Active TCAS Mode S Interrogation for Aircraft Positioning
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Solution Overview
Problem
Current systems fail to accurately determine the position and bearing of non-ADS-B-equipped aircraft due to clock asynchronization and signal interference, leading to potential collisions in high-traffic airports.
Innovation Solution
A method and system that transmit multiple Mode S interrogations, receive responses, and calculate ranges based on time periods, using data from ADS-B-equipped aircraft to improve accuracy, and incorporate a user interface for situational awareness, reducing errors in range and bearing determination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single Mode S interrogation is transmitted to determine range to non-ADS-B-equipped aircraft, then the system can obtain range information, but the range accuracy deteriorates significantly (by 200 feet or more) due to clock asynchronization between TCAS-equipped and non-TCAS-equipped aircraft
Solution Approach 1:
The system transmits multiple Mode S interrogations at different times and processes the returned ranges to determine the most accurate position. This periodic transmission approach allows the system to overcome clock asynchronization issues by collecting multiple measurements and selecting or averaging the most reliable ones, thereby improving range accuracy despite timing differences between aircraft clocks
Solution Approach 2:
The system receives and processes response signals containing range information from multiple interrogations, using this feedback to refine the position determination of non-ADS-B-equipped aircraft. By analyzing the pattern of returned ranges and comparing them against expected values, the system can compensate for clock asynchronization errors and improve measurement precision
2Measurement precision
If bearing is determined using phase or amplitude ratiometric measurements from antenna and bearing processor, then the system can obtain bearing information, but the bearing accuracy deteriorates significantly (by thirty degrees or more) due to antenna sensitivity, obstructions, and signal reflection
Solution Approach 1:
The system combines multiple data sources including ADS-B information, Mode S transponder responses, and radar measurements to determine the position and bearing of aircraft. By merging these different measurement approaches, the system can cross-validate results and achieve more accurate bearing determination while compensating for the limitations of individual methods affected by obstructions and reflections
Solution Approach 2:
The system uses an intermediary processing approach where multiple independent measurement systems (ADS-B, Mode S, radar) provide data that is then synthesized by a central processor. This intermediary layer allows the system to filter out erroneous measurements caused by signal reflections and obstructions by comparing results from multiple sources and selecting the most reliable bearing information
3Measurement precision
If ADS-B systems are mandated on all aircraft by 2020 to enable accurate position tracking, then situational awareness and collision avoidance improve, but the complexity and cost of aircraft equipment increase
Solution Approach 1:
The system is designed to work with multiple types of aircraft equipment including ADS-B, Mode S transponders, and traditional radar systems. By creating a universal tracking system that can process information from various sources, the patent reduces the need for every aircraft to have ADS-B equipment while still achieving accurate position tracking for collision avoidance
Solution Approach 2:
The system leverages existing transponder responses from non-ADS-B-equipped aircraft and uses them directly for position determination without requiring additional specialized equipment on those aircraft. The TCAS-equipped aircraft performs the additional processing work itself, using its own processor to analyze Mode S responses and determine positions, thereby avoiding the need for complex equipment on all aircraft
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 situational awareness by providing accurate range and position data of non-ADS-B-equipped aircraft, reducing collision risks in high-traffic environments through improved clock synchronization and data integration.
Implementation Method 1
A range to the aircraft is determined based on a time period between transmitting the Mode S interrogation and receiving the response
Data Source
AI summary
A method according to the present invention includes transmitting a Mode S interrogation and receiving a response from an aircraft that has received the Mode S interrogation. A range to the aircraft is determined based on a time period between transmitting the Mode S interrogation and receiving the response. The method further includes receiving information from one or more data sources and determining at least one of a bearing to the aircraft and a position of the aircraft using the determined range and the information from the one or more data sources. Information can be received from any number (or type) of data sources, such as ADS-B-equipped aircraft.