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Speech Signal Processing
Published in Richard C. Dorf, Circuits, Signals, and Speech and Image Processing, 2018
Jerry D. Gibson, Bo Wei, Hui Dong, Yariv Ephraim, Israel Cohen, Jesse W. Fussell, Lynn D. Wilcox, Marcia A. Bush
ADPCM operates at 32 kbits/sec or lower, and it achieves performance comparable to log-PCM by using a linear predictor to remove short-term redundancy in the speech signal before quantization. The most common form of ADPCM uses what is called backward adaptation of the predictors and quantizers to follow the waveform closely. Backward adaptation means that the predictor and quantizer are adapted based upon past reproduced values of the signal that are available at the encoder and decoder. No predictor or quantizer parameters are sent along with the quantized waveform values (called forward adaptation). By subtracting a predicted value from each input sample, the dynamic range of the signal to be quantized is reduced, and hence, good reproduction of the signal is possible with fewer bits [1].
Speech Coding for Wireless Communications
Published in Jerry D. Gibson, Mobile Communications Handbook, 2017
ADPCM operates at 32 kbps or lower, and it achieves performance comparable to log-PCM by using an adaptive linear predictor to remove short-term redundancy in the speech signal before quantization. The most common form of ADPCM uses what is called backward adaptation of the predictors and quantizers to follow the waveform closely. Backward adaptation means that the predictor and quantizer are adapted based upon past reproduced values of the signal that are available at the encoder and decoder. No predictor or quantizer parameters are sent along with the quantized waveform values. By subtracting a predicted value from each input sample, the dynamic range of the signal to be quantized is reduced, and hence, good reproduction of the signal is possible with fewer bits.
Voice Transmission
Published in Goff Hill, The Cable and Telecommunications Professionals' Reference, 2012
Stuart D. Walker, Rouzbeh Razavi
By contrast, in forward adaptation, before coding a data frame, the optimal predictor is found and the resulting predictor and quantizer information have to be transmitted with the coded signal as side information; however, compared to the backward scheme the prediction error is less. ADPCM is considered to be the most efficient variation of PCM and is used frequently at 32 kbit/s for landline telephony (G.726 standard). It is also widely employed for voice over IP and voice over Frame Relay as well as to store sound along with text and images on a CD-ROM.
Detection techniques for mitigating the nonlinear distortion of ADPCM link
Published in Australian Journal of Multi-Disciplinary Engineering, 2018
A recommended definition of the 32 kb/s Adaptive Differential Pulse Code Modulation (ADPCM) algorithm was published by International Telephone and Telegraph Consultative Committee (CCITT, the recent name is International Telecommunication Union, ITU) as recommendation G.721 (CCITT Recommendation G.721, 1984). This algorithm has the great advantage of being a proven international standard optimised for the operating environment of the telecommunication networks.