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:
Apr. 22, 1997
Filed:
Mar. 24, 1994
Applicant:
Inventor:
John W Cook, Suffolk, GB;
Assignee:
British Telecommunications public limited company, London, GB;
Attorney:
Primary Examiner:
Assistant Examiner:
Int. Cl.
CPC ...
H04B / ; H04M / ;
U.S. Cl.
CPC ...
379402 ; 379398 ; 379400 ;
Abstract
A twisted-pair telephone line is connected to a conventional telephone via a low-pass filter and equipment for receiving signals in an upper frequency range, e.g., 25-1000 kHz via a high-pass filter. The low-pass filter is primarily passive (to allow passage of line power, ringing and signalling voltages) but, to improve matching to non-resistive line and telephone impedances, at least the main part of the filter is flanked by impedance convertors in which amplifiers having an appropriate transfer function feed voltages back into the line via transformers through which power, ringing and dialing may pass unimpeded.