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    METHOD AND APPARATUS FOR SELECTING AN ENCODING RATE IN A VARIABLE RATE VOCODER
    95.
    发明专利
    METHOD AND APPARATUS FOR SELECTING AN ENCODING RATE IN A VARIABLE RATE VOCODER 未知

    公开(公告)号：CA2488921C

    公开(公告)日：2010-09-14

    申请号：CA2488921

    申请日：1995-08-01

    Applicant: QUALCOMM INC

    Inventor： DEJACO ANDREW P ,  GARDNER WILLIAM R

    IPC: G10L19/14 ,  G10L19/24 ,  G10L19/00 ,  G10L19/04 ,  G10L21/02 ,  G10L25/78 ,  H03M7/30

    Abstract: The present invention provides a method by which to reduce the probability of coding low energy unvoiced speech as background noise. An encoding rate is determined by dividing the input signal into subbands using digital subband filters (4) and (6) and comparing the energy in those bands to a set of thresholds in subband rate decision elements (12) and (14) and then examining those comparisons in an encoding rate selector (15). By this method, unvoiced speech can be distinguished from background noise. The present invention, also, provides a means for setting the threshold levels using the signal to noise ratio of the input signal, and the present invention provides a method for coding music through a variable rate vocoder by examining the periodicity of the input signal to distinguish the music from background noise.

    96.
    发明专利
    未知

    公开(公告)号：DE69535709D1

    公开(公告)日：2008-03-27

    申请号：DE69535709

    申请日：1995-08-01

    Applicant: QUALCOMM INC

    Inventor： DEJACO ANDREW P ,  GARDNER WILLIAM R

    IPC: G10L19/14 ,  G10L19/24 ,  G10L11/02 ,  G10L19/00 ,  G10L19/02 ,  G10L19/04 ,  G10L21/02 ,  G10L25/78 ,  H03M7/30

    Abstract: A method of adding hangover frames to a plurality of frames encoded by a vocoder, the method comprising: detecting that a predefined number of successive frames has been encoded at a first rate; determining that a next successive frame should be encoded at a second rate that is less than the first rate; and selecting a number of successive hangover frames beginning with the next successive frame to encode at the first rate, the numbering dependent upon an estimate of a background noise level.

    METHOD AND APPARATUS FOR DETECTION AND BYPASS OF TANDEM VOCODING
    98.
    发明专利
    METHOD AND APPARATUS FOR DETECTION AND BYPASS OF TANDEM VOCODING 未知

    公开(公告)号：MY121968A

    公开(公告)日：2006-03-31

    申请号：MYPI9600272

    申请日：1996-01-24

    Applicant: QUALCOMM INC

    Inventor： WEAVER LINDSAY A JR ,  LAM S KATHERINE ,  JACOBS PAUL E ,  GARDNER WILLIAM R ,  DEJACO ANDREW P ,  SIH GILBERT C

    IPC: G10L11/02 ,  G10L19/00 ,  G10L19/14 ,  H04B7/26 ,  H04B14/04 ,  H04Q11/04 ,  H04W88/18

    Abstract: A FIRST REMOTE VOCODER RECEIVES ANALOG VOICE AND PRODUCES PACKETIZED VOCODER DATA WHICH IS TRANSMITTED OVER A WIRELESS LINK. A FIRST LOCAL VOCODER RECEIVES THE PACKETIZED VOCODER DATA FROM THE WIRELESS LINK. THE FIRST LOCAL VOCODER CONVERTS THE PACKETIZED DATA TO A MULTIBIT PCM OUTPUT. THE FIRST LOCAL VOCODER ALSO ADDS A DETECTION CODE TO ONE OF THE LEAST SIGNIFICANT BITS (LSB) OF THE PCM OUTPUT. THE FIRST LOCAL VOCODER PASSES THE PCM SIGNAL TO THE PSTN FROM THE SECOND END USER. THE FIRST LOCAL VOCODER ALSO RECEIVES PCM INPUT OVER THE PSTN. THE FIRST LOCAL VOCODER CONSTANTLY MONITORS THE LEAST SIGNIFICANT BIT OF THE PCM INPUT FOR A DETECTION CODE INDICATING THAT A SECOND LOCAL VOCODER IS CONNECTED AT THE RECEIVING END. IF THE FIRST LOCAL VOCODER DETECTS THE DETECTION CODE FROM THE SECOND LOCAL VOCODER, IT BEGINS TO SUBSTITUTE PACKETIZED DATA AND A REDUNDANCY CHECK FOR A SECOND ONE OF THE LSB''S OF THE OUTGOING PCM. THE FIRST LOCAL VOCODER ALSO BEGINS TO MONITOR THE SECOND ONE OF THE LSB''C OF THE INCOMING PCM. IF THE REDUNDANCY CHECK INDICATES THAT VALID PACKETIZED DATA HAS BEEN RECEIVED, THE FIRST LOCAL VOCODER STOPS CONVERTING THE PCM OUTPUT INTO PACKETIZED DATA AND SIMPLY PASSES THE PACKETIZED DATA ON THE SECOND ONE OF THE LSB''S TO THE FIRST REMOTE VOCODER. IF AT ANY TIME THE REDUNDANCY CHECK FAILS AND THE DETECTION CODE IS NOT DETECTED, THE FIRST LOCAL VOCODER RETURNS TO CONVERTING THE INCOMING PCM TO PACKETIZED DATA. IN THIS WAY, THE TANDEM VOCODING ARRANGEMENT IS AVOIDED.

    99.
    发明专利
    未知

    公开(公告)号：DE69534285T2

    公开(公告)日：2006-03-23

    申请号：DE69534285

    申请日：1995-08-01

    Applicant: QUALCOMM INC

    Inventor： DEJACO ANDREW P ,  GARDNER WILLIAM R

    IPC: G10L19/14 ,  G10L19/24 ,  G10L19/00 ,  G10L19/04 ,  G10L21/02 ,  G10L25/78 ,  H03M7/30

    Abstract: A method of adding hangover frames to a plurality of frames encoded by a vocoder, the method comprising: detecting that a predefined number of successive frames has been encoded at a first rate; determining that a next successive frame should be encoded at a second rate that is less than the first rate; and selecting a number of successive hangover frames beginning with the next successive frame to encode at the first rate, the numbering dependent upon an estimate of a background noise level.

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