Fujitsu Ten Limited

Fujitso Ten Limited

Masaaki Nagami

Kazuya Sako

Shoji Fujimoto

Takeshi Chono

Kazuhiro Sakiyama

Katsumaro Yasui

Masahiro Babasaki

Akira Motojima

Yoshihiro Kageyama

Katsumaro Yasu

A noise control device disposed at the outlet of a tail pipe which emits exhaust noise of an automobile to silence noise from the tail pipe comprises a speaker which is arranged near the tail pipe and of which the open surface has a constant angle with respect to a vertical plane, an enclosure which closes the rear portion of the speaker, and a silencing sound guide portion which guides silencing sounds emitted from the front surface of the speaker to the outlet of the tail pipe. A closed space into which a bumper for absorbing impact in case of collision is made, is used as a resonant-cavity of said speaker. Based on the amount of silencing noise which becomes greater as a plurality of microphones are arranged to be closer to the speaker, the outputs of the plurality of microphones apart a constant distance from said speaker are synthesized.

Noise control device

An automatic sound controlling apparatus including a first adaptive filter means that forms a compensating signal for canceling a stationary sound, a signal producer means that produces a predetermined shape signal based on a timing signal with respect to a sound, a second adaptive filter means that forms a compensating signal for canceling a fluctuating sound by the predetermined shape signal, whereby in the case that a sound period changes sharply, an output signal of the second adaptive filter means is output in stead of the first adaptive filter means.

Automatic sound controlling method and apparatus for improving accuracy

In a noise controller which forms a noise cancelling sound having a phase opposite to and a sound pressure equal to those of a noise infiltrating into a closed space, any deviation in its transfer characteristics from the initial equalization is easily checked and judged owing to the provision of an adaptive filter which automatically varies the filter coefficient and forms a cancelling signal for forming a cancelling sound, a coefficient updating means which updates the filter coefficient based on an error signal after the noise has been cancelled, a simulated transfer characteristics compensation means which forms the initial equalization by simulating transfer characteristics of a transmission path via the space in which the noise is to be cancelled and forms a reproduced reference signal, a white noise generating means which generates white noise to check the initial equalization, and an initial equalization judging means which judges the accuracy of the initial equalization based on a ratio (S/N) of the reproduced reference signal obtained from white noise to the error signal. A change in the conditions for cancelling noise is detected in the closed space, and any deviation from the initial equalization is judged.

Noise controller

An automatic sound controlling apparatus including a first adaptive filtering means that forms a compensating signal for canceling a stationary sound, a signal producing means that produces a predetermined shape signal based on a timing signal with respect to a sound, a second adaptive filtering means that forms a compensating signal for canceling a fluctuating sound by the predetermined shape signal, whereby in the case that a sound period changes sharply, an output signal of the second adaptive filtering means is output in stead of the first adaptive filtering means.

Adaptive filtering means for an automatic sound controlling apparatus

Noise sound controller

A noise reducing device including a noise silencing device having a delay unit for delaying a phase of the noise wave, an amplifying unit for adjusting a gain of the delayed noise wave, a superposing unit for superposing the delayed noise wave as the noise silencing wave, a frequency selecting unit for selecting at least one frequency with respect to the noise wave, a factor selecting unit for selecting at least one of a delaying factor used for the delaying unit and a gain factor used for the amplifying unit with respect to the selected frequency, and a controlling unit for controlling at least one of the delaying unit and amplifying unit utilizing the selected delaying factor and a gain factor, respectively, whereby a noise silencing wave having the same frequency and amplitude as that of a noise to reduced but having a reverse phase can be easily obtained, and thus efficient noise reduction can be obtained despite variation of the frequency of the noise.

Noise reducing device

Data transfer apparatus and data transfer system

A digital signal processor comprises a code converter which converts an integer coded in a Binary Two's Complement (BTC) code to an integer coded in a Sign Magnitude Binary (SMB) code and/or a code converter which converts the SMB code to the BTC code. An integer coded in the BTC code and stored in an m-bits register is converted to an integer coded in the SMB code and input to an n-bits register, by an EXCLUSIVE OR processing of the bits with the sign bits and by supplementing a logic '1' in the less significant bit next to the least significant bit of the result of the exclusive OR operation. An integer coded in the SMB code and stored in an n-bits register is converted to an integer coded in the BTC code and input to an m-bits register, by an EXCLUSIVE OR processing of m-1 bits of magnitude bits with a sign bit. The code converters have a relatively simple construction, will not output an incorrect result, and are most suitable for processing AC signals.

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Kobe, Japan

Masaaki Nagami