patent introduces transponders as intermediary devices installed on the vessel, which reflect or retransmit signals from the antenna. This intermediary system enables positioning without direct reliance on external GNSS signals, thereby eliminating susceptibility to GNSS jamming while maintaining navigation reliability
2Reliability
If transponders are installed on the vessel for positioning, then robustness against jamming is improved, but system complexity increases
Solution Approach 1:
The transponders serve multiple functions: they act as position reference points for the antenna, and their known positions on the vessel provide a stable geometric reference system. This multi-functionality reduces the need for separate systems while maintaining positioning robustness
Solution Approach 2:
The patent uses the known geometric relationships between transponders (copied from the vessel's fixed structure) to create a virtual reference framework. This allows the system to leverage the vessel's existing structure without adding complex positioning infrastructure
3Measurement precision
If optimization processes are performed to enhance position calculation robustness, then positioning accuracy is improved, but computational time increases
Solution Approach 1:
The patent performs preliminary calculations of expected range differences based on the antenna's provided coordinate and the known transponder positions. By pre-computing these expected values, the optimization process requires fewer iterative steps to converge, reducing computational time while maintaining accuracy
Solution Approach 2:
The system uses feedback from comparing calculated range differences with expected range differences to iteratively refine the antenna position estimate. This feedback mechanism ensures high positioning accuracy by continuously correcting errors while the iterative nature allows for efficient convergence
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 allows for more accurate and robust position calculation of the antenna, enabling precise landing maneuvers even in challenging environments with reduced solver failures, as demonstrated by Monte-Carlo simulations.
Implementation Method 1
measures the time delay until an answer is received. This time delay—potentially corrected for a fixed delay deliberately introduced by the transponder—corresponds to twice the time of flight of the signal between the antenna of the VTOL aircraft and the respective transponder. The multiplication of the time of flight with the speed of light then yields the range
Data Source
AI summary
A method for position calculation of an antenna is provided. The method comprises calculating ranges between the antenna and the at least three transponders. The calculation includes range measurements between an antenna and at least three transponders. Respective positions of the at least three transponders are known. The method further comprises providing a first coordinate of three coordinates. The three coordinates indicate a position of the antenna. The method further comprises calculating second and third coordinates of the three coordinates based on the calculated ranges between the antenna and the at least three transponders. The method further comprises predicting ranges between the antenna and the at least three transponders based on the provided first coordinate and the calculated two coordinates. The method further comprises performing an optimization process based on the calculated ranges and the predicted ranges to infer an optimized position of the antenna. Further, a system for position calculation and an air vehicle comprising the system are provided.