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:
Aug. 08, 1995
Filed:
May. 13, 1993
Applicant:
Inventors:
David F Wilson, Los Altos, CA (US);
Lawrence F Heyl, Mtn. View, CA (US);
Assignee:
Apple Computer, Inc., Cupertino, CA (US);
Attorneys:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04B / ; H04B / ; H03G / ;
U.S. Cl.
CPC ...
381119 ; 381 94 ; 381106 ;
Abstract
A circuit and method for mixing signals from audio sources provide noise reduction by employing a noise gate to selectively attenuate one of the source signals. The noise gate has a low gain state and a unity gain state. The noise gate switches to its unity gain state when a control signal reaches a predefined threshold voltage. The control signal is generated by rectifying and integrating the noisy source audio signal, so that the noise gate enters the unity gain state only when a useful sound occurs. Thus, the noise in the combined audio signal is reduced, without attenuating useful components of the source signals.