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Results of the Kansas City 1989 Terminal Doppler Weather Radar (TDWR) operational evaluation testing

August 17, 1990
  |
Project Report
Author:
James E. Evans
Published in:
MIT Lincoln Laboratory Report ATC-171
Topic:
weather
R&D area:
R&D group:

Summary

The Lincoln Laboratory Terminal Doppler Weather Radar (TDWR) testbed was used to carry out an experimental and operational hazardous weather product evaluation program for the Federal Aviation Administration (FAA) at the Kansas City International (KCI) Airport during the summer of 1989. The objective of the program was to test and refine previously tested techniques for the automatic detection of low-altitude wind shear phenomena (specifically microbursts and gust fronts) and heavy precipitation in a midwest weather environment, as well as to assess possible new products such as storm movement predictions. A successful operational evaluation of the TDWR products took place at the KCI tower and terminal radar control room (TRACON) from 15 July to 15 August 1989 and from 15 to 30 September 1989. Several supervisor and controller display refinements that had been determined from the 1988 operational evaluation at Denver were assessed as effective. The system was successful in terms of aircraft at KCI avoiding wind shear encounters during the operational period, and it was assessed as "very good" in usefulness for continuing operation by the KCI air traffic control (ATC) personnel.
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Summary

The Lincoln Laboratory Terminal Doppler Weather Radar (TDWR) testbed was used to carry out an experimental and operational hazardous weather product evaluation program for the Federal Aviation Administration (FAA) at the Kansas City International (KCI) Airport during the summer of 1989. The objective of the program was to test and...

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Results of the Kansas City 1989 Terminal Doppler Weather Radar (TDWR) operational evaluation testing

Contributions to the American Meterorological Society 16th Conference on Severe Local Storms

August 15, 1990
  |
Project Report
Author:
Marilyn M. Wolfson
Published in:
MIT Lincoln Laboratory Report ATC-173
Topic:
weather
R&D area:
R&D group:

Summary

Eight papers contributed by the Lincoln Laboratory Weather Sensing Group to the American Meteorological Society's 16th Conference on Severe Local Storms, to be held October 22-26, 1990 in Kananaskis Provincial Park, Alberta, Canada, are compiled in this volume. The FAA sponsored the summer 1989 field test of the Terminal Doppler Weather Radar (TDWR) system in Kansas City, Missouri to detect wind shear aviation hazards at or near the airport. The papers are based on data collected through the summer 1989 field test and on subsequent analyses and product evaluation. The staff members of Group 43, Weather Sensing, have documented their studies of the following topics: a severe microburst; a prototype microburst prediction product; average summer microburst threat prediction at an airport; microburst asymmetry; the effect of radar viewing angle on the performance of the gust front detection algorithm; a comparison of Low-Level Wind Shear Alert System (LLWAS) anemometer-measured winds and Doppler-measured winds; and ASR-9 (Airport Surveillance Radar) adjustment of range-dependent storm reflectivity levels. The final paper is an invited paper for the Conference on microbursts. This paper discusses the precipitation-driven downdraft and the downdraft associated with the "vortex," or gust front, at the leading edge of an expanding thunderstorm outflow as two primary forms of low altitude downdraft phenomena in the microburst problem.
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Summary

Eight papers contributed by the Lincoln Laboratory Weather Sensing Group to the American Meteorological Society's 16th Conference on Severe Local Storms, to be held October 22-26, 1990 in Kananaskis Provincial Park, Alberta, Canada, are compiled in this volume. The FAA sponsored the summer 1989 field test of the Terminal Doppler...

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Contributions to the American Meterorological Society 16th Conference on Severe Local Storms

Summer 1988 TDWR microburst analysis

July 1, 1990
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Conference Paper
Author:
Mark W. Merritt
Published in:
Proc. Airborne Wind Shear Detection and Warning Systems, Second Combined Manufacturers' and Technologists' Conf., Pt. II, 18-20 October 1988, pp. 741-751.
Topic:
wind shear
R&D area:
R&D group:

Summary

The Terminal Doppler Weather Radar (TDWR) testbed system was operated during the months of July-August 1988 in a live operational demonstration providing microburst (and related weather hazard) protection to the Stapleton International Airport in Deilver, CO. During this time period, the performance of the detection system was carefully monitored in an effort to determine the reliability of the system. Initial performance analysis indicates that the microburst detection component of TDWR satisfies the basic performance goals of 90% probability of detection md 10% probability of false alarm. An in-depth study of the system performance, based on analysis of both dual-Doppler radar observations and surface mesonet measurements, is in progress to provide a detailed understanding of the observability of microbursts by the radar, the ability of the algorithms to detect microbursts observed by the radar, and the timeliness and accuracy of the microburst alarms provided to operational users.
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Summary

The Terminal Doppler Weather Radar (TDWR) testbed system was operated during the months of July-August 1988 in a live operational demonstration providing microburst (and related weather hazard) protection to the Stapleton International Airport in Deilver, CO. During this time period, the performance of the detection system was carefully monitored in...

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Summer 1988 TDWR microburst analysis

Clutter rejection in Doppler weather radars used for airport wind shear detection

June 1, 1990
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Conference Paper
Author:
James E. Evans
…
Published in:
Proc. Second Int. Symp. on Noise & Clutter Rejection in Radars & Imaging Sensors (ISNCR-89), 14-16 November 1989, PP. 275-280.
Topic:
aviation weather
R&D area:
R&D group:

Summary

Techniques for the suppression of ground and storm clutter to permit the detection of low altitude windshear by pulse Doppler radars are described. Novel features of the system include the use of clutter residue and range aliased weather echo editing maps which edit out the range-azimuth cells on a "data adaptive" basis.
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Summary

Techniques for the suppression of ground and storm clutter to permit the detection of low altitude windshear by pulse Doppler radars are described. Novel features of the system include the use of clutter residue and range aliased weather echo editing maps which edit out the range-azimuth cells on a "data...

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Clutter rejection in Doppler weather radars used for airport wind shear detection

Analysis of the potential benefits of Terminal Air Traffic Control Automation (TATCA)

May 23, 1990
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Conference Paper
Author:
Steven B. Boswell
…
Published in:
Proc. 1990 American Control Conf., Vol. 1, 23-25 May 1990, pp.535-542
Topic:
air traffic control
R&D area:
R&D group:

Summary

Terminal Air Traffic Control Automation (TATCA) is an FAA research and development program to provide computer-aided sequencing, spacing, and management of air traffic flows in terminal areas. This paper discusses technical and national economic benefits that are attainable with such a terminal automation program.
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Summary

Terminal Air Traffic Control Automation (TATCA) is an FAA research and development program to provide computer-aided sequencing, spacing, and management of air traffic flows in terminal areas. This paper discusses technical and national economic benefits that are attainable with such a terminal automation program.

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Analysis of the potential benefits of Terminal Air Traffic Control Automation (TATCA)

Microburst observability and frequency during 1988 in Denver, CO

May 14, 1990
  |
Project Report
Author:
John T. DiStefano
…
Published in:
MIT Lincoln Laboratory Report ATC-170
Topic:
weather
R&D area:
R&D group:

Summary

The observability of microbursts with single-Doppler radar is investigated through comparison of radar data and surface weather sensor data. The data were collected during 1988 in Denver, CO as part of the FAA Terminal Doppler Weather Radar measurement program. Radar data were collected by both and S-band and C-band radar, while surface data were taken from a mesoscale network of 42 weather sensors in the vicinity of Denver's Stapleton International Airport. Results are compared with previous similar studies of observability using data from 1987 in Denver, and 1986 in Huntsville, AL. A total of 184 microbursts impacting the surface mesonet were identified. For those microbursts for which both radar and surface data were available, 97% were observable by single-Doppler radar. This compares to 94% observability during 1987 in Denver, and 98% during 1986 in Huntsville. Two strong microbursts (at lease 20 m/s differential velocity) were unobservable by radar throughout their lifetime: one due to low signal-to-noise ratio, and the other due initially to an asymmetric outflow with low signal-to-noise ratio also a contributing factor. Two other microbursts, with differential velocities from 10-19 m/s, were unobservable by radar: one due to shallow outflow with a depth limited to a height below that of the radar beam, and one due to asymmetric outflow oriented unfavorably with respect to the radar viewing angle. Consistent with previous observations, microburst occurrence was most frequent during June and July, when 94 microbursts were identified on 20 days. An anomalously high frequency was also seen in April, although the strength of these events was relatively modest. As expected, the diurnal distribution shows the late afternoon to be the most favorable time for microburst development; more than half of all events reached their maximum strength between the hours of 2-5 p.m. local time.
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Summary

The observability of microbursts with single-Doppler radar is investigated through comparison of radar data and surface weather sensor data. The data were collected during 1988 in Denver, CO as part of the FAA Terminal Doppler Weather Radar measurement program. Radar data were collected by both and S-band and C-band radar...

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Microburst observability and frequency during 1988 in Denver, CO

Terminal Doppler Weather Radar clutter control

May 10, 1990
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Conference Paper
Author:
James E. Evans
…
Published in:
Proc. IEEE 1990 Int. Radar Conf., 7-10 May 1990, pp. 12-16.
Topic:
aviation weather
R&D area:
R&D group:

Summary

The FAA is developing the Terminal Doppler Weather Radar system to automatically detect low altitude wind shear due to microbursts and gust fronts. Detection of this phenomenon presents a significant radar engineering challenge due to the need to observe low reflectivity events in the presence of strong clutter from ground objects and range aliased weather returns. This paper describes a number of unique approaches to clutter recognition which have been validated with the TDWR test bed radar.
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Summary

The FAA is developing the Terminal Doppler Weather Radar system to automatically detect low altitude wind shear due to microbursts and gust fronts. Detection of this phenomenon presents a significant radar engineering challenge due to the need to observe low reflectivity events in the presence of strong clutter from ground...

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Terminal Doppler Weather Radar clutter control

Short-time signal representation by nonlinear difference equations

April 6, 1990
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Conference Paper
Author:
Thomas F. Quatieri
…
Published in:
Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, ICASSP, Vol. 3, Digital Signal Processing, 3-6 April 1990, pp. 1551-1554.
Topic:
signal processing
R&D area:
R&D group:

Summary

The solution of a nonlinear difference equation can take on complicated deterministic behavior which appears to be random for certain values of the equation's coefficients. Due to the sensitivities to initial conditions of the output of such "chaotic" systems, it is difficult to duplicate the waveform structure by parameter analysis and waveform synthesis techniques. In this paper, methods are investigated for short-time analysis and synthesis of signals from a class of second-order difference equations with a cubic nonlinearity. In analysis, two methods are explored for estimating equation coefficients: (1) prediction error minimization (a linear estimation problem) and (2) waveform error minimization (a nonlinear estimation problem). In the latter case, which improves on the prediction error solution, an iterative analysis-by-synthesis method is derived which allows as free variables initial conditions, as well as equation coefficients. Parameter estimates from these techniques are used in sequential short-time synthesis procedures. Possible application to modeling "quasi-periodic" behavior in speech waveforms is discussed.
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Summary

The solution of a nonlinear difference equation can take on complicated deterministic behavior which appears to be random for certain values of the equation's coefficients. Due to the sensitivities to initial conditions of the output of such "chaotic" systems, it is difficult to duplicate the waveform structure by parameter analysis...

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Short-time signal representation by nonlinear difference equations

Noise reduction using a soft-decision sine-wave vector quantizer

April 6, 1990
  |
Conference Paper
Author:
Thomas F. Quatieri
…
Published in:
Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, ICASSP, Vol. 2, Speech Processing 2; VLSI, Audio and Electroacoustics, 3-6 April 1990, pp. 821-824.
Topic:
speech enhancement
R&D area:
R&D group:

Summary

The need for noise reduction arises in speech communication channels, such as ground-to-air transmission and ground-based cellular radio, to improve vocoder quality and speech recognition accuracy. In this paper, noise reduction is performed in the context of a high-quality harmonic serc-phase sine-wave analysis/synthesis system which is characterized by sine-wave amplitudes, a voicing probability, and a fundamental frequency. Least-squared error estimation of a harmonic sine-wave representation leads to a "soft decision" template estimate consisting of sine-wave amplitudes and a voicing probability. The least-squares solution is modified to use template-matching with "nearest neighbors." The reconstruction is improved by using the modified least-squares solution only in spectral regions with low signal-to-noise ratio. The results, although preliminary, provide evidence that harmonic zero-phase sine-wave analysis/synthesis, combined with effective estimation of sine-wave amplitudes and probability of voicing, offers a promising approach to noise reduction.
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Summary

The need for noise reduction arises in speech communication channels, such as ground-to-air transmission and ground-based cellular radio, to improve vocoder quality and speech recognition accuracy. In this paper, noise reduction is performed in the context of a high-quality harmonic serc-phase sine-wave analysis/synthesis system which is characterized by sine-wave amplitudes...

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Noise reduction using a soft-decision sine-wave vector quantizer

Automatic talker activity labeling for co-channel talker interference suppression

March 21, 1990
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Conference Paper
Author:
Marc A. Zissman
…
Published in:
Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, Vol. 2, Speech Processing 2; VLSI; Audio and Electroacoustics, ICASSP, 3-6 April 1990, pp. 813-816.
Topic:
signal processing
R&D area:
R&D group:

Summary

This paper describes a speaker activity detector taking co-channel speech as input and labeling intervals of the input as target-only, jammer-only, or two-speaker (target+jammer). The algorithms applied were borrowed primarily from speaker recognition, thereby allowing us to use speaker-dependent test-utterance-independent information in a front-end for co-channel talker interference suppression. Parameters studied included classifier choice (vector quantization vs. Gaussian), training method (unsupervised vs. supervised), test utterance segmentation (uniform vs. adaptive), and training and testing target-to-jammer ratios. Using analysis interval lengths of 100 ms, performance reached 80% correct detection.
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Summary

This paper describes a speaker activity detector taking co-channel speech as input and labeling intervals of the input as target-only, jammer-only, or two-speaker (target+jammer). The algorithms applied were borrowed primarily from speaker recognition, thereby allowing us to use speaker-dependent test-utterance-independent information in a front-end for co-channel talker interference suppression. Parameters...

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Automatic talker activity labeling for co-channel talker interference suppression
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