Pulse or digital communications – Pulse code modulation – Noise or distortion reduction
Reexamination Certificate
2005-07-05
2005-07-05
Ghayour, Mohammad H. (Department: 2631)
Pulse or digital communications
Pulse code modulation
Noise or distortion reduction
C375S217000, C455S212000, C455S219000
Reexamination Certificate
active
06914940
ABSTRACT:
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 (22) 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 (21) 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.
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Seki Kazuhiko
Shinohara Yoshinori
Shinsho Eiji
Tanaka Masato
Wang Meizhong
Ghayour Mohammad H.
Tran Khanh Cong
Uniden Corporation
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