Radar Altimeter Interpolation for Precise VTOL Altitude Measurement
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Solution Overview
Problem
Conventional navigation sensors for VTOL aircraft, such as global navigation satellite systems, inertial navigation systems, and radar altimeters, provide insufficient accuracy in urban environments, leading to potential harm during landing.
Innovation Solution
A method and apparatus for radar distance measurement that involves transforming a beat signal from a time domain to a frequency domain, selecting a primary leading edge bin, interpolating within this bin using complex values, and applying interpolation correction values to enhance accuracy, particularly for determining altitude over terrain.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional radar altimeter is used for distance measurement, then the device complexity is low, but the measurement precision is insufficient
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing correction values in a lookup table before actual distance measurement. The correction values are computed based on known relationships between bin indices and true distances, allowing the system to quickly retrieve and apply corrections during operation without performing complex real-time calculations, thus improving measurement precision while keeping device complexity manageable
Solution Approach 2:
The patent introduces an intermediary correction mechanism that bridges the gap between simple bin-based distance estimation and precise distance measurement. The correction values act as an intermediary layer that adjusts the raw bin index measurements to account for systematic errors, enabling accurate distance measurement without requiring complex real-time signal processing algorithms
2Measurement precision
If interpolation is performed within a bin using complex values, then the measurement precision is improved, but the loss of time increases
Solution Approach 1:
The patent applies preliminary action by pre-computing correction values during system initialization or manufacturing and storing them in a lookup table. During actual distance measurement operations, the system simply retrieves the pre-computed correction value corresponding to the measured bin index and applies it directly, avoiding time-consuming real-time interpolation calculations while maintaining high measurement precision
Solution Approach 2:
The system performs self-service by using the measured bin index itself to directly index into the lookup table and retrieve the appropriate correction value. This self-service mechanism eliminates the need for complex real-time computation, as the measurement process automatically provides the key (bin index) needed to retrieve its own correction factor from pre-stored data
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
Enhances the accuracy of distance measurement, reducing the risk of harm to VTOL aircraft and its passengers or cargo by improving altitude determination precision.
Implementation Method 1
receiving a reflected signal, wherein the reflected signal is a portion of a transmitted signal reflected from the surface
Implementation Method 2
using the reflected signal and a signal representative of the transmitted signal, generating a beat signal
Data Source
AI summary
Techniques are provided which enhance accuracy of determining a distance between a body, e.g., of vehicle, (or a radar thereof) to a surface. Accuracy is improved by more accurately interpolating an estimated distance between the body and the surface. For example, a VTOL, such as a UAM, can more accurately determine its altitude over a surface of terrain or structure. Hence, risk of harm, to the VTOL aircraft and/or its passengers and/or cargo, is diminished.