The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Mar. 12, 1996
Filed:
May. 31, 1995
Masaaki Nagami, Akashi, JP;
Kazuya Sako, Kakogawa, JP;
Masahiro Babasaki, Takatsuki, JP;
Kazuhiro Sakiyama, Akashi, JP;
Fujitsu Ten Limited, Hyogo, JP;
Abstract
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.