Radio Altimeter Frequency Modulation Interference
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Solution Overview
Problem
Dual radio altimetry systems on aircraft often experience interference, leading to measurement errors due to the reflection of radioelectric waves, which is challenging to mitigate, especially on small aircraft like drones, and requires differentiated manufacturing for each configuration, increasing costs.
Innovation Solution
A radio altimetry system that dynamically adjusts its frequency modulation ramps based on an identifier, allowing one system to emit a ramp-up signal and the other a ramp-down signal, minimizing interference and eliminating the need for differentiated manufacturing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If two radio altimetry systems are positioned according to distance recommendations to reduce interference, then measurement reliability is improved, but device complexity and installation difficulty increase
Solution Approach 1:
The patent changes the frequency modulation parameters of the radio altimetry systems dynamically. Each system is configured with a specific frequency excursion direction (positive or negative slope) based on an identifier, allowing the systems to operate simultaneously without interference even when positioned close together. This parameter change approach resolves the contradiction by eliminating the need for complex spatial positioning while maintaining measurement reliability.
2Reliability
If radio altimetry systems use fixed slope modulation signals with differentiated manufacturing for dual installation, then interference is reduced, but manufacturing cost increases
Solution Approach 1:
The patent implements a universal radio altimetry system design where a single hardware configuration can operate in both single and dual installations. The system uses an identifier (software/configuration parameter) to determine the frequency excursion direction, eliminating the need for differentiated manufacturing. This universal design resolves the contradiction by maintaining interference reduction capabilities while simplifying manufacturing processes.
Solution Approach 2:
The patent employs parameter changes through dynamic configuration of the modulation signal slope based on the identifier. Instead of manufacturing different hardware versions, the system changes its operational parameters (frequency excursion direction) based on whether it is operating alone or in a dual installation, thereby reducing interference without increasing manufacturing complexity.
3Ease of manufacture
If radio altimetry systems operate with the same frequency modulation parameters, then manufacturing is simplified, but interference between systems increases
Solution Approach 1:
The patent applies parameter changes by configuring the frequency excursion direction (positive or negative slope) based on the identifier assigned to each radio altimetry system. This ensures that systems in a dual installation use different frequency modulation parameters, preventing interference while maintaining manufacturing simplicity through a universal hardware design.
Solution Approach 2:
The patent introduces asymmetry in the frequency modulation parameters of the two radio altimetry systems. By assigning different frequency excursion directions (one positive slope, one negative slope) based on their identifiers, the systems create asymmetric operational characteristics that prevent mutual interference, while the hardware remains symmetric and universal.
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
Ensures operational safety by minimizing interference between dual radio altimetry systems, reducing manufacturing costs, and maintaining performance without the need for customized production.
Implementation Method 1
measuring the propagation time of radio signals transmitted and received after reflection on the ground
Implementation Method 2
measure height by measuring the propagation time of radio signals transmitted and received after reflection on the ground
Implementation Method 3
use the continuous transmission of radio waves modulated in frequency by a modulation signal comprising ramps, with a substantially linear slope, according to a frequency excursion or slope δF, known as FMCW modulation for 'frequency-modulated continuous wave'
Data Source
Figure 1~2
Figure 3~4
Figure 5
AI summary
The system (22) has a radio wave generator generating a radio wave modulated in frequency by a modulating signal having slopes of variation in frequency according to a maximum frequency deviation defined by a parameter. An identifier obtaining module (26) obtains an identifier for distinguishing the radio altimetry system from other system of a dual radio altimeter installation. A parameter selection module (30) defines the maximum frequency deviation of the modulating signal according to the obtained identifier.