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Journal ArticleDOI

Detecting the Presence of Speech Using ADPCM Coding

R. Schafer, +3 more
- 01 May 1976 - 
- Vol. 24, Iss: 5, pp 563-567
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TLDR
A simple algorithm for locating the beginning and end of a speech utterance has been developed that has been tested in computer simulations and has been constructed with standard integrated circuit technology.
Abstract: 
When speech is coded using a differential pulse-code modulation system with an adaptive quantizer, the digital code words exhibit considerable variation among all quantization levels during both voiced and unvoiced speech intervals. However, because of limits on the range of step sizes, during silent intervals the code words vary only slightly among the smallest quantization steps. Based on this principle, a simple algorithm for locating the beginning and end of a speech utterance has been developed. This algorithm has been tested in computer simulations and has been constructed with standard integrated circuit technology.

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Citations
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Journal ArticleDOI

Variable rate coding of speech

J. J. Dubnowski, +1 more
- 01 Mar 1979 - 
TL;DR: It is shown that by careful design the algorithm can be made to be as robust to channel errors as that of a fixed rate adpcm coder.
Journal ArticleDOI

Digital techniques for computer voice response: Implementations and applications

Lawrence R. Rabiner, +1 more
TL;DR: The general method of concatenating isolated words and phrases to form a message is discussed, along with the various possibilities for digital representations of speech signals.
Journal ArticleDOI

An Integrated Voice/Data System for VHF/UHF Mobile Radio

Samy A. Mahmoud, +3 more
- 01 Dec 1983 - 
TL;DR: This work concludes that relative to conventional radio telephoning in which two channels are dedicated to each transmitter/receiver pair, a bandwidth reduction of 30-35 percent can be achieved.
Proceedings ArticleDOI

Variable rate coding

J. J. Dubnowski, +1 more
TL;DR: It is shown that by careful design the algorithm can be made to be as robust to channel errors as that of a fixed rate ADPCM coder.
Patent

Speech-silence detection with subband coding

Marc Bernard Donvito, +1 more
TL;DR: In this paper, a detection statistic T (i To ), used to estimate the short-term speech energy, is developed from energy estimates made in each subband, and a speech presence energy threshold λ ON a speech silence energy threshold (λ OFF and λ OFF) are computed which adapt to the long-term speaker level.
References
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Journal ArticleDOI

Characterization of Randomly Time-Variant Linear Channels

Phillip A. Bello
- 01 Dec 1963 - 
TL;DR: Several new canonical channel models are derived in this paper, some of which are dual to those of Kailath, and a model called the Quasi-WSSUS channel is presented to model the behavior of such channels.
Book

Fading dispersive communication channels

Robert Spayde Kennedy
Journal ArticleDOI

Digital Transmission Performance on Fading Dispersive Diversity Channels

P. Monsen
- 01 Jan 1973 - 
TL;DR: It is shown that on moderately dispersive channels the equalizer nearly achieves optimum one-shot performance, and an adaptive version of this equalizer exists, this means data transmission on slowly fading channels is possible at rates above the natural rate suggested by the channel dispersion spread without bandwidth expansion and with small intersymbol interference penalty.
Journal ArticleDOI

Theoretical limitations on frequency and time diversity for fading binary transmissions

J. Pierce
TL;DR: In this article, it was shown that the minimum required transmitter power for a specified reliability is strictly larger than zero, and both the value of this minimum and the number of diversity branches yielding the minimum depend upon the diversity-combining method used.
Journal ArticleDOI

Signal design for dispersive channels

Robert S. Kennedy, +1 more
- 01 Mar 1964 - 
TL;DR: An introduction to the principles of communications over dispersive channels — in which a heuristic channel model is developed, and simple formulas and curves are investigated for the selection of communications system parameters.