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Demonstration of GPS Automatic Dependent Surveillance of aircraft using spontaneous Mode S broadcast messages

June 1, 1994
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Journal Article
Author:
Edward T. Bayliss
…
Published in:
Navig. J. Inst. Navig., Vol. 41, No. 2, Summer 1994, pp. 187-206.
Topic:
surveillance
R&D area:
R&D group:

Summary

A new Automatic Dependent Surveillance (ADS) system concept combining GPS-based positions with Mode S data communications is described. Several potential applications of this concept are presented with emphasis on surface surveillance at airports. The navigation and data link performance are analyzed. Compact ADS position formats are included. The results of the first tests at Hanscom Field, demonstrating the feasibility of the spontaneous broadcast of ADS positions using Mode S messages are presented. Test aircraft, vehicles, avionics equipment and the ground system configuration are described. Avionics standards and GPS interface requirements are discussed. Multipath and airport surface coverage issues are addressed. Further testing in an operational environment is continuing at Logan Airport.
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Summary

A new Automatic Dependent Surveillance (ADS) system concept combining GPS-based positions with Mode S data communications is described. Several potential applications of this concept are presented with emphasis on surface surveillance at airports. The navigation and data link performance are analyzed. Compact ADS position formats are included. The results of...

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Demonstration of GPS Automatic Dependent Surveillance of aircraft using spontaneous Mode S broadcast messages

ITWS and the NWS forecaster: what is the connection?

June 1, 1994
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Journal Article
Author:
David A. Sankey
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Published in:
Nat. Weather Dig., Vol. 18, No. 4, June 1994, pp. 43-47.
Topic:
air traffic control
R&D area:
R&D group:

Summary

The Federal Aviation Administration (FAA) is sponsoring the development of the Integrated Terminal Weather System (ITWS), which is designed to acquire all of the weather data that is available in the terminal area, both ground-based and aircraft sensed, and to provide short-term (0 to 30-minute) predictions of microbursts, wind shear, gust fronts, runway winds and terminal-area ceiling and visibility. Additionally, the ITWS will be generating the 4-dimensional wind field at many levels in the terminal area, mainly for use by other FAA terminal air traffic control automation systems, but also available as a graphical display. An area of interest and concern to the developers is the interaction between the automated, very-short-term predictions of the ITWS, and the National Weather Service (NWS) aviation meteorologist, who is responsible for issuing terminal forecasts and other aviation advisory and warning products. This paper will describe the ITWS as currently planned and will explore the possible relationships between the ITWS and the NWS forecaster. Consideration will also be given to the NWS's new Advanced Weather Interactive Processing System (AWIPS) and how ITWS information might be used in the terminal forecasting process. This paper is intended to spark discussion of the role of the ITWS in the NWS forecasting process of the future.
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Summary

The Federal Aviation Administration (FAA) is sponsoring the development of the Integrated Terminal Weather System (ITWS), which is designed to acquire all of the weather data that is available in the terminal area, both ground-based and aircraft sensed, and to provide short-term (0 to 30-minute) predictions of microbursts, wind shear...

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ITWS and the NWS forecaster: what is the connection?

An automated method for low level wind shear alert system (LLWAS) data quality analysis

May 26, 1994
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Project Report
Author:
David A. Clark
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Published in:
MIT Lincoln Laboratory Report ATC-207
Topic:
wind shear
R&D area:
R&D group:

Summary

The Low Level Windshear Alert System (LLWAS) is an anemometer-based surface network used for detection of hazardous wind shear and acquisition of operational wind information in the airport terminal area. The quality of wind data provided by the LLWAS anemometers is important for the proper performance of the LLWAS wind shear detection algorithms. This report describes the development of an automated method for anemometer data quality (DQA). This method identifies potential data quality problems through comparison of wind data from each sensor within a network to the mean wind speed and direction of the entire network. The design approach and implementation are described, and results from testing using data from the demonstration Phase III LLWAS network in Orlando, FL are reported. Potential improvements to the automated DQA algorithm are presented based on experience gained during analysis of the Orlando data. These recommended improvements are provided to assist future development and refinement of the DQA methodology to be performed by the FAA Technical Center.
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Summary

The Low Level Windshear Alert System (LLWAS) is an anemometer-based surface network used for detection of hazardous wind shear and acquisition of operational wind information in the airport terminal area. The quality of wind data provided by the LLWAS anemometers is important for the proper performance of the LLWAS wind...

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An automated method for low level wind shear alert system (LLWAS) data quality analysis

GPS-squitter capacity analysis

May 20, 1994
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Project Report
Author:
Vincent A. Orlando
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Published in:
MIT Lincoln Laboratory Report ATC-214
Topic:
surveillance
R&D area:
R&D group:

Summary

GPS-Squitter is a system concept that merges the capabilities of Automatic Dependent SurveiIlance (ADS) and the Mode S beacon radar. The resuit is an integrated concept for seamless surveillance and data link that permits equipped aircraft to participate in ADS and/or beacon ground environments. This concept offers many possibilities for transition from a beacon to an ADS-based environment. This report provides the details of the techniques used to estimate GPS-Squitter surveillance and data link capacity. Surveillance capacity of airborne aircraft is calculated for the omni and six-sector ground stations. Next, the capacity of GPS-Squitter for surface traffic is estimated. The interaction between airborne and surface operations is addressed to show de independence of these systems. Air ground data link capacity for GPS-Squitter is estimated, together with an estimate of the use of the Mode S link to support other ground surveillance and data link activities as well as TCAS operation. The analysis indicates the low transponder occupancy resulting from the total effect of these activities. Low occupancy is a key requirement in avoiding interference with the operation of the current ATCRRS and future Mode S interrogators.
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Summary

GPS-Squitter is a system concept that merges the capabilities of Automatic Dependent SurveiIlance (ADS) and the Mode S beacon radar. The resuit is an integrated concept for seamless surveillance and data link that permits equipped aircraft to participate in ADS and/or beacon ground environments. This concept offers many possibilities for...

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GPS-squitter capacity analysis

Terminal Doppler Weather Radar (TDWR) Low Level Wind Shear Alert System 3 (LLWAS 3) integration studies at Orlando International Airport Airport in 1991 and 1992

April 20, 1994
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Project Report
Author:
Rodney E. Cole
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Published in:
MIT Lincoln Laboratory Report ATC-216
Topic:
weather
R&D area:
R&D group:

Summary

In 1993 the Federal Aviation Administration (FAA) began deploying two new wind shear detectionsystems: the Terminal Doppler Weather Radar (TDWR) and the third-generation Low Level Windshear Alert System (LLWAS 3). Currently, nine airports are scheduled to receive both a TDWR and an LLWAS 3. This number may eventually increase to as high as 45. When co-located, the systems will be integrated to provide a single set of wind shear alerts and improve system performance. The TDWR production schedule required one of three integration algorithms to be chosen for specification by fall 1991. The three algorithms are the prototype integration algorithm developed at the National Center for Atmospheric Research (NCAR) and two algorithms developed at MIT Lincoln Laboratory (MIT/LL). To assess the performance of the three algorithms, MIT/LL performed a study of the integration, TDWR, and LLWAS 3 algorithms at Orlando International Airport in the summer of 1992. We discuss results of the 1991 comparative study and a follow-up study of the TDWR, LLWAS 3, and Message Level integration algorithms at Orlando in 1992. All of the algorithms met the requirement of detecting 90 percent of microburst level wind shear with loss events. LLWAS 3, Build 5 TDWR, and the MIT/LL integration algorithms run with Build 5 TDWR, all met the requirement that less than 10 percent of wind shear alerts be false. The NCAR prototype did not utilize Build 5 TDWR. Build 4 TDWR and all integration algorithms run with Build 4 TDWR did not meet the false-alert requirement. Detailed descriptions of the algorithms are given. The methodology for estimating various algoirthm performance statistics based on a comparison with a dual-Doppler algorithm is detailed.
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Summary

In 1993 the Federal Aviation Administration (FAA) began deploying two new wind shear detectionsystems: the Terminal Doppler Weather Radar (TDWR) and the third-generation Low Level Windshear Alert System (LLWAS 3). Currently, nine airports are scheduled to receive both a TDWR and an LLWAS 3. This number may eventually increase to...

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Terminal Doppler Weather Radar (TDWR) Low Level Wind Shear Alert System 3 (LLWAS 3) integration studies at Orlando International Airport Airport in 1991 and 1992

Wordspotter training using figure-of-merit back propagation

April 19, 1994
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Conference Paper
Author:
Richard P. Lippmann
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Published in:
Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, ICASSP, Vol. 1, Speech Processing, 19-22 April 1994, pp. 389-392.
Topic:
machine learning
R&D area:
R&D group:

Summary

A new approach to wordspotter training is presented which directly maximizes the Figure of Merit (FOM) defined as the average detection rate over a specified range of false alarm rates. This systematic approach to discriminant training for wordspotters eliminates the necessity of ad hoc thresholds and tuning. It improves the FOM of wordspotters tested using cross-validation on the credit-card speech corpus training conversations by 4 to 5 percentage points to roughly 70% This improved performance requires little extra complexity during wordspotting and only two extra passes through the training data during training. The FOM gradient is computed analytically for each putative hit, back-propagated through HMM word models using the Viterbi alignment, and used to adjust RBF hidden node centers and state-weights associated with every node in HMM keyword models.
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Summary

A new approach to wordspotter training is presented which directly maximizes the Figure of Merit (FOM) defined as the average detection rate over a specified range of false alarm rates. This systematic approach to discriminant training for wordspotters eliminates the necessity of ad hoc thresholds and tuning. It improves the...

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Wordspotter training using figure-of-merit back propagation

Automatic language identification of telephone speech messages using phoneme recognition and N-gram modeling

April 19, 1994
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Conference Paper
Author:
Marc A. Zissman
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Published in:
Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, ICASSP, Vol. 1, Speech Processing, 19-22 April 1994, pp. 305-308.
Topic:
language recognition
R&D area:
R&D group:

Summary

This paper compares the performance of four approaches to automatic language identification (LID) of telephone speech messages: Gaussian mixture model classification (GMM), language-independent phoneme recognition followed by language-dependent language modeling (PRLM), parallel PRLM (PRLM-P), and language-dependent parallel phoneme recognition (PPR). These approaches span a wide range of training requirements and levels of recognition complexity. All approaches were tested on the development test subset of the OGI multi-language telephone speech corpus. Generally, system performance was directly related to system complexity, with PRLM-P and PPR performing best. On 45 second test utterance, average two language, closed-set, forced-choice classification performance, reached 94.5% correct. The best 10 language, closed-set, forced-choice performance was 79.2% correct.
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Summary

This paper compares the performance of four approaches to automatic language identification (LID) of telephone speech messages: Gaussian mixture model classification (GMM), language-independent phoneme recognition followed by language-dependent language modeling (PRLM), parallel PRLM (PRLM-P), and language-dependent parallel phoneme recognition (PPR). These approaches span a wide range of training requirements and...

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Automatic language identification of telephone speech messages using phoneme recognition and N-gram modeling

Demonstrations and applications of spoken language technology: highlights and perspectives from the 1993 ARPA Spoken Language Technology and Applications Day

April 19, 1994
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Conference Paper
Author:
Clifford J. Weinstein
Published in:
Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, ICASSP, Vol. 1, Speech Processing, 19-22 April 1994, pp. 337-340.
Topic:
speech recognition
R&D area:
R&D group:

Summary

The ARPA Spoken Language Technology and Applications Day (SLTA'93) was a special workshop which presented a set of live, state-of-the-art demonstrations of speech recognition and Spoken Language Understanding systems. The purpose of this paper is to provide perspective on current opportunities for applications which they can enable, and reviewing the applications opportunities and needs cited by panelists and other members of the user community.
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Summary

The ARPA Spoken Language Technology and Applications Day (SLTA'93) was a special workshop which presented a set of live, state-of-the-art demonstrations of speech recognition and Spoken Language Understanding systems. The purpose of this paper is to provide perspective on current opportunities for applications which they can enable, and reviewing the...

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Demonstrations and applications of spoken language technology: highlights and perspectives from the 1993 ARPA Spoken Language Technology and Applications Day

Data requirements for ceiling and visibility products development

April 13, 1994
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Project Report
Author:
John L. Keller
Published in:
MIT Lincoln Laboratory Report ATC-212
Topic:
weather
R&D area:
R&D group:

Summary

The Federal Aviation Administration (FAA) Integrated Terminal Weather System (ITWS) is supporting the development of weather products important for air traffic control in the terminal area. These products will take advantage of new terminal area sensors, including Terminal Doppler Weather Radar (TDWR, Next Generation Weather Radar (NEXRAD), and the Meteorological Data Collection and Reporting System (MDCRS). Some of these ITWS products will allow air traffic managers to anticipate significant short-term changes in ceiling and visibility. This report focuses on the scientific data requirements for supporting prototype model-system development and diagnostics. Model diagnostics can include case studies to determine the most important physical processes that were responsible for a particular ceiling and visibility "event," providing the insight necessary for the development of effective ceiling and visibility product algorithms. In time such case study diagnostics could also include careful off-line "failure analyses" that may affect the disign of the operational system. General ceiling and visibility test beds are discussed. Updated reports will be released periodically as the ITWS ceiling and visibility project proceeds.
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Summary

The Federal Aviation Administration (FAA) Integrated Terminal Weather System (ITWS) is supporting the development of weather products important for air traffic control in the terminal area. These products will take advantage of new terminal area sensors, including Terminal Doppler Weather Radar (TDWR, Next Generation Weather Radar (NEXRAD), and the Meteorological...

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Data requirements for ceiling and visibility products development

The influence of data link-provided graphical weather on pilot decision-making

April 6, 1994
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Project Report
Author:
Ann-Marie Lind
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Published in:
MIT Lincoln Laboratory Report ATC-215
Topic:
decision support
R&D area:
R&D group:

Summary

This report documents the findings of a human factor study conducted to estimate the effects of the Graphical-Weather Service (GWS) on general aviation (GA) aircraft utility, pilot situational awareness, and the weather dissemination workload on ground personnel. GWS is a data link application, being developed at MIT Lincoln Lbaoratory through the sponsorship of the Federal Aviation Administration, that will provide near-real time graphical weather information to the General Aviation pilot in the cockpit. Twenty instrument-rated pilots participated in the study. Subjects were presented with recorded actual weather information in the context of a series hypothetical pre-flight briefings and accompanying "flights." GWS images were accessible on a Macintosh TM Computer. The study design enabled the analysis of the effects of GWS and the determination of whether those efforts were influenced by the experience level of the pilot/user. Objective and subjective measures of effectiveness were collected. Results indicate that GWS had a substantial effects on weather-related decision-making. This was true for pilots with varying levels of instrument experience. Subject confidence in the ability to assess the weather situation was markedly increased when GWS was used. Subjects with GWS made fewer calls for weather information to weather dissemination ground personnel, thus indicating a potential decrease in ground personnel workload. Subjects found GWS to be very useful and were enthusiastic about receiving data link services in the GA cockpit in the future.
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Summary

This report documents the findings of a human factor study conducted to estimate the effects of the Graphical-Weather Service (GWS) on general aviation (GA) aircraft utility, pilot situational awareness, and the weather dissemination workload on ground personnel. GWS is a data link application, being developed at MIT Lincoln Lbaoratory through...

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The influence of data link-provided graphical weather on pilot decision-making
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