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. 20, 1978
Filed:
Jun. 20, 1977
Charles David Crawford, Burlington, NC (US);
Bell Telephone Laboratories, Incorporated, Murray Hill, NJ (US);
Abstract
Impedance settings are obtained automatically for manually adjusting a network to obtain a driving point impedance substantially equal to a particular unknown impedance. Discrete impedance settings for setting up, for example, a manually adjustable hybrid balance network are obtained by employing a hybrid network, a noise signal source, at least first and second automatically adjustable balance networks and at least first and second control circuits. An impedance to be matched, for example, a 2-wire telephone cable, is connected to the hybrid. Signals detected at the cable and at the inputs to the respective balance networks are employed to generate control signals for adjusting impedance elements in the automatically adjustable balance networks. Impedance elements in the first balance network are continuously adjusted to match substantially exactly the impedance of the cable. Then, the most sensitive of the corresponding control signals is rounded off to a discrete value and supplied to adjust a corresponding discretely adjustable impedance element in the at least second adjustable balance network. The second control circuit then generates signals for adjusting the remaining impedance elements in the second balance network to obtain the most optimum driving point impedance to match the cable impedance. Values of the impedance control are displayed in binary form to be used by a craftsperson for setting up a corresponding manually adjustable balance network to match the particular cable connected to the hybrid.