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Effects of airborne transponder antenna lobe switching on en route (PCD) and terminal (BDAS) beacon reply processing

January 29, 1974
  |
Project Report
Author:
Ernest H. Day
…
Published in:
MIT Lincoln Laboratory Report ATC-18
Topic:
antennas
R&D area:
R&D group:

Summary

The comparative performances of switching top and bottom transponder antennas versus the bottom antenna alone, in target detection by ARTS III and by PCD, were investigated in order to determine which of the two antenna configurations is preferable. A variety of military aircraft participated, performing climbouts, orbits, straight and level segments, and descents, in order to expose a wide range of aspect angles to the interrogator. Data were collected at Washington, D.C., utilizing the ATCBI at Andrews Air Force Base, and at NAFEC, utilizing the Elwood site. The frequency of occurrence of lost targets, particularly of consecutive lost targets, was found to vary considerably from one aircraft type to another. Analysis of the reduced data provides a reasonable basis, however, for concluding that, to maximize average probability of detection, the bottom antenna is better in the terminal area but switching antennas are better for En Route application. To minimize long sequences of misses which cause track loss on turns, the switching antenna appears more favorable in both flight regimes. The data also suggest that a higher probability of detection can be obtained in both environments, without incurring serious penalties, by reducing the leading edge detection thresholds.
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Summary

The comparative performances of switching top and bottom transponder antennas versus the bottom antenna alone, in target detection by ARTS III and by PCD, were investigated in order to determine which of the two antenna configurations is preferable. A variety of military aircraft participated, performing climbouts, orbits, straight and level...

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Effects of airborne transponder antenna lobe switching on en route (PCD) and terminal (BDAS) beacon reply processing

Effects of ATCRBS P2 pulses on DABS reliability

January 28, 1974
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Project Report
Author:
William H. Harman III
…
Published in:
MIT Lincoln Laboratory Report ATC-20
Topic:
surveillance
R&D area:

Summary

An analytical study is performed to determine the effects of ATCRBS P2 pulses as interference to DABS uplink transmissions. These effects constitute a major component of all uplink error-producing mechanisms that are anticipated to occur in DABS operation. The study is fomulated in a way that includes effects of both receiver noise and P2 pulse interference, where the interference can be received from any of a number of different transmitters at different distances from the receiving aircraft. The model includes the randomness associated with whether or not a particular DABS signal is overlapped by any interference pulse, and also the conditional randomness of error production given that an overlap does occur. In fact, a major portion of the study is the determination of the conditional error probability given the occurrence of an overlap with stated signal-to-interference ratio and stated signal-to-noise ratio. The results are given as the probability of a "miss," where a "miss" is the event that at least one of the bits in the DABS data block is demodulated in error. The study is carried out for both DPSK and PAM which are the two modulation options being considered in the DABS design. Results are given both as general formulas and as evaluations of these fomulas in various specific cases. In these evaluations, the interference environment is based on ATCRBS interrogator locations, transmitter powers, and repetition frequencies as listed in ECAC's IFF Master File. The numerical results are presented graphically to display the dependence on signal level, noise level, and geographical location between Boston and Washington, D.C. A concept referred to as "effective interference tolerance" is introduced, and numerical evaluations are presented to indicate the accuracy of this concept.
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Summary

An analytical study is performed to determine the effects of ATCRBS P2 pulses as interference to DABS uplink transmissions. These effects constitute a major component of all uplink error-producing mechanisms that are anticipated to occur in DABS operation. The study is fomulated in a way that includes effects of both...

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Effects of ATCRBS P2 pulses on DABS reliability

Digital signal processor for air traffic control radars

January 1, 1974
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Conference Paper
Author:
Charles E. Muehe
Published in:
Northeast Electronics Research and Engineering Meeting, NEREM, 28-31 October 1974.
Topic:
air traffic control
R&D area:
R&D group:

Summary

At a previous NEREM Meeting [1] and in a subsequent paper [2], we described the general philosophy and particular ideas which can be used to overcome the problems associated with achieving good radar detection performance in the presence of various types of clutter; ground clutter (including second-time-around returns ), weather clutter and angels (bird flocks). Recently, a digital signal processor called an MTD (Moving Target Detector) has been designed and built for application to an S-band ASR (Airport Surveillance Radar). This paper describes the MTD and presents some preliminary test results. The MTD is a special purpose hard-wired digital signal processor which is capable of processing a full 360 coverage in 1/16 nmi steps out to a nominal range of 48 nmi. The MTD was designed to provide digital radar output to an automated air traffic control system.
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Summary

At a previous NEREM Meeting [1] and in a subsequent paper [2], we described the general philosophy and particular ideas which can be used to overcome the problems associated with achieving good radar detection performance in the presence of various types of clutter; ground clutter (including second-time-around returns ), weather...

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Digital signal processor for air traffic control radars

Final report on task A surveillance and communication issues in the transition to a discrete address beacon system

December 26, 1973
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Project Report
Author:
Walter I. Wells
…
Published in:
MIT Lincoln Laboratory Report ATC-21
Topic:
surveillance
R&D area:
R&D group:

Summary

This report discusses the transition from the ATCRBS-based surveillance function with voice radio only to a DABS-based surveillance function with integral digital communication capability to support IPC and automation. Recommendations are directed toward alleviation of certain problems already evident and toward preparation for the deployment of DABS beginning in the late 1970s. An evaluation of the present ATCRBS system indicates basic adequacy in the present environment for the current mode of operation of the ATC system. The introduction of automation into the ATC system requires capability in the areas of data link and enhances surveillance reliability for automatic tracking that the DABS system will provide. On this basis it is concluded that the ATCRBS system does not need major modifications to continue its role into the DABS period at locations where the environment and operation will be similar to that presently encountered. A number of recommendations are made regarding radar where new technology can provide significantly enhanced performance at little added cost. The introduction of a digital data link provides many opportunities and challenges. Most of them associated with tactical message handling are being addressed within the DABS program but attention is called to a related set of issues for messages originating from or destined for other than ARTS or NAS (e.g., FSS).
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Summary

This report discusses the transition from the ATCRBS-based surveillance function with voice radio only to a DABS-based surveillance function with integral digital communication capability to support IPC and automation. Recommendations are directed toward alleviation of certain problems already evident and toward preparation for the deployment of DABS beginning in the...

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Final report on task A surveillance and communication issues in the transition to a discrete address beacon system

DABS/ATCRBS transponder bench test program

November 28, 1973
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Project Report
Author:
Edmond R. Becotte
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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

Provisional Signal Formats for the Discrete Address Beacon System

November 9, 1973
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Project Report
Author:
Paul R. Drouilhet Jr
Published in:
MIT Lincoln Laboratory Report ATC-30
Topic:
surveillance
R&D area:
R&D group:

Summary

This document specifies provisional DABS signal formats, i.e., the characteristics of the "signals-in-space"which for the DABS interrogations and replies. Also included is a discussion of the utilization of the described formats to effect the surveillance and data link communication functions for which DABS has been designed. These signal formats will be used in the design and construction of engineering development model transponders and interrogators for prototype system test and evaluation at NAFEC during Phase II of the DABS Development Program; and, with modifications resulting from this test and evaluation effort, will form the basis for the operational implementation of DABS.
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Summary

This document specifies provisional DABS signal formats, i.e., the characteristics of the "signals-in-space"which for the DABS interrogations and replies. Also included is a discussion of the utilization of the described formats to effect the surveillance and data link communication functions for which DABS has been designed. These signal formats will...

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Provisional Signal Formats for the Discrete Address Beacon System

Prediction of optical landing guidance system performance in Cat. III-a minimum weather

November 8, 1973
  |
Technical Report
Author:
David G. Kocher
Published in:
MIT Lincoln Laboratory Report TN-1973-47
Topic:
air traffic control
R&D area:
R&D group:

Summary

The feasibility of using a laser optical system to provide precision guidance for the final two miles of aircraft landing approaches in low visibility weather is examined. Since low visibility is caused most frequently by clouds and fog, approximate calculations of the optical signal, scattered light and noise are made as a function of range for various cloud and fog densities. It is concluded that with current laser technology, performance of an optical landing guidance system would be inadequate in the presence of Category III-a minimum visibility clouds and fogs.
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Summary

The feasibility of using a laser optical system to provide precision guidance for the final two miles of aircraft landing approaches in low visibility weather is examined. Since low visibility is caused most frequently by clouds and fog, approximate calculations of the optical signal, scattered light and noise are made...

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Prediction of optical landing guidance system performance in Cat. III-a minimum weather

The Discrete Address Beacon System (DABS)

November 8, 1973
  |
Conference Paper
Author:
Herbert G. Weiss
…
Published in:
IEEE Northeast Electronic Research and Engineering Mtg., NEREM, 8 November 1973.
Topic:
air traffic control
R&D area:
R&D group:

Summary

The requirement for additional automation in the air traffic control process has placed new emphasis on the need for high quality surveillance data and for a ground-to-aircraft data link. The ATCRBS beacon system has proven a valuable complement to radar because it provides the ground controller with position, identity, and altitude data that is not contaminated by ground and weather clutter. However, the growing number of beacon-equipped aircraft and ground interrogators and the inherent self-interference limitations of the ATCRBS beacon system have motivated the need for a more reliable and flexible beacon system. The 1969 the Air Traffic Control Advisory Committee recommended the development of such an improved system which they named the Discrete Address Beacon System (DABS), incorporating both surveillance and a data link. Since 1971, M.I.T. Lincoln Laboratory, under the sponsorship of the FAA, has been investigating various DABS design options.
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Summary

The requirement for additional automation in the air traffic control process has placed new emphasis on the need for high quality surveillance data and for a ground-to-aircraft data link. The ATCRBS beacon system has proven a valuable complement to radar because it provides the ground controller with position, identity, and...

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The Discrete Address Beacon System (DABS)

Empirical assessment of ATCRBS

October 31, 1973
  |
Project Report
Author:
Alan G. Cameron
…
Published in:
MIT Lincoln Laboratory Report ATC-16
Topic:
surveillance
R&D area:
R&D group:

Summary

This report discusses the operational performance of the FAA ATCRBS system, as determined from data extracted from the ARTS III digital processing system. Data was gathered from several sites including Andrews Air Force Base, (Md.), Logan International Airport (Boston, Mass.), and McCarran International Airport (Las Vegas, Nevada). Quantitative performance data, as well as discussion of the problem area and possible techniques and procedures for its solution, are provided in the areas of weak/broken targets, false targets, synchronous garble, interference, erroneous decoding, improper defruiter operation, and insufficient angular resolution. A discussion of improvements that can alleviate some of the deficiences of today's secondary radar (ATCRBS) system is included.
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Summary

This report discusses the operational performance of the FAA ATCRBS system, as determined from data extracted from the ARTS III digital processing system. Data was gathered from several sites including Andrews Air Force Base, (Md.), Logan International Airport (Boston, Mass.), and McCarran International Airport (Las Vegas, Nevada). Quantitative performance data...

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Empirical assessment of ATCRBS

Interrogation scheduling algorithms for a discrete address beacon system

October 17, 1973
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Project Report
Author:
Alex Spiridon
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Published in:
MIT Lincoln Laboratory Report ATC-19
Topic:
surveillance
R&D area:
R&D group:

Summary

This report describes several scheduling algorithms that may form part of the interrogation management function of a discrete address beacon system. These include scheduling algorithms that can handle unequal message lengths and types which can schedule a message very rapidly (dynamic scheduling). The algorithms are evaluated in terms of the computation required to execute them and their packing efficiencies.
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Summary

This report describes several scheduling algorithms that may form part of the interrogation management function of a discrete address beacon system. These include scheduling algorithms that can handle unequal message lengths and types which can schedule a message very rapidly (dynamic scheduling). The algorithms are evaluated in terms of the...

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Interrogation scheduling algorithms for a discrete address beacon system
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