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:
May. 31, 1977
Filed:
Nov. 25, 1975
Shizuo Ando, Kawagoe, JA;
Terumasa Shimizu, Kawagoe, JA;
Pioneer Electronic Corporation, Tokyo, JA;
Abstract
Two circuit embodiments are disclosed for discriminating between a voice signal and other audio standard (busy and dial tone) signals on a telephone line. One embodiment measures the frequency of the envelope of the audio signal and decides voice (speech) presence if (glottal) frequencies above 50 hz. are present. The second embodiment measures the cyclic frequency of the audio signal and decides voice (speech) presence if frequencies above 600 hz are present, assuming busy or dial tones are 400 hz. Features of the second embodiment include gating of the timer-counter to prevent the cycle-counter from erroneously counting chatter during rise-time and fall-time of an audio signal.