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Low rate coding of the spectral envelope using channel gains

May 7, 1996
  |
Conference Paper
Author:
Elliot Singer
…
Published in:
Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, ICASSP, Vol. 2, 7-10 May 1996, pp. 769-772.
Topic:
speech processing
R&D area:
R&D group:

Summary

A dual rate embedded sinusoidal transform coder is described in which a core 14th order allpole coder operating at 2400 b/s is augmented with a set of channel gain residuals in order to operate at the higher 4800 b/s rate. The channel gains are a set of non-uniformly spaced samples of the spline envelope and constitute a lowpass estimate of the short-time vocal tract magnitude spectrum. The channel gain residuals represent the difference between the spline envelope and the quantized 14th order allpole spectrum at the channel gain frequencies. The channel gain residuals are coded using pitch dependent scalar quantization. Informal listening indicates that the quality of the embedded coder at 4800 b/s is comparable to that of an existing high quality 4800 b/s allpole coder.
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Summary

A dual rate embedded sinusoidal transform coder is described in which a core 14th order allpole coder operating at 2400 b/s is augmented with a set of channel gain residuals in order to operate at the higher 4800 b/s rate. The channel gains are a set of non-uniformly spaced samples...

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Low rate coding of the spectral envelope using channel gains

The effects of handset variability on speaker recognition performance: experiments on the switchboard corpus

May 7, 1996
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Conference Paper
Author:
Douglas A. Reynolds
Published in:
Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, ICASSP, Vol. 1, 7-10 May 1996, pp. 113-116.
Topic:
speaker recognition
R&D area:
R&D group:

Summary

This paper presents an empirical study of the effects of handset variability on text-independent speaker recognition performance using the Switchboard corpus. Handset variability occurs when training speech is collected using one type of handset, but a different handset is used for collecting test speech. For the Switchboard corpus, the calling telephone number associated with a file is used to imply the handset used. Analysis of experiments designed to focus on handset variability on the SPIDRE database and the May95 NIST speaker recognition evaluation database, show that a performance gap between matched and mismatched handset tests persists even after applying several standard channel compensation techniques. Error rates for the mismatched tests are over 4 times those for the matched tests. Lastly, a new energy dependent cepstral mean subtraction technique is proposed to compensate for nonlinear distortions, but is not found to improve performance on the databases used.
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Summary

This paper presents an empirical study of the effects of handset variability on text-independent speaker recognition performance using the Switchboard corpus. Handset variability occurs when training speech is collected using one type of handset, but a different handset is used for collecting test speech. For the Switchboard corpus, the calling...

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The effects of handset variability on speaker recognition performance: experiments on the switchboard corpus

Unsupervised topic clustering of switchboard speech messages

May 7, 1996
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Conference Paper
Author:
Beth Carlson Kittel
Published in:
Proc. IEEE Int. Conf. on Acoustics, Speech and Signal Processing, ICASSP, Vol. 1, 7-10 May 1996, pp. 315-318.
Topic:
speaker recognition
R&D area:
R&D group:

Summary

This paper presents a statistical technique which can be used to automatically group speech data records based on the similarity of their content. A tree-based clustering algorithm is used to generate a hierarchical structure for the corpus. This structure can then be used to guide the search for similar material in data from other corpora. The SWITCHBOARD Speech Corpus was used to demonstrate these techniques, since it provides sets of speech files which are nominally on the same topic. Excellent automatic clustering was achieved on the truth text transcripts provided with the SWITCHBOARD corpus, with an average cluster purity of 97.3%. Degraded clustering was achieved using the output transcriptions of a speech recognizer, with a clustering purity of 61.4%.
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Summary

This paper presents a statistical technique which can be used to automatically group speech data records based on the similarity of their content. A tree-based clustering algorithm is used to generate a hierarchical structure for the corpus. This structure can then be used to guide the search for similar material...

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Unsupervised topic clustering of switchboard speech messages

ASR-9 Weather System Processor (WSP): wind shear algorithms performance assessment

May 7, 1996
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Project Report
Author:
Mark E. Weber
…
Published in:
MIT Lincoln Laboratory Report ATC-247
Topic:
wind shear
R&D area:
R&D group:

Summary

Lincoln Laboratory has developed a prototype Airport Surveillance Radar Weather Systems Processor (ASR-WSP) that has been used for field measurements and operational demonstrations since 1987. Measurements acquired with this prototype provide an extensive data base for development and validation of the algorithms the WSP uses to generate operational wind shear information for Air Traffic Controllers. This report addresses the performance of the current versions of the WSP's microburst and gust front wind shear detection algorithms on available data from each of the WSP's operational sites. Evaluation of the associated environmental characteristics (e.g., storm structure, radar ground clutter environment) allows for generalization of results of the other major U.S. climatic regimes where the production version of WSP will be deployed.
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Summary

Lincoln Laboratory has developed a prototype Airport Surveillance Radar Weather Systems Processor (ASR-WSP) that has been used for field measurements and operational demonstrations since 1987. Measurements acquired with this prototype provide an extensive data base for development and validation of the algorithms the WSP uses to generate operational wind shear...

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ASR-9 Weather System Processor (WSP): wind shear algorithms performance assessment

Beacon radar and TCAS interrogation rates: airborne measurements in the 1030 MHz band

May 2, 1996
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Project Report
Author:
William H. Harman III
…
Published in:
MIT Lincoln Laboratory Report ATC-239
Topic:
surveillance
R&D area:
R&D group:

Summary

Airborne measurements were made of the rates of beacon-radar interrogations and suppressions in the 1030 MHz band. These measurements were undertaken in order to provide a basis for interference analysis of the proposed system of GPS-Squitter. The measurements were made during a flight along the East Coast, including New York, Philadelphia, Baltimore, and Washington. Measurements were also made at Atlanta and in the Dallas Fort Worth area. Results were given in a form that shows the rates of interrogations and suppressions as a function of time and location of the aircraft. Interrogations are also separated into those that were transmitted by ground-based interrogators and those that were transmitted by airborne TCAS equipment. Mode S interrogations were also separated from other modes. The number of TCAS aircraft in the vicinity was also measured during the flights. The results indicate that the rates of interrogations and suppressions were consistent in most respects from location to location. The rates Mode A and C interrogations from the ground were consistently less than 100 per second with two brief exceptions. Previous measurements had indicated a trend of decreasing interrogation rates with time since the early 1970's. The new measurements support this observation and indicate that the trend has continued.
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Summary

Airborne measurements were made of the rates of beacon-radar interrogations and suppressions in the 1030 MHz band. These measurements were undertaken in order to provide a basis for interference analysis of the proposed system of GPS-Squitter. The measurements were made during a flight along the East Coast, including New York...

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Beacon radar and TCAS interrogation rates: airborne measurements in the 1030 MHz band

ASR-9 processor augmentation card scan-scan correlator algorithms

April 2, 1996
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Project Report
Author:
Jenifer B. Evans
Published in:
MIT Lincoln Laboratory Report ATC-245
Topic:
algorithms
R&D area:
R&D group:

Summary

This report documents the Scan-Scan correlator algorithms for the ASR-9 Processor Augmentation Card (9-PAC) project. The 9-PAC is a processor card that serves as a processing enhancement to the existing ASR-9's post-processor system. It provides increased speed and memory capabilities to the processor, which allows for the introduction of more complex scan-scan correlator algorithms. These more complex algorithms improve the ASR-9's system performance through decreased false alarms, and increased detection of aircraft. The 9-PAC Scan-Scan correlator, also known as the Tracker, consists of three basic processing tasks: initialization, input/output, and the actual Tracker. The Tracker can be broken down further into four main processing functions: report-to track association, report-to-track correlation, track update, and track initiation.
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Summary

This report documents the Scan-Scan correlator algorithms for the ASR-9 Processor Augmentation Card (9-PAC) project. The 9-PAC is a processor card that serves as a processing enhancement to the existing ASR-9's post-processor system. It provides increased speed and memory capabilities to the processor, which allows for the introduction of more...

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ASR-9 processor augmentation card scan-scan correlator algorithms

Anomalous propagation ground clutter suppression with the Airport Surveillance Radar (ASR) Weather Systems Processor (WSP)

March 15, 1996
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Project Report
Author:
Joseph A. Cullen
Published in:
MIT Lincoln Laboratory Report ATC-244
Topic:
radar
R&D area:
R&D group:

Summary

Ground-clutter breakthrough caused by anomalous propagation (AP)--ducting of the radar beam when passing through significant atmospheric temperature and/or moisture gradients--is a significant issue for air traffic controllers who use Airport Surveillance Radar (ASR) weather channel data to guide aircraft through the airport terminal area. At present, these data are often contaminated with AP, leaving the controller unsure about the validity of information on storm location and intensity. The Weather System Processor (WSP), which is scheduled for deployment at 33 airports in the U.S., includes an AP-Editing algorithm designed to remove AP based on its Doppler-spectrum characteristics in ASR-9 data. This report provides a description of the algorithm currently used in the FAA/Lincoln Laboratory WSP prototype and a measurement of the performance of the algorithm during nine episodes of AP and/or true weather in Orlando, florida in 1991 and 1992.
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Summary

Ground-clutter breakthrough caused by anomalous propagation (AP)--ducting of the radar beam when passing through significant atmospheric temperature and/or moisture gradients--is a significant issue for air traffic controllers who use Airport Surveillance Radar (ASR) weather channel data to guide aircraft through the airport terminal area. At present, these data are often...

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Anomalous propagation ground clutter suppression with the Airport Surveillance Radar (ASR) Weather Systems Processor (WSP)

Lincoln Laboratory Evaluation of TCAS II logic version 6.04a, volume I

February 21, 1996
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Project Report
Author:
Ann C. Drumm
Published in:
MIT Lincoln Laboratory Report ATC-240,I
Topic:
collision avoidance
R&D area:
R&D group:

Summary

This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 6.04a. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in U.S. airspace. Version 6.04a is a logic version mandated by the FAA by 30 December 1994 in order to correct a potential safety problem in earlier versions and to make the TCAS logic more compatible with the air traffic control system. Lincoln Laboratory evaluated the logic by examining approximately two million simulated pairwise TCAS-TCAS encounters, derived from actual aircraft tracks recorded in U.S. airspace. The main goals of the evaluation effort were: (1) to determine if version 6.04a successfully corrected the potential safety problem without introducing new problems; (2) to detect and explain any areas of poor performance; and (3) to understand the performance limits of the logic. Five analysis programs were written to aid in the evaluation, and these programs are described in the report. There were three phases of the evaluation corresponding to the above three goals. For each phase, the report gives an overview of the evaluation approach taken, a description of the results, and a summary. A description of follow-on activities plus overall conclusions and recommendations are given at the end of the report.
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Summary

This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 6.04a. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in...

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Lincoln Laboratory Evaluation of TCAS II logic version 6.04a, volume I

Lincoln Laboratory Evaluation of TCAS II logic version 6.04a, appendices, volume II

February 15, 1996
  |
Project Report
Author:
Ann C. Drumm
Published in:
MIT Lincoln Laboratory Report ATC-240,II
Topic:
collision avoidance
R&D area:
R&D group:

Summary

This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 6.04a. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in U.S. airspace. Version 6.04a is a logic version mandated by the FAA by 30 December 1994 in order to correct a potential safety problem in earlier versions and to make the TCAS logic more compatible with the air traffic control system. Lincoln Laboratory evaluated the logic by examining approximately two million simulated pairwise TCAS-TCAS encounters, derived from actual aircraft tracks recorded in U.S. airspace. The main goals of the evaluation effort were: (1) to determine if version 6.04a successfully corrected the potential safety problem without introducing new problems; (2) to detect and explain any areas of poor performance; and (3) to understand the performance limits of the logic. Five analysis programs were written to aid in the evaluation, and these programs are described in the report. There were three phases of the evaluation corresponding to the above three goals. For each phase, the report gives an overview of the evaluation approach taken, a description of the results, and a summary. A description of follow-on activities plus overall conclusions and recommendations are given at the end of the report.
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Summary

This report documents the Lincoln Laboratory evaluation of the Traffic Alert and Collision Avoidance System II (TCAS II) logic version 6.04a. TCAS II is an airborne collision avoidance system required since 30 December 1993 by the FAA on all air carrier aircraft with more than 30 passenger seats operating in...

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Lincoln Laboratory Evaluation of TCAS II logic version 6.04a, appendices, volume II

Recognition by humans and machines: miles to go before we sleep

February 7, 1996
  |
Journal Article
Author:
Richard P. Lippmann
Published in:
Speech Commun., Vol. 18, No. 3, 1996, pp. 247-8.
Topic:
speech recognition
R&D area:
R&D group:

Summary

Bourlard and his colleagues note that much effort over the past few years has focused on creating large-vocabulary speech recognition systems and reducing error rates measured using clean speech materials. This has led to experimental talker-independent systems with vocabularies of 65,000 words capable of transcribing sentences on a limited set of topics. Instead of comparing these systems to each other, or to last year's performance, this short comment compares them to human listeners, who are the ultimate users and judges of speech recognizers.
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Summary

Bourlard and his colleagues note that much effort over the past few years has focused on creating large-vocabulary speech recognition systems and reducing error rates measured using clean speech materials. This has led to experimental talker-independent systems with vocabularies of 65,000 words capable of transcribing sentences on a limited set...

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Recognition by humans and machines: miles to go before we sleep
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