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Development of improved TCAS II surveillance and interference limiting functions

Published in:
Air Traffic Control Q., Vol. 7, No. 1, 1999, pp. 19-46.

Summary

This paper describes the development and validation of improved TCAS II intruder surveillance tracking and interference limiting algorithms. Improvements in interference limiting were prompted by the FAA Spectrum Management Office and by international aviation administrations in order to further reduce interference to ground-based air traffic control surveillance by TCAS II. Improvements in surveillance tracking were prompted by aircarrier pilot organizations in order to increase the level of traffic situational awareness offered by the TCAS II display. The new algorithms are included in a proposed new version of TCAS II MOPS DO-185A which is commonly referred to as Change 7.0. TCAS II change 7.0 units will be introduced into the US airspace beginning as early as 1999 as part of a program to implement improvements in both TCAS II surveillance and collision avoidance.
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Summary

This paper describes the development and validation of improved TCAS II intruder surveillance tracking and interference limiting algorithms. Improvements in interference limiting were prompted by the FAA Spectrum Management Office and by international aviation administrations in order to further reduce interference to ground-based air traffic control surveillance by TCAS II...

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TCAS II use of ADS-B surveillance data through hybrid surveillance

Published in:
Air Traffic Control Q., Vol. 7, No. 2, 1999, pp. 109-121.

Summary

This paper describes a technique that enables TCAS II to use passive surveillance data obtained via extended squitter, an implementation of automatic dependent surveillance broadcast (ADS-B). The technique, known as hybrid surveillance, is based upon the use of TCAS active surveillance to perform validation of the reported ADS-B position at track acquisition. Aircraft that pass initial validation are maintained on passive surveillance until they become a near threat. At that time, TCAS begins regular active surveillance and thus uses its current surveillance techniques for traffic and resolution advisories. In this way, TCAS is able to use passive extended squitter data while retaining its role as an independent monitor. Simulation results show that the use of passive information for non-threatening aircraft results in a significant decrease in TCAS interrogation rate. This enables TCAS to delay or avoid the range reduction that is now required in order for TCAS to remain within its interference budget in high traffic density airspace. Maintaining TCAS operating range in high density air-space enhances TCAS ability to support situational awareness for the flight crew.
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Summary

This paper describes a technique that enables TCAS II to use passive surveillance data obtained via extended squitter, an implementation of automatic dependent surveillance broadcast (ADS-B). The technique, known as hybrid surveillance, is based upon the use of TCAS active surveillance to perform validation of the reported ADS-B position at...

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Analysis of surveillance performance at Chicago O'Hare Airport

Published in:
MIT Lincoln Laboratory Report ATC-193

Summary

This report describes the results of RF measurements of the 1030 and 1090 MHz environment in the Chicago terminal area conducted by Lincoln Laboratory in October 1991. The measurements were made at the request of the FAA in response to reports by controllers in Chicago that TCAS interrogations are affecting the surveillance performance of the Chicago Secondary Surveillance Radar (SSR). The Airborne Meauserements Facility (AMF), developed at Lincoln Laboratory, was used to gather TCAS and SSR interrogation and reply data in the vicinity of O'Hare Airport during periods of active TCAS operation. Simultaneously, local aircraft track data were collected using the Automated Radar Terminal System (ARTS) data recording facility. Analysis of both the AMF data and the ARTS data show that TCAS interrogations do not cause significant degradation in SSR surveillance performance and that the average Chicago ARTS track performance in the presence of TCAS-equipped aircraft is comparable to earlier measurements of track performance in Chicago as well as at a number of other high-density terminal areas. Specific regions within the CHicago surveillance area were observed to contain concentrations of poor ARTS track performance, and analysis of the data has shown the cause to be differential vertical lobing associated with the SSR antenna and faulty Mode S transponders on certain aircarrier aircraft. Both of these problems have subsequently been corrected.
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Summary

This report describes the results of RF measurements of the 1030 and 1090 MHz environment in the Chicago terminal area conducted by Lincoln Laboratory in October 1991. The measurements were made at the request of the FAA in response to reports by controllers in Chicago that TCAS interrogations are affecting...

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Effect of interference on the performance of a minimum TCAS II

Published in:
MIT Lincoln Laboratory Report ATC-132

Summary

Minimum TCAS II equipment is required to operate reliably in all aircraft densities up to the 0.3 transponder-equipped aircraft per square nautical mile anticipated in the Los Angeles Basin in the year 2000. Prototype TCAS equipment has been developed and shown to be capable of providing reliable surveillance in today's highest densities, which reach an average of about 0.1 aircraft per square nmi. Since there are no existing environments that reach the density of asynchronous interference anticipated for the Los Angeles Basin in the year 2000, it is necessary to generate simulated interference to determine the performance of the TCAS II design in that environment. A series of bench tests were conducted at Lincoln Laboratory for this purpose. Special sources were used to generate asynchronous ATCRBS and Mode S reply signals (Fruit) and TCAN/DME squitter and interrogation signals. Synchronous ATCRBS and Mode S reply sequences were also generated to simulate airborne encounters. The performance was evaluated by observing hoe the interference signals either degraded the ability of a TCAS II unit to receive, process, and track the desired synchronous reply sequences, or caused the TCAS II unit to generate false tracks.
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Summary

Minimum TCAS II equipment is required to operate reliably in all aircraft densities up to the 0.3 transponder-equipped aircraft per square nautical mile anticipated in the Los Angeles Basin in the year 2000. Prototype TCAS equipment has been developed and shown to be capable of providing reliable surveillance in today's...

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Mode S installation and siting criteria

Published in:
MIT Lincoln Laboratory Report ATC-99,REV.A

Summary

This paper provides information on site-associated phenomena that affect the proper operation of a Mode S sensor and therefore warrant serious consideration when siting a sensor. The Mode S related discussion is intended to be a supplement to the ATCRBS siting criteria presented in the FAA Primary/Secondary Terminal Radar Siting Handbook. The paper discusses siting criteria as they relate to the Mode S sensor antenna system, as opposed to the ATCRBS hogtrough antenna, and importantly, addresses those characteristics of the surrounding environment that are crucial to proper Mode S surveillance.
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Summary

This paper provides information on site-associated phenomena that affect the proper operation of a Mode S sensor and therefore warrant serious consideration when siting a sensor. The Mode S related discussion is intended to be a supplement to the ATCRBS siting criteria presented in the FAA Primary/Secondary Terminal Radar Siting...

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Radar Beacon Transponder (RBX) installation and siting criteria

Published in:
MIT Lincoln Laboratory Report ATC-106

Summary

The Radar BEacon Transponder (RBX) is a ground-based facility used in conjunction with other elements of the Active Beacon Collision Avoidance System (BCAS) to control the threat detection sensitivity level of BCAS aircraft and to convey displayed Resolution Advisories from the BCAS aircraft to the local ATC terminal facility. This paper describes the mechanisms of specular multipath reflection and signal shadowing and discussed their impact on the RBX link power budget. Criteria for choice of RBX antenna height and location are presented.
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Summary

The Radar BEacon Transponder (RBX) is a ground-based facility used in conjunction with other elements of the Active Beacon Collision Avoidance System (BCAS) to control the threat detection sensitivity level of BCAS aircraft and to convey displayed Resolution Advisories from the BCAS aircraft to the local ATC terminal facility. This...

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Radar Beacon Transponder (RBX) functional description

Published in:
MIT Lincoln Laboratory Report ATC-104

Summary

The Radar Beacon Transponder (RBX) is a ground-based transponder used to control the threat-detection sensitivity level of BCAS aircraft operating in high density terminal airspace. THe RBX is also used to deliver displayed resolution advisories from BCAS to the ATC facility. The normal DABS interrogation waveforms and message formats are used for communication between the RBX and BCAS aircraft. The appropriate BCAS sensitivity level is selected by comparing the BCAS aircraft position with an internally stored sensitivity level map of the surrounding airspace volume. This document provides a functional description of the RBX and shows that reliable performance is achievable in the presence of interference from ATCRBS and BCAS air-to-air interrogations.
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Summary

The Radar Beacon Transponder (RBX) is a ground-based transponder used to control the threat-detection sensitivity level of BCAS aircraft operating in high density terminal airspace. THe RBX is also used to deliver displayed resolution advisories from BCAS to the ATC facility. The normal DABS interrogation waveforms and message formats are...

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The Transportable Measurements Facility (TMF) system description

Published in:
MIT Lincoln Laboratory Report ATC-91
Topic:

Summary

This report describes the MIT Lincoln Laboratory Transportable Measurements Facility (TMF), a special purpose beacon interrogator patterned after the Discrete Address Beacon Sensor. This van-mounted experimental beacon system includes all ATCRBS/DABS reply processing and monopulse processing, but not other DABS processing. It was developed to collect data at various locations in the United States so that candidate DABS sensor antenna and processing could be evaluated in a real environment. The TMF has been installed and operated at: Logan Airport (Boston), Deer Island, MA (near Logan), Washington National Airport (DCA), Philadelphia Int. Airport (PHL), Clementon, NJ (near Philadelphia), Los Angeles Int. Airport (LAX), Brea, CA (25 miles east of LAX), Salt Lake City, UT (SLC), Layton, UT (near Salt Lake City), Las Vegas Airport (LAS), and Green Airport (Warwick, RI).
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Summary

This report describes the MIT Lincoln Laboratory Transportable Measurements Facility (TMF), a special purpose beacon interrogator patterned after the Discrete Address Beacon Sensor. This van-mounted experimental beacon system includes all ATCRBS/DABS reply processing and monopulse processing, but not other DABS processing. It was developed to collect data at various locations...

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DABS installation and siting criteria

Published in:
MIT Lincoln Laboratory Report ATC-99

Summary

This paper provides information on site-associated phenomena that affect the proper operation of a DABS sensor and therefore warrant serious consideration when siting a radar. The DABS-related discussion is intended to be a supplement to the ATCRBS siting criteria presented in the FAA Primary/Secondary Terminal Radar Siting Handbook. The paper discusses siting criteria as they relate to the DABS sensor antenna system, as opposed to the ATCRBS hogtrough antenna, and importantly, addresses those characteristics of the surrounding environment that are crucial to proper DABS/ATARS surveillance.
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Summary

This paper provides information on site-associated phenomena that affect the proper operation of a DABS sensor and therefore warrant serious consideration when siting a radar. The DABS-related discussion is intended to be a supplement to the ATCRBS siting criteria presented in the FAA Primary/Secondary Terminal Radar Siting Handbook. The paper...

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