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Beacon CAS (BCAS) an integrated air/ground collision avoidance system

March 23, 1976
  |
Project Report
Author:
Vincent A. Orlando
…
Published in:
MIT Lincoln Laboratory Report ATC-62
Topic:
surveillance
R&D area:
R&D group:

Summary

BCAS is a DABS-based airborne collision avoidance system that exploits the feature of DABS discrete addressing and integral data link. This provides for a CAS with the unique capabilities of (1) cooperative threat resolution between BCAS and conflicting aircraft through the transmission of maneuver intent (to DABS-only aircraft) and tie breaking (with other BCAS aircraft) and (2) coordination of CAS activities with the ground ATC control function through the DABS air-ground-air data link. All beacon-equipped aircraft in the vicinity of the BCAS are detected. ATCRBS-equipped aircraft are interrogated using a special Mode C interrogation. DABS aircraft are detected passively through periodic squitters emitted by all DABS transponders. Squitter-detected aircraft are tracked on altitude and only those aircraft that represent a co-altitude threat are discretely interrogated to establish a range/altitude track. The use of discrete addressing eliminates synchronous garble for the BCAS in the same manner as for DABS. This document provides a general description of BCAS from the viewpoint of its operational features and then describes the avionics package required to achieve the capability.
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Summary

BCAS is a DABS-based airborne collision avoidance system that exploits the feature of DABS discrete addressing and integral data link. This provides for a CAS with the unique capabilities of (1) cooperative threat resolution between BCAS and conflicting aircraft through the transmission of maneuver intent (to DABS-only aircraft) and tie...

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Beacon CAS (BCAS) an integrated air/ground collision avoidance system

IPC design validation and flight testing - interim results

March 16, 1976
  |
Project Report
Author:
John W. Andrews
…
Published in:
MIT Lincoln Laboratory Report ATC-57
Topic:
air traffic control
R&D area:
R&D group:

Summary

Intermittent Positive Control, an automated aircraft collision avoidance system requiring the participation of the aircraft pilots involved, is being evaluated in a series of live flight tests. This document provides an interim summary of the results obtained in these flight tests. Results are given for IPC algorithm design evaluation flights (34) and for pilot interaction evaluation flights (14) flown from Hanscom Field, Bedford, Massachusetts between February and October, 1975.
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Summary

Intermittent Positive Control, an automated aircraft collision avoidance system requiring the participation of the aircraft pilots involved, is being evaluated in a series of live flight tests. This document provides an interim summary of the results obtained in these flight tests. Results are given for IPC algorithm design evaluation flights...

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IPC design validation and flight testing - interim results

DABS modulation and coding design - a summary

March 12, 1976
  |
Project Report
Author:
Thomas J. Goblick
Published in:
MIT Lincoln Laboratory Report ATC-52
Topic:
surveillance
R&D area:
R&D group:

Summary

The Discrete Address Beacon System (DABS) has been designed as an evolutionary replacement for the Air Traffic Control Radar Beacon System (ATCRBS). As with ATCRBS, DABS is a cooperative Air Traffic Surveillance System utilizing ground based sensors (interrogators) and airborne transponders. In addition to its surveillance function, DABS integrally accommodates ground-to-air and air-to-ground data link communication within the interrogations and replies. In DABS, each aircraft transponder may be individually interrogated, using its unique 24-bit address, giving the ground based interrogators freedom to schedule interrogations and replies to make efficient use of the channels essentially independent of the aircraft traffic distribution. The evolutionary constraint on DABS, requiring the capability for one-for-one replacement of ATCRBS ground sensors and transponders, dictated the need to maximize commonality between the two systems. Thus, the ATCRBS interrogation and reply frequencies (1030 and 1090 MHz) were prime candidates for DABS operating frequencies. This report presents the rationale for the selection of the DABS signalling waveforms and error control techniques. The main issues in arriving at the final link design were (1) affordable transponder cost, (2) electromagnetic compatibility with ATCRBS and TACAN, and (3) adequate performance in the channel environment, which includes interference from ATCRBS transmissions. The resulting DABS that of ATCRBS, and transmits ground-to-air data link messages with high reliability. This is accomplished without noticeably affecting ATCRBS performance, with less channel occupancy per target report than ATCRBS, and with transponders projected to cost approximately 160% of the cost of ATCRBS transponders.
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Summary

The Discrete Address Beacon System (DABS) has been designed as an evolutionary replacement for the Air Traffic Control Radar Beacon System (ATCRBS). As with ATCRBS, DABS is a cooperative Air Traffic Surveillance System utilizing ground based sensors (interrogators) and airborne transponders. In addition to its surveillance function, DABS integrally accommodates...

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DABS modulation and coding design - a summary

Modes of crossed rectangular waveguide

March 1, 1976
  |
Journal Article
Author:
Henry J. Stalzer Jr
…
Published in:
IEEE Trans. on Antennas Propag., Vol. 24, No. 2, March 1976, pp. 220-223.
Topic:
antennas
R&D area:
R&D group:

Summary

The cutoff frequencies and model fields of dually polarized crossed rectangular waveguide are calculated numerically and the cutoff frequencies verified experimentally. Symmetry arguments and group theory are used to explain mode degeneracies and mode splitting. The single mode bandwidth is 38 percent of center frequency for both polarization when the guide dimensions are chosen appropriately. For applications where symmetric excitation is assured, bandwidths in excess of 2:1 can be obtained.
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Summary

The cutoff frequencies and model fields of dually polarized crossed rectangular waveguide are calculated numerically and the cutoff frequencies verified experimentally. Symmetry arguments and group theory are used to explain mode degeneracies and mode splitting. The single mode bandwidth is 38 percent of center frequency for both polarization when the...

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Modes of crossed rectangular waveguide

MLS multipath studies volume II: application of multipath model to key MLS performance issues

February 25, 1976
  |
Project Report
Author:
James E. Evans
…
Published in:
MIT Lincoln Laboratory Report ATC-63,II
Topic:
L-band
R&D area:
R&D group:

Summary

This report summarizes MLS multipath work carried out at Lincoln Laboratory from March 1974 to Sept. 30, 1975. The focus of the program is the development of realistic models for 1) the multipath in representative real world environments and 2) the multipath characteristic of candidate MLS techniques. These multipath and system models are used in a comprehensive computer simulation to predict the strengths and weaknesses of major MLS systems when subjected to representative real world environments. The report is organized into two volumes. Volume I describes the algorithms and validation of various portions of the program. In Volume II, the simulation (or selected portions thereof) is applied to key multipath related MLS issues. Mathematical models are given for the major MLS multipath sources (ground reflections, building and aircraft reflections, and shadowing by objects and humped runways), and it is shown that they agree (Doppler and scanning beam) considered in phase II of the U.S. MLS program are presented together with validation by comparison with theory and bench tests. Also presented are the results of a general study in motion averaging. The (validated) computer simulation (and portions thereof) is then applied to studying 1) the critical areas required by the TRSB system to avoid excessive reflection effects, 2) the expected TRSB performance of a specific TRSB system at Friendship International Airport (MD).
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Summary

This report summarizes MLS multipath work carried out at Lincoln Laboratory from March 1974 to Sept. 30, 1975. The focus of the program is the development of realistic models for 1) the multipath in representative real world environments and 2) the multipath characteristic of candidate MLS techniques. These multipath and...

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MLS multipath studies volume II: application of multipath model to key MLS performance issues

MLS multipath studies volume I: mathematical models and validation

February 25, 1976
  |
Project Report
Author:
James E. Evans
…
Published in:
MIT Lincoln Laboratory Report ATC-63,I
Topic:
L-band
R&D area:
R&D group:

Summary

This report summarizes MLS multipath work carried out at Lincoln Laboratory from March 1974 to Sept. 30, 1975. The focus of the program is the development of realistic models for 1) the multipath in representative real world environments and 2) the multipath characteristic of candidate MLS techniques. These multipath and system models are used in a comprehensive computer simulation to predict the strengths and weaknesses of major MLS systems when subjected to representative real world environments. The report is organized into two volumes. Volume I describes the algorithms and validation of various portions of the program. In Volume II, the simulation (or selected portions thereof) is applied to key multipath related MLS issues. Mathematical models are given for the major MLS multipath sources (ground reflections, building and aircraft reflections, and shadowing by objects and humped runways), and it is shown that they agree (Doppler and scanning beam) considered in phase II of the U.S. MLS program are presented together with validation by comparison with theory and bench tests. Also presented are the results of a general study in motion averaging. The (validated) computer simulation (and portions thereof) is then applied to studying 1) the critical areas required by the TRSB system to avoid excessive reflection effects, 2) the expected TRSB performance of a specific TRSB system at Friendship International Airport (MD).
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Summary

This report summarizes MLS multipath work carried out at Lincoln Laboratory from March 1974 to Sept. 30, 1975. The focus of the program is the development of realistic models for 1) the multipath in representative real world environments and 2) the multipath characteristic of candidate MLS techniques. These multipath and...

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MLS multipath studies volume I: mathematical models and validation

Optimum elevation angle estimation in the presence of ground reflection multipath

February 9, 1976
  |
Technical Report
Author:
Robert J. McAulay
Published in:
MIT Lincoln Laboratory Report TN-1976-11
Topic:
air traffic control
R&D area:
R&D group:

Summary

An optimal trade-off between the width of the subarray aperture and the width of the interferometer base line is performed that achieves a specified elevation angle estimation error while minimizing the overall height of the interferometer configuration. Statistical decision theory is used to analyze and design a separate sensor for resolving the interferometer ambiguities. For coverage over 2.5 to 40 in elevation and +/-60 in azimuth, two 7-wavelength subarrays separated by 8 wavelengths are sufficient for 1-mrad elevation-angle errors. A 4-element nonuniformly spaced array of dipole antennas mounted on tri-plane reflectors renders the probability of an ambiguity error less than 0.004.
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Summary

An optimal trade-off between the width of the subarray aperture and the width of the interferometer base line is performed that achieves a specified elevation angle estimation error while minimizing the overall height of the interferometer configuration. Statistical decision theory is used to analyze and design a separate sensor for...

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Optimum elevation angle estimation in the presence of ground reflection multipath

Summary of DABS antenna studies

February 3, 1976
  |
Project Report
Author:
Jean-Claude Sureau
Published in:
MIT Lincoln Laboratory Report ATC-53
Topic:
surveillance
R&D area:
R&D group:

Summary

A DBS antenna is characterized by the simultaneous availability of three beams: 1. A sum beam through which all data is transferred. 2. A monopulse difference beam used for target direction finding. 3. A control beam. Its function is to guarantee that all transactions occur in the main beam. Whereas the desirable azimuth characteristics arise from the basic required functions and from the necessity to minimize the effects of the RF (target) environment, the desirable elevation features are such as to reduce the effects of the physical environment. Implementation options are very sensitive to the type (if any) of primary radar with which it is to be collocated.
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Summary

A DBS antenna is characterized by the simultaneous availability of three beams: 1. A sum beam through which all data is transferred. 2. A monopulse difference beam used for target direction finding. 3. A control beam. Its function is to guarantee that all transactions occur in the main beam. Whereas...

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Summary of DABS antenna studies

Design validation of the network management function

February 2, 1976
  |
Project Report
Author:
Patricia H. Mann
…
Published in:
MIT Lincoln Laboratory Report ATC-54
Topic:
air traffic control
R&D area:
R&D group:

Summary

This document presents the results of a major design validation effort of the Network Management function described in the DABS Engineering Requirements document. The design validation is based on simulation of a DABS network of three sensors interacting with airborne traffic of approximately 800 aircraft
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Summary

This document presents the results of a major design validation effort of the Network Management function described in the DABS Engineering Requirements document. The design validation is based on simulation of a DABS network of three sensors interacting with airborne traffic of approximately 800 aircraft

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Design validation of the network management function

Airport survey for MLS multipath issues

December 15, 1975
  |
Project Report
Author:
David A. Shnidman
Published in:
MIT Lincoln Laboratory Report ATC-58
Topic:
air traffic control
R&D area:
R&D group:

Summary

Eight major U.S. civilian airports were visited and data on the surface material of all sizable buildings visible from the runways were obtained. This information is catalogued herein. It is only with the aid of such information that we can address issues such as the likelihood of a system performance changes due to polarization, pattern control and coverage control. A total of 93 buildings and 123 surfaces are included and the breakdown between the various surfaces is as follows: 74 surfaces were corrugated 17 surfaces were cinder block 16 surfaces were brick 9 surfaces were concrete 5 surfaces were metal. Of the 74 corrugated surfaces 18 were of the "flat" variety, 34 were one of five sub-categories and the remaining 22 needed 15 sub-categories for classification.
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Summary

Eight major U.S. civilian airports were visited and data on the surface material of all sizable buildings visible from the runways were obtained. This information is catalogued herein. It is only with the aid of such information that we can address issues such as the likelihood of a system performance...

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Airport survey for MLS multipath issues
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