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Sheep, goats, lambs and wolves: a statistical analysis of speaker performance in the NIST 1998 speaker recognition evaluation

November 1, 1998
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Conference Paper
Author:
George R. Doddington
…
Published in:
NIST 1998 Speaker Recognition Evaluation, November 1998.
Topic:
speaker recognition
R&D area:
R&D group:

Summary

Performance variability in speech and speaker recognition systems can be attributed to many factors. One major factor, which is often acknowledged but seldom analyzed, is inherent differences in the recognizability of different speakers. In speaker recognition systems such differences are characterized by the use of animal names for different types of speakers, including sheep, goats, lambs and wolves, depending on their behavior with respect to automatic recognition systems. In this paper we propose statistical tests for the existence of these animals and apply these tests to hunt for such animals using results from the 1998 NIST speaker recognition evaluation.
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Summary

Performance variability in speech and speaker recognition systems can be attributed to many factors. One major factor, which is often acknowledged but seldom analyzed, is inherent differences in the recognizability of different speakers. In speaker recognition systems such differences are characterized by the use of animal names for different types...

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Sheep, goats, lambs and wolves: a statistical analysis of speaker performance in the NIST 1998 speaker recognition evaluation

A dual-band circularly polarized aperture-coupled stacked microstrip antenna for global positioning satellite

November 1, 1998
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Journal Article
Author:
D. M. Pozar
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Published in:
IEEE Trans. Antennas Propag., Vol. 45, No. 11, November 1997, pp. 1618-25.
Topic:
antennas
R&D area:
R&D group:

Summary

This paper describes the design and testing of an aperture-coupled circularly polarized antenna for global positioning satellite (GPS) applications. The antenna operates at both the L1 and L2 frequencies of 1575 and 1227 MHz, which is required for differential GPS systems in order to provide maximum positioning accuracy. Electrical performance, low-profile, and cost were equally important requirements for this antenna. The design procedure is discussed, and measured results are presented. Results from a manufacturing sensitivity analysis are also included.
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Summary

This paper describes the design and testing of an aperture-coupled circularly polarized antenna for global positioning satellite (GPS) applications. The antenna operates at both the L1 and L2 frequencies of 1575 and 1227 MHz, which is required for differential GPS systems in order to provide maximum positioning accuracy. Electrical performance...

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A dual-band circularly polarized aperture-coupled stacked microstrip antenna for global positioning satellite

Techniques for improved reception of 1090 MHz ADS-B signals

October 31, 1998
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Conference Paper
Author:
William H. Harman III
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Published in:
17th DASC: Proc. of the 17th. Digital Avionics Systems Conf., 31 October - 7 November 1998, Vol. 2, pp. G25-1 - G25-9.
Topic:
surveillance
R&D area:
R&D group:

Summary

The recent development of ADS-B (Automatic Dependent Surveillance-Broadcast) is based on the use of the Mode S transponders now carried by all air carrier and commuter aircraft. ADS-B aircraft broadcast aircraft positions, identity, and other information via semi-random Mode S transponder squitters. Other aircraft or ground facilities receive the squitters and the associated position and status. Squitter reception includes the detection of the Mode S 1090 MHz waveform preamble, declaration of the bit and confidence values, error detection, and (if necessary) error correction. The current techniques for squitter reception are based upon methods developed for use in Mode S narrow-beam interrogators and for ACAS. In both of these applications, the rate of Mode NC fruit that is stronger than the Mode S waveform is relatively low, nominally less than 4,000 fruit per second. Extended squitter applications now include long range (up to 100 nmi) air-air surveillance in support of free flight. This type of surveillance is sometimes referred to as Cockpit Display of Traffic Information (CDTI). In high density environments, it is possible to operate with fruit rates of 40,000 fruit per second and higher. Operation of extended squitter in very high ModeNC fruit environments has led to the need to re-evaluate squitter reception techniques to determine if improved performance is achievable. The purpose of this paper is to provide a summary of work in progress to investigate improved squitter reception techniques. Elements of improved squitter reception being investigated include (1) the use of amplitude to improve bit and confidence declaration accuracy, (2) more capable error correction algorithms, and (3) more selective preamble detection approaches.
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Summary

The recent development of ADS-B (Automatic Dependent Surveillance-Broadcast) is based on the use of the Mode S transponders now carried by all air carrier and commuter aircraft. ADS-B aircraft broadcast aircraft positions, identity, and other information via semi-random Mode S transponder squitters. Other aircraft or ground facilities receive the squitters...

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Techniques for improved reception of 1090 MHz ADS-B signals

Vulnerabilities of reliable multicast protocols

October 21, 1998
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Conference Paper
Author:
Thomas M. Parks
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Published in:
IEEE MILCOM '98, Vol. 3, 21 October 1998, pp. 934-938.
Topic:
cryptography
R&D area:
R&D group:

Summary

We examine vulnerabilities of several reliable multicast protocols. The various mechanisms employed by these protocols to provide reliability can present vulnerabilities. We show how some of these vulnerabilities can be exploited in denial-of-service attacks, and discuss potential mechanisms for withstanding such attacks.
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Summary

We examine vulnerabilities of several reliable multicast protocols. The various mechanisms employed by these protocols to provide reliability can present vulnerabilities. We show how some of these vulnerabilities can be exploited in denial-of-service attacks, and discuss potential mechanisms for withstanding such attacks.

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Vulnerabilities of reliable multicast protocols

AM-FM separation using shunting neural networks

October 6, 1998
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Conference Paper
Author:
Robert A. Baxter
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Published in:
Proc. of the IEEE-SP Int. Symp. on Time-Frequency and Time-Scale Analysis, 6-9 October 1998, pp. 553-556.
Topic:
signal processing
R&D area:
R&D group:

Summary

We describe an approach to estimating the amplitude-modulated (AM) and frequency-modulated (FM) components of a signal. Any signal can be written as the product of an AM component and an FM component. There have been several approaches to solving the AM-FM estimation problem described in the literature. Popular methods include the use of time-frequency analysis, the Hilbert transform, and the Teager energy operator. We focus on an approach based on FM-to-AM transduction that is motivated by auditory physiology. We show that the transduction approach can be realized as a bank of bandpass filters followed by envelope detectors and shunting neural networks, and the resulting dynamical system is capable of robust AM-FM estimation in noisy environments and over a broad range of filter bandwidths and locations. Our model is consistent with recent psychophysical experiments that indicate AM and FM components of acoustic signals may be transformed into a common neural code in the brain stem via FM-to-AM transduction. Applications of our model include signal recognition and multi-component decomposition.
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Summary

We describe an approach to estimating the amplitude-modulated (AM) and frequency-modulated (FM) components of a signal. Any signal can be written as the product of an AM component and an FM component. There have been several approaches to solving the AM-FM estimation problem described in the literature. Popular methods include...

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AM-FM separation using shunting neural networks

1.5-um Tapered-Gain-Region Lasers with High-CW Output Powers

October 1, 1998
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Journal Article
Author:
Joseph P. Donnelly
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Published in:
IEEE Photonics Technol. Lett., Vol. 10, No. 10, October 1998, pp. 1377-1379.
Topic:
optics
R&D area:
R&D group:

Summary

High-power diode lasers consisting of a ridge-waveguide section coupled to a tapered region have been fabricated in 1.5um InGaAsP-InP multiple-quantum-well material. Self-focusing at high current densities and high-intensity input into the taper section has been identified as a fundamental problem in these devices that has to be dealt with. To date, continuous-wave output powers>1 W with=80% of the power in the near-diffraction-limited central lobe of the far field have been obtained through a judicious choice of device parameters.
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Summary

High-power diode lasers consisting of a ridge-waveguide section coupled to a tapered region have been fabricated in 1.5um InGaAsP-InP multiple-quantum-well material. Self-focusing at high current densities and high-intensity input into the taper section has been identified as a fundamental problem in these devices that has to be dealt with. To...

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1.5-um Tapered-Gain-Region Lasers with High-CW Output Powers

Comparisons between total lightning data, mesocyclone strength, and storm damage associated with the Florida tornado outbreak of February 23 1998

September 14, 1998
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Conference Paper
Author:
Stephen Hodanish
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Published in:
19th Conf. on Severe Local Storms, 14-18 September 1998, pp. 681-684.
Topic:
weather
R&D area:
R&D group:

Summary

During the late evening and early morning hours of February 22/23 1998, the worst tornado outbreak in recorded history occurred over the peninsula of central Florida. Analysis of KMLB Doppler radar data indicated at least 9 supercells developed over the region, with 4 of the supercells producing tornadoes. These 4 tornadic supercells produced a total of 7 tornadoes, some of them on the ground for tens of miles (Fig. 1.). A total of 42 fatalities were reported with over 260 injured. Monetary losses totaled over 100 million dollars. During this severe weather outbreak, National Weather Service Melbourne, in collaboration with the National Aeronautics and Space Administration and the Massachusetts Institute of Technology, was collecting data from a unique lightning observing system called Lightning Imaging Sensor Data Applications Display (LISDAD). This system has the capability to combine radar reflectivity data collected from the KMLB WSR-88D, cloud to ground data collected from the National Lightning Detection Network, and total lightning data collected from NASA's Lightning Detection And Ranging (LDAR) system. The object of this study is to compare total lightning data collected from the LISDAD system to mesocyclone strength as observed from the KMLB WSR-88D. These data will then be compared to the times of tornadic winds.
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Summary

During the late evening and early morning hours of February 22/23 1998, the worst tornado outbreak in recorded history occurred over the peninsula of central Florida. Analysis of KMLB Doppler radar data indicated at least 9 supercells developed over the region, with 4 of the supercells producing tornadoes. These 4...

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Comparisons between total lightning data, mesocyclone strength, and storm damage associated with the Florida tornado outbreak of February 23 1998

Observations of total lightning associated with severe convection during the wet season in Central Florida

September 14, 1998
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Conference Paper
Author:
Stephen Hodanish
…
Published in:
19th Conf. on Severe Local Storms, 14-18 September 1998, 635-638.
Topic:
weather
R&D area:
R&D group:

Summary

This paper will discuss findings of a collaborative lightning research project between the Massachusetts Institute of Technology, the National Weather Service (NWS) office in Melbourne (MLB), Florida and the National Aeronautics and Space Administration. In August 1996, NWS MLB received a workstation which incorporates data from the KMLB WSR-88D, Cloud to Ground (CG) stroke data from the National Lightning Detection Network (NLDN), and 3D volumetric lightning data collected from the Kennedy Space Centers' Lightning Detection And Ranging (LDAR) system. The two primary objectives of this lightning workstation, called Lightning Imaging Sensor Data Applications Display (L1SDAD), are to: a.) Observe how total lightning relates to severe convective storm morphology over central Florida, and, b.) Compare ground based total lightning data (LDAR) to a satellite based lightning detection system. This presentation will focus on objective #1.
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Summary

This paper will discuss findings of a collaborative lightning research project between the Massachusetts Institute of Technology, the National Weather Service (NWS) office in Melbourne (MLB), Florida and the National Aeronautics and Space Administration. In August 1996, NWS MLB received a workstation which incorporates data from the KMLB WSR-88D, Cloud...

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Observations of total lightning associated with severe convection during the wet season in Central Florida

The design and evaluation of the Lightning Imaging Sensor Data Applications Display (LISDAD)

September 14, 1998
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Conference Paper
Author:
Robert A. Boldi
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Published in:
19th Conf. on Severe Local Storms, 14-18 September 1998, pp. 631-634.
Topic:
weather
R&D area:
R&D group:

Summary

The ultimate goal of the LISDAD system is to quantify the utility of total lightning infomation in short-term, severe-weather-forecasting operations. Secondary goals were to collect times series of various storm-cell parameters that relate to storm development and electrification and subsequently make these data available for post-facto analysis. To these ends scientists from NASA, NWS, and MIT/LL organized an effort to study the relationship of lightning and severe-weather on a storm-by-storm, and even cell-by-cell basis for as many storms as possible near Melbourne, Florida. Melbourne was chosen as it offers a unique combination of high probability of severe weather and proximity to major relevant sensors, specifically: NASA's total lightning mapping system at Kennedy Space Center (the LDAR system) at KSC [Lennon and Maier, 1991], a NWS / NEXRAD radar at Melbourne, and a prototype Integrated Terminal Weather System (ITWS), at Orlando. The ITWS system obtains cloud-to-ground lightning information from the National Lightning Detection Network (NLDN) via a link to Lexington, MA, and also uses NSSL's Severe Storms Analysis Package (NSSL / SSAP) to obtain information about various storm-cell parameters
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Summary

The ultimate goal of the LISDAD system is to quantify the utility of total lightning infomation in short-term, severe-weather-forecasting operations. Secondary goals were to collect times series of various storm-cell parameters that relate to storm development and electrification and subsequently make these data available for post-facto analysis. To these ends...

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The design and evaluation of the Lightning Imaging Sensor Data Applications Display (LISDAD)

Total lightning as a severe weather diagnostic in strongly baroclinic systems in Central Florida

September 14, 1998
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Conference Paper
Author:
Earle R. Williams
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Published in:
19th Conf. on Severe Local Storms, 14-18 September 1998, pp. 643-647.
Topic:
weather
R&D area:
R&D group:

Summary

Severe weather is defined by specific thresholds in wind. hail size and vorticity. All of these phenomena have close physical connections with vertical drafts in deep convection, which are themselves not directly measured with scanning Doppler radars of the NEXRAD type. Cloud electrification and lightning are particularly sensitive to these drafts because they modulate the supply of supercooled water which is the growth agent for the ice particles (ice crystals, graupel and hail) believed essential for electrical charge separation. For these reasons, one can expect correlations at the outset between total lightning activity and the development of severe weather which may aid in the understanding and prediction of these extreme weather conditions. The exploration of these ideas has historically been impeded by lack of good quantitative observations. A recent review of results on severe storm electrification (Williams, 1998) indicates a general absence of cases for which total lightning activity is documented over the lifetime of a severe storm. The recent development of LISDAD (Lightning Imaging Sensor Data Application Display) (Boldi, et aI., 1998) has largely remedied this problem. This paper is concerned with the use of LISDAD to quantify the behavior of total lightning in all types of severe weather, with a focus on a pair of extraordinarily electrified supercells in the Florida dry season.
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Summary

Severe weather is defined by specific thresholds in wind. hail size and vorticity. All of these phenomena have close physical connections with vertical drafts in deep convection, which are themselves not directly measured with scanning Doppler radars of the NEXRAD type. Cloud electrification and lightning are particularly sensitive to these...

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Total lightning as a severe weather diagnostic in strongly baroclinic systems in Central Florida
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