Aircraft Height Data Validation Using Radar and Navigation Fusion
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Solution Overview
Problem
Radar altimeters in aircraft struggle to provide instant height above the landing threshold point (HATh) information due to limitations in navigation system accuracy and the periodic scanning of airborne radar systems, which results in errors and limited availability of accurate altitude data during precision approach procedures.
Innovation Solution
A system that combines radar-based reflection data with vertically-travelled data, processed at a faster rate than reflection data, to generate and update instant height data, allowing for independent validation of navigation data sources and providing real-time HATh information through a processor that integrates data from multiple sources, including radar systems and navigation systems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If satellite navigation system is used to determine HATh, then HATh information can be obtained, but navigation performance accuracy required by RNP standards is not achieved
Solution Approach 1:
The patent combines satellite navigation system with airborne radar system to determine HATh. The radar system provides high-precision range measurements to the runway threshold point, while the navigation system provides geographic position information. By merging these two independent measurement systems, the patent achieves both RNP accuracy requirements and continuous HATh information, resolving the contradiction between measurement precision and reliability.
2Measurement precision
If airborne radar system is used to provide HATh information, then instant HATh data can be obtained, but the information is limited to periodic calculation at slow rate due to full scene scanning
Solution Approach 1:
The patent extracts the specific function of measuring range to the runway threshold point from the full scene scanning radar system. By dedicating the radar to this specific measurement task rather than continuous full scene scanning, the system achieves both high update rates and accurate HATh information, resolving the contradiction between measurement precision and productivity.
3Reliability
If radar altimeter is used for precision approach, then decision height information can be provided, but instant height above LTP information is not available because LTP is not beneath aircraft
Solution Approach 1:
The patent introduces an intermediary calculation method that uses the radar's range measurement to the LTP and the aircraft's geographic position from the navigation system to compute HATh. This intermediary approach allows derivation of instant HATh information without requiring the LTP to be directly beneath the aircraft, thus resolving the information loss while maintaining reliability for precision approach.
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 solution enables accurate and continuous generation of aircraft height data, validating altitude information and providing timely HATh data, thereby enhancing the reliability of precision approach procedures by reducing errors associated with navigation system inaccuracies and periodic radar scanning limitations.
Implementation Method 1
A radio altimeter, commonly referred to as a radar altimeter, is a system used for accurately measuring and displaying the height above terrain directly beneath an aircraft. A typical system could be comprised of a receiver-transmitter unit, antenna(s) for transmitting a signal to the terrain and receiving of such signal reflected by the terrain
Data Source
AI summary
Present novel and non-trivial systems and methods for generating aircraft height data are disclosed. A processor is configured to receive both first data comprised of radar-based reflection data of a stationary reference point based upon a horizontal distance between the geographic position of an aircraft and the geographic position of the stationary reference point (e.g., landing threshold point) and second data comprised of internally sourced vertical travel data more frequently than the first data. From the first data and second data, an instant vertical distance above the stationary reference point is determined by updating the first data with the second data. Then, instant height data representative of the instant vertical distance above the stationary reference point is generated. Provided with the instant height data, a presentation system comprised of display unit, aural alert unit and/or a tactile alert unit may present the instant vertical distance to the pilot.