Scintera Networks, Inc.

Opnext Subsystems, Inc.

Maxim Integrated Products, Inc.

Inphi Corporation

Greensand Networks Inc.

Edem Ibragimov

Qian Yu

Debanjan Mukherjee

Abhijit M Phanse

Jishnu Bhattacharjee

Abhijit G Shanbhag

Venugopal Balasubramonian

Prashant Choudhary

Fabian Giroud

Theodore John Schmidt

Charles John Razzell

Sunil Kumar Singh Khatana

Madabusi Govindarajan

Venu Balasubramonian

Jishnu Bhatacharjee

Sunil Kumar Singh Khantana

Real-time systems and methods prevent duplication of independent signal streams in a coherent receiver subject to source separation controlled by multiplicative coefficients under adaptive feedback control. In various embodiments, this is achieved by first obtaining a first set of coefficients associated with a first signal stream and a second set of coefficients associated with a second signal stream. In response to the sets of coefficients satisfying a condition, the first set modified into a set of coefficients that is mutually orthogonal with respect to and replaces the second set of coefficients. The resulting series of coefficient values may then be used to perform source separation of independent signal streams without duplicating independent signal streams.

Analog coherent signal processing systems and methods

The technology disclosed in this patent document can be implemented to provide an analog front part of an optical receiver module for coherent optical detection where the optical receiver module receives the optical input from a fiber link, performs optical to electrical conversion and analog processing for carrier frequency compensation, optical phase noise compensation and polarization rotation, and generates an analog electrical output for subsequent signal processing for coherent optical detection. The analog processing for the polarization rotation is placed downstream from the analog processing for carrier frequency compensation, and in some implementations, downstream from the analog processing for optical phase noise compensation.

Coherent optical receiver with improved noise performance for optical fiber communication links

A method for detecting and measuring time skew in high-speed DP-QPSK coherent optical receivers is described.

Quadrature time skew detection for coherent optical signals

Systems and techniques for optical communications based on polarization division multiplexing are described.

Polarization monitoring in polarization division multiplexing in optical communications

I/Q data skew in a QPSK modulator may be detected by sending identical or complementary data streams to I and Q channel PSK modulators, setting the relative carrier phase between I and Q to zero or &#x3c0;, and monitoring the average QPSK output power, where the data streams sent to the I and Q channels include pseudorandom streams of ones and zeroes.

In-phase and quadrature pattern alignment for quadrature phase shift keying optical transmitters

An apparatus and method for adaptively introducing a compensating signal latency related to a signal latency of a data symbol decision circuit. Adaptive timing control circuitry, including an interpolating mixer implemented as a tapped delay line with correlated tap coefficients, introduces a latency adaptively and substantially matching the latency of the data decision circuit for use within an adaptive equalizer, thereby minimizing the mean-squared error of such decision circuit. This adaptive latency is used in generating the feedback error signal which, in turn, can be used by the feedforward equalizer for dynamically adjusting its adaptive filter tap coefficients.

Adaptive signal latency control for communications systems signals

Systems and methods are disclosed to provide channel monitoring and/or performance monitoring for a communication channel. For example, in accordance with an embodiment of the present invention, an equalizer is disclosed that equalizes for channel distortions and also provides channel and performance monitoring information, such as for example bandwidth estimation, channel identification, signal-to-noise ratio, chromatic dispersion, and/or polarization-mode dispersion.

Channel monitoring and identification and performance monitoring in a flexible high speed signal processor engine

A continuous time equalizer for equalizing an input signal using a feedforward equalizer portion and a feedback equalizer portion is provided that includes: a slicer operable to make bit decisions on a combined output from the feedforward and feedback equalizer portions; an adaptive delay circuit operable to delay the combined output to form a delayed output; and a controller operable to control the delay provided by the adaptive delay circuit such that a first group delay through the slicer and a second group delay through the adaptive delay circuit in response to a sinusoidal form of the input signal are substantially equal.

Accurate timing alignments for decision directed continuous time equalizers

An adaptive signal equalizer with a feedforward filter in which the feedback error signal and corresponding incoming data signal are dynamically aligned in time using signal interpolation, and further, to control the precursor/postcursor filter taps configuration, thereby producing more adaptive filter tap coefficient signals for significantly improved and robust signal equalization.

Adaptive signal equalizer with adaptive error timing and precursor/postcursor configuration control

A decision feedback equalizer with dynamic feedback control for use in an adaptive signal equalizer. Timing within the decision feedback loop is dynamically controlled to optimize recovery of the data signal by the output signal slicer. The dynamic timing is controlled by a signal formed as a combination of feedback and feedforward signals. The feedback signal is an error signal related to a difference between pre-slicer and post-slicer signals. The feedforward signal is formed by differentiating and delaying the incoming data signal.

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Santa Clara, CA, United States of America

Edem Ibragimov