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New techniques applied to air-traffic control radars

June 1, 1974
  |
Journal Article
Author:
Charles E. Muehe
…
Published in:
Proc. IEEE, Vol. 62, No. 6, June 1974, pp. 716-723.
Topic:
air traffic control
R&D area:
R&D group:

Summary

During the past two years a program has been carried out to show how new techniques can greatly improve the performance of radars used for air-traffic control. A survey of problems associated with presently used radars was undertaken. This survey indicates that primary radar in an automated air-traffic control system can be made significantly more effective by the use of new techniques. The radar's handling of extraneous reflections (clutter) is critical to its performance. Three types of interfering clutter were found to predominate: ground clutter, weather clutter, and angels. Angels are generally accepted to be radar returns from flocks of birds. In addition, second-time-around clutter is often troublesome. For each type of clutter, all known remedies for improving the signal-to-clutter ratio were studied and radar systems were configured using appropriate sets of remedies. Some specific solutions incorporated in the resulting radar systems are: a) the use of linear large dynamic range, near-optimum digital signal processors to filter signals from clutter, b) the use of electronically step-scanned antennas to improve the correlation of aircraft and clutter returns from pulse to pulse, c) the use of multiple PRF's instead of staggered PRF's together with coherent transmitters to keep second-time-around clutter returns well correlated while still overcoming blind speeds, d) the use of a fine grained ground clutter map to give superclutter visibility on tangential targets, and e) the use of lower operating frequencies to greatly reduce weather and angel returns. Two demonstration radar systems have been implemented, an S-band radar using a mechanically rotating antenna and a UHF radar using an electronically step-scanned cylindrical antenna. Experimental results are described.
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Summary

During the past two years a program has been carried out to show how new techniques can greatly improve the performance of radars used for air-traffic control. A survey of problems associated with presently used radars was undertaken. This survey indicates that primary radar in an automated air-traffic control system...

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New techniques applied to air-traffic control radars

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

May 24, 1974
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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

Improved satellite constellations for CONUS ATC coverage

May 1, 1974
  |
Project Report
Author:
Harry B. Lee
…
Published in:
MIT Lincoln Laboratory Report ATC-23
Topic:
air traffic control
R&D area:
R&D group:

Summary

This report examines the problem of designing a constellation of orbiting satellites capable of supporting an aircraft navigation/surveillance service over CONUS. It is assumed that the aircraft positions are determined by hyperbolic multilateration using all satellites visible at elevation angles exceeding a minimum angle. Comprehensive analyses are presented of three "baseline" constellations. The constellations are representative of previous large, medium, and small constellations. The analyses include calculation of The Geometric Dilution of Precision (GDOP) during level flight, calculation of GDOP after a key satellite is deleted, and calculation of GDOP during aircraft banking. Comparison of the resulting GDOP's with the theoretical minimum values indicates that there is considerable room for improvement. A new method of calculating GDOP is described. The method suggests that improved GDOP's can be obtained by placing satellites in retrograde orbits rather than the previous posigrade orbits. Accordingly, nine new constellations are designed that employ retrograde orbits. When subjected to the same analyses as the baseline constellations, the new constellations exhibit significantly improved GDOP's.
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Summary

This report examines the problem of designing a constellation of orbiting satellites capable of supporting an aircraft navigation/surveillance service over CONUS. It is assumed that the aircraft positions are determined by hyperbolic multilateration using all satellites visible at elevation angles exceeding a minimum angle. Comprehensive analyses are presented of three...

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Improved satellite constellations for CONUS ATC coverage

False target elimination at Albuquerque using ARTS-III software

March 12, 1974
  |
Technical Report
Author:
Alan G. Cameron
Published in:
MIT Lincoln Laboratory Report TN-1974-12
Topic:
air traffic control
R&D area:
R&D group:

Summary

Lincoln Laboratory has been assisting the U.S. Air Force Weapons Laboratory in the study of ATCRBS false targets caused by reflections from buildings at Albuquerque International Airport/Kirtland AFB. This paper discusses the false target situation there and proposes two algorithms for correcting it in ARTS-III software. The simpler of the two appears applicable to the Albuquerque situation today, and is easily extendable to correct false targets caused by new buildings. Since the process appears directly applicable to many FAA Secondary Radar installations, a more complex algorithm is also presented, which is suitable for use in very high density terminal areas.
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Summary

Lincoln Laboratory has been assisting the U.S. Air Force Weapons Laboratory in the study of ATCRBS false targets caused by reflections from buildings at Albuquerque International Airport/Kirtland AFB. This paper discusses the false target situation there and proposes two algorithms for correcting it in ARTS-III software. The simpler of the...

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False target elimination at Albuquerque using ARTS-III software

A summary of the DABS transponder design/cost studies

March 1, 1974
  |
Project Report
Author:
Thomas J. Goblick
…
Published in:
MIT Lincoln Laboratory Report ATC-27
Topic:
surveillance
R&D area:
R&D group:

Summary

One of the major concerns in the DABS development program has been the cost of the DABS transponder. In order to realistically assess the impact on transponder cost of the many alternative techniques and design choices being considered for DABS, four study contracts were awarded to avionics manufacturers to design and estimate costs of special circuitry (in Phase I) and complete transponders (in Phase II). This report summarizes the major results of these design/cost studies, which cover general aviation, military, and air carrier transponder designs (including a retrofit kit for the military APX-72 transponder). The transponder design/cost studies have had a marked influence on the design of the DABS signal and message formats. Since the cost studies were basically intended for comparing link options for DADS, the transponder specifications used in these cost studies do not correspond in detail to current DABS transponder specifications. Therefore the cost data contained in this report cannot be taken to be completely representative of the cost of the finally specified DABS transponders.
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Summary

One of the major concerns in the DABS development program has been the cost of the DABS transponder. In order to realistically assess the impact on transponder cost of the many alternative techniques and design choices being considered for DABS, four study contracts were awarded to avionics manufacturers to design...

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A summary of the DABS transponder design/cost studies

Technical Assessment of Satellites for CONUS Air Traffic Control, Volume II - Random Access Aircraft-To-Satellite Techniques

February 28, 1974
  |
Project Report
Author:
Kenneth S. Schneider
…
Published in:
MIT Lincoln Laboratory Report ATC-26,II
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 deals with RAST, CAST and SAT are treated in companion volumes. A system employing RAST could operate by having each aircraft transmit a unique signature periodically, without any coordination of transmissions. The position of the aircraft is then obtained by multilateration using the arrival times of its signature at four or more satellites. Since aircraft transmissions are not coordinated, there is the possibility that different signatures may overlap at a satellite receiver. The resulting mutual interference is a factor in the performance of systems employing RAST. The critical technical aspects of RAST are explored with special emphasis on signaling formats, satellite coverage issues, degradation due to mutual interference 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 II - Random Access Aircraft-To-Satellite Techniques

Summary of results of antenna design cost studies

February 19, 1974
  |
Project Report
Author:
Jean-Claude Sureau
Published in:
MIT Lincoln Laboratory Report ATC-22
Topic:
antennas
R&D area:
R&D group:

Summary

Design/cost studies on antenna systems for DABS have been carried out by Texas Instruments and Westinghouse under Lincoln Laboratory sponsorship. For independent, mechanically-rotating systems aperture widths between 10' and 35' and heights between 4' and 16' were considered, with estimated corresponding production costs ranging from $10K to more than $200K. No generally-recommended implementation emerged although the trend was to choose planar arrays for stringent performance requirements and to accept less expensive reflectors when requirements were sufficiently relaxed. Although the aperture size was found to have a significant cost impact on the remainder of the system (pedestal, drive, tower), the antenna usually accounted for less than half of the total antenna installation cost. With the use of off-boresight monopulse direction-finding, agile beam arrays require only slightly more than one beam position per beamwidth. Even with the resulting simplification in the beamforming circuitry, their cost is about twice that of comparable rotators and starts at about $200K. DABS systems which share the same pedestal as primary radars ("co-located") are inherently highly constrained and tend to lead to unique implementations. For an ASR installation, an integral monopulse beacon feed constitutes an economical (less than $5K) and expedient implementation with performance parameters which, though not optimum, are acceptable for DABS (4 degrees beamwidth and 2 dB/degree elevation cut-off rate). A back-mounted antenna of the same (or smaller) aperture size as the AST reflector can also be implemented as a retrofit for about $40K. For ARSR installations, integral monopulse beacon feeds are also feasible at a very nominal cost but some performance compromises have to be accepted. Back-mounted DABS antennas can be accommodated in a large range of aperture sizes.
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Summary

Design/cost studies on antenna systems for DABS have been carried out by Texas Instruments and Westinghouse under Lincoln Laboratory sponsorship. For independent, mechanically-rotating systems aperture widths between 10' and 35' and heights between 4' and 16' were considered, with estimated corresponding production costs ranging from $10K to more than $200K...

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Summary of results of antenna design cost studies

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

February 19, 1974
  |
Project Report
Author:
Harry B. Lee
…
Published in:
MIT Lincoln Laboratory Report ATC-26,III
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 three-volume report is a technical assessment of all three techniques. The present volume examines satellite-to-aircraft techniques (SAT). The remaining two volumes treat CAST and RAST. 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, Volume III - Satellite-To-Aircraft Techniques

The effect of phase error on the DPSK receiver performance

February 4, 1974
  |
Project Report
Author:
David A. Shnidman
Published in:
MIT Lincoln Laboratory Report ATC-32
Topic:
surveillance
R&D area:
R&D group:

Summary

Several methods of realizing a DPSK receiver use a delay line. Temperature variations cause changes in the delay which, in turn, cause errors in the phase differences between the reference and information signals. The effect of these errors on the performance of an optimum DPSK receiver is studied in this report.
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Summary

Several methods of realizing a DPSK receiver use a delay line. Temperature variations cause changes in the delay which, in turn, cause errors in the phase differences between the reference and information signals. The effect of these errors on the performance of an optimum DPSK receiver is studied in this...

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The effect of phase error on the DPSK receiver performance
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