Radar Beat-Signal 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-based 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 surfaces.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional navigation sensors (radar altimeters, inertial navigation systems) are used for VTOL aircraft, then the device complexity is reduced, but the measurement precision of altitude is insufficient
Solution Approach 1:
The patent applies parameter changes by transforming the measurement approach from direct range bin selection to interpolated distance calculation. The system changes the parameter representation from discrete bin indices to continuous distance values through interpolation techniques (quadratic, Gaussian, or parabolic interpolation), thereby improving measurement precision without adding hardware complexity
Solution Approach 2:
The patent implements preliminary action by pre-calculating and storing correction values in lookup tables during system initialization or calibration phases. These correction values compensate for interpolation errors in advance, allowing the system to achieve high precision measurements during operation without real-time computational overhead
2Measurement precision
If interpolation techniques with correction values are applied, then the measurement precision is improved, but the loss of time increases due to additional processing steps
Solution Approach 1:
The patent resolves the time penalty by performing interpolation corrections in advance. Lookup tables are pre-computed and stored during system initialization, containing correction values that account for interpolation errors. During actual distance measurement, the system simply retrieves pre-computed values rather than performing complex real-time calculations, thus maintaining high precision while minimizing processing time
Solution Approach 2:
The patent uses copying by creating simplified representations of complex interpolation relationships. Instead of performing full interpolation calculations during measurement, the system copies pre-computed correction data from lookup tables into the active measurement process, effectively replicating the results of complex calculations in a time-efficient manner
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
Conventional navigation sensors including global navigation satellite system receiver(s), inertial navigation system(s), barometric altimeter(s), and radar altimeter(s) provide insufficient accuracy
Implementation Method 2
receiving a reflected signal, wherein the reflected signal is a portion of a transmitted signal reflected from the surface
Implementation Method 3
using the reflected signal and a signal representative of the transmitted signal, generating a beat signal
Data Source
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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.