Patent
Multirate digital voice communication processor
George S. Kang,Lawrence J. Fransen,Evans L. Kline +2 more
- 28 Jan 1980
61
TL;DR: In this paper, a multirateigital processor generates a data frame of 216 bits representing sync and voice encoded at both rates, with the 2.4 Kb/s embedded as a subset within the frame.
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Abstract: To provide alternative operation at 2.4 or 9.6 Kb/s bit rates, a multirateigital processor generates a data frame of 216 bits representing sync and voice encoded at both rates, with the 2.4 Kb/s embedded as a subset within the frame. Rate conversion is made by inserting or deleting 162 bits per frame. Speech signal is transformed by linear prediction into coefficients and residual signals. The coefficients are transmitted similarly at both 2.4 and 9.6 Kb/s rates. However, the residual is processed into a simple pitch/hiss excitation signal for 2.4 Kb/s, but is processed into a Fourier transform of its baseband (250-1500 Hz) for 9.6 Kb/s excitation signal transmission.
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Citations
Speech bandwidth extension method and apparatus
TL;DR: In this paper, a speech bandwidth extension method and apparatus analyzes narrowband speech sampled at 8 kHz using LPC analysis to determine its spectral shape and inverse filtering to extract its excitation signal.
346
Reconstruction of wideband speech from narrowband speech using codebooks
Masanobu Abe,Yuki Yoshida +1 more
TL;DR: In this article, a wideband speech signal (8 kHz) of high quantity is reconstructed from a narrowband speech signals (300 Hz to 3.4 kHz) by LPC-analyzing to obtain spectrum information parameters.
219
Patent
Digital audio signal coding using a CELP coder and a transform coder
Gilad Cohen,Yossef Cohen,Doron Hoffman,Hagai Krupnik,Aharon Satt +4 more
- 04 Mar 1998
TL;DR: In this paper, a method for adaptively switching between transform audio coder and CELP coder, which makes use of the superior performance of cELP coders for speech signal coding, while enjoying the benefits of transform coder for other audio signals.
148
Patent
Methods for improving high frequency reconstruction
Kristofer Kjörling,Ekstrand Per,Holger Hoerich +2 more
- 28 Nov 2002
TL;DR: In this article, a detection mechanism on the encoder side is used to assess what parts of the spectrum will not be correctly reproduced by the HFR method in the decoder.
120
References
Patent
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Daniel Esteban,Claude Galand,Daniel Mauduit,Jean Menez +3 more
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TL;DR: In this article, the original frequency components of a telephone band width of the voice signal sampled at 8 KHz and quantized with 12 bits are transformed into three parameters: SIGNAL data representing adaptive quantization for lower frequency (300-800 Hz) sub-bands; COEF data representing pre-emphasized parcor type coefficients for the higher frequency (800-3000 Hz) band; and, ENERGY data representing higher frequency short term energy level.
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James Monroe Clark,Stuart Barry Cohen,Arthur Howard Magnus +2 more
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TL;DR: In this article, an asynchronous digital time division multiplexer and demultiplexer combination at one communication terminal is disclosed that will multiplex first N asynchronous source data signals having a first mixture of different bit rates into a transmitted synchronous data stream having a predetermined fixed data format and a given bit rate greater than the total of the bit rates of the source data.
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Patent
Method and means for improving the spectrum utilization of communications channels
Leonard R. Kahn
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TL;DR: In this paper, a multiplicity of speech signals jointly utilize a common transmission facility and circuitry shifts the amount of bandwidth assigned to each channel as a function of the short term characteristics of the individual speech signal.
24
Patent
Time division switching network for switching multirate multiplexed data
Alain Texier,Edgar L. Lapeyronnie +1 more
- 29 Dec 1975
TL;DR: In this paper, a time division digital switching network comprises first multiplexing means in which first-order digital data channels transmitting words which have a format selected amongst two formats and a first rate selected amongst a plurality of rates different from, but multiple of, one another undergo a first multiple-xing converting them into a second order digital data channel having a second predetermined rate.
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Patent
Bit regeneration for time division multiplexers
Ackerman Philip W,Cohen Peter J +1 more
- 06 Jan 1972
TL;DR: In this paper, the bit center is located by high speed sampling techniques which count to the center of each bit on the basis of predetermined programs which are preset in accordance with the expected bit rate in each channel.
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