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Plan for flight testing intermittent positive control

June 1, 1975
  |
Project Report
Author:
John W. Andrews
…
Published in:
MIT Lincoln Laboratory Report ATC-46
Topic:
air traffic control
R&D area:
R&D group:

Summary

Intermittent Positive Control is an automated aircraft collision avoidance system requiring the participation of the aircraft pilots involved. The operational interface between pilots and the IPC system is being evaluated in a series of live flight tests. The Lincoln Laboratory DABS Experimental Facility, augmented to include the IPC function, is the test bed for these evaluation flights. This document described the objectives and methods of the IPC flight testing being conducted by Lincoln Laboratory.
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Summary

Intermittent Positive Control is an automated aircraft collision avoidance system requiring the participation of the aircraft pilots involved. The operational interface between pilots and the IPC system is being evaluated in a series of live flight tests. The Lincoln Laboratory DABS Experimental Facility, augmented to include the IPC function, is...

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Plan for flight testing intermittent positive control

Model aircraft L-band beacon antenna pattern gain maps

May 16, 1975
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Project Report
Author:
Douglas W. Mayweather
Published in:
MIT Lincoln Laboratory Report ATC-44
Topic:
L-band
R&D area:
R&D group:

Summary

This document presents L-band antenna patterns for a variety of general aviation and air carrier aircraft; these pattern were based on scale-model measurements. The antenna patterns are described by aircraft-coordinate-referenced elevation vs azimuth gain-contour maps. This method of presentation conveniently displays the effects of aircraft configuration on antenna patterns and allows one to observe the changes in a pattern that result from a change in wheel, flap, or antenna location.
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Summary

This document presents L-band antenna patterns for a variety of general aviation and air carrier aircraft; these pattern were based on scale-model measurements. The antenna patterns are described by aircraft-coordinate-referenced elevation vs azimuth gain-contour maps. This method of presentation conveniently displays the effects of aircraft configuration on antenna patterns and...

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Model aircraft L-band beacon antenna pattern gain maps

Network management

May 16, 1975
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Project Report
Author:
Herman F. Vandevenne
Published in:
MIT Lincoln Laboratory Report ATC-45
Topic:
air traffic control
R&D area:
R&D group:

Summary

This report provides a discussion of the design of the DABS network management function. Network management is responsible for the interaction between the local sensor and the adjacent connected sensors. Based on a dynamic interpretation of the coverage map and the status of the network, network management determines (a) the coverage responsibility of the local sensor, (b) which other sensors are covering the same area, and (c) which of the sensors has principal data link responsibility. Interaction is effected through message exchange over ground communication links connecting the DABS sensors.
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Summary

This report provides a discussion of the design of the DABS network management function. Network management is responsible for the interaction between the local sensor and the adjacent connected sensors. Based on a dynamic interpretation of the coverage map and the status of the network, network management determines (a) the...

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Network management

Experimental validation of PALM - a system for precise aircraft location

April 29, 1975
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Technical Report
Author:
James E. Evans
…
Published in:
MIT Lincoln Laboratory Report TN-1975-29
Topic:
air traffic control
R&D area:
R&D group:

Summary

A ground based system to precisely locate aircraft in three dimensions based on transponder replies has been designed. Field tests have been conducted to validate the design of the elevation performance. This document reports on the principle of operation, experimental hardware and field test of the Precision Altitude and Landing Monitor (PALM). The key features incorporated in the PALM design include: (a) no new avionics required, i.e., uses standard aircraft transponder; (b) high accuracy position data, i.e., a 1-mrad (0.06 degree) rms error in elevation and in azimuth; (c) broad airspace coverage, e.g., 40 degrees in elevation, 120 degrees in azimuth (expandable to 360 degrees) and several 10s of miles in range; and (d) low life cycle equipment cost. The high accuracy in the difficult airport multipath environment is a direct result of (a) newly developed antenna synthesis procedure, (b) the development of adaptive multipath suppression techniques, and (c) the use of digital signal processing. The program, to date, has focused on an experimental evaluation of the elevation performance. The electronics required for the tests have been built into a self-powered van to facilitate experiments at remote airports. The actual flight test data demonstrated experimental errors on the order of 1 mrad; moreover, as predicted by theory, the resulting errors were essentially independent of elevation angle. Potential applications for the PALM position data include parallel approach monitoring, independent altitude monitoring, and/or performance assurance monitoring of landing guidance systems.
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Summary

A ground based system to precisely locate aircraft in three dimensions based on transponder replies has been designed. Field tests have been conducted to validate the design of the elevation performance. This document reports on the principle of operation, experimental hardware and field test of the Precision Altitude and Landing...

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Experimental validation of PALM - a system for precise aircraft location

DABS link performance considerations

April 28, 1975
  |
Project Report
Author:
Gary J. Schlieckert
Published in:
MIT Lincoln Laboratory Report ATC-41
Topic:
surveillance
R&D area:
R&D group:

Summary

The DABS link performance is computed using the present values for the system operating parameters and the available models that describe environment and aircraft antenna effects. The various fade mechanisms are described, and a statistical determination of performance is proposed. The performance is computed for various sets of conditions including different ground antennas, aircraft maneuvers, antenna obstructions and the performance when aircraft are in the cone of silence. The DABS link is found to have very good overall performance with only small regions of reduced reliability that are at low angles or due to maneuvers. Those missed replies due to maneuvers are found to be sporadic from scan to scan.
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Summary

The DABS link performance is computed using the present values for the system operating parameters and the available models that describe environment and aircraft antenna effects. The various fade mechanisms are described, and a statistical determination of performance is proposed. The performance is computed for various sets of conditions including...

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DABS link performance considerations

Scale model pattern measurements of aircraft L-band beacon antennas

April 4, 1975
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Project Report
Author:
Kimball J. Keeping
…
Published in:
MIT Lincoln Laboratory Report ATC-47
Topic:
L-band
R&D area:
R&D group:

Summary

This report describes the techniques and apparatus used to measure the directional patterns of aircraft ATC transponder antennas (L-Band) using digital techniques and magnetic tapes for data storage. Algorithms involved in data normalization, cross-polarization correction and coordinate conversations are discussed. Some typical applications of the data are illustrated with actual computer outputs obtained from the model measurements.
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Summary

This report describes the techniques and apparatus used to measure the directional patterns of aircraft ATC transponder antennas (L-Band) using digital techniques and magnetic tapes for data storage. Algorithms involved in data normalization, cross-polarization correction and coordinate conversations are discussed. Some typical applications of the data are illustrated with actual...

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Scale model pattern measurements of aircraft L-band beacon antennas

Improved MTI radar signal processor

April 3, 1975
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Project Report
Author:
William H. Drury
Published in:
MIT Lincoln Laboratory Report ATC-39
Topic:
surveillance
R&D area:
R&D group:

Summary

A new type of radar digital signal processor for use with ASR radars is described. It features spectral processing accomplished by combining a 3-pulse canceller with an 8-point, weighted, discrete Fourier transform and adaptive thresholds. This combination of circuits provides a 20-dB increase in MTI improvement factor over present ASR's and is within 2 dB of optimum processing results. An auxiliary channel is provided to allow detection of any target traveling tangentially if its return exceeds the level of ground clutter return in the occupied range/azimuth cell. The spectral processing technique provides discrimination against weather clutter if the returns from weather and from the target fall into different Doppler frequency regions. The output from this equipment is digital hit reports for transmittal to the ARTS-III IOP computer.
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Summary

A new type of radar digital signal processor for use with ASR radars is described. It features spectral processing accomplished by combining a 3-pulse canceller with an 8-point, weighted, discrete Fourier transform and adaptive thresholds. This combination of circuits provides a 20-dB increase in MTI improvement factor over present ASR's...

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Improved MTI radar signal processor

DABS uplink encoder

March 4, 1975
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Project Report
Author:
John R. Samson
Published in:
MIT Lincoln Laboratory Report ATC-40
Topic:
surveillance
R&D area:
R&D group:

Summary

This report explains the operation of the DABS uplink encoder and provides information useful in diagnosing its performance. Several techniques which may be useful in analyzing encoder operation are presented. One technique involves only the use of address-parity tables and modulo-2 addition. The address-parity tables included are based upon the encoding polynomial prescribed in "Provisional Signal Formats for the Discrete Address Beacon System," Lincoln Laboratory Project Report ATC-30 Rev. 1, dated 25 April 1974. The error detection and correction properties of polynomial encoding schemes are not the subject of this report.
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Summary

This report explains the operation of the DABS uplink encoder and provides information useful in diagnosing its performance. Several techniques which may be useful in analyzing encoder operation are presented. One technique involves only the use of address-parity tables and modulo-2 addition. The address-parity tables included are based upon the...

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DABS uplink encoder

An analysis of aircraft L-band beacon antenna patterns

January 15, 1975
  |
Project Report
Author:
Gary J. Schlieckert
Published in:
MIT Lincoln Laboratory Report ATC-37
Topic:
L-band
R&D area:
R&D group:

Summary

Radiation patterns are examined for L-Band beacon antennas mounted on aircraft ranging from small, single-engine, general aviation aircraft to the Boeing 747. The data analyzed consists of antenna gain values taken in two degree steps over a spherical surface centered at the antenna location. Data from three representative scale model aircraft are studied in detail and show the effects of various airframe structural members on the radiation lobing patterns and the relative performance of antennas located at a number of positions on each scale model aircraft. Significant observations were that: -Landing gear and flaps complicate the lobing structure but do not introduce many more low gain values. -In general, antennas mounted forward of the leading edge of the wing and on fuselage bottom centerline (not too close to nosewheel) provide the best overall performance. -As an aircraft maneuvers, antenna performance degrades in direct relationship with the severity of the roll or pitch.
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Summary

Radiation patterns are examined for L-Band beacon antennas mounted on aircraft ranging from small, single-engine, general aviation aircraft to the Boeing 747. The data analyzed consists of antenna gain values taken in two degree steps over a spherical surface centered at the antenna location. Data from three representative scale model...

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An analysis of aircraft L-band beacon antenna patterns

DABS channel management

January 8, 1975
  |
Project Report
Author:
Edward J. Kelly
Published in:
MIT Lincoln Laboratory Report ATC-43
Topic:
surveillance
R&D area:
R&D group:

Summary

This report provides a full discussion of the design of the DABS channel management function. Channel management regulates all activity on the RF channel, scheduling ATCRBS interrogations and DABS roll-call interrogations and replies. Channel management arranges for multiple interrogations when required to satisfy both the surveillance and the communications functions of the sensor, and for reinterrogations in the event of link failure. The report consists of three major parts: Part I, Channel Control; Part II, Roll-Call Scheduling; and Part III, Transaction Preparation, Target List Update, and Transaction Update. Together they encompass the five basic subfunctions of channel management.
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Summary

This report provides a full discussion of the design of the DABS channel management function. Channel management regulates all activity on the RF channel, scheduling ATCRBS interrogations and DABS roll-call interrogations and replies. Channel management arranges for multiple interrogations when required to satisfy both the surveillance and the communications functions...

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DABS channel management
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