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Geiger-mode avalanche photodiodes for three-dimensional imaging

January 1, 2002
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Journal Article
Author:
Brian F. Aull
…
Published in:
Lincoln Laboratory Journal, Vol. 13, No. 2, 2002, pp. 335-350.
Topic:
ladar
R&D area:
R&D group:

Summary

We discuss the properties of Geiger-mode avalanche photodiodes (APDs) and their use in developing an imaging laser radar (ladar). This type of photodetector gives a fast electrical pulse in response to the detection of even a single photon, allowing for sub-nsec-precision photon-flight-time measurement. We present ongoing work at Lincoln Laboratory on three-dimensional (3D) imaging with arrays of these diodes, and the integration of the arrays with fast complementary metal-oxide semiconductor (CMOS) digital timing circuits.
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Summary

We discuss the properties of Geiger-mode avalanche photodiodes (APDs) and their use in developing an imaging laser radar (ladar). This type of photodetector gives a fast electrical pulse in response to the detection of even a single photon, allowing for sub-nsec-precision photon-flight-time measurement. We present ongoing work at Lincoln Laboratory...

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Geiger-mode avalanche photodiodes for three-dimensional imaging

Aircraft Vortex Spacing System (AVOSS) initial 1997 system deployment at Dallas/Ft. Worth (DFW) Airport

July 8, 1998
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Project Report
Author:
Timothy J. Dasey
…
Published in:
MIT Lincoln Laboratory Report NASA-L-3
Topic:
aviation weather
R&D area:
R&D group:

Summary

The potential hazard of aircraft encounters with the wake turbulence of preceding aircraft requires the use of minimum separations on landing that are a significant constraint on airport arrival capacity during instrument flight rules (IF) conditions. The National Aeronautics and Space Administration (NASA) Langley Research Center has been researching the development of the Aircraft Vortex Spacing System (AVOSS) which would dynamically change aircraft arrival separations based on the forecasted weather conditions and vortex behavior. An experimental AVOSS test system has been constructed at DFW airport and includes a large set of meteorological instruments, wake vortex sensors from three organizations, and an aircraft data collection system. All of this data are relayed to a central processing center at DFW for processing by automated meteorological data fusion algorithms and by NASA vortex behavior predictions software. An initial deployment and test of the DFW system was conducted during a three-week period in September/October of 1997. This document describes the overall system, the Lincoln-deployed sensors, including the Continuous-Wave Coherent lidar, and the meteorological data collection and processing system. Algorithms that were used to process the data for scientific use are described, as well as the conditions of the data collection and the data formats, for potential users of this database.
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Summary

The potential hazard of aircraft encounters with the wake turbulence of preceding aircraft requires the use of minimum separations on landing that are a significant constraint on airport arrival capacity during instrument flight rules (IF) conditions. The National Aeronautics and Space Administration (NASA) Langley Research Center has been researching the...

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Aircraft Vortex Spacing System (AVOSS) initial 1997 system deployment at Dallas/Ft. Worth (DFW) Airport

A comprehensive system for measuring wake vortex behavior and related atmospheric conditions at Memphis, Tennessee

January 1, 1997
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Journal Article
Author:
Timothy J. Dasey
…
Published in:
Air Traffic Control Q., Vol. 5, No. 1, January 1997, pp. 49-68.
Topic:
aviation weather
R&D area:
R&D group:

Summary

Models of vortex behavior as a function of atmospheric conditions are being developed in an attempt to improve safety and minimize unnecessary airport capacity restrictions due to wake vortices. Direct measurements of vortices and the relevant meteorological conditions in an operational setting, which would serve to improve the understanding of vortex behavior, are scarce and incomplete. A comprehensive vortex, meteorological, and aircraft measurement system has been constructed at Memphis International Airport and operated in two I-month periods during 1994 and 1995. A 10.6 um continuous-wave (CW) coherent lidar was used to measure vortex parameters with high fidelity. This lidar features a number of improvements over previous systems, including an automatic vortex detection and tracking algorithm to ensure efficient scanning. Meteorological data were collected from a 45 m instrumented tower, balloon soundings, a wind profiler/radio acoustic sounding system (RASS), sonic detection and ranging (SO DAR), and other sensors. This paper presents ensemble distributions of the conditions under which the over 500 aircraft were measured, and samples of vortex and atmospheric measurements. These data will be compared with theoretical predictions of vortex behavior as part of the development of an operational system designed to reduce aircraft spacings in the terminal area.
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Summary

Models of vortex behavior as a function of atmospheric conditions are being developed in an attempt to improve safety and minimize unnecessary airport capacity restrictions due to wake vortices. Direct measurements of vortices and the relevant meteorological conditions in an operational setting, which would serve to improve the understanding of...

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A comprehensive system for measuring wake vortex behavior and related atmospheric conditions at Memphis, Tennessee

1995 wake vortex program at Memphis, TN

January 5, 1996
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Conference Paper
Author:
Steven D. Campbell
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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

Development and performance of a CW coherent laser radar for detecting wake vortices

July 23, 1995
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Journal Article
Author:
Richard M. Heinrichs
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Published in:
Optical Society of America, Coherent Laser Radar Topical Mtg., 1995 Technical Digest Series, Vol. 19, 23-27 July 1995, pp. 186-189
Topic:
ladar
R&D area:
R&D group:

Summary

A CW-coherent laser radar using a 20-Watt CO2 laser has been constructed and deployed for the measurement of wake-vortext turbulence. This is part of a larger effort to understand the motion and decay of wake vortices as a function of the local atmospheric conditions. The construction and operation of the lidar and the initial fielding at Memphis International Airport are described.
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Summary

A CW-coherent laser radar using a 20-Watt CO2 laser has been constructed and deployed for the measurement of wake-vortext turbulence. This is part of a larger effort to understand the motion and decay of wake vortices as a function of the local atmospheric conditions. The construction and operation of the...

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Development and performance of a CW coherent laser radar for detecting wake vortices

Overview of 1994 Memphis Wake Vortex testing program

January 15, 1995
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Conference Paper
Author:
Steven D. Campbell
…
Published in:
Proc. Sixth Conf. on Aviation Weather Systems, 15-20 January 1995, pp. 515-520.
Topic:
air traffic control
R&D area:
R&D group:

Summary

Significant restrictions currently exist in the air traffic control system due to wake vortex considerations. Eliminating or reducing these restrictions would yield increased capacity, decreased delays and significant cost savings (Evans & Welch, 1991). These improvements would be especially desirable at high traffic airports which cannot expand (e.g., Boston, JFK, LaGuardia, Newark, Washington National, O'Hare, etc.). However, scientific uncertainty about wake vortex behavior under various weather conditions is a major concern. The current wake vortex restrictions me normally very conservative but could be insufficient under certain transient atmospheric conditions. A successful adaptive wake vortex advisory system must be able to 1) monitor for unsafe conditions, 2) predict wake vortex behavior over 2&30 minutes in the future and 3) provide an interface to air traffic controllers. Operational implementation of such a system will involve synergism between the Wake Vortex (WV), Integrated Terminal Weather System (ITWS) and Terminal Air Traffic Control Automation (TATCA) programs. The Wake Vortex program is a new effort at Lincoln Laboratory sponsored by NASA Langley Research Center in cooperation with the FAA. The joint NASA/FAA/Lincoln program seeks to aid in resolving wake vortex behavior issues as a function of the weather environment with a series of field measurements. The field measurements will include obtaining aircraft, meteorological and wake vortex data in an operational airport environment. The data collected will support efforts at NASA and elsewhere to validate wake vortex behavior models, aircraft/vortex interaction and atmospheric diagnosis/prognosis methods. The first of these field measurements is scheduled for the fall of 1994 at the Memphis International Airport.
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Summary

Significant restrictions currently exist in the air traffic control system due to wake vortex considerations. Eliminating or reducing these restrictions would yield increased capacity, decreased delays and significant cost savings (Evans & Welch, 1991). These improvements would be especially desirable at high traffic airports which cannot expand (e.g., Boston, JFK...

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Overview of 1994 Memphis Wake Vortex testing program
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