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. 23, 1992
Filed:
Apr. 26, 1991
David L Hershberger, Nevada City, CA (US);
The Grass Valley Group, Inc., Nevada City, CA (US);
Abstract
A multiple section cable equalizer with a signal level detector produces a clipping control signal for amplifiers in each equalizer section, so that a variable level input signal is restored to an equalized output signal that is free of distortion and attendant bit errors. A fixed reference clipping stage after the last equalizing stage produces a signal clipped to a final output level. A feedback path restores DC and low frequencies lost due to AC coupling. A test output stage permits monitoring of the operation of the equalizer stages. The signal level detector contains (in series), a differential amplifier with low pass filtering, a balanced modulator detector, a voltage amplifier, a comparator and peak detector, a transconductance amplifier and a plurality of current mirrors operatively connected to determine a difference current from the output of the transconductance amplifier and convert this to a clipping control signal voltage level. A defeat comparator monitors the output of the comparator and peak detector and replaces the variable difference current with a fixed reference current when an external capacitor used by the peak detector appears to be shorted.