| Model-Based Optimization of Airborne Collision Avoidance Logic |
26 Jan 2010 |
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| Authors:
M J Kochenderfer; J P Chryssanthacopoulos; L P Kaelbling; T Lozano-Perez; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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 | The Traffic Alert and Collision Avoidance System (TCAS) is designed to reduce the risk of mid-air collisions by providing resolution advisories to pilots. The current version of the collision avoidance logic was hand-crafted over the course of many years and contains many parameters that have been tuned to varying extents and heuristic rides whose justification has been lost. Further development of the TCAS system is required to make the system ... |
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| Phase-Enhanced 3D Snapshot ISAR Imaging and Interferometric SAR |
28-Dec-2009 |
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| Authors:
Joseph T Mayhan; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| Previously, a novel formulation for the generation of three-dimensional (3D) inverse synthetic aperture radar (ISAR) images based on recent developments in high resolution spectral estimation theory was presented. Because this technique requires only snapshots of data, where a snapshot is defined as a block of Nyquist sampled frequency-time pulses of data, we refer to it as 3D snapshot imaging. Concomitant with these results, recent advances in interferometric SAR imaging have ... |
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| RF Radiation Environment Over Millstone Hill |
14-Dec-2009 |
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| Authors:
T A Cott; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| This report documents a study of the RP radiation environment in the vicinity of the Lincoln Space Surveillance Complex radars. The focus of this HOPEhe study is a model-based analysis of the hazards to occupants of aircraft flying in the vicinity of the radars, comparing computed exposure levels with safety standards for the general public set by the Massachusetts Department of Public Health. |
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| A Comparison of Query-by-Example Methods for Spoken Term Detection |
Sep 2009 |
5 pages |
| Authors:
Wade Shen; Christopher M White; Timothy J Hazen; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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 | In this paper we examine an alternative interface for phonetic search, namely query-by-example, that avoids OOV issues associated with both standard word-based and phonetic search methods. We develop three methods that compare query lattices derived from example audio against a standard ngrambased phonetic index and we analyze factors affecting the performance of these systems. We show that the best systems under this paradigm are able to achieve 77% precision when ... |
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| Validating the Modeling and Simulation of a Generic Tracking Radar |
28-Jul-2009 |
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| Authors:
H C Lambert; S R Vogel; A S Brewster; K Dunn; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| This report proposes acceptability criteria for validating the modeling and simulation of a generic tracking radar. The approach is based on a statistical hypothesis test that strives to minimize risk to both the model user and the model maker. The validation process is limited to the comparison of a set of Monte Carlo realizations of judiciously selected validation metrics with single discrete-event observations made by the actual sensor. The effectiveness ... |
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| Measurement of Trace Explosive Residues in a Surrogate Operational Environment: Implications for Tactical Use of Chemical Sensing in C-IED Operations |
Dec-2008 |
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| Authors:
Dennis Hardy; Fountain; Augustus W III; Roderick R Kunz; Kerin Clow; Stanley A Ostazeski; Jonathan Oyler; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| A campaign to measure the amount of trace explosive residues in an operational military environment was conducted on May 27-31, 2007, at the National Training Center at Fort Irwin, CA. The objectives to this campaign were to develop the methods needed to collect and analyze samples from tactical military settings, to use the data obtained to determine what the trace-explosive signatures suggest about the potential capabilities of chemical-based means to ... |
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| Status of the Air Force's Improved Technology Maturity Assessment Project (TD-1-12) |
Sep-2008 |
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| Authors:
Kyle Yang; James Bilbro; William Nolte; Robert Frueholz; Duane Sauve; Greg Barnette; Mark Wilson; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| The Improved Technology Maturity Assessment Project (TD-1-12) consists of 1) Training for TRL Assessments, MRAs, future RI3; 2) Software TRL definition clarification; and 3) Risk Identification: Integration & 'ilities (RI3) methodology. This briefing discusses 1) improving existing techniques, 2) methodology for integration and 'ilities, and 3) worksheet and tool concepts. The goal of the program is to reduce schedule slip and cost growth due to immature technology by reducing the ... |
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| Statistical Inference in Graphical Models |
17 JUN 2008 |
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| Authors:
K. Gimpel; D. Rudoy; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| Graphical models fuse probability theory and graph theory in such a way as to permit efficient representation and computation with probability distributions. They intuitively capture statistical relationships among random variables and provide a succinct formalism that allows for the development of tractable algorithms for statistical inference. In recent years, certain types of graphical models, particularly Bayesian networks and dynamic Bayesian networks (DBNs), have been applied to various problems in missile ... |
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| Elementary Surveillance (ELS) and Enhanced Surveillance (EHS) Validation via Mode S Secondary Radar Surveillance |
23 APR 2008 |
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| Authors:
Robert D. Grappel; Garrett S. Harris; Mark J. Kozar; Randall T. Wiken; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| This report presents a set of algorithms that may be employed to monitor the conformation and performance of Mode S avionics in aircraft equipped for the Elementary Surveillance (ELS) and Enhanced Surveillance (ERS) data link applications. The intended audience for this report is an engineering staff assigned the task of implementing a monitoring system used to determine ELS and EHS compliance. It is assumed that surveillance data and Mode S ... |
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| Advanced Narrowband Electromagnetic Size and Shape Determination |
15 FEB 2008 |
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| Authors:
S. Kusiak; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| This report discusses a fundamental radar imaging problem for narrowband electromagnetic waves that extends the recent results originally obtained in [1, 2] in the scalar, or acoustic, setting. In particular we demonstrate the ability to efficiently image three-dimensional convex conducting bodies by using the knowledge of the scattered electric field for one fixed monochromatic illumination of the target. In this problem our knowledge of the scattered electric wave is understood ... |
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| Analog-to-Information Study Phase |
10 OCT 2007 |
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| Authors:
K. W. Forsythe; J. I. Goodman; M. R. Green; B. A. Miller; G. M. Raz; J. H. Jackson; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| Many communications and Radar receivers must process data over a very wide band, which requires either high-rate analog-to-digital converters (ADCs) or multichannel receivers. The information content of that wideband data, however, is often sparse in some basis. Analog-to-Information (A2I) receivers exploit this sparseness in both the digital and analog domains by non-adaptively spreading the signal energy (analog) and using digital signal processing to recover the signal from an ADC sampling ... |
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| Guidance Material for Mode S-Specific Protocol Application Avionics |
04 JUN 2007 |
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| Authors:
R. D. Grappel; R. T. Wiken; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| This ATC report presents guidance material for the use of the "Ground-Initiated Comm. B" (GICB) register set contained in a Mode S transponder. The guidance material is intended to provide assistance for implementers of Mode S avionics installations. A common summary of the requirements and specifications for Mode S GICB transponder register data link applications is developed. While this ATC report focuses primarily on the "Elementary Surveillance" (ELS), "Enhanced Surveillance" ... |
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| Making Network Intrusion Detection Work With IPsec |
11 MAY 2007 |
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| Authors:
C. D. McLain; A. Studer; R. P. Lippmann; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| Network-based intrusion detection systems (NIDSs) are one component of a comprehensive network security solution. The use of IPsec, which encrypts network traffic, renders network intrusion detection virtually useless unless traffic is decrypted at network gateways. One alternative to NIDSs, host-based intrusion detection systems (HIDSs), provides some of the functionality of NIDSs but with limitations. HIDSs cannot perform a network-wide analysis and can be subverted if a host is compromised. We ... |
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| Coverage Maximization Using Dynamic Taint Tracing |
28 MAR 2007 |
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| Authors:
T. R. Leek; G. Z. Baker; R. E. Brown; M. A. Zhivich; R. P. Lippmann; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| We present COMET, a system that automatically assembles a test suite for a C program to improve line coverage, and give initial results for a prototype implementation. COMET works dynamically, running the program under a variety of instrumentations in a feedback loop that adds new inputs to an initial corpus with each iteration. One instrumentation in particular is crucial to the success of this approach: dynamic taint tracing. Inputs are ... |
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| Auditory Modeling as a Basis for Spectral Modulation Analysis with Application to Speaker Recognition |
31 JAN 2007 |
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| Authors:
Tianyu T. Wang; Thomas F. Quatieri; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| This report explores auditory modeling as a basis for robust automatic speaker verification. Specifically, we have developed feature-extraction front-ends that incorporate (1) time-varying, level-dependent filtering, (2) variations in analysis filter-bank size, and (3) nonlinear adaptation. Our methods are motivated both by a desire to better mimic auditory processing relative to traditional front-ends (e.g., the mel-cepstrum) as well as by reported gains in automatic speech recognition robustness exploiting similar principles. Traditional ... |
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| Performance Assessment of Intelligence, Surveillance, and Reconnaissance (ISR) Enterprise Workflows |
31 JAN 2007 |
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| Authors:
M. B. Hurley; P. B. Jones; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| This report presents an end-to-end assessment framework for C4ISR enterprises that identifies potential FOMs and thereby eliminates a significant fraction of the uncertainty the currently exists on how to assess the performance of these systems. The framework delineates how measurements from laboratory tests, operational experiments, and field deployments can be analyzed to produce accurate, quantitative descriptions of system performance. These FOMs not only inform the development and acquisition processes but ... |
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| Computational Workloads for Commonly Used Signal Processing Kernels |
30 NOV 2006 |
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| Authors:
M. Arakawa; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| In the course of designing or evaluating signal processing algorithms, one often must determine the computational workload needed to implement the algorithms on a digital computer. The floating-point operation (flop) counts for real versions of the most common signal processing kernels are well documented. However, the flop counts for kernels operating on complex inputs are not as readily found. This report collects the flop count expressions for both real and ... |
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| BSAR Computational Analysis and Proposed Mapping. Revision 1 |
30 NOV 2006 |
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| Authors:
M. Arakawa; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| This report details the MIT Lincoln Laboratory computational performance analysis of the CBASS BSAR. We describe: (1) the BSAR algorithm, in both the original mode and the new, default mode; (2) the algorithm's computational workload for both nodes; (3) the 12-Hammerhead DR on which the BSAR algorithm is executed; (4) a proposed mapping of the algorithm onto the DR; (5) an estimated execution time for the algorithm in both modes ... |
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| The MIT-LL/AFRL IWSLT-2006 MT System |
Nov 2006 |
7 pages |
| Authors:
Wade Shen; Brian Delaney; Tim Anderson; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| The MIT-LL/AFRL MT system is a statistical phrase-based translation system that implements many modern SMT training and decoding techniques. Our system was designed with the long-term goal of dealing with corrupted ASR input and limited amounts of training data for speech-to-speech MT applications. This paper will discuss the architecture of the MIT-LL/AFRL MT system, improvements over our 2005 system, and experiments with manual and ASR transcription data that were run ... |
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| Asymptotic Error for Windowed Discrete Fourier Transforms |
25 AUG 2006 |
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| Authors:
A. F. Yegulalp; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| The windowed discrete Fourier transform (DFT) is a widely used tool in countless signal processing applications. Surprisingly, there has been little analysis of the accuracy for the processing of random bandlimited signals. This report derives an error formula at leading asymptotic order in the number of data samples. The formula applies to essentially any window function, with explicit results tabulated for some of the most common cases. The asymptotic error ... |
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| Channel Characterization for EHF Satellite Communications on the Move |
12 JUL 2006 |
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| Authors:
W. M. Smith; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| In addition to long signal propagation delays, the mobile satellite terminal in a land-mobile satellite communications system is subject to channel impairments imposed by the terrestrial environment. Statistical channel models are needed for protocol development and performance evaluation of systems for satellite communications (SATCOM) on the move. Experimental measurements were made in and around Boston, MA, using a prototype system for SATCOM on the move. The measurements characterize the 20 ... |
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| Polymorphous Computing Architecture (PCA) Kernel Benchmark Measurements on the MIT Raw Microprocessor |
14 JUN 2006 |
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| Authors:
R. J. Haney; J. M. Lebak; M. A. Alexander; H. Chan; P. A. Jackson; E. L. Wong; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| The DARPA Polymorphous Computing Architecture (PCA) program is a research initiative aimed at developing new computer architectures with a high degree of flexibility. Unlike current computer architectures that are rigid in nature, PCAs will have the capability to adapt ("morph") to match the problem being solved. This flexibility will allow higher overall system performance in a broad range of applications. MIT Lincoln Laboratory has defined a set of kernel benchmarks ... |
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| A Smallbox and an Inhalation Anthrax Model Implemented Using Ordinary Differential Equations |
14 MAR 2006 |
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| Authors:
D. C. Jamrog; A. A. Szpiro; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| This report presents one approach for modeling smallpox and inhalation anthrax outbreaks using ODEs (ordinary differential equations). This approach is related to a standard SEIR (susceptible exposed infected recovered) model. For each model, we define the states that characterize the uninfected and infected populations, the parameters governing disease progression, and the ODEs that govern the transitions between the population states. In both models, medical capacity and treatment limitations are considered. ... |
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| A Smallpox and an Inhalation Anthrax Model Implemented Using Ordinary Differential Equations |
14 MAR 2006 |
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| Authors:
D. C. Jamrog; A. A. Szpiro; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| This report presents one approach for modeling smallpox and inhalation anthrax outbreaks using ODEs (ordinary differential equations). This approach is related to a standard SEIR (susceptible exposed infected recovered) model. For each model, we define the states that characterize the uninfected and infected populations, the parameters governing disease progression, and the ODEs that govern the transitions between the population states. In both models, medical capacity and treatment limitations are considered. ... |
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| Thoughts on the Meaning of "Asymmetric Threats" |
08 MAR 2006 |
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| Authors:
C. A. Primmerman; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| This monograph was written in the summer of 2000, thus, it predates the attacks of 11 September 2001 and the subsequent war on terrorism. It appears to the author, however, that events since the summer of 2000 have validated the definitions and list of asymmetric threats given in this monograph. Therefore, it is being reproduced now as a Lincoln Laboratory technical report. A new afterword has been added, relating recent ... |
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| Performance-Based Comparison of Low-Light Video Technologies for Night Surveillance |
03 MAR 2006 |
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| Authors:
C. Fischer; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| Differences in spectral response, pixel size, and noise characteristics between low-light video technologies complicate the direct comparison of field performance for a surveillance application. Commonly measured camera properties such as modulation transfer function and read noise do not directly relate to field performance (e.g., probability of target recognition). In modeling camera field performance based on these measured properties, many assumptions are often made such as constant prereadout gain, signal-independent noise ... |
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| Distribution Models for Optical Scintillation Due to Atmospheric Turbulence |
12 DEC 2005 |
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| Authors:
R. R. Parenti; R. J. Sasiela; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| Traditional analyses ot optical scintillation usually invoke the Rytov approximation and the associated assumptions regarding weak phase perturbations throughout the propagation channel. Associated with that approach is the prediction that the statistics of scintillation will be log-normal. This report, which uses the Fresnel propagation function as a basis, challenges many of the standard descriptions of far-field irradiance fluctiiations. A key finding of this study is the importance of the ratio ... |
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| Extended-Range Signal Recovery Using Multi-PRI Transmission for Doppler Weather Radars |
01 NOV 2005 |
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| Authors:
John Y. Cho; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| Range-velocity (RV) ambiguity is a source of data quality degradation common to all weather radars. Various methods have been developed in recent years to combat this problem. For example, for the new NEXRAD Open Radar Data Acquisition (ORDA) system, the primary focus for range-overlay separation has been on phase-code transmission and processing techniques. There are, however, conditions under which the phase-code method fails to separate range-overlaid signals, e.g., when the ... |
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| Capon and Bartlett Beamforming: Threshold Effect in Direction-of-Arrival Estimation Error and On the Probability of Resolution |
16 MAY 2005 |
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| Authors:
C. D. Richmond; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| Below a specific threshold signal-to-noise ratio (SNR), the mean squared error (MSE) perfor- mance of signal direction-of arrival (DOA) estimates derived from the Capon algorithm degrades swiftly. Prediction of this threshold SNR point is of practical significance for robust system design and analysis. The exact pairwise error probabilities for the Capon (and Bartlett) algorithm are derived herein, given by simple finite sums involving no numerical integration, include finite sample effects, ... |
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| Solid State Research |
12 MAY 2005 |
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| Authors:
David C. Shaver; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| This report covers in detail the research work of the Solid State Division at Lincoln Laboratory for the period 1 August through 31 October 2004. The topics covered are Quantum Electronics, Electro-optical Materials and Devices, Submicrometer Technology, Biosensor and Molecular Technologies, Advanced Imaging Technology, Analog Device Technology, and Advanced Silicon Technology. Funding is provided by several DoD organizations-including the Air Force, Army, DARPA, MDA, Navy, NSA, and OSD-and also by ... |
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| Measuring Translation Quality by Testing English Speakers with a New Defense Language Proficiency Test for Arabic |
May-2005 |
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| Authors:
Clifford Weinstein; DOUGLAS JONES; Wade Shen; Martha Herzog; Neil Granoien; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| We present results from an experiment in which educated English-native speakers answered questions from a machine translated version of a standardized Arabic language test. We compare the machine translation (MT) results with professional reference translations as a baseline for the purpose of determining the level of Arabic reading comprehension that current machine translation technology enables an English speaker to achieve. Furthermore, we explore the relationship between the current, broadly accepted ... |
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| An Annotated Review of Past Papers on Attack Graphs |
31 MAR 2005 |
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| Authors:
R. P. Lippmann; K. W. Ingols; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| This report reviews past research papers that describe how to construct attack graphs, how to use them to improve security of computer networks, and how to use them to analyze alerts from intrusion detection systems. Two commercial systems are described 1, 2, and a summary table compares important characteristics of past research studies. For each study, information is provided on the number of attacker goals, how graphs are constructed, sizes ... |
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| Measuring Human Readability of Machine Generated Text: Three Case Studies in Speech Recognition and Machine Translation |
Mar-2005 |
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| Authors:
Clifford Weinstein; DOUGLAS JONES; Wade Shen; Martha Herzog; Neil Granoien; Edward Gibson; Douglas Reynolds; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| We present highlights from three experiments that test the readability of current state-of-the art system output from (1) an automated English speech-to-text system (2) a textbased Arabic-to-English machine translation system and (3) an audiobased Arabic-to-English MT process. We measure readability in terms of reaction time and passage comprehension in each case, applying standard psycholinguistic testing procedures and a modified version of the standard Defense Language Proficiency Test for Arabic called ... |
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| Standoff Polarimetric Aerosol Detection (SPADE) for Biodefense |
01 FEB 2005 |
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| Authors:
J. W. Snow; W. E. Bicknell; A. T. George; H. K. Burke; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| The polarization of laser light elastically scattered by small particles is investigated for the purpose of remotely detecting bio-aerosol presence in typical ambient background aerosols. The information source is small-particle scattering code computations, not actual measurements. Two separate types of particles - natural background aerosols vs. bio-aerosols - are combined with a concentration ratio of 100-to-1. The objective is to assess the feasibility of detecting the introduction of the bio-aerosol ... |
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| PMatlab Takes the HPCchallenge |
01 FEB 2005 |
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| Authors:
Ryan Haney; Hahn Kim; Andrew Funk; Jeremy Kepner; Charles Rader; Albert Reuther; Nadya Travinin; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| The HPCchallenge benchmark suite has been released by the DARPA HPCS program to help define the performance boundaries of future Petascale computing systems. The suite is composed of several well known computational kernels (STREAM, Top500, FFT, and RandomAccess) that span high and low spatial and temporal locality. These kernels also encompass key aspects of embedded signal processing: vector computations, matrix multiplies, corner turns and random selection operations. MATLAB 2 is ... |
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| Supercomputing:HPCMP, Performance Measures and Opportunities |
01 FEB 2005 |
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| Authors:
Cray J. Henry; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| Briefing charts only. |
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| A Systolic FFT Architecture for Real Time FPGA Systems |
01 FEB 2005 |
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| Authors:
Preston A. Jackson; Cy P. Chan; Jonathan E. Scalera; Charles M. Rader; M. M. Vai; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| MIT Lincoln Laboratory has recently developed a new systolic FFT architecture for FPGAs. This architecture utilizes a parallel design to provide high throughput and excellent numerical accuracy. Using this design, an 8192- point real-time FFT, operating at 1.2 billion samples per second and performing 78 Gops with 70 dB of accuracy, fits on a single Xilinx Virtex II 8000. |
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| Amending Moore's Law for Embedded Applications: Panel Discussion |
01 FEB 2005 |
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| Authors:
David R. Martinez; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| DoD Embedded Processing Applications: Future systems need: 1) Higher performance with reduced cost, size, weight, and power consumption; 2) Adaptability, flexibility, scalability, reconfigurability; 3) High bandwidth internal and network data communications. |
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| A KASSPER Real-Time Signal Processor Testbed |
01 FEB 2005 |
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| Authors:
Glenn Schrader; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| The Knowledge Aided Sensor Signal Processing and Expert Reasoning (KASSPER) Program is a Defense Advanced Research Projects Agency (DARPA) program which has the goal of improving the performance of Ground Moving Target Indicator (GMTI) radar systems by incorporating external sources of knowledge into the signal processing chain. The KASSPER Real-Time Signal Processor Testbed and its associated Signal Processing Architecture is a prototype radar system scheduling and signal processing framework that ... |
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| Examples of EO-1 Hyperion Data Analysis |
12 JAN 2005 |
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| Authors:
M. K. Griffin; S. M. Hsu; H. K. Burke; S. M. Orloff; C. A. Upham; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| The EO-1 satellite is part of NASA's New Millennium Program (NMP). It consists of three imaging sensors: the multispectral Advanced Land Imager (ALI), Hyperion, and Atmospheric Corrector. Hyperion provides a high-resolution hyperspectral imager capable of resolving 220 spectral bands (from 0.4 to 2.5 micron) with a 30-m resolution. The instrument images a 7.5 km by 100 km land area per image. Hyperion is currently the only spaceborne HSI data source ... |
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| The MIT-LL/AFRL MT System |
Jan 2005 |
|
| Authors:
Wade Shen; Brian Delaney; Tim Anderson; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| The MIT-LL/AFRL MT system is a statistical phrase-based translation system that implements many modern SMT training and decoding techniques. Our system was designed with the long term goal of dealing with corrupted ASR input for Speech-to-Speech MT applications. This paper will discuss the architecture of the MIT-LL/AFRL MT system, and experiments with manual and ASR transcription data that were run as part of the IWSLT-2005 Chinese-to-English evaluation campaign. |
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| Effects of Lossy Compression of Hyperspectral Imagery |
30 DEC 2004 |
|
| Authors:
J. K. Su; M. K. Griffin; S. M. Hsu; S. Orloff; C. A. Upham; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| Hyperspectral imaging (HSI) sensors provide imagery with hundreds of spectral bands, typically covering VNIR and/or SWIR wavelengths. This high spectral resolution offers promise for many applications, but it also produces enormous volumes of data, which may be problematic for storage and transmission. Lossy compression may therefore be necessary, but application performance degradation that results from compression is of concern. This report documents results for a spectral-spatial lossy compression scheme and ... |
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| Adaptive Beamforming for SAR Ambiguity Rejection |
20 DEC 2004 |
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| Authors:
Gerald Benitz; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| The Lincoln SPARTA program is developing next-generation phased arrays for enhanced radar performance and efficiency. One novel capability being explored is simultaneous operation of MTI (moving target indicator) and SAR (synthetic aperture radar) imaging two functions that are usually mutually exclusive. MTI scans large areas quickly using short integration (^10 msec) and low bandwidth (^10 MHz). SAR in contrast stares for seconds at each location and has high bandwidth (^600 ... |
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| Long CPI Wideband GMTI |
20 DEC 2004 |
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| Authors:
Ali Yegulalp; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| The conventional approach to GMTI uses narrowband signals and a short coherent processing interval (CPI). In this talk, we examine some of the fundamental theoretical issues involved in GMTI with wideband signals and long CPIs (WL-GMTI). The possibility of wideband long CPI GMTI has received some attention in recent years and there are a number of potential benefits: 1) Improved minimum detectable velocity (MDV). 2) Detection of targets with zero ... |
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| Information Theoretic Comparison of MIMO Wireless Communication Receivers in the Presence of Interference |
20 DEC 2004 |
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| Authors:
Daniel W. Bliss; Keith W. Forsythe; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| Multiple-input multiple-output (MI MO) wireless communication provides a number of advantages over traditional single-input single-output (SISO) approaches including increased data rates for a given total transmit power and improved robustness to interference. Many of these advantages depend strongly upon the details of the receiver implementation. For practical communication systems a competition between communication performance and computational complexity exists. To reduce computation complexity suboptimal receivers are commonly employed. In this paper ... |
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| The Capon-MVDR Algorithm Threshold Region Performance Prediction and Its Probability of Resolution |
20 DEC 2004 |
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| Authors:
Christ D. Richmond; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| The Capon-MVDR algorithm exhibits a threshold effect in mean-squared error (MSE) performance 1. Below a specific threshold signal-to-noise ratio (SNR) the MSE of signal parameter estimates derived from the Capon algorithm rises rapidly. Prediction of this threshold SNR point is clearly of practical significance for system design and performance. Via an adaptation of an interval error-based method referred to herein as the method of interval errors (MIE) 2, 3 the ... |
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| Statistical Clustering Methods Applied to Adaptive Matched Field Processing |
20 DEC 2004 |
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| Authors:
Brian H. Tracey; Nigel Lee; Srinivas Turaga; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| Cluster analysis provides a tool for mapping out regions of ambiguous response in sparse array beam forming problems. This paper discusses clustering and its application to matched field processing (MFP) problems in ocean acoustics. The map of the ambiguity volume provided by clustering can be used for improved interpretation and postprocessing. By peak-picking in cluster space, rather than in spatial dimensions, the authors are able to identify and discard ambiguous ... |
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| Radiation Pattern Measurements of the Expanded Very Large Array (EVLA) C-Band Feed Horn in the MIT Lincoln Laboratory New Compact Range: Range Validation at 4 GHz |
29 NOV 2004 |
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| Authors:
A. J. Fenn; S. Srikanth; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
|
| The National Radio Astronomy Observatory is developing and installing several new feeds and receivers on the expanded very large array (EVLA) antennas in New Mexico. Antenna pattern measurements of the EVLA C-band feed horn in a new compact range reflector system at MIT Lincoln Laboratory are described in this report. Measured and calculated antenna radiation patterns of the EVLA C- band feed at 4 GHz are in good agreement. |
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| Design of a Novel, Multi-Port-Addressable Bioaerosol Collection System |
17 NOV 2004 |
|
| Authors:
Trina Vian; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| Pathogen Detection Using Headspace Analysis |
15 NOV 2004 |
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| Authors:
Christina M. Rudzinski; Rachel Herzig-Marx; Jonathan Lin; Adam Szpiro; Bernadette Johnson; MASSACHUSETTS INST OF TECH LEXINGTON LINCOLN LAB
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| The ability to rapidly screen samples for the presence of pathogens offers many advantages. From a security standpoint, the rapid classification of samples as pathogenic or non-pathogenic (suspicious powders, for example) can elicit a more rapid first response and can minimize the labor intensive processing of countless samples in the laboratory, thus saving both time and money. In a clinical setting, pre-symptomatic diagnosis of infection can prevent the onset of ... |
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