Si Corporation

Shirai Shiro

An apparatus for accurately transmitting and receiving acoustic waves indoors is provided. The apparatus contains a microphone, a speaker, a processing circuit, a first amplifier, a second amplifier, and a power control circuit. The microphone converts an input acoustic wave into an electric signal, and the speaker generates an output acoustic wave based on input data. The processing circuit processes the electric signal to produce processed data and outputs the input data to drive the speaker. The first amplifier receives a power signal and detects if a starting signal is contained in the electric signal output from the speaker. Then, the amplifier outputs a first detection signal when the starting signal is detected and outputs the power signal when the first detection signal is output. The second amplifier receives the power signal from the first amplifier and detects if a non-starting signal is contained in the electric signal when the starting signal is detected. The amplifier outputs a second detection signal when the non-starting signal is detected. The power control circuit supplies the power signal to the processing circuit when the first and second detection signals have a predetermined relationship. Furthermore, methods for accurately detecting data contained in the input acoustic wave are also provided.

Acoustic wave communication apparatus and method

An acoustic communication apparatus includes a microphone/speaker for converting a power voltage and an aerial acoustic wave into an electric signal, and generating an acoustic wave corresponding to the input of data; a signal processing circuit for signal processing the electric signal output from the microphone/speaker in response to the input of the power voltage, the signal being received as data, the circuit outputting data responding thereto to thereby drive the microphone/speaker; a starting signal selection amplifier for always receiving the power voltage during a reception waiting mode, and detecting a starting signal having a predetermined frequency from the electric signal output from the speaker; a non-starting signal selection amplifier for receiving the power voltage in response to the detection of the starting signal, and selectively amplifying only a band excluding the frequency band of the starting signal; and a power voltage supply control circuit for supplying the power voltage to the signal processing circuit when the outputs of the detected starting signal and non-starting signal are maintained at a predetermined state.

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Seoul, South Korea

Shirai Shiro