Palo Alto, CA, United States
Palo Alto, CA, United States

Time filter

Source Type

System and method for the calibration of interleave time errors in an n-level PAM Digital to Analog Converter (DAC), according to which a set of two samplers with adjustable sample time and threshold are introduced at the output of the DAC, which are separated in time. The set of samplers is swept through a n unit interval (UI) window and the n-UI window is classified to periods of transitions and non-transitions on an eye diagram. The relative timing of the lower rate clocks into an n:1 multiplexer is controlled using a control loop, to force equal eye width within the n-UI window and the interleaved timing errors are measured and corrected, until the uneven distribution is being reduced below a predetermined level.


System and method for digitally equalizing a data channel having wide channel impulse response for clock recovery of heavily ISI-induced received signals operating at one sample per symbol, according to which the received signal is pre-processed to provide a received signal with modified constellation, which is pre-processed for the decision process of signal with Inter-Symbol Interference by introducing controlled ISI to the received signal. The decision process is performed, based on a higher order vocabulary according to the introduced controlled ISI.


A method for improving the resilience of a communication channel (such as an optical communication channel) to correlated errors (e.g., burst errors), the channel is being formed by a time-multiplexed aggregation of a plurality of lower rate constituent lanes and employs a Forward Error-Correction (FEC) mechanism for forming codewords from data carried by the constituent lanes. Accordingly, the distribution of errors among the codewords is modified by introducing, at the transmitter side, specific delays to the transmission times via the constituent lanes, relative to each other.


A system for digitally equalizing a data channel with heavily ISI-induced signals received after passing a data communication channel using a combination of a linear equalizer and a nonlinear equalizer, which comprises an ADC, for sampling a received signal and converting it to a digital form; a Linear Equalizer for pre-processing said received signal, said Linear Equalizer is adapted to pre-process a first group consisting of echoes/channel taps of the induced ISI, which are not equalized by said nonlinear equalizer, by eliminating the echoes/channel taps of said first group; pre-process a second group consisting of the combination of the entire echoes/channel taps of the induced ISI, by eliminating the echoes/channel taps of said second group; and a nonlinear equalizer for receiving the signals preprocessed by said Linear Equalizer and for further processing said preprocessed signals and eliminating the echoes/channel taps of the induced ISI to be equalized by said nonlinear equalizer, thereby compensating for the entire ISI induced by said channel.


The present invention is directed to a MIMO equalization system and method, optimized for baud rate clock recovery in coherent symbol-spaced DP-QPSK Metro systems. According to this method, the Mueller & Muller timing function is extended to cope with controlled ISI induced signals, while decoupling between MIMO equalization and clock recovery loops, using a midpoint output of the equalizer for timing estimation, instead of its final output. At least a portion of controlled Inter-Symbol Interference (ISI) is kept intact and the controlled ISI is compensated by an MLSE, right after carrier timing synchronization.


An optical communication system with nonlinear equalization capability for equalizing distortions of a data communication channel, which comprises a processor for periodically gathering a predetermined number of consecutive data segments from an input data stream to a group and adding a known pilot sequence to the group, thereby forming a data frame; an optical transmitter at the input of the channel, for transmitting the data frames to a receiver, over the channel; a receiver at the output of the channel, for detecting the transmitted frames, the receiver including a demodulator. The demodulator is adapted to recover the pilot sequence of each frame; compare each recovered pilot sequence which its corresponding original transmitted pilot sequence; extract the current Channel State Information indicative of changes in the channel distortion, using the comparison results; use changes in the Channel State Information for updating the coefficients of the estimator and of the equalizer, every time a frame is received; and equalize the channel estimator and of said equalizer, every time a frame is received; and equalize the channel using the equalizer coefficients, and based on the current Channel State Information.


Patent
MultiPhy | Date: 2016-07-19

Method and system for providing seamless match point switching in an adaptive decoder (e.g., an MLSE decoder) that is based on estimation of symbol sequences, according to which statistics regarding samples corresponding to different symbol sequences in alternative match points are collected by a statistics collector, to create a set of figures of merit representing the quality of each alternative match point, while different match points are obtained by changing the delay of symbols decoded by the adaptive decoder and samples entering the statistics collector. A figure of merit of the current match point is compared to the figure of merit of alternative match points. Whenever an alternative match point figure of merit is better than the current match point by a predefined threshold, a decision to switch to the alternative match point is made. Seamless switching to the alternative match point is performed by shifting the sampling phase forward or backward, until obtaining better performance, while performing adaptation of the decoder to the sampling phase shift.


Method and system for estimating an eye diagram display of a real signal passing through a data communication channel, according to which decoded symbols of the transmitted real signal are captured, along with their corresponding ADC sample values and sampled at a rate of 1 SPS or more. Then statistic data is collected for each captured sequence of bits/symbols for each particular phase and a synthetic signal is created, based on the collected statistics, using a signal generator that produces samples by randomly creating a bit stream by generating a corresponding one or more samples for any symbol sequences in the bit stream according to the number of collected phases. Interpolation on the corresponding samples is then performed, according to required display time resolution and the synthetic signal is then displayed as a two-dimensional eye diagram image, representing all the statistics collected at all phases.


Patent
MultiPhy | Date: 2016-05-26

A driver for performing efficient low-power high-swing modulation, which comprises a first plurality of N controllable switching elements and introducing low impedance between the contacts in response to a low control level and vice versa; a second plurality of N controllable switching elements and introducing high impedance between the contacts in response to a low control level and vice versa; a DC power supply for feeding the driver, the positive port of which is connected to the common contact of the first plurality and the negative port of which is connected to the common contact of the second plurality; a plurality of N voltage dividers, each divider consisting of two serially connected resistors connecting between a free contact of a controllable switching element from the first plurality and a free contact of a controllable switching element from the second plurality, where each two controllable switching elements connected by a voltage divider forming a pair; a plurality of N control inputs, each of which jointly controlling the control inputs of a different pair; and a common output connecting between all N common points of all pairs of serially connected resistors forming the N voltage dividers.


Patent
MultiPhy | Date: 2016-05-27

A nonlinear equalizer for iteratively equalizing a data communication channel, which comprises a transmitter at the input of the channel, for transmitting data and one or more training sequences over the channel; a receiver at the output of the channel, for receiving the data and the one or more training sequences; a sampling circuit for sampling received data; a processor, for processing the samples. The processor is adapted to calculate the derivative of the MSE for each of the FFE taps; calculate the derivative of the variance of the enhanced noise with the FFE taps; iteratively update the FFE coefficients, while during each update, injecting samples of a known training sequence into the channel. During each update, the processor computes the derivative of the output noise variance, by applying convolution between the noise correlation and the current FFE taps; computes the effective channel and the modified effective channel; computes the derivative of the residual ISI, by applying correlation between the original channel h and the modified effective channel; and updates the FFE coefficients, with a step proportional to the opposite of the gradient.

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