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Beacon radar and TCAS interrogation rates: airborne measurements in the 1030 MHz band

May 2, 1996
  |
Project Report
Author:
William H. Harman III
…
Published in:
MIT Lincoln Laboratory Report ATC-239
Topic:
surveillance
R&D area:
R&D group:

Summary

Airborne measurements were made of the rates of beacon-radar interrogations and suppressions in the 1030 MHz band. These measurements were undertaken in order to provide a basis for interference analysis of the proposed system of GPS-Squitter. The measurements were made during a flight along the East Coast, including New York, Philadelphia, Baltimore, and Washington. Measurements were also made at Atlanta and in the Dallas Fort Worth area. Results were given in a form that shows the rates of interrogations and suppressions as a function of time and location of the aircraft. Interrogations are also separated into those that were transmitted by ground-based interrogators and those that were transmitted by airborne TCAS equipment. Mode S interrogations were also separated from other modes. The number of TCAS aircraft in the vicinity was also measured during the flights. The results indicate that the rates of interrogations and suppressions were consistent in most respects from location to location. The rates Mode A and C interrogations from the ground were consistently less than 100 per second with two brief exceptions. Previous measurements had indicated a trend of decreasing interrogation rates with time since the early 1970's. The new measurements support this observation and indicate that the trend has continued.
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Summary

Airborne measurements were made of the rates of beacon-radar interrogations and suppressions in the 1030 MHz band. These measurements were undertaken in order to provide a basis for interference analysis of the proposed system of GPS-Squitter. The measurements were made during a flight along the East Coast, including New York...

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Beacon radar and TCAS interrogation rates: airborne measurements in the 1030 MHz band

ASR-9 processor augmentation card scan-scan correlator algorithms

April 2, 1996
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Project Report
Author:
Jenifer B. Evans
Published in:
MIT Lincoln Laboratory Report ATC-245
Topic:
algorithms
R&D area:
R&D group:

Summary

This report documents the Scan-Scan correlator algorithms for the ASR-9 Processor Augmentation Card (9-PAC) project. The 9-PAC is a processor card that serves as a processing enhancement to the existing ASR-9's post-processor system. It provides increased speed and memory capabilities to the processor, which allows for the introduction of more complex scan-scan correlator algorithms. These more complex algorithms improve the ASR-9's system performance through decreased false alarms, and increased detection of aircraft. The 9-PAC Scan-Scan correlator, also known as the Tracker, consists of three basic processing tasks: initialization, input/output, and the actual Tracker. The Tracker can be broken down further into four main processing functions: report-to track association, report-to-track correlation, track update, and track initiation.
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Summary

This report documents the Scan-Scan correlator algorithms for the ASR-9 Processor Augmentation Card (9-PAC) project. The 9-PAC is a processor card that serves as a processing enhancement to the existing ASR-9's post-processor system. It provides increased speed and memory capabilities to the processor, which allows for the introduction of more...

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ASR-9 processor augmentation card scan-scan correlator algorithms

Anomalous propagation ground clutter suppression with the Airport Surveillance Radar (ASR) Weather Systems Processor (WSP)

March 15, 1996
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Project Report
Author:
Joseph A. Cullen
Published in:
MIT Lincoln Laboratory Report ATC-244
Topic:
radar
R&D area:
R&D group:

Summary

Ground-clutter breakthrough caused by anomalous propagation (AP)--ducting of the radar beam when passing through significant atmospheric temperature and/or moisture gradients--is a significant issue for air traffic controllers who use Airport Surveillance Radar (ASR) weather channel data to guide aircraft through the airport terminal area. At present, these data are often contaminated with AP, leaving the controller unsure about the validity of information on storm location and intensity. The Weather System Processor (WSP), which is scheduled for deployment at 33 airports in the U.S., includes an AP-Editing algorithm designed to remove AP based on its Doppler-spectrum characteristics in ASR-9 data. This report provides a description of the algorithm currently used in the FAA/Lincoln Laboratory WSP prototype and a measurement of the performance of the algorithm during nine episodes of AP and/or true weather in Orlando, florida in 1991 and 1992.
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Summary

Ground-clutter breakthrough caused by anomalous propagation (AP)--ducting of the radar beam when passing through significant atmospheric temperature and/or moisture gradients--is a significant issue for air traffic controllers who use Airport Surveillance Radar (ASR) weather channel data to guide aircraft through the airport terminal area. At present, these data are often...

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Anomalous propagation ground clutter suppression with the Airport Surveillance Radar (ASR) Weather Systems Processor (WSP)

Lincoln Laboratory Evaluation of TCAS II logic version 6.04a, volume I

February 21, 1996
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Project Report
Author:
Ann C. Drumm
Published in:
MIT Lincoln Laboratory Report ATC-240,I
Topic:
collision avoidance
R&D area:
R&D group:

Summary

This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 6.04a. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in U.S. airspace. Version 6.04a is a logic version mandated by the FAA by 30 December 1994 in order to correct a potential safety problem in earlier versions and to make the TCAS logic more compatible with the air traffic control system. Lincoln Laboratory evaluated the logic by examining approximately two million simulated pairwise TCAS-TCAS encounters, derived from actual aircraft tracks recorded in U.S. airspace. The main goals of the evaluation effort were: (1) to determine if version 6.04a successfully corrected the potential safety problem without introducing new problems; (2) to detect and explain any areas of poor performance; and (3) to understand the performance limits of the logic. Five analysis programs were written to aid in the evaluation, and these programs are described in the report. There were three phases of the evaluation corresponding to the above three goals. For each phase, the report gives an overview of the evaluation approach taken, a description of the results, and a summary. A description of follow-on activities plus overall conclusions and recommendations are given at the end of the report.
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Summary

This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 6.04a. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in...

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Lincoln Laboratory Evaluation of TCAS II logic version 6.04a, volume I

Lincoln Laboratory Evaluation of TCAS II logic version 6.04a, appendices, volume II

February 15, 1996
  |
Project Report
Author:
Ann C. Drumm
Published in:
MIT Lincoln Laboratory Report ATC-240,II
Topic:
collision avoidance
R&D area:
R&D group:

Summary

This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 6.04a. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in U.S. airspace. Version 6.04a is a logic version mandated by the FAA by 30 December 1994 in order to correct a potential safety problem in earlier versions and to make the TCAS logic more compatible with the air traffic control system. Lincoln Laboratory evaluated the logic by examining approximately two million simulated pairwise TCAS-TCAS encounters, derived from actual aircraft tracks recorded in U.S. airspace. The main goals of the evaluation effort were: (1) to determine if version 6.04a successfully corrected the potential safety problem without introducing new problems; (2) to detect and explain any areas of poor performance; and (3) to understand the performance limits of the logic. Five analysis programs were written to aid in the evaluation, and these programs are described in the report. There were three phases of the evaluation corresponding to the above three goals. For each phase, the report gives an overview of the evaluation approach taken, a description of the results, and a summary. A description of follow-on activities plus overall conclusions and recommendations are given at the end of the report.
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Summary

This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 6.04a. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in...

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Lincoln Laboratory Evaluation of TCAS II logic version 6.04a, appendices, volume II

Recognition by humans and machines: miles to go before we sleep

February 7, 1996
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Journal Article
Author:
Richard P. Lippmann
Published in:
Speech Commun., Vol. 18, No. 3, 1996, pp. 247-8.
Topic:
speech recognition
R&D area:
R&D group:

Summary

Bourlard and his colleagues note that much effort over the past few years has focused on creating large-vocabulary speech recognition systems and reducing error rates measured using clean speech materials. This has led to experimental talker-independent systems with vocabularies of 65,000 words capable of transcribing sentences on a limited set of topics. Instead of comparing these systems to each other, or to last year's performance, this short comment compares them to human listeners, who are the ultimate users and judges of speech recognizers.
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Summary

Bourlard and his colleagues note that much effort over the past few years has focused on creating large-vocabulary speech recognition systems and reducing error rates measured using clean speech materials. This has led to experimental talker-independent systems with vocabularies of 65,000 words capable of transcribing sentences on a limited set...

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Recognition by humans and machines: miles to go before we sleep

1995 wake vortex program at Memphis, TN

January 5, 1996
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Conference Paper
Author:
Steven D. Campbell
…
Published in:
AIAA 34th Aerospace Sciences Meeting and Exhibit, 15-18 January 1996.
Topic:
aircraft
R&D area:
R&D group:

Summary

This paper describes wake vortex field measurements conducted during August, 1995 at Memphis, TN. The objective of this effort was to record wake vortex behavior for varying atmospheric conditions and aircraft types. Wake vortex behavior was observed using a mobile CW coherent lidar. This lidar features a number of improvements over previous systems, including the first-ever demonstration of an automatic wake vortex detection and tracking algorithm. An extensive meteorological data collection system was deployed in support of the wake vortex measurements, including a 150-ft instrumented tower, wind profiler/RASS (radio acoustic sounding system), sonar and balloon soundings. Aircraft flight plan and beacon data were automatically collected to determine aircraft flight number, type, speed, and descent rate. Additional data was received from airlines in postprocessing to determine aircraft weight and model. Preliminary results from the field measurement program are presented illustrating differences in wake vortex behavior depending on atmospheric conditions and aircraft type.
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Summary

This paper describes wake vortex field measurements conducted during August, 1995 at Memphis, TN. The objective of this effort was to record wake vortex behavior for varying atmospheric conditions and aircraft types. Wake vortex behavior was observed using a mobile CW coherent lidar. This lidar features a number of improvements...

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1995 wake vortex program at Memphis, TN

Selected abstracts on aviation weather hazard research

January 2, 1996
  |
Project Report
Author:
Leslie R. Mahn
Published in:
MIT Lincoln Laboratory Report ATC-242
Topic:
weather
R&D area:
R&D group:

Summary

This paper consists of bibliographic information and abstracts for literature on the topics of weather-related aviation hazards. These abstracts were selected from reports written for the ASR-9, ITWS, TDWR programs, sponsored by the Federal Aviation Administration (FAA), and the Wake Vortex program, sponsored by NASA Langley Research Center. All research was performed by MIT Lincoln Laboratory; some research was performed in collaboration with other organizations. These abstracts were compiled to allow participants in the ASR-9 program to conduct research related to their design, development, and production effort. The abstracts and bibliographic information were retrieved from several commercial databases (INSPEC, Ei Compendex*Plus, Aerospace Database, and NTIS) through an open literature search at the Lincoln Laboratory library. Sufficient information is included for readers to obtain documents of interest to them, but documents will not be provided directly by Lincoln Laboratory.
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Summary

This paper consists of bibliographic information and abstracts for literature on the topics of weather-related aviation hazards. These abstracts were selected from reports written for the ASR-9, ITWS, TDWR programs, sponsored by the Federal Aviation Administration (FAA), and the Wake Vortex program, sponsored by NASA Langley Research Center. All research...

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Selected abstracts on aviation weather hazard research

Comparison of four approaches to automatic language identification of telephone speech

January 1, 1996
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Journal Article
Author:
Marc A. Zissman
Published in:
IEEE Trans. Speech Audio Process., Vol. 4, No. 1, January 1996, pp. 31-44.
Topic:
language recognition
R&D area:
R&D group:

Summary

We have compared the performance of four approaches for automatic language identification of speech utterances: Gaussian mixture model (GMM) classification; single-language phone recognition followed by language-dependent, interpolated n-gram language modeling (PRLM); parallel PRLM, which uses multiple single-language phone recognizers, each trained in a different language; and language dependent parallel phone recognition (PPR). These approaches which space a wide range of training requirements and levels of recognition complexity, were evaluated with the Oregon Graduate Institute Multi-Language Telephone Speech Corpus. Systems containing phone recognizers performed better than the simpler GMM classifier. The top-performing system was parallel PRLM, which exhibited an error rate of 2% for 45-s utterances and 5% for 10-s utterances in two-language, closed-set, forced-choice classification. The error rate for 11-language, closed-set, forced-choice classification was 11% for 45-s utterances and 21% for 10-s utterances.
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Summary

We have compared the performance of four approaches for automatic language identification of speech utterances: Gaussian mixture model (GMM) classification; single-language phone recognition followed by language-dependent, interpolated n-gram language modeling (PRLM); parallel PRLM, which uses multiple single-language phone recognizers, each trained in a different language; and language dependent parallel phone...

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Comparison of four approaches to automatic language identification of telephone speech

Initial evaluation of terminal-area atmospheric vertical structure prediction algorithms using Fall 1994 ITWS/Wake Vortex Programs' meteorological data

November 6, 1995
  |
Project Report
Author:
John L. Keller
…
Published in:
MIT Lincoln Laboratory Report ATC-237
Topic:
weather
R&D area:
R&D group:

Summary

A Dynamic Atmospheric Vertical Structure Nowcast System (DAVS-NS) is being developed that will add value to the Integrated Terminal Weather System (ITWS) by providing current and short-term forecasts of the vertical atmospheric structure focused at specific sites within the terminal domain. Operational applications of these estimates of the atmospheric vertical structure include predicting changes in airport operation rates due to ceiling and visibility (C&V) changes and in predicting wake vortex behavior. The core of this system would be a one-dimensional boundary layer column model. This report summarizes the evaluation of a modified Oregon State University (OSU) column model using data collected during the fall 1994 combined National Aeronautics and Space Administration (NASA) wake vortex project and the ITWS site operations at Memphis International Airport (MEM). Further efforts are necessary to develop and test an operational DAVS-NS prototype. The accuracy typically seen in column model predictions of the vertical temperature structure will limit errors in wake vortex dissipation rates to within a factor of two. Given the current working hypothesis for the San Francisco stratus burn-off phenomenon that rests largely on warming of the marine boundary layer by surface heat flux, the OSU model will also appear to be well suited for addressing this particular problem.
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Summary

A Dynamic Atmospheric Vertical Structure Nowcast System (DAVS-NS) is being developed that will add value to the Integrated Terminal Weather System (ITWS) by providing current and short-term forecasts of the vertical atmospheric structure focused at specific sites within the terminal domain. Operational applications of these estimates of the atmospheric vertical...

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Initial evaluation of terminal-area atmospheric vertical structure prediction algorithms using Fall 1994 ITWS/Wake Vortex Programs' meteorological data
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