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A new asteroid observation and search technique

October 1, 1981
  |
Journal Article
Author:
Laurence G. Taff
Published in:
Publ. Astronom. Soc. Pacific, Vol. 93, No. 555, October 1981, pp. 658-660.
Topic:
asteroids
R&D area:
R&D group:

Summary

A prototype observatory was constructed near Socorro, New Mexico to search for and observe earth-approaching asteroids. Hardware modifications were made so that the discrimination of artificial satellites at an angular speed of 15 arcsec/sec can be used to observe minor planets at an angular speed of 0.01 arcsec/sec. Assuming no correlations between time of perigee passage and time of year, a recovery of 25 asteroids per year is expected.
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Summary

A prototype observatory was constructed near Socorro, New Mexico to search for and observe earth-approaching asteroids. Hardware modifications were made so that the discrimination of artificial satellites at an angular speed of 15 arcsec/sec can be used to observe minor planets at an angular speed of 0.01 arcsec/sec. Assuming no...

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A new asteroid observation and search technique

ATCRBS uplink environment measurements near Jacksonville, Florida

September 25, 1981
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Project Report
Author:
Ferenc Nagy Jr
Published in:
MIT Lincoln Laboratory Report ATC-94
Topic:
surveillance
R&D area:
R&D group:

Summary

Airborne measurements of the Air Traffic Control Radar Beacon System (ATCRBS) 1030 MHz uplink environment are described. Measurements were made using the AMF, a special purpose airborne sensor-recorder, during a 23 May 1979 flight in the greater Jacksonville, Florida area. The 2-way flight covered the 450 nm coastline between Fayetteville (NC) and Vero Beach (FL) first at 10,000 then at 25,000 feet. Data recorded at 61 locations have been analyzed to plot combined pulse, interrogation and suppression rates for all locations and individual rates, received powers and angles for 37 locations. Fifty-nine ground interrogators were detected and a list included serves as an all-interrogator/all-location (59 x 37) visibility matrix. PRI/PRF distributions of interrogations received are shown at three selected measurement locations. A pulse-by-pulse plot of over 50 Mode 4 interrogations shows their effect on a typical transponder. A "worst" location is examined for peak instantaneous interrogation rates capable of causing transponder reply-rate limiting (RRL), desensitization and track loss. Durations and periods of recurrence of "synchronous jamming" for 23 near-equal scan periods are computed. Probabilities of multiple mainbeam coincidences ("multi-PRF jamming") are also calculated. Airborne (AMF) and ground based (FAA En-Route) coverages are compared, and reported operational problems (target splits, lost tracks, poor coverage) are addressed.
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Summary

Airborne measurements of the Air Traffic Control Radar Beacon System (ATCRBS) 1030 MHz uplink environment are described. Measurements were made using the AMF, a special purpose airborne sensor-recorder, during a 23 May 1979 flight in the greater Jacksonville, Florida area. The 2-way flight covered the 450 nm coastline between Fayetteville...

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ATCRBS uplink environment measurements near Jacksonville, Florida

Results of L band multipath measurements at operational United States (U.S.) airports in support of the Microwave Landing System (MLS) Precision Distance Measuring Equipment (DME/P)

July 23, 1981
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Project Report
Author:
James E. Evans
…
Published in:
MIT Lincoln Laboratory Report ATC-109
Topic:
L-band
R&D area:
R&D group:

Summary

This report presents the results of a short duration L band multipath measurement program at five major U.S. airports (St. Louis, Tulsa, Wright Patterson Air Force Base, Philadelphia and Washington National) and one smaller airport (Quonset, RI) to better quantify the expected multipath environment for the Microwave Landing System (MLS) Precision Distance Measuring Equipment (DME/P). Specific objectives included: (1) Measurements of the principal multipath parameters (amplitude and time delay) with realistic aircraft/ground site locations at runways which had the major DME/multipath sources (large buildings) identified in previous analytical (simulation) studies. (2) Determination of whether significant DME/P multipath sources exist which had not been considered to date and (3) Comparison of the measured results with computer simulation results obtained with simplified airport models (such as have been used for DME/P system design to date). Particular emphasis was placed on the final approach region including the flare and rollout regions since these areas correspond to the most stringent DME/P accuracy requirements and, have not been utilized operationally with the current L band DME. All of the above objectives were achieved although in some cases the experimental data in the flare/rollout region was of poor quality due to low signal to noise ratio. The spatial region and time delay of specular multipath generally correlated well with expectations based on simple ray tracing. With the exception of Washington National, no significant (multipath to direct signal ratio (M/D >110 dB) multipath was encountered in operationally relevant areas which was not predicted. The quantitative predictions of the simple airport models agreed with the experimental data, although in some cases, (especially, near threshold) the measured M/D values were considerably higher than predictions.
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Summary

This report presents the results of a short duration L band multipath measurement program at five major U.S. airports (St. Louis, Tulsa, Wright Patterson Air Force Base, Philadelphia and Washington National) and one smaller airport (Quonset, RI) to better quantify the expected multipath environment for the Microwave Landing System (MLS)...

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Results of L band multipath measurements at operational United States (U.S.) airports in support of the Microwave Landing System (MLS) Precision Distance Measuring Equipment (DME/P)

MLS Multipath Studies, Phase 3 Final Report, Volume III: Application of Models to MLS Assessment Issues, Part 2

June 8, 1981
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Project Report
Author:
James E. Evans
…
Published in:
MIT Lincoln Laboratory Report ATC-88,III,PT-2
Topic:
air traffic control
R&D area:
R&D group:

Summary

This report presents work done during phase 3 of the US national Microwave Landing System (MLS) program toward developing a computer simulation model of the MLS multipath effects, the experimental validation ot the model, and the application of the model to investigate multipath performance of ICAO proposals for the new approach and landing guidance system. The first two volumes of the report presented an overview of the simulation effort as well as describing in detail the propagation and MLS technique mathematical models and their validation by comparison with experimental data. In this volume, we describe the results of comparative simulations for the various MLS techniques in various scenarios and analyze in detail certain multipath performance features which were found to be significant in the scenario simulations. Simulation results are presented for several scenarios, and shadowing of the MLS azimuth by taxiing and overflying aircraft is analyzed. The remainder of the report focuses onmultipath performance factors specific to various individual techniques. These include: (1) the effects of angle data outlier tests and filtering in the TRSB receivers, (2) the effects on the DMLS system due to receiver AGC, receiver motion-induced Doppler shifts, and the use of commutated reference systems, and (3) acquisition/validation algorithms for all three techniques. The report concludes with a summary and suggestions for future work. Part I of this volume consists of Chapters I through IV; Part II contains Chapters V through VIII and the Appendices.
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Summary

This report presents work done during phase 3 of the US national Microwave Landing System (MLS) program toward developing a computer simulation model of the MLS multipath effects, the experimental validation ot the model, and the application of the model to investigate multipath performance of ICAO proposals for the new...

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MLS Multipath Studies, Phase 3 Final Report, Volume III: Application of Models to MLS Assessment Issues, Part 2

MLS Multipath Studies, Phase 3 Final Report, Volume III: Application of Models to MLS Assessment Issues, Part 1

June 8, 1981
  |
Project Report
Author:
James E. Evans
…
Published in:
MIT Lincoln Laboratory Report ATC-88,III,PT-1
Topic:
air traffic control
R&D area:
R&D group:

Summary

This report presents work done during phase 3 of the US national Microwave Landing System (MLS) program toward developing a computer simulation model of the MLS multipath effects, the experimental validation ot the model, and the application of the model to investigate multipath performance of ICAO proposals for the new approach and landing guidance system. The first two volumes of the report presented an overview of the simulation effort as well as describing in detail the propagation and MLS technique mathematical models and their validation by comparison with experimental data. In this volume, we describe the results of comparative simulations for the various MLS techniques in various scenarios and analyze in detail certain multipath performance features which were found to be significant in the scenario simulations. Simulation results are presented for several scenarios, and shadowing of the MLS azimuth by taxiing and overflying aircraft is analyzed. The remainder of the report focuses on multipath performance factors specific to various individual techniques. These include: (1) the effects of angle data outlier tests and filtering in the TRSB receivers, (2) the effects on the DMLS system due to receiver AGC, receiver motion-induced Doppler shifts, and the use of commutated reference systems, and (3) acquisition/validation algorithms for all three techniques. The report concludes with a summary and suggestions for future work. Part I of this volume consists of Chapters I through IV; Part II contains Chapters V through VIII and the Appendices.
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Summary

This report presents work done during phase 3 of the US national Microwave Landing System (MLS) program toward developing a computer simulation model of the MLS multipath effects, the experimental validation ot the model, and the application of the model to investigate multipath performance of ICAO proposals for the new...

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MLS Multipath Studies, Phase 3 Final Report, Volume III: Application of Models to MLS Assessment Issues, Part 1

Coordinated radar and aircraft observations of turbulence

May 26, 1981
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Project Report
Author:
Melvin Labitt
Published in:
MIT Lincoln Laboratory Report ATC-108
Topic:
weather
R&D area:
R&D group:

Summary

Interim results of a program to measure and correlate radar- and aircraft-sensed turbulence in rainstorms are presented. The dissipation factor of a turbulence air mass can be measured by an aircraft and a weather radar. Comparisons are made between precipitation reflectivity and spectral width measurements as indicators of turbulence. The instrumentation and data processing procedures are described. Examples of turbulence observations made with a storm-penetrating aircraft and the weather radar are given. The relationship between the radar observations and the physical properties of the turbulence atmosphere are derived. The relationship of radar spectral width (variance) to turbulence intensity is discussed.
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Summary

Interim results of a program to measure and correlate radar- and aircraft-sensed turbulence in rainstorms are presented. The dissipation factor of a turbulence air mass can be measured by an aircraft and a weather radar. Comparisons are made between precipitation reflectivity and spectral width measurements as indicators of turbulence. The...

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Coordinated radar and aircraft observations of turbulence

Recursive two-dimensional signal reconstruction from linear system input and output magnitudes

May 1, 1981
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Journal Article
Author:
Thomas F. Quatieri
Published in:
Proc. IEEE, Vol. 69, No. 5, May 1981, pp. 667-668.
Topic:
signal processing
R&D area:
R&D group:

Summary

A recursive algorithm is presented for reconstructing a two-dimensional complex signal from its magnitude and the magnitude of the output of a known linear shift-invariant system whose input is the desired signal. The recursion has a simple geometric interpretation, and is easily extended to causal, shift-varying systems.
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Summary

A recursive algorithm is presented for reconstructing a two-dimensional complex signal from its magnitude and the magnitude of the output of a known linear shift-invariant system whose input is the desired signal. The recursion has a simple geometric interpretation, and is easily extended to causal, shift-varying systems.

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Recursive two-dimensional signal reconstruction from linear system input and output magnitudes

On best approximation by truncated series

May 1, 1981
  |
Journal Article
Author:
Harold Z. Ollin
Published in:
J. Approx. Theory, Vol. 32, May 1981, pp. 82-84.
Topic:
algorithms
R&D area:
R&D group:

Summary

Let T, be the Chebyshev polynomial of the first kind of degree k.
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Summary

Let T, be the Chebyshev polynomial of the first kind of degree k.

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On best approximation by truncated series

An improved technique for altitude tracking of aircraft

March 25, 1981
  |
Project Report
Author:
John W. Andrews
Published in:
MIT Lincoln Laboratory Report ATC-105
Topic:
surveillance
R&D area:
R&D group:

Summary

When simple linear recursive tracking techniques are applied to quantized altitude reports, certain errors in estimation of altitude and altitude rate can be attributed to the response of the tracker to transitions between quantization levels. These errors can be reduced by use of an estimation technique which explicitly recognizes the quantized nature of the inputs. Smoothing of the level occupancy time (i.e., the time spent at each quantization level) can be used to control the response to redundant samples taken at the same quantization level. Further improvement is achieved by consistency tests which use particular properties of quantized data to detect changes in rate. This document presents a theoretical analysis of tracker repsonse to quantized inputs. A tracking algorithm is synthesized using these techniques and simulation results using various altitude profiles are presented.
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Summary

When simple linear recursive tracking techniques are applied to quantized altitude reports, certain errors in estimation of altitude and altitude rate can be attributed to the response of the tracker to transitions between quantization levels. These errors can be reduced by use of an estimation technique which explicitly recognizes the...

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An improved technique for altitude tracking of aircraft

Radar Beacon Transponder (RBX) installation and siting criteria

March 13, 1981
  |
Project Report
Author:
Ronald G. Sandholm
Published in:
MIT Lincoln Laboratory Report ATC-106
Topic:
surveillance
R&D area:
R&D group:

Summary

The Radar BEacon Transponder (RBX) is a ground-based facility used in conjunction with other elements of the Active Beacon Collision Avoidance System (BCAS) to control the threat detection sensitivity level of BCAS aircraft and to convey displayed Resolution Advisories from the BCAS aircraft to the local ATC terminal facility. This paper describes the mechanisms of specular multipath reflection and signal shadowing and discussed their impact on the RBX link power budget. Criteria for choice of RBX antenna height and location are presented.
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Summary

The Radar BEacon Transponder (RBX) is a ground-based facility used in conjunction with other elements of the Active Beacon Collision Avoidance System (BCAS) to control the threat detection sensitivity level of BCAS aircraft and to convey displayed Resolution Advisories from the BCAS aircraft to the local ATC terminal facility. This...

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Radar Beacon Transponder (RBX) installation and siting criteria
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