Patent ID: 9584074
Date: 2017-02-28
CPC Classifications: H03F,H04B

Claim:
1. An optical receiver having composite second order (CSO) distortion correction logic for reducing receiver distortion in a received signal during operation of a cable television (CATV) optical system via a closed-loop operation, the correction logic comprising: a monitor circuit for sampling received signals delayed by a first delay line combined with an output of a second delay line connected to an output of a composite second order (CSO) distortion generation circuit circuit for composite second order distortion; a composite second order distortion detector for measuring a combination of received distortion products and generated distortion products in the output of the composite second order (CSO) distortion generation circuit in the sampled signals, the received distortion products attributable to at least laser distortion or optical fiber distortion generated during operation of the CATV optical system; a microprocessor configured to adjust a control voltage input to the composite second order (CSO) distortion generation circuit during the closed-loop operation, wherein the control voltage input to the CSO distortion generation circuit during the closed-loop operation is in response to a determination whether a direction of control voltage change made previously during the closed-loop operation results in less distortion detected by the distortion detector, wherein the CSO distortion generation circuit generates distortion products having a frequency signature shaped to correspond to a frequency signature of the received distortion products; and the second delay line for outputting the generated distortion products caused by the second delay line to be out of phase with the received distortion products, said output of the second delay line for combination with signals delayed by the first delay line.