Publications
Clutter suppression for low altitude wind shear detection by doppler weather radars
Summary
Summary
Low altitude wind shear (LAWS) has been recognized as a major cause of commercial airline aircraft accidents in the United States. The FAA is actively conducting the Terminal Doppler Weather Radar (TDWR) program to detect and identify dangerous wind fields at and around airports using Doppler radar techniques. Clutter poses...
Microburst recognition: an expert system approach
Summary
Summary
Expert systems have gained much recent attention as a means for capturing the performance of human experts in specialized fields of knowledge. Areas in which expert systems have been successfully developed include such varied applications as mass spectrogram interpretation, disease diagnosis, geological data analysis and computer configuration (Hayes-Roth et al...
Mode S beacon system: functional description (revision D)
Summary
Summary
This document provides a functional description of the Mode S Beacon System, a combined secondary surveillance radar (beacon) and ground-air-ground data link system capable of providing the aircraft surveillance and communications necessary to support ATC automation in future traffic environments. Mode S is capable of common-channel interoperation with the current...
A coordinate conversion algorithm for multisensor data processing
Summary
Summary
Processing of aircraft surveillance data from several geographically separated radars is most easily accomplished using a common coordinate system to represent data from all sensors. The Multisensor Data Processing system currently being developed for the FAA in support of the Advanced Automation System (AAS) requires a degree of accuracy and...
Speech analysis/synthesis based on a sinusoidal representation
Summary
Summary
A sinusoidal model for the speech waveform is used to develop a new analysis/synthesis technique that is characterized by the amplitudes, frequencies, and phases of the component sine waves. These parameters are estimated from the short-time Fourier transform using a simple peak-picking algorithm. Rapid changes in the highly resolved spectral...
Assessment of ASR-9 weather channel performance: analysis and simulation
Summary
Summary
In this report, we use pencil-beam Doppler weather radar data, combined with on-airport ground clutter measurements, to analyze the performance of the six-level weather channel in the next generation airport surveillance radar, the ASR-9. A key tool was a computer procedure that used these data to simulate the output of...
TCAS Experimental Unit (TEU) hardware description
Summary
Summary
This report describes the hardware design of the TCAS Experimental Units (TEU's) constructed by Lincoln Laboratory to support the design and validation of the Traffic Alert and Collision Avoidance System (TCAS) for the FAA. Section 1.0 presents an overview of the operation of hte TEU's, in order to give some...
Pilot evaluation of TCAS in the Long Ranger helicopter
Summary
Summary
A specially modified version of the Traffic Alert and Collision Avoidance System (TCAS) was installed in a Bell Long Ranger helicopter in order to investigate the feasibility of TCAS operation in rotorcraft. This installation employed TCAS air-to-air surveillance to provide automated traffic advisories that were displayed in the cockpit on...
Robust HMM-based techniques for recognition of speech produced under stress and in noise
Summary
Summary
Substantial improvements in speech recognition performance on speech produced under stress and in noise have been achieved through the development of techniques for enhancing the robustness of a base-line isolated-word Hidden Markov Model recognizer. The baseline HMM is a continuous-observation system using mel-frequency cepstra as the observation parameters. Enhancement techniques...
The Cooperative Huntsville Meteorological Experiment (COHMEX)
Summary
Summary
A unique meteorological field experiment (COHMEX) is scheduled to be conducted from March-July 1986 with a core period of operation in June and July. It is taking place in the region covering northern Alabama and the adjoining portion of central Tennessee. The experiment's uniqueness derives from the fact that it...