The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 07, 1998
Filed:
Jan. 23, 1997
Paul E Jacobs, San Diego, CA (US);
William R Gardner, San Diego, CA (US);
Chong U Lee, San Diego, CA (US);
Klein S Gilhousen, San Diego, CA (US);
S Katherine Lam, San Diego, CA (US);
Ming-Chang Tsai, San Diego, CA (US);
QualComm Incorporated, San Diego, CA (US);
Abstract
An apparatus and method for performing speech signal compression, by variable rate coding of frames of digitized speech samples. The level of speech activity for each frame of digitized speech samples is determined and an output data packet rate is selected from a set of rates based upon the determined level of frame speech activity. A lowest rate of the set of rates corresponds to a detected minimum level of speech activity, such as background noise or pauses in speech, while a highest rate corresponds to a detected maximum level of speech activity, such as active vocalization. Each frame is then coded according to a predetermined coding format for the selected rate wherein each rate has a corresponding number of bits representative of the coded frame. A data packet is provided for each coded frame with each output data packet of a bit rate corresponding to the selected rate. At the decoder, if a frame is lost due to a channel error, the error is masked by maintaining a fraction of the previous frame's energy and smoothly transitioning to background noise.