Accession Number : AD0778952

Title :   Entropy Coded Adaptive Differential PCM for Speech.

Descriptive Note : Interim rept.,

Corporate Author : NORTH CAROLINA STATE UNIV RALEIGH DEPT OF ELECTRICAL ENGINEERING

Personal Author(s) : Virupaksha,K. ; O'Neal,J. B. , Jr

Report Date : 04 JAN 1974

Pagination or Media Count : 31

Abstract : The paper is a study of combining two ways of reducing the redundancy in the digital representation of speech signals. Differential PCM encodes the signal into digital form and reduces the redundancy due to correlation in adjacent sample values of the signal. Following this differential PCM operation, entropy coding is used to reduce redundancy due to the unequal probabilities of the differential PCM quantizer levels to be transmitted. Theoretical studies agree with computer simulation results with real speech signals. The concepts of sliding entropy and sliding signal to quantizing noise ratio are developed to measure the way in which the entropy and signal to noise ratio vary with time during a speech utterance. Plots of these quantities vs. time for four different utterances are shown. (Modified author abstract)

Descriptors :   *Speech transmission, *Pulse code modulation, *Coding, *Entropy, Computerized simulation, Statistical analysis, Quantization

Subject Categories : Voice Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE