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Study of microburst detection performance during 1985 in Memphis, TN

August 5, 1987
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Project Report
Author:
John T. DiStefano
Published in:
MIT Lincoln Laboratory Report ATC-142
Topic:
doppler radar
R&D area:
R&D group:

Summary

This report focuses on the detectability of microbursts using pulse Doppler weather radars and surface anemometers. The data used for this study were collected in the Memphis, TN area during the FLOWS project of 1985. The methods used for declaring a microburst from both Doppler radar and surface anemometer data are described. The main objective of this report was to identify the results that were generated by comparing the 1985 radar detected microbursts (which impacted the surface anemometer system) wit the surface mesonet detected microbursts. In so doing, the issue of missed microburst detections, for which there occurred two (both by the radar), is identified. Possible reasons as to why there two microbursts were not detected are discussed in detail.
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Summary

This report focuses on the detectability of microbursts using pulse Doppler weather radars and surface anemometers. The data used for this study were collected in the Memphis, TN area during the FLOWS project of 1985. The methods used for declaring a microburst from both Doppler radar and surface anemometer data...

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Study of microburst detection performance during 1985 in Memphis, TN

A gust front case studies handbook

January 10, 1985
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Project Report
Author:
Diana L. Klingle-Wilson
…
Published in:
MIT Lincoln Laboratory Report ATC-129
Topic:
doppler radar
R&D area:
R&D group:

Summary

Gust fronts produce low altitude wind shear that can be hazardous to aircraft operations, especially during takeoff and landing. Radar meteorologists have long been able to identify gust front signatures in Doppler radar data, but in order to use the radars efficiently, automatic detection of such hazards is essential. Eight gust front case studies are presented. The data include photographs of the Doppler weather radar displays, thermodynamic and wind measurements from a 440 m high tower, environmental soundings and tables of gust front characteristics. The tabulated characteristics are those thought to be most important in developing rules for automatic gust front detection such as length and height, maximum and minimum values of reflectivity, velocity and spectrum width, and estimates of radial shear. For the cases studied, outflows could be detected most reliably in the velocity field, but useful information also could be gleaned from the spectrum width and reflectivity fields. The signal-to-noise ratio threshold was found to be a major factor in the ability of an observer to discern the gust front signature in the Doppler radar displays. Detection within the spectrum width field required a higher SNR than did the radial velocity field.
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Summary

Gust fronts produce low altitude wind shear that can be hazardous to aircraft operations, especially during takeoff and landing. Radar meteorologists have long been able to identify gust front signatures in Doppler radar data, but in order to use the radars efficiently, automatic detection of such hazards is essential. Eight...

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A gust front case studies handbook

An automatic weather station network for low-altitude wind shear investigations

September 18, 1984
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Project Report
Author:
Diana L. Klingle-Wilson
…
Published in:
MIT Lincoln Laboratory Report ATC-128
Topic:
weather
R&D area:
R&D group:

Summary

During the summer of 1983 an experimental network of automatic weather stations (a mesonet) was operated in the vicinity of Hanscom Field, northwest of Boston, as part of a larger effort to collect Doppler radar and meteorological data on thunderstorms and other potentially hazardous weather events in this area. This report describes the mesonet system used and presents in detail the data collected on 21-22 July 1983. Conclusions about the limitations and the future use of the mesonet system are also included.
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Summary

During the summer of 1983 an experimental network of automatic weather stations (a mesonet) was operated in the vicinity of Hanscom Field, northwest of Boston, as part of a larger effort to collect Doppler radar and meteorological data on thunderstorms and other potentially hazardous weather events in this area. This...

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An automatic weather station network for low-altitude wind shear investigations

Moving Target Detector (Mod II) summary report

November 3, 1981
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Project Report
Author:
David Karp
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Published in:
MIT Lincoln Laboratory Report ATC-95
Topic:
surveillance
R&D area:
R&D group:

Summary

Under FAA sponsorship, MIT/Lincoln Laboratory has developed a second generation, field operable Moving Target Detection System (MTD-II) which has been tested at operational FAA terminal and enroute radar sites, and serves as the basis for the ASR-9 MTD technical performance specifications. This summary report covers the period October, 1976 through September, 1979 in which design, development, field testing and system performance evaluation were carried out. Report No. FAA-RD-76-190, ATC-69, "Description and Performance Evaluation of the Moving Target Detector" dated 8 March 1977, serves as the technical foundation of this work. MTD-processing design modifications were effected to handle conditions of excessive ground clutter and moving ground traffic. The rationale for the modified algorithms is provided, and measured performance characteristics at several FAA field sites are discussed.
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Summary

Under FAA sponsorship, MIT/Lincoln Laboratory has developed a second generation, field operable Moving Target Detection System (MTD-II) which has been tested at operational FAA terminal and enroute radar sites, and serves as the basis for the ASR-9 MTD technical performance specifications. This summary report covers the period October, 1976 through...

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Moving Target Detector (Mod II) summary report

Comparison of the performance of the moving target detector and the radar video digitizer

April 26, 1977
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Project Report
Author:
Robert M. O'Donnell
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Published in:
MIT Lincoln Laboratory Report ATC-70
Topic:
surveillance
R&D area:
R&D group:

Summary

Results of side by side simultaneous tests to compare the performance of the Moving Target Detector (MID) digital signal processor and that of a newly developed adaptive sliding window detector, the Radar Video Digitizer (RVD-4), are described. The MTD, used with a highly modified FPS-18, employs coherent linear doppler filtering, adaptive thresholding, and a fine grained clutter map which together reject all forms of clutter simultaneously. The RVD-4, which was used with an ASR-7, is a non-linear, non-coherent digital processor. The detection and false alarm performance of both processors in thermal noise was identical. Measured detection and sub-clutter visibility performance of the MTD on controlled aircraft flying in heavy rain, in heavy ground clutter, and at near-zero radial velocity is shown to be superior to that of the RVD-4. MID report data is also shown to be more accurate than the RVD-4 data resulting in improved ARTS-Ill tracker performance when using MID processed data.
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Summary

Results of side by side simultaneous tests to compare the performance of the Moving Target Detector (MID) digital signal processor and that of a newly developed adaptive sliding window detector, the Radar Video Digitizer (RVD-4), are described. The MTD, used with a highly modified FPS-18, employs coherent linear doppler filtering...

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Comparison of the performance of the moving target detector and the radar video digitizer

Radar detection of thunderstorm hazards for air traffic control volume I: storm cell detection

October 7, 1976
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Project Report
Author:
Robert K. Crane
Published in:
MIT Lincoln Laboratory Report ATC-67,I
Topic:
weather
R&D area:
R&D group:

Summary

A procedure was developed to detect hazardous regions within thunderstorms using weather radar data. The procedure is based upon the hypothesis that convective turbulence occurs within 2-3 km of relative radar reflectivity maxima (cells). The hypothesis was tested using a limited set of simultaneous aircraft and radar data. Good agreement was found between the observed regions of convective turbulence and the cell locations determined by radar. The viability of the hazard detection hypothesis as a basis for automatic warning and forcast depends upon the reliability of the cell detection and tracking algorithms. Analysis of precision radar data revealed that the cells are small in area extent, have a detection probability in excess of 0.9 using multiple radar scans, and are readily tracked for periods between 10 and 20 minutes. The characteristics of radar systems for acquiring data to support cell detection, are discussed. The role of Doppler spectral data is explored, and it is found that practical limitations on radar beamwidth hamper direct observation of turbulence on the scale size hazardous to aircraft.
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Summary

A procedure was developed to detect hazardous regions within thunderstorms using weather radar data. The procedure is based upon the hypothesis that convective turbulence occurs within 2-3 km of relative radar reflectivity maxima (cells). The hypothesis was tested using a limited set of simultaneous aircraft and radar data. Good agreement...

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Radar detection of thunderstorm hazards for air traffic control volume I: storm cell detection

Multipath parameter computations for the MLS simulation computer program

April 8, 1976
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Project Report
Author:
Jack Capon
Published in:
MIT Lincoln Laboratory Report ATC-68
Topic:
L-band
R&D area:
R&D group:

Summary

A set of mathematical models and computer programs have been developed to characterize multipath propagation in an airport environment. When combined with system mathematical models, these models are intended to provide a firm technical basis for assessing the performance of candidate Microwave Landing Systems (MLS) in realistic airport environments. The two paramount issues in developing these models have been 1) validation based on actual field test data and 2) computer running time. The obstacles modeled include buildings and aircraft, as well as the ground which can cause both specular reflections and diffuse scattering. In addition, the shadowing effects due to runway humps, and aircraft, buildings approaching the line of sight between transmitter and receiver are included. Computational procedures are presented for obtaining the salient multipath parameters, i.e., relative magnitude, phase, directional angles, Doppler frequency, and time delay. Computer programs have been written for these algorithms using the Fortran programming language, with structured programming methods, such as Iftran, employed whenever possible. A presentation is given of computer validation data for the computational procedures. A comparison of these computer validation results with experimental field data demonstrates good agreement in all cases of interest. The computer running time for these computer programs is quite reasonable, e.g., it takes about five times longer than actual flight time to run a model of typical airport environment on an IBM 370 model 168.
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Summary

A set of mathematical models and computer programs have been developed to characterize multipath propagation in an airport environment. When combined with system mathematical models, these models are intended to provide a firm technical basis for assessing the performance of candidate Microwave Landing Systems (MLS) in realistic airport environments. The...

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Multipath parameter computations for the MLS simulation computer program

Logan MLS multipath experiment

September 23, 1975
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Project Report
Author:
David A. Shnidman
Published in:
MIT Lincoln Laboratory Report ATC-55
Topic:
air traffic control
R&D area:
R&D group:

Summary

The National Plan for a Microwave Landing System (MLS) has specified a carrier frequency for the system in the vicinity of 5.1 GHz. At that frequency, no multipath data taken at a major civilian airport existed. The purpose of this experiment was to obtain such data at Logan International Airport in order to ascertain: 1) which objects are the major causes of measurable multipath reflections and their levels relative to the direct signal (MID level), 2) whether or not the reflections from these objects can be satisfactorily simulated by the Lincoln computer model and, if so, how complicated must that model be, and 3) if the characteristics of multipath provide a significant discriminant between the Doppler and scanning beam techniques. It was found in the experiment that regions where reflections were noted could be predicted from ray optics and diffraction. No measurable reflections were noted elsewhere. For the purpose of modeling for multipath, building surfaces could be characterized as a flat plate with a reflection coefficient determined by measurement if it were a complicated surface, or by the dielectric properties of the surface material, if a simple surface. The airplane reflection model was also found to agree well with measurements.
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Summary

The National Plan for a Microwave Landing System (MLS) has specified a carrier frequency for the system in the vicinity of 5.1 GHz. At that frequency, no multipath data taken at a major civilian airport existed. The purpose of this experiment was to obtain such data at Logan International Airport...

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Logan MLS multipath experiment

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

Concepts for improvement of airport surveillance radars

February 26, 1973
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Project Report
Author:
Charles E. Muehe
…
Published in:
MIT Lincoln Laboratory Report ATC-14
Topic:
radar
R&D area:
R&D group:

Summary

This report reviews the performance of operational ASR's, discusses each type of clutter with which the target must compete, examines presently employed methods of overcoming clutter and several state-of-the-art techniques which have not found their way into the ASR's for one reason or another. It concludes by describing two radars, one at S-band and one at UHF, which are believed to come closest to fulfilling ASR requirements in advanced ARTS facilities. The major improvements in performance will be derived from the use of linear optimum signal processing. Further gains will be achieved through the use of adaptive thresholds. STC will combat bird clutter. The radar will incorporate proper shaping of the antenna pattern so that aircraft off the peak of the antenna elevation beam will not be at a disadvantage compared to moving clutter at the peak. The recommended radar concepts also include radial velocity determination by Doppler measurement. This should prove of value in maintaining target tracks and in discrimination against ground vehicles.
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Summary

This report reviews the performance of operational ASR's, discusses each type of clutter with which the target must compete, examines presently employed methods of overcoming clutter and several state-of-the-art techniques which have not found their way into the ASR's for one reason or another. It concludes by describing two radars...

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Concepts for improvement of airport surveillance radars
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