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:
Oct. 11, 1994
Filed:
Aug. 11, 1992
Yoshihiro Iwata, Saitama, JP;
Mitsuo Shiraishi, Tokyo, JP;
Hitachi Denshi Kabushiki Kaisha, Tokyo, JP;
Abstract
A squelch circuit for a radio transmitter/receiver includes an amplifier, a digitally-controlled electronic volume control, a volume adjusting variable resistor, and a volume controller. The amplifier amplifies a received audio signal input and provides the received audio signal to a loudspeaker. The digitally-controlled electronic volume control changes the output level of the amplifier. The volume adjusting variable resistor outputs data representing a volume value. The volume controller constantly detects changes in volume value data output from the variable resistor, and controls an attenuation amount of the digitally-controlled electronic volume control in accordance with the volume value represented by the variable resistor. While in a 'mute' state, this volume control continues until a predetermined time has elapsed since the detection of the change in volume value data. The volume controller then sets the attenuation amount of the digitally-controlled electronic volume control to an infinite attenuation amount.