Abstract: A reconfigurable chip level equalizer having circuitry that restores signal orthogonality and eliminates channel interference for a wireless transmitted signal. In at least some embodiments, the reconfigurable chip level equalizer comprises two or more adaptive equalizers, a plurality of operational blocks that interconnect the two or more adaptive equalizers, and a control mechanism that configures the two or more adaptive equalizers and operational blocks according to different signal delay profiles.

Abstract: In one aspect of the invention, a carrier frequency offset (CFO) estimation method to estimate a CFO value of a received signal is provided, and the method comprises: receiving a preamble signal which includes several non-perfect repeat segments; applying an interpolation procedure to interpolate the perfect repeat point of one segment compared with the next segment or the previous segment; acquiring a delay correlation value based on the two perfect repeat signal segments and estimating the CFO value based on the delay correlation value.

Abstract: The present invention discloses a method and device for transmitting and receiving a signal in a wireless communication system. The method for transmitting a signal in a wireless communication system according to the present invention comprises: receiving an original data block to be transmitted, the length of the original data block being M, wherein M is an integer; disordering the original data block for one or more times, whereby M data symbols in the original data block are rearranged in each of the one or more times of the disordering, so as to obtain one or more disordered data blocks with length of M; cascading the original data block and the one or more disordered data blocks with a cyclic prefix, to form an equalized signal of frequency domain diversity with time-frequency interleaving; and transmitting the equalized signal of frequency domain diversity through a single carrier.

Abstract: A signal detection apparatus and method in a Multiple Input Multiple Output (MIMO) wireless communication system are provided. The apparatus includes a receiver for receiving training symbol vectors and a data signal vector from a transmitting end through a plurality of receive (Rx) antennas and a detector for expanding the training symbol vectors into second- or higher-order polynomials, for generating a weighting parameter vector for multivariate polynomial expansion of the data signal vector by using the polynomials expanded from the training symbol vectors and thereafter for expanding the data signal vector into a second- or higher-order multivariate polynomial using the weighting parameter vector, and for detecting Transmit (Tx) values of the data signal vector from the multivariate polynomial. Therefore, signal detection performance in a Multiple Input Multiple Output (MIMO) wireless communication system resembles that of a non-linear scheme while complexity resembles that of a linear scheme.

Abstract: A radio receiver has a multipath equalizer that includes a filter and a coefficient estimator. The filter provides a reconstructed signal by applying a transfer function including a reflection coefficient and a delay coefficient to a multipath radio signal. The coefficient estimator adapts the reflection coefficient and the delay coefficient in response to a deviation in magnitude of the reconstructed signal from a normalized value. In one form, the coefficient estimator adapts at least one of the reflection coefficient and the delay coefficient by estimating a partial derivative using a predetermined number of terms. In another form, the coefficient estimator acquires an initial value of the delay coefficient by determining a global minimum as a lowest one of a plurality of local minimums, each determined using a plurality of values of the delay coefficient, and selecting the initial value of the delay coefficient as its value at the global minimum.

Abstract: Teachings presented herein combine the relative simplicity of equalization with the performance of maximum likelihood (ML) processing. These teachings are applied to the detection of symbols in a stream of symbol blocks. In one or more embodiments, block-based equalization, including feedforward filtering, suppresses inter-block interference and produces detection statistics for the symbols in each symbol block, and joint detection addresses intra-block interference by jointly detecting the most likely combination of symbols within each symbol block, based on the corresponding detection statistics. The joint detection obviates the need to address intra-block interference within the equalization filters, while, at the same time, the block-based equalization produces detection statistics for each symbol block thereby simplifying the joint detection process.

Abstract: Apparatus, and an associated method, for the receive part of a receiving station, such as a mobile station or other transceiver of a cellular communication system. Selection is made of filter characteristics to be exhibited by an adaptive, input noise whitening filter. A noise estimator estimates a noise component of a noise sequence. An autocorrelation estimator estimates the noise-component autocorrelation. A determination is made as to whether the autocorrelation exceeds a threshold. If so, filter characteristics are selected to cause the input noise whitening filter to operate to inject whitening noise into the received sequence.

Abstract: A system and method for processing signals are disclosed. The method may include performing by one or more processors and/or circuits in a wireless device that includes a plurality of transmit and/or receive antennas for one or more of HSDPA, space-time transmit diversity (STTD), Closed Loop, Normal Mode and spatial multiplexing, the one or more processors and/or circuits comprising a minimum mean square error (MMSE) equalizer, generating a plurality of chip-rate synchronously sampled signals utilizing a plurality of received clusters. At least a portion of said generated plurality of chip-rate synchronously sampled signals may be simultaneously equalized in time domain and in spatial domain, based on a plurality of weight values calculated for the plurality of received clusters. The plurality of weight values may be iteratively computed utilizing a time-based adaptation method.

Abstract: A communications system receives a modulated communication signal that carries encoded communications data. A signal input receives the communication signal. An adaptive filter circuit is connected to the signal input and comprises N number of parallel adaptive filters. Each adaptive filter has non-adaptive and adaptive taps with weighted coefficients that are different in number from the respective other parallel adaptive filters within the adaptive filter circuit. A selection output circuit is connected to each adaptive filter and selects for output the adaptive filter having the most suppression or least output power or other criterion which can indicate a best choice to use of the N parallel adaptive filters. A demodulator demodulates the signal and a decoder receives the filtered output signal from the demodulator and decodes the signal to obtain the communications data.

Abstract: An apparatus and method for implementing an equalizer which (1) combines the benefits of a decision feedback equalizer (DFE) with a maximum-a-posterori (MAP) equalizer (or a maximum likelihood sequence estimator, MLSE) (2) performs equalization in a time-forward or time-reversed manner based on the channel being minimum-phase or maximum-phase to provide an equalization device with significantly lower complexity than a full-state MAP device, but which still provides improved performance over a conventional DFE. The equalizer architecture includes two DFE-like structures, followed by a MAP equalizer. The first DFE forms tentative symbol decisions. The second DFE is used thereafter to truncate the channel response to a desired memory of L1 symbols, which is less than the total delay spread of L symbols of the channel. The MAP equalizer operates over a channel with memory of L1 symbols (where L1<=L), and therefore the overall complexity of the equalizer is significantly reduced.

Abstract: Provided are a channel estimation device and an equalization device capable of achieving high channel estimation accuracy with less amount of calculation processing. The equalization device includes: a channel estimation section including a ZF calculation/clipping processing section and correlation processing section; a weight calculation section; and an equalization filter. The ZF calculation/clipping processing section uses a signal obtained by converting a pilot code into a frequency domain to calculate a pilot reference signal according to a Zero Forcing (ZF) method and clips the gain of the calculated pilot reference signal to a predetermined value to generate a clipped pilot reference signal. The correlation processing section performs correlation between a pilot reception signal in the frequency domain and clipped pilot reference signal to estimate channel characteristics of the frequency domain.

Abstract: A method for adaptive selection of floating taps in a decision feedback equalizer including the steps of (A) determining values for a predefined metric for tap positions within a range covered by a decision feedback equalizer (DFE) and (B) setting one or more floating taps of the DFE to tap positions based upon the values of the predefined metric.

Abstract: A coaxial network communication node receives multimedia content with one or more other nodes in a coaxial network. The node determines a delay-spread of a coaxial channel based on receipt of a probe from a transmitting node and configures a channel-shortening time-domain equalizer (TEQ) filter to effectively shorten the channel based on the delay spread. The node instructs the transmitting node to shorten a length of a cyclic prefix for subsequent packet-based transmissions to be received from the transmitting node. The probe is stored and reused until the channel-shortening TEQ filter converges. The nodes may be configured to communicate in accordance with the Multimedia over Coax Alliance (MoCA®) specifications.

Abstract: An equalizer. The equalizer, either operated in a blind mode or a decision directed mode, comprises a feed-forward filter, a feedback filter, a decision device, a control circuit, and a multiplexer. The feed-forward filter receives an input signal. The feedback filter filters an equalized signal. The combiner combines the feed-forward filtered signal and the feedback filtered signal. The decision device maps the combined signal to one symbol of a symbol set. The control circuit receives the combined output and generates a slice control signal. The multiplexer selects the combined signal or the mapped signal as the equalized according to the slice control signal when operated in the blind mode.

Abstract: The present invention has an object to provide a sampling filter apparatus and a wireless communication apparatus, which are capable of changing a filter characteristic without employing complex waveforms as control signals, and also, capable of performing filtering process operations without performing a decimation, while utilizing a wide frequency space. A sampling filter apparatus 100 includes a controller 140, a plurality of integrators 150 to 154, a plurality of switches 130, 160 to 164, 170 to 174, 180 to 184, and a plurality of voltage/current converters 120 to 123. An inputted current is stored in four pieces of integrators selected among the plurality of integrators 150 to 154 by one clock, and electric charges which have been stored from four preceding clocks up to one preceding clock are added to each other so as to output the added electric charges from the remaining one integrator.

Abstract: A system for removing low frequency offset distortion from a digital signal, the system comprising an analog-to-digital converter to convert an analog frequency signal associated with an optical storage medium to a digital frequency signal; an equalizer to equalize the digital frequency signal; an estimator to estimate a low frequency offset distortion of the digital frequency signal; a compensator to substantially cancel the low frequency offset distortion of the digital frequency signal from the equalized digital frequency signal using the estimate; and a decoder to decode the equalized digital frequency signal having the low frequency offset distortion substantially cancelled therefrom.

Abstract: An embodiment of the invention provides a single-ended polar transmitting circuit. The single-ended polar transmitting circuit comprises a DAC, a differential-to-single-ended converter, a GmC filter and a load. The GmC filter comprises two gain stages, two filters, two switching devices, a translinear loop and a current mirror. When a second clock signal is high, a first current is conducted through the load, a second switching device and a second gain stage. When a first clock signal is high, a second current is conducted through a first switching device and the second gain stage. The first gain stage has a transconductance Gm1 and the second gain stage has a transconductance Gm2. The bandwidth of the GmC filter is approximately equal to the square root of the quantity (Gm1*Gm2)/(C1*C2). The bandwidth of the GmC filter is substantially a constant value.

Abstract: The present invention relates to a communication system and method that allows a transmitter segment (ground end of uplink segment) to dynamically combine power from plurality of propagation channels (transponders) in order to improve power levels of signals being transmitted, without affecting the receiver segment (user end of downlink segment) and the propagation segment (space segment), and without modifying the configuration of the propagation apparatus (satellite). Specifically, the transmitter segment generates mixtures of input signals by using Wavefront-Multiplexing and transmits the wavefront-multiplexed (WFM) signals through propagation channels to a receiver segment that coherently separates the mixtures of received WFM signals by using adaptive equalization and Wavefront-De-Multiplexing.

Abstract: Circuits and methods for performing adaptive frequency compensation in a serial receiver coupled to a differential signal channel link are disclosed. In an exemplary embodiment, a receiver for signals over a serial channel link is provided including a linear equalization function. A data recovery circuit is coupled to the output of the receiver and receives frequency compensated analog signals. A digital feedback control circuit observes the digital output. A data accumulator circuit receives the output of a comparator and a signal indicating the data pattern observed in the digital data output. A digital filter receives the accumulator data and outputs control signals for modifying the linear equalization in a feedback loop. The receiver and linear equalization function are automatically and adaptively modified to provide frequency compensation. Methods for adaptively modifying the frequency response of a receiver and linear equalizer using digital feedback are disclosed.

Abstract: An apparatus for estimating and correcting baseband frequency error in a receiver is disclosed. An equalizer performs equalization on a sample data stream and generates filter tap values based on the equalization. An estimated frequency error signal is generated based on at least one of the filter tap values. A rotating phasor is generated based on the estimated frequency error signal. The rotating phasor signal is multiplied with the sample data stream to correct the frequency of the sample data stream. Alternatively, a channel estimator performs channel estimation and generates Rake receive finger weights based on at least one of the finger weights. An estimated frequency error signal is generated based on at least one of the finger weights.

Abstract: The present invention provides a cost-effective TEQ hardware architecture to support multiple VDSL2 profiles. It supports variable TEQ tap length programmable through firmware. Larger TEQ tap length at low-speed profiles is supported by the unique design without adding additional multipliers. The maximum number of TEQ taps supported is actually inversely proportional to the profile frequency. This perfectly meets the requirement to have longer TEQ for low-speed profile and shorter TEQ for high-speed profile.

Abstract: A receiver is provided that can receive a first signal transmitted on a first carrier and a second signal transmitted on a second carrier. The receiver includes a channel estimation portion, a multicarrier nonlinear equalizer, a first log likelihood computing portion and a second log likelihood computing portion. The channel estimation portion can output a first estimation. The multicarrier nonlinear equalizer can output a first equalized signal and a second equalized signal. The first log likelihood ratio computing portion can output a first log likelihood ratio signal based on the first equalized signal. The second log likelihood ratio computing portion can output a second log likelihood ratio signal based on the second equalized signal. The multicarrier nonlinear equalizer can further output a third equalized signal and a fourth equalized signal. The third equalized signal is based on the first signal, the second signal and the first estimation.

Abstract: Methods and apparatus are provided for determining receiver filter coefficients for a plurality of phases. One or more coefficients for a receiver filter are determined by determining a first coefficient for a first phase of a data eye; and determining a second coefficient for a second phase of the data eye. The receiver filter may be, for example, a decision-feedback equalizer. The first and second coefficients may be determined by performing an LMS adaptation of decision-feedback equalization coefficients. In another embodiment, the first and second coefficients may be determined by obtaining eye opening metrics from a data eye monitor corresponding to each of the respective first phase and the second phase; and determining the respective first and second coefficients based on the eye opening metrics. The first and second phases can correspond to odd and even phases.

Abstract: An equalizer includes: a replica generation means for generating a replica of a multipath component by applying an adaptive filter to a received signal; a removal means for generating a multipath-component removed signal from which the multipath component has been removed by subtracting the replica from the received signal; a correlation value calculation means for calculating a correlation value between the received signal and the replica; a power value calculation means for calculating a power value of the replica; a determination means for determining whether the replica is the replica of the multipath component based on the correlation value and the power value; and a selection means for outputting the multipath-component removed signal when it is determined that the replica is the replica of the multipath component, and outputting the received signal when it is determined that the replica is not the replica of the multipath component.

Abstract: A process for equalizing streams of OFDM subcarrier data computes the noise variance for each stream, and forms a stream weighting coefficient by equalizing the noise variance, such that for a first stream having a noise variance ?1 and a second stream having a noise variance of ?2, the first stream is scaled by k 1 = 2 ? ? 2 ? 1 2 + ? 2 2 and the second stream is scaled by k 2 = 2 ? ? 1 ? 1 2 + ? 2 2 .

Abstract: An agile RF tuner circuit capable of converting a wide portion of RF signal into an IF signal suitable for analog-to-digital conversion. The circuit up converts a received RF signal to a high IF signal and then down converts the high IF signal to a low IF signal. Embodiments of the RF circuit incorporate harmonic reject mixers to suppress harmonies and intermodulations typically associated with the frequency conversion process.

Abstract: A digital broadcast transmitting/receiving system and a signal processing method thereof that can improve the receiving performance of the system. A digital broadcast transmitter has a randomizer to randomize an input data stream which has null bytes being inserted at a specified position, a multiplexer to output a data stream formed by inserting specified known data into the position of the null bytes of the randomized data stream, an encoder to encode the data stream outputted from the multiplexer, and a modulator/RF-converter to modulate the encoded data, RF-convert the modulated data and transmit the RF-converted data. The receiving performance of the digital broadcast transmitting/receiving system can be improved even in a multi-path channel by detecting the known data from the received signal and using the known data in synchronization and equalization in a digital broadcast receiver.

Abstract: Techniques to facilitate estimating the frequency response of a wireless channel in an OFDM system are provided. The method and systems allow for combining signal information across multiple communication channels at one or more channel tap delays in order to determine appropriate taps for channel information.

Abstract: A communications system receives a modulated signal that carries encoded communications data. An adaptive filter circuit has a plurality of adaptive filters each having a plurality of non-adaptive and adaptive filter taps with weighted coefficients. At a selected adaptive filter, an interference reduction circuit is responsive to one of at least a received state of a demodulator, the type of modulation used by communication system and the input and output power of adaptive filter for updating the adaptive gain of the adaptive filter, selecting the number and order of adaptive filter taps, separating the spacing of multipath introduced by adaptive filter, controlling input and output normalizing circuits to adaptive filter(s) and selecting if signal passed to demodulator is original received signal or signal output by adaptive filter. A demodulator and decoder receive the filtered output signal and demodulate and decode the signal to obtain the communications data.

Abstract: An equalizer for a multi carrier signal for carrying out equalization adapted to each carrier or group of carriers, Fourier transforms the multi carrier signal, and obtains difference terms of the multi carrier signal. Both are input to an adaptive filter, to output equalized signals, wherein decimation is applied to at least some of the difference terms input to the filter. This enables the complexity to be reduced for a given performance level. In particular since only non-zero filter taps need to be stored and updated, coefficient memory and coefficient calculation capacity can be reduced. Another way to reduce complexity involves measuring noise for at least some of the carriers, and dynamically adapting the size of the filter on a per carrier basis according to global optimizion heuristic algorithms which adapt this filter size based on the comparison between this noise and an optimal performance figure achieved in a previous ISI-ICI free measurement phase.

Abstract: A multi-input multi-output (MIMO) radio communication apparatus and method are provided. The MIMO apparatus includes a plurality of reception antennas each having a plurality of antenna patterns; a channel matrix estimation unit for estimating a channel matrix between a plurality of transmission antennas and the plurality of reception antennas; a channel capacity calculation unit for calculating a channel capacity corresponding to a combination of antenna patterns of the plurality of reception antennas by using the estimated channel matrix; and an antenna pattern control unit for changing the antenna patterns of the plurality of reception antennas to maximize the channel capacity. According to the MIMO radio communication apparatus and method, direction can be controlled adaptively to a propagation environment.

Abstract: An apparatus generally having a first circuit and a second circuit. The first circuit may be configured to (i) generate an equalizer parameter in response to an input signal, the equalizer parameter causing a cancellation of post-cursor inter-symbol interference from a plurality of symbols in the input signal and (ii) generate an output signal in response to both the input signal and the equalizer parameter. The second circuit may be configured to (i) generate a target parameter signal in response to the input signal, the target parameter signal representing a mean value of a plurality of sample points of the symbols and (ii) generate a control signal in response to the target parameter signal, the control signal causing a reduction of the equalizer parameter, the reduction causing a decrease in the cancellation of the post-cursor inter-symbol interference from the symbols, wherein the apparatus does not cancel pre-cursor inter-symbol interference.

Abstract: A communications system receives a modulated signal that carries encoded communications data. An adaptive filter has a plurality of non-adaptive and adaptive filter taps with weighted coefficients and a input and output normalizing circuit that obtain sample values from a received signal input to or output from the adaptive filter to increase gain recovery based on type of modulation of encoded communication data, on state of demodulator (preamble search, preamble detected, data state) or other signal acquisition information. A demodulator and decoder receive the filtered output signal and demodulate and decode the signal to obtain the communications data.

Abstract: A method to receive a signal transmitted over a transmission link comprising coded channels, the method comprising: —equalization operations (110-116) to compensate for signal distortion introduced by the transmission link in a signal burst, and—block decoding operations (120-126) to perform channel decoding operation from the equalized signal bursts. If one of the block decoding operations has not been executed before a predetermined time limit, the method comprises at least one step (146) of discarding one of the next burst equalization operations.

Abstract: A method and apparatus for providing a single-chip digital multimedia receiver for multi-channel/multi-tuner rendering comprising receiving multiple independently encoded input streams on a system-on-a-chip, and independently locking each video output to a corresponding input channel, to ensure that each video and audio output has a clock matched to an encoder clock.

Abstract: A method for communication includes receiving signals at a receiver from multiple sources, including a target signal transmitted by a given transmitter, and estimating a channel response from the given transmitter to the receiver. A filter response is computed by taking a sum including a first autocorrelation of the received signals with a second autocorrelation of the channel response, and applying the sum to the estimated channel response. The filter response is applied to the received signals in order to recover the target signal.

Abstract: A communications system receives a modulated signal that carries encoded communications data. An adaptive filter has a plurality of non-adaptive and adaptive filter taps with weighted coefficients and an adaptive gain circuit for updating the adaptive gain of the adaptive filter responsive to a received state of a modem or the type of modulation used by communications system. A demodulator and decoder receive the filtered output signal from the adaptive filter and demodulate and decode the signal to obtain the communications data.

Abstract: A correction coefficient calculating section 20 calculates a correction coefficient ? so as to obtain a noise power equivalent to detected path and adjacent path transmission channel estimation values. A noise power correcting section 21 calculates a corrected noise power ?N0. A weight calculating section 8 receives as its input a frequency-domain transmission channel estimation value H(f) being an output of an FFT section 7 and the noise power ?N0 corrected by the noise power correcting section 21 and calculates a weight of an equalization filter by MMSE.

Abstract: An apparatus, computer software, and method for data detection in channels suffering from intersymbol interference comprising receiving a signal representative of a binary digit of data, computing a reliability score for that binary digit of data via windowed Chase equalization, and based on the reliability score, causing a signal to be output that the binary digit is a zero or a one.

Abstract: In accordance with a method for processing a received orthogonal frequency division multiple access (OFDMA) signal that comprises a duplicated signal, sub-carriers within the OFDMA signal may be arranged into a duplicated format. The OFDMA signal may be equalized and combined after the sub-carriers have been arranged into the duplicated format. The equalizing and combining may be performed in accordance with a maximum ratio combining (MRC) scheme. The OFDMA signal may be demapped after the equalizing and combining is performed.

Abstract: A portable communications device communicates based upon constant envelope orthogonal frequency-division multiplexing (CE-OFDM). The portable communications device may include an antenna for receiving a CE-OFDM signal, and a receiver coupled to the antenna. The receiver may include a frequency domain equalizer (FDE) operating based upon a channel estimate of the received CE-OFDM signal, a non-linear function block coupled to and downstream from the FDE, and a demodulation correction block coupled to and downstream from the non-linear function block for correcting an output of the non-linear function block.

Abstract: A system having a filter is disclosed. One embodiment includes at least two polyphase filter branches, each of the polyphase filter branches including a respective recursive allpass filter, wherein the filter approximates a linear filter.

Abstract: Methods and systems for a quadrature local oscillator generator utilizing a DDFS for extremely high frequencies. Aspects of one method may include utilizing the DDFS to generate a first signal that may comprise an in-phase (I) component and a quadrature phase (Q) component. A base signal may be divided to generate a second signal with an in-phase (I) component and a quadrature phase (Q) component. The I and Q components of the first and second signals may be mixed by a plurality of mixers, and the outputs of the mixers may be combined to generate an in-phase component of a local oscillator signal and a quadrature phase component of the local oscillator signal. The frequency of the local oscillator signal may be controlled by inverting or not inverting outputs of one or more of the mixers.

Abstract: A decision feedback equalizer (DFE) and method including a branch coupled to an input and including a sample-and-hold element configured to receive and sample a received input signal from the input and a current-integrating summer. The current-integrating summer is coupled to an output of the sample-and-hold element. The summer is configured to receive and sum currents representing at least one previous decision and an input sample. The at least one previous decision and the input sample are integrated onto a node, wherein the input sample is held constant during an integration period, thereby mitigating the effects of input transitions on an output of the summer.

Abstract: The present invention provides a system and method for performing ranging operations in a able modern system. In accordance with embodiments of the present invention, transmission times, transmission power levels, transmission carrier frequencies, and pre-equalization parameters are adjusted to provide for robust operation of the cable modem system. More particularly, iterative processing steps are used to provide coefficient ordering, scaling, and aligning between the multiple cable modems and the cable modem termination system present in a cable modern system.

Abstract: A receiver comprises an adaptive filter having an input for a digitized input signal, means for storing a pre-designed filter characteristic, means for analyzing a digital representation of the input signal to determine a desired position of the filter characteristic to match the system requirements, and means for adapting the stored pre-designed filter characteristic in the frequency domain and/or the time domain to match the system requirements and for transforming the adapted filter characteristic to the time domain to update coefficients for the adaptive filter and for loading updated coefficients into adaptive filter. The updating of the coefficients may be done periodically. The adaptation may be one or more of adjusting bandwidth, frequency shift and, in the case of a bandpass characteristic, superimposing characteristics.

Abstract: A diversity receiver includes a first RF front end module for receiving a first RF signal, and frequency converting the first RF signal and outputting a first diversity signal, a second RF front end module for receiving a second RF signal, frequency converting the second RF signal and outputting a second diversity signal, a first converter for converting the first diversity signal to a first time-domain signal, a second converter for converting the second diversity signal to a second time-domain signal, a first transformer for translating the first time-domain signal to a first frequency-domain signal, a second transformer for translating the second time-domain signal to a second frequency-domain signal, a first pre-equalizer for equalizing the first frequency-domain signal, a second pre-equalizer for equalizing the second frequency-domain signal, and a combiner for combining the first and second pre-equalized frequency-domain signals.

Abstract: A signaling system includes a pre-emphasizing transmitter and an equalizing receiver coupled to one another via a high-speed signal path. The receiver measures the quality of data conveyed from the transmitter. A controller uses this information and other information to adaptively establish appropriate transmit pre-emphasis and receive equalization settings, e.g. to select the lowest power setting for which the signaling system provides some minimum communication bandwidth without exceeding a desired bit-error rate.

Abstract: Systems and techniques for adapting and/or optimizing an equalizer of a receiver are described. The equalizer's behavior can be adjusted by modifying one or more equalization parameters. At the beginning of the adaptation and/or optimization process, the system can determine robust initial values for the one or more equalization parameters. The system can then adapt and/or optimize the equalizer by iteratively adjusting the one or more equalization parameters. Specifically, in each iteration, the system can use the receiver's clock and data recovery (CDR) circuitry to determine the number of early and late data transitions associated with one or more data patterns. Next, the system can adjust the one or more equalization parameters so that, for each data pattern in the one or more data patterns, the ratio between the number of early data transitions and the number of late data transitions is substantially equal to a desired value.

Abstract: In accordance with the teachings described herein, an extended equalizer circuit is provided for equalizing a digital communication signal transmitted over a transmission medium that causes a frequency-dependent attenuation of the digital communication signal. An equalizer may be used that includes a linear equalization circuit and a non-linear equalization circuit, the linear equalization circuit being configured to apply a linear filter to the digital communication signal to compensate for the frequency-dependent attenuation caused by a first portion of the transmission medium, and the non-linear equalization circuit being configured to apply one or more non-linear operations to the digital communication signal.