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:
Sep. 23, 1980
Filed:
Mar. 12, 1979
James L Neigh, Fair Haven, NJ (US);
Richard G Sparber, Wheaton, IL (US);
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
Abstract
An electronic loop identification circuit identifies loaded and nonloaded customer telephone loops. The loops can then be segregated to allow separate balance networks to be used for hybrid circuits which connect the customer loops to a digital switching office. Separate balance networks for loaded and nonloaded loops improve singing margin on those loops. An impedance measuring circuit (214) measures the real part of the impedance of a connected loop which is compared to a reference signal. If the real part of the loop impedance is greater than the reference signal, a loaded loop is identified; and, if the real part of the loop impedance is less than the reference signal, a nonloaded loop is identified. The circuit includes a self-calibrating arrangement which connects a reference impedance (209) to the impedance measuring circuit so that a capacitor (304) held reference signal can be set before each loop identification operation.