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A human factors approach to the development and evaluation of the Graphical Weather Service

November 5, 1995
  |
Conference Paper
Author:
Ann-Marie Lind
…
Published in:
14th AIAA/IEEE Digital Avionics Systems Conf., 5-9 November 1995, pp. 264-269.
Topic:
aviation weather
R&D area:
R&D group:

Summary

With the sponsorship of the Federal Aviation Administration, MIT Lincoln Laboratory is developing the Graphical Weather Service (GWS), a data link application that provides near-real-time ground-based weather information to pilots. Through the use of GWS, the pilot will be able to access both graphical and text weather information for any location in the contiguous United States. In-cockpit access to near-real-time weather information may substantially affect the situational awareness and subsequent decision making of pilots. In developing and evaluating this service, a human factors approach has been taken. This paper is an overview of the human factors activities performed in the development and evaluation of GWS.
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Summary

With the sponsorship of the Federal Aviation Administration, MIT Lincoln Laboratory is developing the Graphical Weather Service (GWS), a data link application that provides near-real-time ground-based weather information to pilots. Through the use of GWS, the pilot will be able to access both graphical and text weather information for any...

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A human factors approach to the development and evaluation of the Graphical Weather Service

A subband approach to time-scale expansion of complex acoustic signals

November 1, 1995
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Journal Article
Author:
Thomas F. Quatieri
…
Published in:
IEEE Trans. Speech Audio Process., Vol. 3, No. 6, November 1995, pp. 515-519.
Topic:
speech modification
R&D area:
R&D group:

Summary

A new approach to time-scale expansion of short-duration complex acoustic signals is introduced. Using a subband signal representation, channel phases are selected to preserve a desired time-scaled temporal envelope. The phase representation is derived from locations of events that occur within filter bank outputs. A frame-based generalization of the method imposes phase consistency across consecutive synthesis frames. The method is applied to synthetic and actual complex acoustic signals consisting of closely spaced rapidly damped sine wave. Time-frequency resolution limitations are discussed.
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Summary

A new approach to time-scale expansion of short-duration complex acoustic signals is introduced. Using a subband signal representation, channel phases are selected to preserve a desired time-scaled temporal envelope. The phase representation is derived from locations of events that occur within filter bank outputs. A frame-based generalization of the method...

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A subband approach to time-scale expansion of complex acoustic signals

Description of radar correlation and interpolation algorithms for the ASR-9 Processor Augmentation Card (9-PAC)

October 27, 1995
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Project Report
Author:
Oliver J. Newell
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Published in:
MIT Lincoln Laboratory Report ATC-236
Topic:
signal processing
R&D area:
R&D group:

Summary

MIT Lincoln Laboratory, under sponsorship from the Federal Aviation Adminstration (FAA), is conducting a program to replace/upgrade the existing ASR-9 array signal processor (ASP) and associated algorithms to improve performance and future maintainability. The ASR-9 processor augmentation card (9-PAC) replaces the ASP four-board set with a single card containing three TMS320c40 processors and 32 Megabytes of memory. The resulting increase in both processing speed and memory size allows more sophisticated beacon and radar processing algorithms to be implemented. The majority of the improvement to the radar correlation and interpolation (C&I) function lies in the area of geocensoring and adaptive thresholding, where the larger memory capacity of the 9-PAC allows more detailed maps to be maintained. A dynamic road map mechanism has been implemented to reduce the need for manual tuning of the system when the radars are first installed or when new road construction occurs. The map is twice the resolution of the original geocensormap, resulting in a decrease in total area desensitized to radar-only targets. In addition, the new geocensor mechanism makes use of target amplitude information, allowing aircraft with amplitudes significantly greater than the road traffic returns at a particular cell to pass through uncensored. The adaptive thresholding cell geometry has been modified so that adaptive map cells now overlap one another, eliminating the false target breakthrough that occurs in the present system when regions of false alarms due to birds or weather transition from one cell to the next. The entire C & I function has been recorded in a high-level language (ANSI-C), allowing it to be easily ported between platforms and better facilitating off-line analysis.
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Summary

MIT Lincoln Laboratory, under sponsorship from the Federal Aviation Adminstration (FAA), is conducting a program to replace/upgrade the existing ASR-9 array signal processor (ASP) and associated algorithms to improve performance and future maintainability. The ASR-9 processor augmentation card (9-PAC) replaces the ASP four-board set with a single card containing three...

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Description of radar correlation and interpolation algorithms for the ASR-9 Processor Augmentation Card (9-PAC)

Time-scale modification with inconsistent constraints

October 15, 1995
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Conference Paper
Author:
Thomas F. Quatieri
…
Published in:
Proc. 1995 Workshop on Applications of Signal Processing to Audio Acoustics, 15-18 October 1995.
Topic:
speech enhancement
R&D area:
R&D group:

Summary

A set theoretic estimation approach is introduced for timescale modification of complex acoustic signals. The method determines a signal that meets, in a least-squared error sense, desired temporal and spectral envelope constraints that are inconsistent. These constraints are generalized within the set theoretic framework to include other signal characteristics such as instantaneous frequency and group delay. The approach can enhance acoustic signals consisting of closely-spaced sequential time components, and is applicable to biological, underwater, and music sound processing.
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Summary

A set theoretic estimation approach is introduced for timescale modification of complex acoustic signals. The method determines a signal that meets, in a least-squared error sense, desired temporal and spectral envelope constraints that are inconsistent. These constraints are generalized within the set theoretic framework to include other signal characteristics such...

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Time-scale modification with inconsistent constraints

GPS-squitter automatic dependent surveillance broadcast: flight testing in the Gulf of Mexico

October 13, 1995
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Project Report
Author:
Robert E. Boisvert
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Published in:
MIT Lincoln Laboratory Report ATC-235
Topic:
surveillance
R&D area:
R&D group:

Summary

During November - December 1994, MIT Lincoln Laboratory conducted a field evaluation of the air surveillance capabilities of GPS-Squitter in the Gulf of Mexico. Three squitter ground stations were located in the vincinity of Morgan City, Louisiana, for this evaluation: two were located on offshore oil platforms, and the third was located at an onshore heliport. Surveillance coverage tests were flown over the Gulf with three test aircraft - two helicopters and one Cessna 421 fixed wing aircraft. The helicopters flew at altitudes ranging from 100 to 2000 feet above sea level and the Cessna flew at 7500 and 20,000 feet. Extended squitter messages broadcast by each of the test aircraft provided aircraft position and identification. This report documents results of these texts and compares measured coverage to predicted coverage from the ground stations. Based on the good agreement between predicted and measured performance, a description of a possible operational system is included that would provide surveillance of the entire Gulf region serviced by oil platform helicopters. The report concludes that GPS Squitter is a near-term option for providing accurate, real time surveillance of aircraft operating in the offshore airspace in the Gulf of Mexico.
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Summary

During November - December 1994, MIT Lincoln Laboratory conducted a field evaluation of the air surveillance capabilities of GPS-Squitter in the Gulf of Mexico. Three squitter ground stations were located in the vincinity of Morgan City, Louisiana, for this evaluation: two were located on offshore oil platforms, and the third...

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GPS-squitter automatic dependent surveillance broadcast: flight testing in the Gulf of Mexico

Runway status light system demonstration at Logan Airport

October 12, 1995
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Project Report
Author:
James R. Eggert
…
Published in:
MIT Lincoln Laboratory Report ATC-206
Topic:
surveillance
R&D area:

Summary

The Runway Status Light System (RSLS), developed under the FAA's Airport Surface Traffic Automation (ASTA) program, is intended to help reduce the incidence of runway incursions and airport surface accidents. It will do so by providing a preventive, back-up system of automatically controlled lights on the airport surface that inform pilots when runways are unsafe for entry or takeoff, and by providing controllers with enhanced surface radar displays. This report documents a proof-of-concept evaluation of the RSLS at Boston's Logan Airport. It details the methods used to provide the necessary surface surveillance and safety logic to allow a computer to operate the runway status lights and associated controller displays without human assistance. The system was installed and tested off-line at Boston's Logan Airport using an inexpensive commercial marine radar as a primary surveillance source. The system operated live and in real time but the runway status lights were not physically installed. They were displayed on a scale model of Logan Airport located in a demonstration room that had a good view of the airport. This allowed visual comparison between the actual aircraft and the resulting lights and displays. In addition to providing a convincing demonstration of the system, real-timing viewing of the aircraft movement was an important aid in the development of the surveillance processing and safety logic software. Surveillance performance and runway status light operational performance were evaluated quantitatively. The probability of tracking an aircraft in movement areas with line-of-sight coverage was better than 98%. The false track rate was about four per hour, and the surveillance jitter was about 1 meter rms. From an operational point of view, had there been real lights on the field, it appears that they would have provided the intended safety back-up with little impact on airport capacity or controller and pilot workload, Only once in 15 minutes would the pilot population have observed a light in an incorrect state for more than four seconds. From the point of view of a specific cockpit crew, only once in 36 operations would a runway status light have been seen in an incorrect state for more than four seconds, and, furthermore, only once in 50 operations would light illuminations have interfered with normal, safe traffic flow. These are encouraging results for a system in an early demonstration phase because significant improvement is possible in all of these performance measures. Specific suggestions for improvement are included in this document.
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Summary

The Runway Status Light System (RSLS), developed under the FAA's Airport Surface Traffic Automation (ASTA) program, is intended to help reduce the incidence of runway incursions and airport surface accidents. It will do so by providing a preventive, back-up system of automatically controlled lights on the airport surface that inform...

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Runway status light system demonstration at Logan Airport

The ASR-9 Processor Augmentation Card (9-PAC)

October 2, 1995
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Project Report
Author:
James V. Pieronek
Published in:
MIT Lincoln Laboratory Report ATC-232
Topic:
surveillance
R&D area:
R&D group:

Summary

Since 1990, the Airport Surveillance Radar-9 (ASR-9) has been commissioned and installed at more than 60 of the largest airports in the United States, and future installations are planned at more than 60 additional airports. After the first several systems were put into daily operation, air traffic controllers began to lodge complaints about the radar's performance. Problems included the detection of "phantom" aircraft caused by the reflection of beacon interrogation signals off buildings and other aircraft, the radar's losing track of targets during parallel approaches and departures, the inability to track highly maneuverable military aircraft through high-G turns, radar clutter caused by highways and weather, and system overloading as a result of signal returns from flocks of migrating birds. An initial investigation of the sources of these problems focused on the radar's post-processor. Nearly all of the problems could be addressed by additions to the post-processor software, but the post-processor was already running near capacity and there was no means for expansion. Thus, a new processor - the ASR-9 Processor Augmentation Card (9-PAC) - was designed to augment the existing system to allow for a significant increase in processing power. New algorithms were developed to run in 9-PAC to address the problems cited by the controllers.
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Summary

Since 1990, the Airport Surveillance Radar-9 (ASR-9) has been commissioned and installed at more than 60 of the largest airports in the United States, and future installations are planned at more than 60 additional airports. After the first several systems were put into daily operation, air traffic controllers began to...

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The ASR-9 Processor Augmentation Card (9-PAC)

Military and government applications of human-machine communication by voice

October 1, 1995
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Conference Paper
Author:
Clifford J. Weinstein
Published in:
Proc. Natl. Acad. Sci., Vol. 92, October 1995, pp. 10011-10016.
Topic:
speech recognition
R&D area:
R&D group:

Summary

This paper describes a range of opportunities for military and government applications of human-machine communication by voice, based on visits and contacts with numerous user organizations in the United States. The applications include some that appear to be feasible by careful integration of current state-of-the-art technology and others that will require a varying mix of advances in speech technology and in integration of the technology into applications environments. Applications that are described include (1) speech recognition and synthesis for mobile command and control; (2) speech processing for a portable multifunction soldier's computer; (3) speech- and language-based technology for naval combat team tactical training; (4) speech technology for command and control on a carrier flight deck; (5) control of auxiliary systems, and alert and warning generation, in fighter aircraft and helicopters; and (6) voice check-in, report entry, and communication for law enforcement agents or special forces. A phased approach for transfer of the technology into applications is advocated, where integration of applications systems is pursued in parallel with advanced research to meet future needs.
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Summary

This paper describes a range of opportunities for military and government applications of human-machine communication by voice, based on visits and contacts with numerous user organizations in the United States. The applications include some that appear to be feasible by careful integration of current state-of-the-art technology and others that will...

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Military and government applications of human-machine communication by voice

Sine-wave amplitude coding using a mixed LSF/PARCOR representation

September 20, 1995
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Conference Paper
Author:
Robert B. Dunn
…
Published in:
Proc. 1995 IEEE Workshop on Speech Coding for Telecommunications, 20-22 Spetember 1995, pp. 77-8.
Topic:
speech processing
R&D area:
R&D group:

Summary

An all-pole model of the speech spectral envelope is used to code the sine-wave amplitudes in the Sinusoidal Transform Coder. While line spectral frequencies (LSFs) are currently used to represent this all-pole model, it is shown that a mixture of line spectral frequencies and partial correlation (PARCOR) coefficients can be used to reduce complexity without a loss in quantization efficiency. Objective and subjective measures demonstrate that speech quality is maintained. In addition, the use of split vector quantization is shown to substantially reduce the number of bits needed to code the all-pole model.
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Summary

An all-pole model of the speech spectral envelope is used to code the sine-wave amplitudes in the Sinusoidal Transform Coder. While line spectral frequencies (LSFs) are currently used to represent this all-pole model, it is shown that a mixture of line spectral frequencies and partial correlation (PARCOR) coefficients can be...

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Sine-wave amplitude coding using a mixed LSF/PARCOR representation

Automated storm tracking for terminal air traffic control

September 1, 1995
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Journal Article
Author:
Edward S. Chornoboy
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Published in:
Lincoln Laboratory Journal, Vol. 7, No. 2, Fall 1994, pp. 427-448.
Topic:
air traffic control
R&D area:
R&D group:

Summary

Good estimates of storm motion are essential to improved air traffic control operations during times of inclement weather. Automating such a service is a challenge, however, because meteorological phenomena exist as complex distributed systems that exhibit motion across a wide spectrum of scales. Even when viewed from a fixed perspective, these evolving dynamic systems can test the extent of our definition of motion, as well as any attempt at automated tracking of this motion. Image-based motion detection and processing appear to provide the best route toward robust performance of an automated tracking system.
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Summary

Good estimates of storm motion are essential to improved air traffic control operations during times of inclement weather. Automating such a service is a challenge, however, because meteorological phenomena exist as complex distributed systems that exhibit motion across a wide spectrum of scales. Even when viewed from a fixed perspective...

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Automated storm tracking for terminal air traffic control
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