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:
Jun. 08, 1999
Filed:
Jun. 23, 1997
Thomas Fenn, San Jose, CA (US);
Brian Robert Carey, Cupertino, CA (US);
Siemens Information and Communication Networks, Inc., Boca Raton, FL (US);
Abstract
A loop detector circuit for detecting the loop current of a telephone circuit in a ground start mode and a normal mode which obviates the need for a separate TIP ground detector circuit. A pair of light emitting diodes (LED) 52, 54 are associated with a photoelectric device, such as a phototransistor 56, 58, connected across TIP and RING with a series resistor. Each resistor 60, 62, is selected to provide a predetermined voltage drop during a ground start mode and a normal mode, thus enabling the loop detector to detect loop current during both modes. The loop detector circuit is thus able to detect the off-hook status of a subscriber handset during a ground start mode without the use of a separate TIP ground circuit.