Hitachi, Ltd.

Ryujiro Muramatsu

Toshiro Suzuki

Toshiaki Suzuki

Akio Amano

Takanori Miyamoto

Toshiyuki Odaka

Nobuo Hataoka

Kazuhiro Kondo

Tetsuo Takemura

A telephone communication terminal responsive to a voice for originating a call includes an antenna, a diplexer, a radio unit, a base band unit, a controller, a loudspeaker, a microphone, a key input and display unit, a sound level measuring instrument, threshold generators, comparators, an analyzer, and a destination number storage. The sound level measuring instrument always measures the sound level of an input signal, such as a voice inputted from the microphone. The sound level measuring instrument conducts processing such as calculating signal power at fixed intervals. The output of the sound level measuring instrument is compared in a first comparator with the output of a first threshold generator outputting a preset threshold value. In the case where the output of the sound level measuring instrument is greater than the threshold value, a result of comparison is conveyed to the controller. The analyzer effects an analysis on an input signal and outputs information. The output of the analyzer is compared in a second comparator with lower and upper limit threshold values outputted from a second threshold generator.

Telephone communication terminal and communication method

A telephone exchange enables subscribers to use voice dialing more easily with existing telephone systems. The voice dialing does not require special input operations or preregistration of called parties. Rather, a subscriber can make a telephone call easily without having to perform multiple operations. The telephone exchange includes structure for discriminating dial pulse information, push-button tone information, and spoken information so that one or more of these types of information can be input by a caller to achieve connection to the called party.

Telephone exchange network using telephone exchanges with speech

A speech coding system includes apparatus for generating a variable threshold dependent upon the power of an input speech signal, and a comparator for comparing the power of the input speech signal with the variable threshold value to generate a discriminating signal for discriminating between a period when a speech continues and a period when the speech pauses, to change the coding operation for the input speech signal in accordance with the level of the discriminating signal, thereby forming voiced and unvoiced frames independently of each other.

Speech coding system using variable threshold values for noise reduction

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Yokohama, Japan

Ryujiro Muramatsu