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DABS/ATCRBS transponder bench test program

Published in:
MIT Lincoln Laboratory Report ATC-25

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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Provisional Signal Formats for the Discrete Address Beacon System

Published in:
MIT Lincoln Laboratory Report ATC-30

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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The Discrete Address Beacon System (DABS)

Published in:
IEEE Northeast Electronic Research and Engineering Mtg., NEREM, 8 November 1973.

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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Empirical assessment of ATCRBS

Published in:
MIT Lincoln Laboratory Report ATC-16

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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Interrogation scheduling algorithms for a discrete address beacon system

Published in:
MIT Lincoln Laboratory Report ATC-19

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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Recent advances in air traffic control radars

Published in:
IEEE Northeast Electronic Research and Engineering Meeting, NEREM, 8 November 1973.

Summary

This paper describes recent improvements in microwave radars used for air traffic control. These improvements have been designed to increase the target-to-clutter ratio so that adaptive thresholding can be used to give a very low false alarm rate and high probability of detection even when the aircraft target is in the presence of strong clutter. Studies show that detection suffers when three types of clutter returns are strong; namely, ground clutter, weather clutter or angels. Angels have been almost universally identified as bird flocks. Under certain terrain and propagation conditions, second-time-around clutter can also be a problem. Here ground returns from the second to last transmitted pulse are received from targets beyond the nonambiguous range. These may be from mountains or from the ground when anomalous propagation conditions occur. Meaningful improvements in this class of radar can be conveniently grouped as shown in Table I. We will briefly discuss each of the three classes listed.
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Summary

This paper describes recent improvements in microwave radars used for air traffic control. These improvements have been designed to increase the target-to-clutter ratio so that adaptive thresholding can be used to give a very low false alarm rate and high probability of detection even when the aircraft target is in...

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Dual lane runway study, final report

Published in:
MIT Lincoln Laboratory Report ATC-17

Summary

The issues in the dual lane runway problem were investigated via computer real time (man in the loop) and fast time (no human input during the simulation run) simulations in order to identify a dual lane runway configuration and determine operation strategies. The real time experiments were conducted using experienced ATC controllers and a pilot to observe the situation at interactive graphics CRT displays. Headsets and microphones were utilized to permit the normal controller/pilot interchanges. Flight strips as used in control tower cabs were employed to further simulate controller workload. Based on information gained during early real time controller experiments, a programmed controller concept (fast time) was adopted. A series of dual lane runway computer simulation experiments were performed to investigate the pertinent dual lane issues: centerline spacing, arrival/departure preference, parallel taxiway, threshold stagger, and hiqh speed exits. In addition, time was spent analyzing operational high density airport terminal facilities. Airport administrative and operations personnel were interviewed to obtain their views on high density operations and the dual lane concept. Peak rush hour periods were sought out to detenTIine control strategies employed indirecting peak period traffic. Air crews utilizing these high density airport terminals were interviewed in the course of their operations into and out of these major hub airports.
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Summary

The issues in the dual lane runway problem were investigated via computer real time (man in the loop) and fast time (no human input during the simulation run) simulations in order to identify a dual lane runway configuration and determine operation strategies. The real time experiments were conducted using experienced...

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Concepts for improvement of airport surveillance radars

Summary

This report reviews the performance of operational ASR's, discusses each type of clutter with which the target must compete, examines presently employed methods of overcoming clutter and several state-of-the-art techniques which have not found their way into the ASR's for one reason or another. It concludes by describing two radars, one at S-band and one at UHF, which are believed to come closest to fulfilling ASR requirements in advanced ARTS facilities. The major improvements in performance will be derived from the use of linear optimum signal processing. Further gains will be achieved through the use of adaptive thresholds. STC will combat bird clutter. The radar will incorporate proper shaping of the antenna pattern so that aircraft off the peak of the antenna elevation beam will not be at a disadvantage compared to moving clutter at the peak. The recommended radar concepts also include radial velocity determination by Doppler measurement. This should prove of value in maintaining target tracks and in discrimination against ground vehicles.
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Summary

This report reviews the performance of operational ASR's, discusses each type of clutter with which the target must compete, examines presently employed methods of overcoming clutter and several state-of-the-art techniques which have not found their way into the ASR's for one reason or another. It concludes by describing two radars...

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A high performance, low cost, air traffic control radar

Published in:
MIT Lincoln Laboratory Report TN-1973-12

Summary

Recent improvements in the technology of electronically switched antennas and digital signal processing make possible a relatively high performance, low cost, surveillance radar. The radar described employs an electronically step-scanned, cylindrical antenna together with an advanced digital signal processor to give superior MTI performance at an estimated cost of less than half the present S-band ASRs. The radar output consists of narrow band, digital target reports free of false alarms, suitable for transmission over telephone lines. Remote radar operation using digital, bright, scan-history displays becomes practical as does easy incorporation of beacon and direction finder outputs along with digitally generated video maps. The complete absence of moving parts, the low power transmitter and the largely solid-state construction will provide high reliability and low maintenance costs. These techniques are most easily and economically implemented in the UHF band, but a similar L-band radar can be designed with somewhat increased complexity and cost. The techniques and background studies employed in the design of the proposed radar evolved over a period of three or four years as a result of work for the Air Force under Contract F19628-73-C-0002. Some of these techniques are being applied to improve the MTI performance of the ASR under FAA Contract DOT-FA71WAI-242.
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Summary

Recent improvements in the technology of electronically switched antennas and digital signal processing make possible a relatively high performance, low cost, surveillance radar. The radar described employs an electronically step-scanned, cylindrical antenna together with an advanced digital signal processor to give superior MTI performance at an estimated cost of less...

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A maximum-likelihood multiple-hypothesis testing algorithm, with an application to monopulse data editing

Author:
Published in:
MIT Lincoln Laboratory Report TN-1973-7

Summary

A simple algorithm for multiple-hypothesis testing, based on a generalization of likelihood ratio testing between pairs of hypotheses, is developed and applied to a specific problem. The problem arises in connection with an amplitude comparison monopulse system in an Air Traffic Control application. In particular, it is desired to measure target azimuth in a beacon system in the presence of interference and multipath. The multiple hypotheses relate to the presence or absence of a desired signal, with or without either of two kinds of interfering signal. The analysis leads to a new technique of data editing, or processing, to detect the presence of interference.
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Summary

A simple algorithm for multiple-hypothesis testing, based on a generalization of likelihood ratio testing between pairs of hypotheses, is developed and applied to a specific problem. The problem arises in connection with an amplitude comparison monopulse system in an Air Traffic Control application. In particular, it is desired to measure...

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