Speech processing system using adaptive vector quantization
First Claim
1. A speech processing system having an encoder comprising:
- (a) means for receiving successive samples of PCM (pulse code modulated) encoded speech signals,(b) means for applying sequential groups of said PCM encoded speech signals as primary vector signals to an encoder code book memory for selecting code words stored in said memory most closely approximating said vector signals,(c) means for outputting to an output line said selected code words at a first bit rate,(d) means for converting said selected code words to converted vector signals,(e) means for comparing the primary vector signals and converted vector signals and for providing difference signals therefrom,(f) means for quantizing the difference signals and for providing quantized error signals therefrom,(g) means for applying the quantized error signals to the output line at the first or at a second bit rate for enabling the processing system to transmit said speech signals at an effective bit rate constituting either double the first bit rate or the sum of the first and second bit rate, or for inhibiting the quantized error signals from being applied to the line whereby the processing system can transmit said speech signals at an effective rate of the first bit rate thus increasing traffic carrying capacity of the line.
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Abstract
A speech processing system having an encoder comprising apparatus for receiving successive samples of PCM (pulse code modulated) encoded speech signals and apparatus, for applying sequential groups of the PCM encoded speech signals as primary vector signals to an encoder code book memory for selecting code words stored in the memory most closely approximating the vector signals. Apparatus is included for outputting to an output line the selected code words at a first bit rate. Further apparatus connects the selected code words to converted vector signals. The primary vector signals and converted vector signals are compared and difference signals result. The difference signals are quantized error signals are provided thereby. The quantized error signals are applied to the output line at the first or at a second bit rate to enable the processing system to transmit the speech signals at an effective bit rate constituting double the first bit rate or the sum of the first and second bit rate, or the quantized error signals is inhibited from being applied to the line. The processing system can thereby transmit the speech signals at an effective rate of the first bit rate thus incressing the traffic carrying capacity of the line.
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Citations
19 Claims
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1. A speech processing system having an encoder comprising:
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(a) means for receiving successive samples of PCM (pulse code modulated) encoded speech signals, (b) means for applying sequential groups of said PCM encoded speech signals as primary vector signals to an encoder code book memory for selecting code words stored in said memory most closely approximating said vector signals, (c) means for outputting to an output line said selected code words at a first bit rate, (d) means for converting said selected code words to converted vector signals, (e) means for comparing the primary vector signals and converted vector signals and for providing difference signals therefrom, (f) means for quantizing the difference signals and for providing quantized error signals therefrom, (g) means for applying the quantized error signals to the output line at the first or at a second bit rate for enabling the processing system to transmit said speech signals at an effective bit rate constituting either double the first bit rate or the sum of the first and second bit rate, or for inhibiting the quantized error signals from being applied to the line whereby the processing system can transmit said speech signals at an effective rate of the first bit rate thus increasing traffic carrying capacity of the line. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A speech processing system for receiving successive samples of PCM (pulse code modulated) input signals and corresponding scalar quantized error signals comprising:
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(a) a plurality of speech encoders for vector quantization of said PCM input signals, each providing output signals comprising a code book entry signal corresponding to a group of samples of said PCM input signals and corresponding scalar quantized error signals, (b) a multiplexer for multiplexing all of the code book entry signals and error signals for transmission to a decoder, (c) means for sensing demands for transmission of additional digital signals, and p1 (d) means for progressively eliminating the error signals from being multiplexed in the multiplexer and for substituting said additional signals in place thereof as said demands increase, whereby the capacity of the processing system to transmit code book entry signals and said additional signals is progressingly increased while decreasing the resolution of multiplexed transmission of the PCM input signals.
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16. A speech processor as defined in claim 16, in which each of the speech encoders is comprised of:
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(a) means for receiving successive samples of PCM (pulse code modulated) encoded speech signals, (b) means for applying sequential groups of said PCM encoded speech signals as primary vector signals to an encoder code book memory for selecting code words stored in said memory most closely approximating said vector signals, (c) means for outputting to an output line said selected code words at a first bit rate, (d) means for converting said selected code words to converted vector signals, (e) means for comparing the primary vector signals and converted vector signals and for providing difference signals therefrom, (f) means for quantizing the difference signals and for providing quantized error signals therefrom, (g) means for applying the quantized error signals to the output line at the first or at a second bit rate for enabling the processing system to transmit said speech signals at an effective bit rate constituting either double the first bit rate or the sum of the first and second bit rate, or for inhibiting the quantized error signals from being applied to the line whereby the processing system can transmit said speech signals at an effective rate of the first bit rate thus increasing traffic carrying capacity of the line. - View Dependent Claims (18)
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- 19. A speech processor system comprising means for digitally encoding a plurality of input signals into a corresponding plurality of first low resolution (low bit rate) signals for transmission in a first group of channels, and for encoding a corresponding group of error signals for transmission in a second group of channels for subsequent receipt by a decoder whereby the error signals can be combined with corresponding low resolution signals into high resolution (high equivalent bit rate) output signals, means for substituting additional low resolution encoded input signals in one or more of said second group of channels in place of said error signals for subsequent decoding of the additional low resolution signals into additional output signals, and substituting of the original low resolution signals corresponding to the error signals into low resolution output signals.
Specification