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Traffic Alert and Collision Avoidance System (TCAS): a functional overview of active TCAS I

April 8, 1983
  |
Project Report
Author:
Vincent A. Orlando
…
Published in:
MIT Lincoln Laboratory Report ATC-118
Topic:
collision avoidance
R&D area:
R&D group:

Summary

The Traffic Alert and Collision Avoidance System (TCAS) is a beacon-based airborne collision avoidance system that is able to operate in all airspace without reliance on ground equipment. The TCAS concept encompasses a range of capabilities that include TCAS I, a low-cost, limited-performance version, and TCAS II, which is intended to provide a comprehensive level of separation assurance in all current and predicted airspace enviornments through the end of this century. This document provides a functional overview of a TCAS I equipped with a low power active transponder detector. It includes a definition of TCAS I functions, calculated and measured surveillance performance for a low power interrogator and an implementation approach that incorporates the TCAS I functions in a Mode S transponder.
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Summary

The Traffic Alert and Collision Avoidance System (TCAS) is a beacon-based airborne collision avoidance system that is able to operate in all airspace without reliance on ground equipment. The TCAS concept encompasses a range of capabilities that include TCAS I, a low-cost, limited-performance version, and TCAS II, which is intended...

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Traffic Alert and Collision Avoidance System (TCAS): a functional overview of active TCAS I

TCAS I design guidelines

September 24, 1982
  |
Project Report
Author:
William H. Harman III
…
Published in:
MIT Lincoln Laboratory Report ATC-114
Topic:
collision avoidance
R&D area:
R&D group:

Summary

A description of the FAA airborne Traffic Alert and Collision Avoidance System known as TCAS I introduces the main topic of the report: results of an investigation of simple techniques suitable for the passive and active detection of nearby aircraft by TCAS I. This is followed by a review of the measurement facilities and data used to evaluate the detection techniques. Techniques for identifying passively detected returns from potentially threatening aircraft, i.e., the rejection or "filtering out" of non-threat aircraft, are described and evaluated. Alternatives for time-sharing the 1090 MHz channel between the TCAS I transponder and the passive detector are described. A candidate passive detector is defined and its performance is evaluated using flight test data. Predictions of the performance of a low-power TCAS I based on active detection are made via link calculations and flight test measurements. A summary of results concludes the report.
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Summary

A description of the FAA airborne Traffic Alert and Collision Avoidance System known as TCAS I introduces the main topic of the report: results of an investigation of simple techniques suitable for the passive and active detection of nearby aircraft by TCAS I. This is followed by a review of...

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TCAS I design guidelines

Active Beacon Collision Avoidance System (BCAS) functional overview

December 17, 1980
  |
Project Report
Author:
Jerry D. Welch
…
Published in:
MIT Lincoln Laboratory Report ATC-102
Topic:
collision avoidance
R&D area:
R&D group:

Summary

The Active Beacon Collision Avoidance System (BCAS) is a beacon-based airborne collision avoidance system that provides for cooperative threat resolution between BCAS and conflicting aircraft and coordination with the ground ATC control function through the DABS data link. All beacon-equipped aircraft in the vicinity of the BCAS are detected. ATCRBS-equipped aircraft are interrogated using a special Mode C interrogation. DABS aircraft are initially detected passively. Those aircraft that represent a possible threat are discretely interrogated to maintain a range/altitude track. This document provides a functional overview of BCAS including operational features, a description of the avionics package, and examples of surveillance data obtained with experimental BCAS equipment. The results show that reliable surveillance performance is achieved in low and medium density airspace.
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Summary

The Active Beacon Collision Avoidance System (BCAS) is a beacon-based airborne collision avoidance system that provides for cooperative threat resolution between BCAS and conflicting aircraft and coordination with the ground ATC control function through the DABS data link. All beacon-equipped aircraft in the vicinity of the BCAS are detected. ATCRBS-equipped...

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Active Beacon Collision Avoidance System (BCAS) functional overview

Active BCAS: design and validation of the surveillance subsystem

December 17, 1980
  |
Project Report
Author:
William H. Harman III
…
Published in:
MIT Lincoln Laboratory Report ATC-103
Topic:
collision avoidance
R&D area:
R&D group:

Summary

Lincoln Laboratory, under FAA sponsorship, is developing an Active Beacon Collision Avoidance System (BCAS), concentrating primarily on the air-to-air surveillance subsystem. The surveillance functions required are to detect the presence of nearby aircraft (whether they are equipped with ATCRBS transponders or DABS transponders), and then generate a surveillance track on each aircraft, issuing range and altitude reports once per second. The development effort consisted of airborne measurements complemented by simulation studies and analyses. The basic effects of ground-bounce multipath, interference, and power fading were assessed by air-to-air measurements. In other measurements, the BCAS interrogation and reply signal formats were transmitted between aircraft, and the results recorded for later playback and computer processing using the BCAS surveillance algorithms. This is a flexible means of experimentation which allows many of the design parameters to be changed as the effects are noted. In the most recent phase of the program, Lincoln designed and built realtime BCAS Experimental Units (BE Us), flight tested them, and then delivered them to the FAA for more extensive flight testing. In one of these flight tests, a BEU-equipped Boeing 727 flew to New York, Atlanta, and other major terminal areas in the eastern U.S. An analysis of BEU performance during this "Eastern Tour" is given in this report.
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Summary

Lincoln Laboratory, under FAA sponsorship, is developing an Active Beacon Collision Avoidance System (BCAS), concentrating primarily on the air-to-air surveillance subsystem. The surveillance functions required are to detect the presence of nearby aircraft (whether they are equipped with ATCRBS transponders or DABS transponders), and then generate a surveillance track on...

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Active BCAS: design and validation of the surveillance subsystem

Proposed technical characteristics for the Discrete Address Beacon System (DABS)

September 30, 1977
  |
Project Report
Author:
Jerry D. Welch
…
Published in:
MIT Lincoln Laboratory Report ATC-71
Topic:
surveillance
R&D area:
R&D group:

Summary

This report parallels the Proposed U. S. National Aviation Standard for the Discrete Address Beacon System. However, in addition to the material contained in the Proposed Standard this document provides a more detailed performance specification for the DABS transponder including specifications on transponder receiver sensitivity and performance in interference. It includes specifications for a proposed digital datalink interface and defines message and control fields associated with experimental transponder data applications. It also includes guidance material on the performance of an optional transponder antenna diversity scheme.
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Summary

This report parallels the Proposed U. S. National Aviation Standard for the Discrete Address Beacon System. However, in addition to the material contained in the Proposed Standard this document provides a more detailed performance specification for the DABS transponder including specifications on transponder receiver sensitivity and performance in interference. It...

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Proposed technical characteristics for the Discrete Address Beacon System (DABS)

Beacon CAS (BCAS) an integrated air/ground collision avoidance system

March 23, 1976
  |
Project Report
Author:
Vincent A. Orlando
…
Published in:
MIT Lincoln Laboratory Report ATC-62
Topic:
surveillance
R&D area:
R&D group:

Summary

BCAS is a DABS-based airborne collision avoidance system that exploits the feature of DABS discrete addressing and integral data link. This provides for a CAS with the unique capabilities of (1) cooperative threat resolution between BCAS and conflicting aircraft through the transmission of maneuver intent (to DABS-only aircraft) and tie breaking (with other BCAS aircraft) and (2) coordination of CAS activities with the ground ATC control function through the DABS air-ground-air data link. All beacon-equipped aircraft in the vicinity of the BCAS are detected. ATCRBS-equipped aircraft are interrogated using a special Mode C interrogation. DABS aircraft are detected passively through periodic squitters emitted by all DABS transponders. Squitter-detected aircraft are tracked on altitude and only those aircraft that represent a co-altitude threat are discretely interrogated to establish a range/altitude track. The use of discrete addressing eliminates synchronous garble for the BCAS in the same manner as for DABS. This document provides a general description of BCAS from the viewpoint of its operational features and then describes the avionics package required to achieve the capability.
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Summary

BCAS is a DABS-based airborne collision avoidance system that exploits the feature of DABS discrete addressing and integral data link. This provides for a CAS with the unique capabilities of (1) cooperative threat resolution between BCAS and conflicting aircraft through the transmission of maneuver intent (to DABS-only aircraft) and tie...

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Beacon CAS (BCAS) an integrated air/ground collision avoidance system

Provisional message formats and protocols for the DABS IPC/PWI display

May 24, 1974
  |
Project Report
Author:
Peter H. Robeck
…
Published in:
MIT Lincoln Laboratory Report ATC-35
Topic:
surveillance
R&D area:
R&D group:

Summary

This document specifies provisional formats for the data link portion of the ?signals-in-space? which are part of the DABS interrogations and replies. Also included is a discussion of the characteristics that these signals assume while transmitted from the transponder proper to the instrument which delivers the messages to the pilot. Specifically, formats, algorithms, and protocols are assigned to serve the IPC (lntermittent Positive Control), PWI (Proximity Warning Indicator), and ATC (numerical indicator) functions. The protocol and algorithm for the pilot acknowledgment link is also included in this paper.
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Summary

This document specifies provisional formats for the data link portion of the ?signals-in-space? which are part of the DABS interrogations and replies. Also included is a discussion of the characteristics that these signals assume while transmitted from the transponder proper to the instrument which delivers the messages to the pilot...

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Provisional message formats and protocols for the DABS IPC/PWI display

Provisional message formats and protocols for the DABS 32-character alphanumeric display

May 20, 1974
  |
Project Report
Author:
Jerry D. Welch
…
Published in:
MIT Lincoln Laboratory Report ATC-36
Topic:
surveillance
R&D area:
R&D group:

Summary

Formats and protocols are described for tactical ATC displays to be driven by the Standard Message interface of a DABS transponder and capable of handling a succession of data transmissions, each of which is individually acknowledged via a transponder reply before the transmission of the succeeding segment. Specific codes are defined for a display device of up to 32 alphanumeric characters. Any displays defined or implied by this document are intended solely for use in the DABS test and evaluation program, and are not necessarily representive of recommended or require display devices for an operational DABS system.
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Summary

Formats and protocols are described for tactical ATC displays to be driven by the Standard Message interface of a DABS transponder and capable of handling a succession of data transmissions, each of which is individually acknowledged via a transponder reply before the transmission of the succeeding segment. Specific codes are...

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Provisional message formats and protocols for the DABS 32-character alphanumeric display

Provisional data link interface standard for the DABS transponder

April 25, 1974
  |
Project Report
Author:
George V. Colby
…
Published in:
MIT Lincoln Laboratory Report ATC-34
Topic:
surveillance
R&D area:
R&D group:

Summary

This document specifies provisional data link interface standards for the DABS transponder. It describes the function, timing, and electrical properties of the signals flowing to and from both the Standard Message Interface and the Extended Length Message Interface.
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Summary

This document specifies provisional data link interface standards for the DABS transponder. It describes the function, timing, and electrical properties of the signals flowing to and from both the Standard Message Interface and the Extended Length Message Interface.

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Provisional data link interface standard for the DABS transponder

DABS/ATCRBS transponder bench test program

November 28, 1973
  |
Project Report
Author:
Edmond R. Becotte
…
Published in:
MIT Lincoln Laboratory Report ATC-25
Topic:
surveillance
R&D area:
R&D group:

Summary

The objective of this program was the determination of the effect on ATCRBS transponders of candidate modulation schemes in DABS uplink transmissions. Bench test were conducted on twenty-two different transponder samples, including representative air carrier and general aviation transponders and a military transponder. In this report, individual test procedures are outlined, the reduced data are presented, and some conclusions regarding the selection of the DABS uplink waveforms based upon the data are given. The basis of these conclusions is a DABS design goal of generating the least possible interference to the existing ATCRBS system. In addition to performing tests whose purpose was the direct measurement of response of ATCRBS transponders to candidate DABS uplink waveforms, tests were also run to obtain other link-related characteristic, such as response to non-standard pulses. Conclusions, based upon the test performed, were the DABS signals modulated by either PSK or FSK would be demodulated by a significant fraction of ATCRBS transponders and that there are no feasible PAM pulse widths or spacings which would not be decoded by a significant fraction of ATCRBS transponders. ATCRBS transponder reply probability drops nearly to zero when the DABS message (of arbitrary modulation type) has a duration less than 30 microseconds and is preceded by ATCRBS suppressing preamble. It was further shown that the reliability of suppression al interrogation levels near MTL can be improved by increasing the peak power of the preamble relative to the message.
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Summary

The objective of this program was the determination of the effect on ATCRBS transponders of candidate modulation schemes in DABS uplink transmissions. Bench test were conducted on twenty-two different transponder samples, including representative air carrier and general aviation transponders and a military transponder. In this report, individual test procedures are...

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DABS/ATCRBS transponder bench test program
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