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. 24, 1982
Filed:
Mar. 17, 1980
Applicant:
Inventors:
Alfred M Hestad, Chicago, IL (US);
Levi L Rose, Chicago, IL (US);
Assignee:
United Networks, Inc., Chicago, IL (US);
Attorney:
Primary Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
179 / ; 179 / ;
Abstract
A speaker telephone system having hands-free telephone sets with microphones and loud-speakers and including circuitry for preventing feedback between the loud-speakers and the microphones in both the transmitting and receiving modes by automatically controlling the amplification of the signals coming from the microphones and going to the loud-speakers, as a function of the signal direction, while still maintaining the microphones and loud-speakers electrically coupled to the telephone lines.