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Technical Assessment of Satellites for CONUS Air Traffic Control, Executive Summary

January 31, 1974
  |
Project Report
Author:
Irvin G. Stiglitz
Published in:
MIT Lincoln Laboratory Report ATC-26
Topic:
air traffic control
R&D area:
R&D group:

Summary

A number of satellite system techniques have been suggested as candidates to provide ATC surveillance, communication, and/or navigation service over CONUS. All techniques perform postion determination by multilateration using a constellation of satellites. They can be categorized as follows: 1) Coordinated Aircraft-to-Satellite Techniques (CAST), 2) Random Access Aircraft-to-Satellite Techniques (RAST), and 3) Satellite-to-Aircraft Techniques (SAT). A technical assessment is made of the various techniques with no one particular technique emerging as superior; several feasible alternatives are identified. The assessment indicates that satellite bases techniques for CONUS ATC can be developed without relying on high risk technology. This volume summarizes the results of a technical assessment of all three techniques. The detailed assessment is presented in companion volumes. The assessment has shown that workable systems could be configured using any one of the three techniques without reliance on high risk technology. No one technique has emerged as superior. Rather several viable alternatives have been identified. All techniques appear to require more costly avionics than today's ground-based system.
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Summary

A number of satellite system techniques have been suggested as candidates to provide ATC surveillance, communication, and/or navigation service over CONUS. All techniques perform postion determination by multilateration using a constellation of satellites. They can be categorized as follows: 1) Coordinated Aircraft-to-Satellite Techniques (CAST), 2) Random Access Aircraft-to-Satellite Techniques (RAST)...

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Technical Assessment of Satellites for CONUS Air Traffic Control, Executive Summary

Technical Assessment of Satellites for CONUS Air Traffic Control, Volume I - Coordinated Aircraft-To-Satellite Techniques

January 31, 1974
  |
Project Report
Author:
Richard S. Orr
…
Published in:
MIT Lincoln Laboratory Report ATC-26,I
Topic:
air traffic control
R&D area:

Summary

A number of satellite system techniques have been suggested as candidates to provide ATC surveillance, communication, and/or navigation service over CONUS. All techniques perform postion determination by multilateration using a constellation of satellites. They can be categorized as follows: 1) Coordinated Aircraft-to-Satellite Techniques (CAST), 2) Random Access Aircraft-to-Satellite Techniques (RAST), and 3) Satellite-to-Aircraft Techniques (SAT). A technical assessment is made of the various techniques with no one particular technique emerging as superior; several feasible alternatives are identified. The assessment indicates that satellite bases techniques for CONUS ATC can be developed without relying on high risk technology. This volume deals with CAST, RAST and SAT are treated in companion volumes. A system employing CAST could operate by having each aircraft transmit only in response to interrogation from a satellite. The position of the aircraft is then obtained by multilateration using the arrival times of its response at coordinating the interrogations, mutual interference between different response can be avoided. The critical technical aspects of CAST are explored with special emphasis on signaling formats, avionics, the satellite antenna and susceptibility to jamming.
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Summary

A number of satellite system techniques have been suggested as candidates to provide ATC surveillance, communication, and/or navigation service over CONUS. All techniques perform postion determination by multilateration using a constellation of satellites. They can be categorized as follows: 1) Coordinated Aircraft-to-Satellite Techniques (CAST), 2) Random Access Aircraft-to-Satellite Techniques (RAST)...

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Technical Assessment of Satellites for CONUS Air Traffic Control, Volume I - Coordinated Aircraft-To-Satellite Techniques

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
  |
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
  |
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

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

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)

Interrogation scheduling algorithms for a discrete address beacon system

October 17, 1973
  |
Project Report
Author:
Alex Spiridon
…
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

An optimum interference detector for DABS monopulse data editing

September 26, 1973
  |
Technical Report
Author:
Robert J. McAulay
…
Published in:
MIT Lincoln Laboratory Report TN-1973-48
Topic:
air traffic control
R&D area:
R&D group:

Summary

In the application of the Discrete Address Beacon System (DABS) concept to Air Traffic Control (ATC) surveillance, estimates of aircraft position must be made using as few replies as possible, preferably one. This requires the use of monopulse techniques. Since the beacon system provides high signal-to-noise ratios (SNR), the fundamental limitation to direction finding (DF) performance is due to externally generated interference from multipath signals and from the present Air Traffic Control Radar Beacon System (ATCRBS). Since there are many bits in any one DABS reply it should be possible to generate an accurate azimuth estimate if those that bear interference could be detected and deleted from the sample. In this report, the generalized likelihood ratio test is used to derive an optimum interference statistic. The detector performance is then analyzed in detail with respect to its dependence on SNR, interference-to-signal ratio (ISR) and on the relative phase between the target and interfering signals. It is shown that good detection performance can be obtained if the phase difference between the target and interference signals are either in- or out-of-phase.
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Summary

In the application of the Discrete Address Beacon System (DABS) concept to Air Traffic Control (ATC) surveillance, estimates of aircraft position must be made using as few replies as possible, preferably one. This requires the use of monopulse techniques. Since the beacon system provides high signal-to-noise ratios (SNR), the fundamental...

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An optimum interference detector for DABS monopulse data editing
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