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. 22, 2002
Filed:
Dec. 24, 1997
Rodney C. Hemminger, Raleigh, WI (US);
Albert H. Maxwell, Jr., Raleigh, WI (US);
Michael A. Murphy, Raleigh, WI (US);
Thomas J. Van Heuklon, Kaukauna, WI (US);
Richard L. Tenor, Green Bay, WI (US);
Todd P. Kelsey, Appleton, WI (US);
Fred F. Schleifer, Roseville, MN (US);
ABB Automation Inc., Wickliffe, OH (US);
Abstract
A method and apparatus to detect off-hook and intrusion conditions on a telephone line. A voltage to frequency converter is used to convert the voltage measured between the TIP and RING terminals of a telephone line to a frequency. The voltage is continuously monitored, once during each sample period. The measured frequency is compared to predetermined threshold values to determine the state of the telephone line. The predetermined threshold values are updated in each sample period.