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Automatic dependent surveillance-broadcast in the Gulf of Mexico

December 1, 2008
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Journal Article
Author:
Steven D. Thompson
…
Published in:
Lincoln Laboratory Journal, Vol. 17, No. 2, December 2008, pp. 55-69.
Topic:
air traffic control
R&D area:
R&D group:

Summary

The Federal Aviation Administration is adopting Automatic Dependent Surveillance-Broadcast (ADS-B) to provide surveillance in the National Airspace System (NAS). Aircraft separation services are currently provided by a system of en route and terminal radars, and the performance of these radars in part dictates the separation distance required between aircraft. ADS-B is designed to provide comparable service in areas where no radar coverage exists. It will eventually be the primary surveillance source in the NAS, if it is proven to provide performance equal to or better than radar.
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Summary

The Federal Aviation Administration is adopting Automatic Dependent Surveillance-Broadcast (ADS-B) to provide surveillance in the National Airspace System (NAS). Aircraft separation services are currently provided by a system of en route and terminal radars, and the performance of these radars in part dictates the separation distance required between aircraft. ADS-B...

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Automatic dependent surveillance-broadcast in the Gulf of Mexico

GROK secure multi-user chat at Red Flag 2007-03

November 17, 2008
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Conference Paper
Author:
Roger I. Khazan
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Published in:
MILCOM 2008, 16-18 November 2008.
Topic:
cryptography
R&D area:
R&D group:

Summary

This paper describes the GROK Secure Chat experimental activity performed by MIT Lincoln Laboratory at USAF Red Flag 2007-03 exercises and its results.
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Summary

This paper describes the GROK Secure Chat experimental activity performed by MIT Lincoln Laboratory at USAF Red Flag 2007-03 exercises and its results.

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GROK secure multi-user chat at Red Flag 2007-03

Uncorrelated encounter model of the National Airspace System version 1.0

November 14, 2008
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Project Report
Author:
Mykel J. Kochenderfer
…
Published in:
MIT Lincoln Laboratory Report ATC-345
Topic:
collision avoidance
R&D area:
R&D group:

Summary

Airspace encounter models, covering close encounter situations that may occur after standard separation assurance has been lost, are a critical component in the safety assessment of aviation procedures and collision avoidance systems. Of particular relevance to Unmanned Aircraft Systems (UAS) is the potential for encountering general aviation aircraft that are flying under Visual Flight Rules (VFR) and which may not be in contact with air traffic control. In response to the need to develop a model of these types of encounters, Lincoln Laboratory undertook an extensive radar data collection and modeling effort involving more than 120 sensors across the U.S. This report describes the structure and content of that encounter model. The model is based on the use of Bayesian networks to represent relationships between dynamic variables and to construct random aircraft trajectories that are statistically similar to those observed in the radar data. The result is a framework from which representative intruder trajectories can be generated and used in fast-time Monte Carlo simulations to provide accurate estimates of collision risk. The model described in this report is one of three developed by Lincoln Laboratory. An encounter with an intruder that does not have a transponder, or between two aircraft using a Mode A code of 1200 (VFR), is uncorrelated in the sense that it is unlikely that there would be prior intervention by air traffic control. The uncorrelated model described in this report is based on transponder-equipped aircraft using a 1200 (VFR) Mode A code observed by radars across the U.S. As determined from a comparison against primary-only tracks, in addition to representing VFR-on-VFR encounters, this model is representative of encounters between a cooperative aircraft and conventional noncooperative aircraft similar to those that use a 1200 transponder code. A second uncorrelated model is also being developed for unconventional aircraft that have different flight characteristics than 1200-code aircraft. Finally, a correlated encounter model has been developed to represent situations in which it is likely that there would be air traffic control intervention prior to a close encounter. The correlated model applies to intruders that are using a discrete (non-1200) code. Separate electronic files are available from Lincoln Laboratory that contain the statistical data required to generate and validate encounter trajectories. Details on how to interpret the data file and an example of how to randomly construct trajectories are provided in Appendices A and B, respectively. A Matlab software package is also available to generate random encounter trajectories based on the data tables. A byproduct of the encounter modeling effort was the development of National aircraft track and traffic density databases. Example plots of traffic density data are provided in this report, but the complete track and density databases are not provided in electronic form due to their size and the complexity of processing specific locations, altitudes, and times.
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Summary

Airspace encounter models, covering close encounter situations that may occur after standard separation assurance has been lost, are a critical component in the safety assessment of aviation procedures and collision avoidance systems. Of particular relevance to Unmanned Aircraft Systems (UAS) is the potential for encountering general aviation aircraft that are...

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Uncorrelated encounter model of the National Airspace System version 1.0

Efficient speech translation through confusion network decoding

November 1, 2008
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Journal Article
Author:
Nicola Bertoldi
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Published in:
IEEE Trans. Audio Speech Lang. Proc., Vol. 16, No. 8, November 2008, pp. 1696-1705.
Topic:
speech recognition
R&D area:
R&D group:

Summary

This paper describes advances in the use of confusion networks as interface between automatic speech recognition and machine translation. In particular, it presents a decoding algorithm for confusion networks which results as an extension of a state-of-the-art phrase-based text translation decoder. The confusion network decoder significantly improves both in efficiency and performance over previous work along this direction, and outperforms the background text translation system. Experimental results in terms of translation accuracy and decoding efficiency are reported for the task of translating plenary speeches of the European Parliament from Spanish to English and from English to Spanish.
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Summary

This paper describes advances in the use of confusion networks as interface between automatic speech recognition and machine translation. In particular, it presents a decoding algorithm for confusion networks which results as an extension of a state-of-the-art phrase-based text translation decoder. The confusion network decoder significantly improves both in efficiency...

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Efficient speech translation through confusion network decoding

Detection of condensed-phase explosives via laser-induced vaporization, photodissociation, and resonant excitation

November 1, 2008
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Journal Article
Author:
Charles M. Wynn
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Published in:
Appl. Opt., Vol. 47, No. 31, 1 November 2008, pp. 5767-5776.
Topic:
detection systems
R&D area:
R&D group:

Summary

We investigate the remote detection of explosives via a technique that vaporizes and photodissociates the condensed-phase material and detects the resulting vibrationally excited NO fragments via laser-induced fluorescence. The technique utilizes a single 7 ns pulse of a tunable laser near 236:2nm to perform these multiple processes. The resulting blue-shifted fluorescence (226 nm) is detected using a photomultiplier and narrowband filter that strongly block the scatter of the pump laser off the solid media while passing the shorter wavelength photons. Various nitro-bearing compounds, including 2,6-dinitrotoluene (DNT), 2,4,6-trinitrotoluene (TNT), pentaerythritol tetranitrate (PETN), and hexahydro-1,3,5- trinitro-1,3,5-triazine (RDX) were detected with a signal-to-noise of 25 dB. The effects of laser fluence, wavelength, and sample morphology were examined.
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Summary

We investigate the remote detection of explosives via a technique that vaporizes and photodissociates the condensed-phase material and detects the resulting vibrationally excited NO fragments via laser-induced fluorescence. The technique utilizes a single 7 ns pulse of a tunable laser near 236:2nm to perform these multiple processes. The resulting blue-shifted...

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Detection of condensed-phase explosives via laser-induced vaporization, photodissociation, and resonant excitation

A polyphase nonlinear equalization architecture and semi-blind identification method

October 26, 2008
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Conference Paper
Author:
Benjamin A. Miller
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Published in:
42th Asilomar Conf. on Signals, Systems, and Computers, 27 October 2008, pp. 593-597.
Topic:
signal processing
R&D area:
R&D group:

Summary

In this paper, we present an architecture and semiblind identification method for a polyphase nonlinear equalizer (pNLEQ). Such an equalizer is useful for extending the dynamic range of time-interleaved analog-to-digital converters (ADCs). Our proposed architecture is a polyphase extension to other architectures that partition the Volterra kernel into small nonlinear filters with relatively low computational complexity. Our semi-blind identification technique addresses important practical concerns in the equalizer identification process. We describe our architecture and demonstrate its performance with measured results when applied to a National Semiconductor ADC081000.
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Summary

In this paper, we present an architecture and semiblind identification method for a polyphase nonlinear equalizer (pNLEQ). Such an equalizer is useful for extending the dynamic range of time-interleaved analog-to-digital converters (ADCs). Our proposed architecture is a polyphase extension to other architectures that partition the Volterra kernel into small nonlinear...

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A polyphase nonlinear equalization architecture and semi-blind identification method

The cube coefficient subspace architecture for nonlinear digital predistortion

October 26, 2008
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Conference Paper
Author:
Matthew A. Herman
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Published in:
42th Asilomar Conf. on Signals, Systems, and Computers, 27 October 2008, pp. 1857-1861.
Topic:
signal processing
R&D area:
R&D group:

Summary

In this paper, we present the cube coefficient subspace (CCS) architecture for linearizing power amplifiers (PAs), which divides the overparametrized Volterra kernel into small, computationally efficient subkernels spanning only the portions of the full multidimensional coefficient space with the greatest impact on linearization. Using measured results from a Q-Band solid state PA, we demonstrate that the CCS predistorter architecture achieves better linearization performance than state-of-the-art memory polynomials and generalized memory polynomials.
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Summary

In this paper, we present the cube coefficient subspace (CCS) architecture for linearizing power amplifiers (PAs), which divides the overparametrized Volterra kernel into small, computationally efficient subkernels spanning only the portions of the full multidimensional coefficient space with the greatest impact on linearization. Using measured results from a Q-Band solid...

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The cube coefficient subspace architecture for nonlinear digital predistortion

Correlated encounter model for cooperative aircraft in the National Airspace System, version 1.0

October 24, 2008
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Project Report
Author:
Mykel J. Kochenderfer
…
Published in:
MIT Lincoln Laboratory Report ATC-344
Topic:
collision avoidance
R&D area:
R&D group:

Summary

This document describes a new cooperative aircraft encounter model for the National Airspace System (NAS). The model is used to generate random close encounters between transponder-equipped (cooperative) aircraft in fast-time Monte Carlo simulations to evaluate collision avoidance system concepts. An extensive set of radar data from across the United States, including more than 120 sensors and collected over a period of nine months, was used to build the statistical relationships in the model to ensure that the encounters that are generated are representative of actual events in the airspace.
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Summary

This document describes a new cooperative aircraft encounter model for the National Airspace System (NAS). The model is used to generate random close encounters between transponder-equipped (cooperative) aircraft in fast-time Monte Carlo simulations to evaluate collision avoidance system concepts. An extensive set of radar data from across the United States...

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Correlated encounter model for cooperative aircraft in the National Airspace System, version 1.0

Characterization of a three-dimensional SOI integrated-circuit technology

October 6, 2008
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Conference Paper
Author:
Chenson K. Chen
…
Published in:
2008 IEEE Int. SOI Conf. Proc., 6 October 2008, pp. 109-110.
Topic:
integrated circuit
R&D area:

Summary

At Lincoln Laboratory, we have established a three dimensional (3D) integrated circuit (IC) technology that has been developed and demonstrated over eight designs, bonding two or three active circuit layers or tiers to form monolithically integrated 3D circuits. This technology has been used to successfully demonstrate a large-area 8 x 8 mm2 high-3D-via-count 1024 x 1024 visible image, a 64 x 64 laser radar focal plane based on single-photon-sensitive avalanche photodiodes, and a 10Gb/s/pin low power interconnect for 3DICs. 3DIC technology in our most recently completed 3D multiproject (3DM2) run includes three active fully-depleted-SOI (FDSOI) circuit tiers, eleven interconnect-metal layers, and dense unrestricted 3D vias interconnecting stacked circuit layers, as shown in Figure 1. While we continue our efforts to scale our 3DIC technology and increase 3D via density, we are also working to improve our understanding of 3D integration impact on transistor and process monitor circuits. In this paper, we describe our process and test results after single tier circuit fabrication as well as after three-tier integration, determine impact of 3D vias on ring oscillator performance, and demonstrate functionality of single and multi-tier circuits of varying complexity.
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Summary

At Lincoln Laboratory, we have established a three dimensional (3D) integrated circuit (IC) technology that has been developed and demonstrated over eight designs, bonding two or three active circuit layers or tiers to form monolithically integrated 3D circuits. This technology has been used to successfully demonstrate a large-area 8 x...

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Characterization of a three-dimensional SOI integrated-circuit technology

Operational usage of the Route Availability Planning Tool during the 2007 convective weather season : executive summary

October 6, 2008
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Project Report
Author:
Michael Robinson
…
Published in:
MIT Lincoln Laboratory Report ATC-339-1
Topic:
air traffic control
R&D area:
R&D group:

Summary

The Route Availability Planning Tool (RAPT) is an integrated weather/air traffic management decision support tool that has been designed to help traffic managers better anticipate weather impacts on jet routes and thus improve NY departure route usage efficiency. A field study was conducted in 2007 to evaluate RAPT technical performance at forecasting route blockage, to assess RAPT operational use during adverse weather, and to evaluate RAPT benefits. The operational test found that RAPT guidance was operationally sound and timely in many circumstances. RAPT applications included increased departure route throughput, more efficient reroute planning, and more timely decision coordination. Estimated annual NY departure delay savings attributed to RAPT in 2007 totaled 2,300 hours, with a cost savings of $7.5 M. The RAPT field study also sought to develop a better understanding of NY traffic flow decision-making during convective weather impacts since the RAPT benefi ts in 2007 were significantly limited by a number of factors other than direct weather impacts. Observations were made of the multi-facility departure management decision chain, the traffic management concerns and responsibilities at specific FAA facilities, and the procedures and pitfalls of the current process for capturing and disseminating key information such as route/fix availability and restrictions.
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Summary

The Route Availability Planning Tool (RAPT) is an integrated weather/air traffic management decision support tool that has been designed to help traffic managers better anticipate weather impacts on jet routes and thus improve NY departure route usage efficiency. A field study was conducted in 2007 to evaluate RAPT technical performance...

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Operational usage of the Route Availability Planning Tool during the 2007 convective weather season : executive summary
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