| 摘要 |
PURPOSE:To ensure the switching from voice transmission to data transmission by inputting only a noise in a room to a transmitter, extracting intensity information so as to form a threshold value, comparing this value with the intensity information of an output of a speech analyzer so as to use the result as silence detection information. CONSTITUTION:A switch SW is closed before the start of voice communication so as to attain reflection connection, only the noise in a room is inputted from the transmitter MIC and the intensity information being an output of a synthesizer SYN at that time is inputted to a room noise setting board SET. The intensity information being an output of the device SYN is added by some value in this case and th result is stored in an internal storage circuit. The room noise level before the start of communication is set automatically to the set board SET as mentioned above. Then the SW is opened. A serial/parallel converter CONV selects only the intensity information of the output of an analyzer AN, converts it into a parallel signal and inputs the result to a comparator circuit COMP. The comparator circuit COMP compares this input with the said noise level of the set board SET, and when the former is smaller than the latter, it is decided as a silence part and the silence detection information is transmitted to a data terminal equipment DTE.
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