Uniden Corporation

Meizhong Wang

Masato Tanaka

Kazuhiko Seki

Eiji Shinsho

Yoshinori Shinohara

Provided is a device for improving voice signal in quality by discriminating a radio environment of a signal transmission path and detecting a click noise. The device for improving voice signal in quality calculates an average value for a short interval of a received ADPCM code, identifies from such average value the nature of a radio environment of a signal transmission path, and considers that a click noise is occurred when the average value exceeds a threshold value assigned radio environment. The present invention comprises a click noise detector () for outputting a click noise detecting signal, and a click noise suppressing circuit for suppressing the click noise by setting the velocity coefficient of an ADPCM decoder () as '0' for a frame in which a frame error detecting signal, which represents the detection of a frame error of the received ADPCM code, and a click noise detecting signal are both detected.

Device for improving voice signal in quality

Provided is a code correction circuit for presuming an error pattern of the received code when a received ADPCM code contains a click noise and correcting such error. A device for improving voice signal comprises a click noise detector () which judges that a received ADPCM code contains a click noise when a short interval average value of the absolute value of the received ADPCM code exceeds a predetermined value, and a code correction circuit () which presumes an error position of the bit of the received ADPCM code and corrects such error so as to minimize the variation in the short interval average value of the absolute value of the received ADPCM code when a transmission error is generated in the receiving ADPCM code judged to be containing a click noise.

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Tokyo, Japan

Meizhong Wang