Accession Number : ADD017772

Title :   Voice Communication Processing System.

Descriptive Note : Patent, Filed 12 Feb 92, patented 5 Sep 95

Corporate Author : DEPARTMENT OF THE NAVY WASHINGTON DC

Personal Author(s) : Kang, George S ; Fransen, Lawrence J

Report Date : 05 Sep 1995

Pagination or Media Count : 25

Abstract : A voice communication processing system and method for processing a speech waveform as a digital bit stream having a reduced number of bits representing speech parameters. The bit representation of amplitude parameters is reduced by storing only probable amplitude parameter transitions corresponding to amplitude parameter indices in an amplitude table and by joint encoding the amplitude parameter indices over multiple frames. The bit representation of the pitch period is reduced by storing a range of pitch periods in a pitch table and by joint encoding pitch period indices corresponding to an average pitch period over two frames. The bit representation of the vocal tract filter coefficients is reduced by storing only probable filter coefficient transitions corresponding to filter coefficient indices in a filter coefficient table and by joint encoding the filter coefficient indices over two frames. Voicing decisions are inferred by an associated vocal tract filter coefficient index obtained by searching the filter coefficient table where the table is divided according to the voicing decisions, and thus separate voicing decisions do not have to be transmitted. By providing a reduced bit representation of the various speech parameters as explained above, the present invention processes the speech waveform at a more efficient data rate. In addition, the present invention converts prediction coefficients (PCs) into line spectra pairs (LSPs) to be used as filter parameters when performing a linear predictive coder (LPC) analysis. Thus, by using LSPs, the present invention is able to more efficiently encode and decode speech.

Descriptors :   *DATA RATE, *DIGITAL COMMUNICATIONS, *VOICE COMMUNICATIONS, *PATENTS, SIGNAL PROCESSING, PARAMETERS, PROBABILITY, WAVEFORMS, EFFICIENCY, REDUCTION, CODING, COEFFICIENTS, MILITARY APPLICATIONS, TABLES(DATA), INDEXES, FRAMES, SPEECH, FILTERS, AMPLITUDE, SECURE COMMUNICATIONS, INVENTIONS, LINE SPECTRA

Subject Categories : Voice Communications

Distribution Statement : APPROVED FOR PUBLIC RELEASE