Chaos Telecom, Inc.

Applied Nonlinear Sciences, LLC

Paul Henry Bryant

James U Lemke

Nikolai F Rulkov

Lev Korzinov

Lev S Tsimring

Henry D I Abarbanel

Mikhail M Sushchik

In a transmission line, nonlinear impairments resulting from imperfect splices are mitigated by providing a bias current that shifts the operating points of these impairments resulting in improved stability, conductivity and linearity.

Method and apparatus for reversibly correcting nonlinear impairments in a communications channel

A series of time domain reflectometry (tdr) measurements are made on a channel having nonlinear impairments as well as linear impairments. In a given measurement, the reflected signals from the impairments are digitized and sequentially stored in memory. The parameters characterizing the channel are then changed, preferably by biasing the line by means of a dc current. The changed bias condition modifies the impedance of nonlinear impairments in a nonlinear manner, while the impedance of linear impairments are unchanged by the bias. A second tdr measurement is initiated, and the reflected signals digitized and sequentially stored. The two sets of stored reflected signals are then sequentially compared, and corresponding signals having either the same amplitudes or linearly proportional amplitudes are identified as reflected from linear impairments, while those not the same, nor proportional, are identified as from nonlinear impairments.

Apparatus and method for locating nonlinear impairments in a communication channel by use of nonlinear time domain reflectometry

In a recording/playback system, increased information is achieved by 4 level biased magnetic recording where the maximum amplitude 4 level recording signal drives the medium's magnetization into a nonlinear region of its transfer function. The bias does not eliminate distortion at the maximum signal input level, however the system's signal to noise ratio is improved due to an increase in the amplitude of the playback signal resulting from the increased recording level. The nonlinear mapping capability of a neural network provides equalization of playback signals distorted due to the record/playback nonlinearity. The 4 level recorded signals provide a factor of 2 in information storage compared to binary recording, and quadrature amplitude modulation (QAM) combined with the 4 level recording technique provides an additional factor of 2, for a factor of 4 in the information content stored.

Multilevel signal equalization utilizing nonlinear maps

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Encinitas, CA, United States of America

Paul Henry Bryant