Publications

We describe the key features and performance data of a 1024 x 1026-pixel frame-transfer imager for use as a soft-x-ray detector on the NASA X-ray observatory Advanced X-ray Astrophysics Facility (AXAF). The four-port device features a floating-diffusion output circuit with a responsivity of 20/spl mu/V/e/sup -/ and noise of about...

This paper compares two approaches to background model representation for a text-independent speaker verification task using Gaussian mixture models. We compare speaker-dependent background speaker sets to the use of a universal, speaker-independent background model (UBM). For the UBM, we describe how Bayesian adaptation can be used to derive claimant speaker...

Language-identification (LID) techniques that use multiple single-language phoneme recognizers followed by n-gram language models have consistently yielded top performance at NIST evaluations. In our study of such systems, we have recently cut our LID error rate by modeling the output of n-gram language models more carefully. Additionally, we are now...

An important limitation of precipitation sensors is contamination from ground clutter targets under conditions of anomalous propagation (AP). This problem can be mitigated significantly by high-pass clutter filters such as used by the Terminal Doppler Weather Radar (TDWR) and Next Generation Weather Radar (NEXRAD) systems....MIT Lincoln Laboratory (MIT/LL) has developed...

This paper describes the development of a dual-rate Sinusoidal Transformer Coder in which a 2400 b/s coder is embedded as a separate packet in the 4800 b/s bit stream. The underlying coding structure provides the flexibility necessary for multirate speech coding and multimedia applications.

The Federal Aviation Administration (FAA) is currently embarking on programs, such as the Terminal Doppler Weather Radar (TDWR) and Integrated Terminal Weather Systems (ITWS), that will significanlty improve the aviation weather information in the terminal area. For example, TDWR data will be available at 47 airports across the United States...

The Airport Surveillance Radar (ASR-9) weather channel is an invaluable tool to air-traffic and flight management specialists. The precipitation data from this sensor is currently displayed on air-traffic specialists' radar scopes and is incorporated into the Integrated Terminal Weather System (ITWS). The data are used to determine optimum routes for...

Spatial power combining of many MMIC amplifiers at millimeter wave frequencies using a fixed array of microstrip antenna elements places unique demands on dielectric media. The substrate must be relatively thick to allow space for MMIC placement, must provide rather high thermal conductivity to disipate MMIC heat, and be of...

Telegraphic messages with numerous instances of omission pose a new challenge to parsing in that a sentence with omission causes a higher degree of ambiguity than a sentence without omission. Misparsing reduced by omissions has a far-reaching consequence in machine translation. Namely, a misparse of the input often leads to...

This paper reviews past work comparing modern speech recognition systems and humans to determine how far recent dramatic advances in technology have progressed towards the goal of human-like performance. Comparisons use six modern speech corpora with vocabularies ranging from 10 to more than 65,000 words and content ranging from read...