US 12,395,384 B1
Adaptive equalizer performance monitor
Hongbin Zhang, Maynard, MA (US)
Filed by ACACIA TECHNOLOGY, INC., San Jose, CA (US)
Filed on Jan. 28, 2022, as Appl. No. 17/587,916.
Int. Cl. H04L 25/03 (2006.01)
CPC H04L 25/03057 (2013.01) [H04L 2025/03611 (2013.01); H04L 2025/03687 (2013.01)] 15 Claims
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1. A method of equalizer performance monitoring, comprising:
receiving a signal;
adjusting step size of an adaptive equalizer in response to changes in state of polarization (SOP) of the received signal, wherein the adaptive equalizer is in communication with one or more digital signal processing (DSP) components, the adaptive equalizer comprising one or more filter coefficients;
increasing or decreasing the step size of the adaptive equalizer in response to updates to the one or more filter coefficients;
determining a spectral correlation of an output of the adaptive equalizer;
monitoring changes to the spectral correlation over time;
updating the one or more filter coefficients in response to the spectral correlation changes;
selecting a first trial matrix M(1) and a second trial matrix M(2) and applying the matrices M(1) and M(2) to output of the adaptive equalizer, wherein the matrices M(1) and M(2) are each a trial Jones matrix, and wherein the matrices M(1) and M(2) each comprise a parameter α=±α0; and
synchronizing pilot symbols at the output of the adaptive equalizer, wherein the pilot symbols are represented by

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