Uniden Corporation

Eiji Shinsho

Shigeo Sato

Masato Tanaka

Kazuhiko Seki

Masaki Matsui

Meizhong Wang

Yoshinori Shinohara

Minoru Ogino

A prediction signal calculator with a limit function is provided with a multiplier calculating a partial prediction signal composed of the product of a polar prediction coefficient for generating a regenerative signal and a quantized regenerative signal, a display conversion section for converting the partial prediction signal from floating point representation to an absolute value display, and a limiter executing processing for substituting limit values in the partial prediction signal satisfying overflow conditions during conversion of the partial prediction signal from floating point representation to an absolute value display in the event that the error detector determines that there are code errors in the audio data for a predetermined number of frames of the audio data.

Digital wireless communication apparatus

A digital wireless communications device enabling call distance to be increased while avoiding mute processing as far as possible, even if code error occurs in an ADPCM code. The digital wireless communications device may be configured to include: an error detector for detecting code error in an ADPCM code received via a wireless circuit; an ADPCM decoder for generating a PCM signal by decoding the ADPCM code; and a substitution unit for determining that a click noise is generated if the high-speed scale factor and the low-speed scale factor determined by the ADPCM decoder within a predetermined time period after the error detector has judged that there is a code error in the ADPCM code, and the received ADPCM code itself, respectively exceed prescribed threshold values, and for substituting the ADPCM code with a predetermined prescribed code.

Digital wireless communications device

According to the present invention, all terminals can establish synchronization in a radio communications system formed only of a plurality of mobile terminals. This radio terminal communicates by the time division connection method, and comprises a control portion for synchronizing its transmission/reception timing to that of a group including a plurality of radio terminals. The control portion determines the overall cycle including basic cycles in a number corresponding to the number of radio terminals within said group, conducts control to transmit a signal in a basic cycle that is included in said overall cycle and that is set by a unique terminal number allotted in advance to each of said radio terminals, conducts control to receive signals from another radio terminal in another basic cycle, adjusts the transmission/reception timing based on the data received from said other radio terminal in said other basic cycle, and saves the reception timing until a process to adjust the transmission/reception timing is conducted.

Radio terminal, radio synchronization system having no base station, and recording medium

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.

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Tokyo, Japan

Eiji Shinsho