Radio Altimeter Fusion With Millimeter-Wave Radar Against 5G Interference
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Solution Overview
Problem
Conventional RF front-end filters fail to suppress spurious 5G signals interfering with radio altimeters, leading to reduced filter efficiency and increased interference as aircraft altitude decreases, impacting radio altimeter operation.
Innovation Solution
A system utilizing a primary radio altimeter and a secondary millimeter wave radar sensor to detect and mitigate 5G interference by correlating altitude estimates and applying correction factors, discarding or processing signals based on altitude thresholds and signal abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If RF front-end filters are used to mitigate 5G interference, then out of band 5G noise is suppressed, but spurious signals leaked into the radio altimeter band cannot be suppressed
Solution Approach 1:
The patent combines multiple mitigation techniques including RF front-end filtering, digital signal processing, and frequency hopping into a unified interference mitigation system. This hybrid approach addresses both out-of-band and in-band spurious signals by layering multiple defense mechanisms rather than relying on filtering alone.
Solution Approach 2:
The system dynamically changes operating parameters such as frequency offset and signal processing filters based on detected interference conditions. When 5G interference is detected, the radio altimeter adjusts its frequency offset from the nominal value and applies adaptive digital filters to maintain measurement accuracy despite the presence of spurious signals.
2Object-affected harmful factors
If RF front-end filters are used, then filtering is effective at higher altitudes, but filter efficiency reduces as frequency separation between 5G band and radio altimeter band narrows at lower altitudes
Solution Approach 1:
The system implements dynamic frequency offset adjustment where the radio altimeter continuously monitors for 5G interference and adjusts its operating frequency in real-time. This dynamic adaptation allows the system to maintain measurement precision across varying altitude conditions where the frequency separation changes, rather than relying on a static filter design.
Solution Approach 2:
The patent incorporates feedback mechanisms where altitude measurement data and interference detection results are continuously monitored and fed back to adjust signal processing parameters. This closed-loop control enables the system to compensate for reduced filter efficiency at lower altitudes by applying digital corrections based on detected interference patterns.
3Device complexity
If only primary radio altimeter is used, then system complexity is low, but reliability decreases when 5G interference impacts radio altimeter operation at low altitudes
Solution Approach 1:
The patent applies different processing qualities to different altitude regions. At higher altitudes where interference is minimal, the system uses standard processing to maintain low complexity. At lower altitudes where 5G interference becomes significant, the system automatically activates enhanced signal processing and frequency offset adjustment mechanisms, applying complexity only where locally needed to maintain reliability.
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
Effectively mitigates 5G interference by ensuring accurate altitude estimation through a secondary radar altimeter, maintaining radio altimeter operation at lower altitudes.
Implementation Method 1
a secondary radio altimeter comprising a millimeter wave radar sensor onboard the vehicle
Implementation Method 2
a primary radio altimeter onboard the vehicle and operatively connected to the RF antenna
Data Source
AI summary
A system comprises a RF antenna connected to a vehicle, a primary radio altimeter connected to the antenna, a secondary radio altimeter comprising a millimeter wave radar sensor, and a processor coupled to the primary and secondary radio altimeters. The processor determines whether an altitude detected by the primary radio altimeter is greater than a threshold altitude. If the altitude is greater than the threshold altitude, the altitude detected is used and signals from the secondary radio altimeter are discarded. If the altitude is not greater than the threshold altitude, the processor identifies whether signal interference from a cellular network source is present based on any abnormal signals from the primary radio altimeter. If abnormal signals are not present, altitude estimates detected by the primary and secondary radio altimeters are correlated. If abnormal signals are present, signals from the secondary radio altimeter are processed to detect a vehicle altitude.