Upper Lower Antenna Beam Multipath Mitigation
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Solution Overview
Problem
Aircraft systems receiving Automatic Dependent Surveillance-Broadcast (ADS-B) messages often experience signal loss due to multipath interference, where original and multipath signals cancel or interfere with each other, especially in environments with reflective surfaces like the ground or buildings, leading to inaccurate bearing calculations and loss of ADS-B signals.
Innovation Solution
The system monitors and processes signals from both upper and lower antenna beams simultaneously, determining which beam has the strongest or least interference to ensure accurate ADS-B signal reception, using phase differences and error correction techniques to mitigate multipath effects and recover data.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single antenna beam is used to receive ADS-B signals, then the device complexity is reduced, but the reliability of signal reception deteriorates due to multipath interference causing signal cancellation
Solution Approach 1:
The antenna system is segmented into multiple independent beams (upper and lower beams) that can be monitored separately. Each beam provides an independent signal path, allowing the system to segment the reception function across multiple beams to mitigate multipath interference effects on any single beam.
Solution Approach 2:
The system changes the spatial parameter of signal reception by utilizing beams at different angular positions (upper and lower beams). This parameter change in beam orientation allows the system to receive signals from different geometric paths, reducing the impact of multipath interference that affects specific beam directions.
2Reliability
If multiple antenna beams are monitored simultaneously to mitigate multipath interference, then the reliability of signal reception is improved, but the device complexity increases
Solution Approach 1:
The monitoring functions for upper and lower beams are merged into a unified signal processing system. The processor combines the monitoring of both beams and applies error correction techniques jointly, merging the capabilities to handle multipath interference across different beam configurations rather than treating them as separate independent systems.
Solution Approach 2:
The system implements feedback through error correction techniques that monitor signal quality from multiple beams and adjust processing accordingly. The processor uses feedback from signal strength and quality measurements to determine which beam provides the most reliable signal and applies appropriate error correction to maintain reception reliability.
3Measurement precision
If signal processing uses both upper and lower beam data, then the measurement precision of bearing calculations is improved, but the loss of time for signal processing increases
Solution Approach 1:
The system performs preliminary monitoring of both upper and lower beams simultaneously to assess signal quality before final processing. By preliminarily evaluating which beam has the strongest signal or least interference, the system prepares the optimal signal path in advance, reducing the time required for bearing calculations while maintaining precision.
Solution Approach 2:
The system applies partial processing by focusing computational resources on the beam that provides the most reliable signal. Rather than fully processing both beams with equal computational effort, the system performs excessive monitoring on both beams but applies detailed processing only to the optimal beam, reducing overall processing time while maintaining measurement precision.
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 approach effectively mitigates multipath interference, allowing for reliable ADS-B signal reception and accurate bearing measurements, even in environments where multipath propagation nulls or interferes with direct signals, enhancing the accuracy and reliability of ADS-B message decoding.
Implementation Method 1
using phase differences and error correction techniques to mitigate multipath effects
Data Source
AI summary
Multipath mitigation can be performed in a surface environment by various systems and methods. For example, antenna beams from multiple antennas can be used to reduce the impact of multipath on a received signal. Thus, a method can include monitoring for a signal on at least one upper antenna beam of an aircraft. The method can also include monitoring for the signal on at least one lower antenna beam of the aircraft while monitoring on the at least one upper antenna beam. The method can further include processing the signal received by the at least one upper antenna beam and/or the at least one lower antenna beam.