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
A hybrid circuit for coupling a bidirectional telephone cable to two unidirectional cables is balanced automatically by employing an adjustable balance network and a control circuit. Optimum adjustment of the balance network is achieved over a frequency band of interest by employing a signal source having one or more frequency components within the frequency band of interest and by generating signals for controlling magnitude and phase components in the balance network. The magnitude control signal is representative of the difference between the absolute magnitudes of signals detected at the bidirectional cable connection to the hybrid and at the balance network connection to the hybrid in the frequency band of interest. Signals for controlling the phase components of the balance network are representative of the difference between the absolute magnitudes of the detected signals modified by a first prescribed weighting function less a component proportional to the phase difference between the detected signals modified by a second prescribed weighting function within the frequency band of interest. The weighting functions are obtained by employing a filter having a prescribed low-pass characteristic. The component values of the filter are determined by the locations of adjustable pole(s) and/or zero(s) within the frequency band. The filter characteristic may be adjusted during the balance process further to optimize the balance network adjustments.