Abstract: A method and apparatus is disclosed to compensate for impairments within a data converter such that its output is a more accurate representation of its input. The data converter includes a main data converter, a reference data converter, and a correction module. The main data converter may be characterized as having the impairments. As a result, the output of the main data converter is not the most accurate representation of its input. The reference data converter is designed such that the impairments are not present. The correction module estimates the impairments present within the main data converter using its output and the reference data converter to generate corrections coefficients. The correction module adjusts the output of the main data converter using the corrections coefficients to improve the performance of the data converter.

Abstract: Provided is a method and system for estimating distortion in a communications channel including an adaptive equalizer. The method includes determining one or more adaptive filter coefficients associated with a signal passed through the equalizer. The method also includes estimating un-equalized channel distortion based upon the determined adaptive filter coefficients.

Abstract: Embodiments provide histogram-based methods and system to estimate the transfer function of an ADC, and subsequently to linearize a non-linear ADC transfer function. Embodiments include blind algorithms that require no a priori knowledge of the input signal distribution. Embodiments can be implemented using cumulative (i.e., cumulative distribution function (CDF)) or non-cumulative (i.e., probability density function (PDF)) histograms. According to embodiments, a non-linear transfer function can be estimated by linearly approximating successive local intervals of the transfer function. Linearly approximated successive local intervals of the transfer function can then be used to fully characterize and closely estimate the transfer function.

Abstract: Distortion and aliasing reduction for digital to analog conversion. Synthesis of one or more distortion terms made based on a digital signal (e.g., one or more digital codewords) is performed in accordance with digital to analog conversion. The one or more distortion terms may correspond to aliased higher-order harmonics, distortion, nonlinearities, clipping, etc. Such distortion terms may be known a priori, such as based upon particular characteristics of a given device, operational history, etc. Alternatively, such distortion terms may be determined based upon operation of a device and/or based upon an analog signal generated from the analog to conversion process. For example, frequency selective measurements made based on an analog signal generated from the digital to analog conversion may be used for determination of and/or adaptation of the one or more distortion terms. One or more DACs may be employed within various architectures operative to perform digital to analog conversion.

Abstract: A communication system performs burst noise cancellation. A transmitter produces and transmits a spread signal that comprises at least one known-value symbol spread by a plurality of non data-carrying orthogonal codes and data symbols spread by at least one data-carrying orthogonal code. The transmitter transmits the spread signal across a communication link that introduces burst noise. A burst noise detector determines burst noise affected chips of the orthogonal codes. A weight computation functional block calculates a plurality of complex-valued combining weights based upon the burst noise affected chips. A vector de-spreader and a linear combiner operate in combination to use the plurality of non data-carrying orthogonal codes, the at least one data-carrying orthogonal code, and the plurality of complex-valued combining weights to de-spread the received spread signal to produce the data symbols with the burst noise substantially removed.

Abstract: Distortion and aliasing reduction for digital to analog conversion. Synthesis of one or more distortion terms made based on a digital signal (e.g., one or more digital codewords) is performed in accordance with digital to analog conversion. The one or more distortion terms may correspond to aliased higher-order harmonics, distortion, nonlinearities, clipping, etc. Such distortion terms may be known a priori, such as based upon particular characteristics of a given device, operational history, etc. Alternatively, such distortion terms may be determined based upon operation of a device and/or based upon an analog signal generated from the analog to conversion process. For example, frequency selective measurements made based on an analog signal generated from the digital to analog conversion may be used for determination of and/or adaptation of the one or more distortion terms. One or more DACs may be employed within various architectures operative to perform digital to analog conversion.

Abstract: A communications receiver includes a noise analyzer to characterize the composition of the interference and/or distortion impressed onto a transmitted communications signal in the presence of one or more time-varying conditions. The noise analyzer may provide a selection signal indicating the composition of the interference and/or distortion impressed onto a transmitted communications signal in the presence of one or more time-varying conditions to be used by the communications receiver. In an exemplary embodiment, the communications receiver selects at least one set of filter coefficients to compensate for the interference and/or distortion impressed onto a transmitted communications signal in the presence of a particular time-varying interference and/or distortion condition.

Abstract: A method of transmitting data in a cable modem system includes the steps of encoding the data using forward error correction. The data is then encoded with Turbo encoding. The data is then sent to a modulation scheme. The data is then transmitted over a cable channel. The data is then demodulated. The data is then decoded using a Turbo decoder. An inverse of the forward error correction is then applied to the data.

Abstract: Herein described is a system and method that tracks the face of a person engaged in a videophone conversation. In addition to performing facial tracking, the invention provides stabilization of facial images that are transmitted during the videophone conversation. The face is tracked by employing one or more algorithms that correlate videophone captured facial images against a stored facial image. The face may be better identified by way of employing one or more voice recognition algorithms. The one or more voice recognition algorithms may correlate utterances of the person engaged in a conversation to one or more stored utterances. The identified utterances are subsequently mapped to a stored facial image. In a representative embodiment, the system used for performing facial tracking and image stabilization comprises an image sensor, a lens, an actuator, and a controller/processor.

Abstract: A method and apparatus is disclosed to map a sequence of data to Quadrature Amplitude Modulation (QAM) constellation symbols. The method and apparatus encodes only a portion of the sequence of data and leaves a remaining portion of the sequence of data unencoded. The encoded portion of the sequence of data and the remaining unencoded portion of the sequence of data are then mapped into modulation symbols of the QAM constellation. The encoded portion of the sequence of data selects subsets of the QAM constellation, and the remaining unencoded portion of the sequence of data determines a specific modulation symbol within each subset of the QAM constellation.

Abstract: A method of transmitting data in a cable modem system includes the steps of encoding the data using forward error correction. The data is then encoded with Turbo encoding. The data is then sent to a modulation scheme. The data is then transmitted over a cable channel. The data is then demodulated. The data is then decoded using a Turbo decoder. An inverse of the forward error correction is then applied to the data.

Abstract: A filter settings generation operation includes sampling a communication channel to produce a sampled signal. The sampled signal is spectrally characterized across a frequency band of interest to produce a spectral characterization of the sampled signal. This spectral characterization may not include a signal of interest. The spectral characterization is then modified to produce a modified spectral characterization. Filter settings are then generated based upon the modified spectral characterization. Finally, the communication channel is filtered using the filter settings when the signal of interest is present on the communication channel. In modifying the spectral characterization, pluralities of spectral characteristics of the spectral characterization are independently modified to produce the modified spectral characterization. Modifications to the spectral characterization may be performed in the frequency domain and/or the time domain.

Abstract: Upstream frequency response measurement and characterization. Signaling is provided between respective communication devices within a communication system. Based upon at least one of these signals, one of the communication devices captures a number of sample sets corresponding thereto at different respective frequencies (e.g., a different respective center frequencies, frequency bands, etc.). Then, spectral analysis is performed with respect to each of the sample sets to generate a respective and corresponding channel response estimate there from. After this number of channel response estimates is determined, they are combined or splice together to generate a full channel response estimate. In implementations including an equalizer, different respective sample sets may correspond to those that have undergone equalization processing and those that have not.

Abstract: Characterization and assessment of communication channel average group delay variation. A signal having repeated signal components therein is received by a communication device, and that signal undergoes appropriate processing to determine respective amplitude and phase of a number of frequency bins. The phase difference from bin to bin (including respecting unwrapping, and proper normalization) is used to determine the group delay of a communication channel, or portion thereof, as a function of frequency. Multiple respective group delay measurements may be averaged to generate a wideband group delay of the communication channel as a function of frequency. Overlap between different respective band-edge portions of the communication channel may assist in generating a seamless continuous wideband spectrum estimation for use in determining the wideband group delay of the communication channel.

Abstract: Upstream burst noise measurement and characterization. One or more communication devices is implemented to detect and measure burst noise event(s) within channel(s) associated with communication link(s) within communication system(s) or network(s). Detection and measurement of a burst noise event may be made during active communications on one or more other channels, and may be made during active communications on two channels respectively adjacent to the channel on which the burst noise event is being detected and measured. The channel on which the burst noise event is detected and measured may be an unused channel. The detection and measurement of the burst noise event may be made during a quiet time slot within one of the channels. Correlation (e.g., with respect time) may be determined with respect to different respective layers within a communication device (e.g., with respect to MAC and PHY layers).

Abstract: Detection and characterization of laser clipping within communication devices. Identification of one or more harmonics associated with a fundamental frequency by which signaling is effectuated within the communication system for laser clipping identification. Appropriate spectral signal analysis is made to identify the presence of characteristic(s) (e.g., energy, amplitude, phase, and/or other characteristic(s)), if any, at one or more harmonic frequencies within a received signal. Appropriate time correlation is performed to distinguish whether or not characteristic(s) associated with at one or more of these harmonic bands is a result of laser clipping or from some other source (e.g., such as other signals within a communication system that happened to reside at those respective harmonic bands). Such appropriate identified correlation between characteristic(s) corresponding to a fundamental frequency band of the communication signal and characteristic(s) corresponding to one or more harmonics (e.g.

Abstract: A method and apparatus is disclosed to map a sequence of data to Quadrature Amplitude Modulation (QAM) constellation symbols. The method and apparatus encodes only a portion of the sequence of data and leaves a remaining portion of the sequence of data unencoded. The encoded portion of the sequence of data and the remaining unencoded portion of the sequence of data are then mapped into modulation symbols of the QAM constellation. The encoded portion of the sequence of data selects subsets of the QAM constellation, and the remaining unencoded portion of the sequence of data determines a specific modulation symbol within each subset of the QAM constellation.

Abstract: A method and apparatus is disclosed to compensate for impairments within a data converter such that its output is a more accurate representation of its input. The data converter includes a main data converter, a reference data converter, and a correction module. The main data converter may be characterized as having the impairments. As a result, the output of the main data converter is not the most accurate representation of its input. The reference data converter is designed such that the impairments are not present. The correction module estimates the impairments present within the main data converter using its output and the reference data converter to generate corrections coefficients. The correction module adjusts the output of the main data converter using the corrections coefficients to improve the performance of the data converter.

Abstract: Narrowband ingress estimation and characterization using equalizer taps. A equalizer including a feed forward equalizer (FFE) and a decision feedback equalizer (DFE) is implemented to process an input signal thereby generating an output signal. Analysis of the frequency response of the equalizer including the FFE and the DFE of the equalizer allows for the determination of whether or not narrowband ingress exists within the signal received by the equalizer. For example, analysis of the signal output from the equalizer provides for determination of the overall frequency response of the equalizer. In addition, analysis of the respective equalizer coefficients within one or both of the FFE and the DFE of the equalizer may be used to determine the overall frequency response of the equalizer. Narrowband ingress may be identified when the combination of the FFE (having a notch therein) and the DFE provides for an overall flat frequency response.

Abstract: Linear distortion and interference estimation using decision feedback equalizer coefficients. Processing of different respective groups of equalizer coefficients may be made to determine the residual frequency response of an equalizer and/or device in which the equalizer is implemented. Such an equalizer may be in woman within any of a number of respective communication devices including those operative within satellite, wireless, wired, fiber-optic, and/or mobile communication systems. A first group of equalizer coefficients corresponds to certain filtering characteristics of the equalizer and/or device in which the equalizer is implemented. The equalizer is implemented to process a signal to generate a second group of equalizer coefficients.