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:
Jul. 11, 1989
Filed:
May. 18, 1987
Gary L Larson, Waseca, MN (US);
AMP Incorporated, Harrisburg, PA (US);
Abstract
An improved threshold circuit (30) for reconstructing digitally-encoded, optically-transmitted signals is disclosed. The threshold circuit (30) automatically compensates for amplitude variations in the received signal due to noise, gain variations, and the like, and thereby provides improved accuracy in reproduction of the digitally-encoded signal. An amplifier (120) generates an output signal the level of which, under low signal amplitude, is linearly related to the instantaneous level of the digitally-encoded input signal. An active low pass linear filter (122, 124, 132) generates from the amplified output signal a signal the level of which corresponds to the average level of the amplified output signal. A bias signal generator (40) receives the average level signal on one input and a selected reference signal on the other. The bias generator (40) outputs a bias signal the level and polarity of which are related to the degree and polarity of difference between the average level signal and the reference signal. The bias signal biases the linear amplifier (120) to compensate for any variations of the average level of the amplified input signal from a selected threshold value that corresponds to the reference signal. A trigger circuit (45) converts the bias-controlled, amplified signal to digital square wave pulses corresponding to the transmitted digitally-encoded signal.