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:
Dec. 28, 1999
Filed:
Aug. 22, 1997
Applicant:
Inventor:
Mark J Karnowski, Long Beach, CA (US);
Assignee:
Casio PhoneMate, Inc., Torance, CA (US);
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04M / ;
U.S. Cl.
CPC ...
379420 ; 379388 ; 379390 ; 341110 ;
Abstract
The improved full duplex speakerphone system replaces two A/D converters normally required in conventional speakerphone systems with a single A/D converter. This single A/D converter is a higher speed A/D converter which is multiplexed at its input. By alternately connecting the A/D converter between a microphone input circuit and a telephone line input circuit, the single higher speed A/D converter can be used to digitize both input signals. Because the A/D converter samples the data at a much higher rate and uses a digital filter to greatly reduce the impact of aliasing, very simple, low cost external filters may be used.