Beacon-Based Approach Guidance with PRN Signal Correlation
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Solution Overview
Problem
VTOL aircraft, particularly passenger-carrying autonomous commercial aircraft, require precise guidance and redundant systems for landing, necessitating complex and costly software development and infrastructure, which can be time-consuming and unreliable.
Innovation Solution
A beacon-based approach guidance system using a ground-based beacon that transmits a signal modulated with a pseudorandom noise (PRN) code, received by an antenna array on the vehicle, which is down-converted and digitized to determine the vehicle's heading and elevation relative to the beacon, utilizing CDMA and DSSS signals to minimize interference and multipath signals.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If complex software and redundant guidance systems are implemented for VTOL aircraft landing, then reliability and precision positioning are improved, but device complexity and cost increase
Solution Approach 1:
The patent introduces ground-based beacons as intermediary devices that transmit pseudorandom noise codes to the aircraft. These beacons serve as mediators between the landing infrastructure and the aircraft's guidance system, enabling precise positioning through signal correlation and direction of arrival calculations without requiring complex onboard software or multiple redundant systems
Solution Approach 2:
The system uses pseudorandom noise codes that are transmitted from ground beacons and copied/correlated by the aircraft receiver. By correlating the received signal with locally generated pseudorandom codes, the system achieves precise timing and position information without needing complex processing algorithms
2Measurement precision
If complex software development is undertaken for regulatory certification, then guidance precision is improved, but time consumption and certification difficulty increase
Solution Approach 1:
The patent replaces complex software-based guidance systems with a physics-based signal processing approach using pseudorandom noise correlation and direction of arrival calculations. This substitution of mathematical/physical principles for complex software algorithms reduces certification requirements and development time while maintaining high positioning precision
Solution Approach 2:
The system achieves precise positioning by measuring and analyzing parameters such as signal phase differences, time delays, and direction of arrival angles from multiple ground beacons. By focusing on precise parameter measurement rather than complex software control, the system reduces certification complexity and development time
3Object-affected harmful factors
If pseudorandom noise codes and CDMA signals are used, then interference and multipath signals are reduced, but signal processing complexity increases
Solution Approach 1:
The patent uses pseudorandom noise codes that have the property of being uncorrelated with themselves at different time delays. This converts the potential harm of signal interference into a benefit where multipath signals and interference automatically cancel out during correlation processing, as they do not align with the expected signal timing
Solution Approach 2:
The ground-based beacon system serves multiple functions simultaneously: it provides positioning information, velocity information through Doppler shift measurement, and guidance information through direction of arrival calculations. This multi-functionality is achieved through a single unified signal structure using pseudorandom noise codes, reducing overall system complexity
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 system reduces complexity and cost, enhances reliability, and allows for easy deployment with deterministic state machines, eliminating the need for complex software certification, while providing precise guidance with minimal interference and multipath rejection.
Implementation Method 1
an antenna array of a receiver of a vehicle to digitized data streams of I and Q samples, the at least one signal received from a beacon, the at least one signal modulated with a pseudorandom code at the beacon
Implementation Method 2
down convert and digitize signals received at the antenna array to baseband I and Q samples
Implementation Method 3
correlate the I and Q samples to a locally generated pseudorandom code to align the received signals in time
Implementation Method 4
recover carrier signals by modulating the received signals with a synchronized pseudorandom noise (PRN) code to despread the received signals
Implementation Method 5
calculate, based on relative phase characteristics of the recovered carrier signals, a heading and an elevation of a direction of arrival of the signal transmitted from the beacon in a vehicle reference frame
Data Source
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AI summary
A beacon-based approach guidance system is disclosed. A disclosed method includes digitizing at least one signal received at an antenna array of a receiver of a vehicle to digitized data streams of I and Q samples, the at least one signal received from a beacon, the at least one signal modulated with a pseudorandom code at the beacon, correlating the I and Q samples to a locally generated pseudorandom code of the receiver to recover carrier signals, and calculating, based on relative phase characteristics of the recovered carrier signals, a direction of arrival of the at least one signal from the beacon in a vehicle reference frame.