Abstract: Methods and apparatus are provided for performing equalization of communication channels. In an embodiment of the invention, at least one tap can be selected from a set of feedforward taps of feedforward filter circuitry, where each tap of the selected at least one tap has a magnitude that is greater than or substantially equal to a magnitude of any tap of the set of feedforward taps that is not in the selected at least one tap. In addition, at least one tap can be added to a set of taps of feedback filter circuitry in communication with the feedforward filter circuitry. The invention advantageously allows for more efficient and reliable equalization of communication channels.

Abstract: A receiver is provided for a quadrature-modulated signal, which can be divided into an inphase signal and a quadrature signal. The inphase signal is fed to first and third equalizers, and the quadrature signal is fed to second and fourth equalizers, wherein the first and second equalizers each perform a first equalization of the respective signal. An output of the first equalizer is connected to a second input of the fourth equalizer, which, by means of a second equalization of the quadrature signal, transmits an equalized quadrature signal as a function of the previously fed equalized inphase signal of the first equalizer. An output of the second equalizer is connected to the second input of the third equalizer, which, through a second equalization of the inphase signal, transmits an equalized inphase signal as a function of the previously fed equalized quadrature signal of the second equalizer.

Abstract: A reception circuit includes: a sampling circuit to sample an input data signal based on a clock signal and output a sampled signal; a data interpolation circuit to interpolate the sampled signal based on phase information corresponding to the sampled signal and output an interpolated data signal; an interpolation error decision circuit to output an interpolation error based on the sampled signal and the phase information; a decision/equalization circuit to equalize the interpolated data signal using an equalization coefficient set based on the interpolation error, to check an equalized interpolated data signal and to output a checked signal; and a phase detection circuit to generate the phase information based on at least one of the checked signal and the equalized interpolated data signal and output the phase information to the data interpolation circuit and the interpolation error decision circuit.

Abstract: A method of wireless communication with improved performance employs an equalizer receiver with multiple receive antennas. Equalizer taps for linear filters of the equalizer receiver are generated by determining a conditioned covariance matrix of a first data path and a second data path based on a first gain (g0) of this first data path and a second gain (g1) of the second data path. The equalizer taps of the first data path and the second data path are determined based on the conditioned covariance matrix. The first data path and the second data path are then equalized using the equalizer taps. An equalized signal is generated by combining the equalized first data path with the equalized second data path.

Abstract: A programmable logic device is provided with adaptive equalization circuitry that is programmable in one or more respects. Examples of the programmable aspects of the equalization circuitry are (1) the number of taps used, (2) whether integer or fractional spaced taps are used, (3) what starting values are used in the computation of coefficient values, (4) whether satisfactory coefficient values are computed only once or on an on-going basis, (5) whether an error signal is generated using a decision directed algorithm or using a training pattern, (6) what training pattern (if any) is used, and/or (7) the location of the sampling point in the bit period of the signal to be equalized.

Abstract: A filter weight estimation device (D), for an equaliser of a communication receiver, comprises i) a tap delay line connected to N branches each comprising a descrambler (DS1-DSN) and a despreader (DE1-DEN), for despreading received signals, corresponding to one or more available multiplexed channels associated with different channelization codes, with a reference code equal to the sum of all the channelization codes associated to the available multiplexed channels, Ë) an adaptive filter (AF) comprising N input filter taps respectively connected to the N branches and a regression input and arranged to estimate the sum of the symbols outputted by the despreaders (DE1-DEN) and associated to each available channel, said symbol sum constituting a pseudo-symbol estimate defining a reference symbol estimate (rs), and to implement a mechanism of a LMS type to deliver a chosen number of filter weights (fi), iË) a quantiser (SM) arranged to quantise the reference symbol estimate (rs) to estimate a desired reference sym

Abstract: A receiver in which computation is simplified can be obtained by using a common factor for filter coefficients of FIR filters corresponding to a plurality of transmitting antennas and by using only the middle column of an inverse matrix of a gain matrix when the common factor is computed.

Abstract: A system and apparatus for compensating cable losses in a video signal transmission system includes feedback circuits to determine the spectral attenuation of a received signal and to control an equalizer circuit to amplify selected frequencies of the received signal, and to determine the various times of arrival of two or more video signals and selectively adjust one or more delay lines to reduce the differences in their arrival times.

Abstract: An on-die scope is described. The on-die scope can include one or more scope slicers, phase sweeping circuitry, voltage sweeping circuitry, and eye-diagram data collection circuitry. The clock and data recovery circuitry can receive an input signal, and output a recovered clock signal and a recovered bit-stream. The phase sweeping circuitry can receive the recovered clock signal, and output the scope clock signal by adding a phase offset to the recovered clock signal. A scope slicer can receive the voltage threshold, the scope clock signal, and the input signal, and output a scope bit-stream. The eye-diagram data collection circuitry can detect one or more bit-patterns in the recovered bit-stream, and modify values of one or more scope counters based solely or partly on the scope bit-stream and the recovered bit-stream.

Abstract: An apparatus and method for orthogonal frequency division multiplexing (OFDM) channel equalization are disclosed. The apparatus includes a compensation value setting unit setting a compensation value in the form of a diagonal matrix by use of a diagonal matrix of diagonal elements extracted from a channel matrix of an OFDM receiver, and a preset divergence suppression value, an initial estimation value calculation unit calculating an initial estimate value by use of a fast Fourier transform (FFT)-processed signal of the OFDM receiver and the compensation value, an equalization unit detecting a transmission signal to be processed by use of the compensation value, the channel matrix and the diagonal matrix, and a symbol decision unit determining a symbol for an adjacent signal of a transmission signal, which is to be processed among a plurality of signals output from the equalization unit, and providing the symbol-determined adjacent signal to the equalization unit.

Abstract: An embodiment for wirelessly communicating a signal includes a transmitter combining a plurality of phase shifted input data signals with a plurality of synchronization/pilot sequences to produce a plurality of combined signals, performing frequency domain-to-time domain transformations of the combined signals to produce a plurality of candidate signals, determining peak-to-average ratios for at least some of the plurality of candidate signals, identifying a selected signal from the plurality of candidate signals based on the peak-to-average ratios, and transmitting the selected signal over a wireless communication channel.

Abstract: A communication signal receiver includes a feed-forward filter and a coefficient adjusting circuit. The feed-forward filter generates an estimated imaginary-part component signal according to a real-part component of a complex data signal by using tap coefficients of the feed-forward filter. The coefficient adjusting circuit adjusts the tap coefficients of the feed-forward filter according to a control information, wherein the control information comprises a phase error information. The phase error information changes as a phase of the complex data signal changes, wherein the phase is adjusted or not adjusted by the coefficient adjusting circuit.

Abstract: A receiver circuit is described. In the receiver circuit, an analog-to-digital converter (ADC) generates first samples of a data signal based on a first clock signal, and a clock-data-recovery (CDR) error-detection circuit generates second samples of the data signal based on a second clock signal. In addition, the CDR error-detection circuit estimates intersymbol interference (ISI) at a current sample in the second samples from an adjacent, subsequent sample in the second samples. Based on the second samples and the estimated ISI, a CDR circuit generates the first clock signal and the second clock signal, which involves modifying the skews of either or both of these clock signals so that the current sample is associated with a zero crossing of a pulse response of a communication channel from which the data signal was received, thereby reducing or eliminating the ISI from the adjacent, subsequent sample.

Abstract: The present invention discloses an OFDM signal demodulation method and device thereof.

Abstract: A device includes a semiconductor die having a surface, a plurality of proximity connectors proximate to the surface, and a circuit coupled to at least one of the plurality of proximity connectors. The semiconductor die is configured to communicate voltage-mode signals through capacitive coupling using one or more of the plurality of proximity connectors. The circuit also includes a filter with a capacitive-summing junction to equalize the signals.

Abstract: A communication system comprises a receiver, which may generate broadcast coefficients that represent the characteristics of a channel using the channel information encoded in the segment synchronization units. The receiver may also use the channel information encoded in both the segment synchronization units and the field synchronization units to accurately determine the characteristics of a long channel.

Abstract: A method for communication includes receiving signals at a receiver from one or more sources, including a target signal transmitted by a given transmitter. A channel response is estimated from the given transmitter to the receiver, and a filter response is computed by taking a sum of an autocorrelation of the received signals with an adaptive noise factor, 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 method and apparatus for calibrating an equalizer. The method comprises the steps of defining one or more equalization parameters and calculating a bit error rate of a signal for one or more values of a first of the one or more equalization parameters by counting at least one of running disparity errors and incorrect symbol errors. A value for the first of the one or more equalization parameters which provides the lowest bit error rate is set.

Abstract: A method, and circuitry, for choosing the correct equalization curve in adaptive equalization uses a feedback loop in which the incoming high-speed serial data are digitized and deserialized for use in the remainder of the device, and also are used by an adaptive state machine to both extract the reference levels for digitization and to control the equalization curve. Detection of the reference level and selection of the equalization curve may be performed at a different rates to avoid interfering with one another. The state machine preferably is programmable. This is useful in any device, but is particularly well-suited for a programmable device, such as a PLD or other programmable integrated circuit device, where conditions may vary according a user logic design.

Abstract: A receiver is described including circuitry for deriving at least a first stream of first digitized samples from a received analog signal at a first sampling rate, circuitry for selecting a first sampling point and at least a second sampling point, a demodulator for demodulating first and second symbols from the at least first stream of samples based on the first and the at least second sampling points, and circuitry for determining a value related to a demodulation accuracy for the first and second symbols and for outputting a signal, the circuitry for selecting being adapted to alter the sampling point based on the signal. By assessing a demodulation accuracy in real time clock drift can be compensated. The demodulation accuracy can be a value related to a phase error or an error energy such as EVM or DEVM for each demodulated symbol.

Abstract: Provided is an apparatus for channel equalization in frequency domain, including: a channel estimation unit for estimating a channel on received signal from outside, a channel matched filter for changing channel characteristic of the channel estimated by the channel estimation unit and the received signal to channel characteristic to meet condition required for noncausal filtering, a noncausal filter for changing the channel characteristic changed by the channel matched filter from nonminimum phase channel to minimum phase channel, a reverse channel calculation unit for calculating a reverse of the channel changed by the noncausal filter in frequency domain, and a frequency domain equalization unit for performing channel equalization with respect to the channel changed by the noncausal filter in the frequency domain by using the reverse obtained by the reverse channel calculation unit as coefficients of the frequency domain equalization apparatus.

Abstract: A signaling system is described. The signaling system comprises a transmit device, a receive device including a partial response receive circuit, and a signaling path coupling the transmit device and the receive device. The receive device observes an equalized signal from the signaling path, and includes circuitry to use feedback from the most recent previously resolved symbol to sample a currently incoming symbol. The transmit device equalizes transmit data to transmit the equalized signal, by applying weighting based on one or more data values not associated with the most recent previously resolved symbol value.

Abstract: A method for modulating a sequence of data symbols such that the transmit signal exhibits spectral redundancy. Null symbols are inserted in the sequence of data symbols such that a specified pattern of K data symbols and N?K null symbols is formed in every period of N symbols in the modulated sequence, N and K being positive integers and K being smaller than N.

Abstract: The invention refers to an equalizer system for emitting a quasi-constant power output RF signal in a first frequency band, the system comprising a programmable RF signal generator (10) for providing a modulated signal; a variable gain amplifier (40) for receiving the modulated signal and generating a RF signal to an antenna (70). The system further comprises a sensing devices (60, 61, 62) for providing a sensing signal which is either a signal proportional with the RF signal or a signal proportional with a supply current of the variable gain amplifier and a user interface (110) for determining an initial RF frequency signal and adjusting circuit (100) for providing a control signal to the variable gain amplifier (40) based on the initial RF frequency signal and the sensing signal, the adjusting circuit (100) comprising an arithmetic unit for calculating a value of the control signal.

Abstract: An equalizing filter circuit includes a first transmission line in which a plurality of first delay devices 104a are connected in cascade to input terminal 101, a second transmission line in which a plurality of second delay devices 107a are connected in cascade to output terminal 102, a plurality of weighting circuits 105a connected in parallel between the first transmission line and the second transmission line and having a gain which is adjustable by setting coefficients, and variable adjusting circuit 108a arranged at the output side of at least one of weighting circuits 105a for correcting a fluctuation of the output characteristics of the weighting circuits.

Abstract: The present invention is intended to realize a transmitter whose internal signal processing function can be duplicated without having to add any hardware components. The transmitter converts an input signal into an output signal using a plurality of calculation steps, comprising a backward calculation means for executing the plurality of calculation steps in reverse direction.

Abstract: Disclosed herein is a reception apparatus including a calculation section and a storage section. The calculation section calculates correlation values between a data sequence included in a known signal and a received signal at a given point in time. The storage section has at least an area sufficient for storing the correlation values calculated for one frame using the received signal which is one frame long and to which the known signal is added.

Abstract: An apparatus and a method for interference cancellation in a Multiple Input Multiple Output (MIMO) wireless communication system. The method for interference cancellation includes equalizing first reception signals received through two or more reception antennas to estimate transmission signals transmitted through two or more transmission antennas, generating two or more second reception signals in which a mutual interference between the transmission signals is removed from the first reception signals by using the estimated transmission signals, independently equalizing the generated two or more second reception signals, and combining the independently equalized two or more second reception signals to estimate a transmission signal in which an interference is removed.

Abstract: Tap coefficients of an FIR filter are prevented from converging to wrong values. A waveform equalizer for performing waveform equalization of an input signal and outputting a waveform equalization result as an output signal includes: an FIR filter for performing a convolution operation between the input signal and a plurality of tap coefficients; an IIR filter for performing a convolution operation between the output signal and a plurality of tap coefficients; an adding section for adding an operation result of the FIR filter and an operation result of the IIR filter and outputting an addition result as the output signal; an error detecting section for detecting an error of the output signal; and a tap coefficient updating section for updating respective tap coefficients of the FIR filter and the IIR filter based on the error.

Abstract: By assigning a plurality of subcarriers 31 to a data channel 33 and assigning fewer subcarriers 32 than the plurality of subcarriers 31 to a control channel 34 and, in addition, locating the control channel 34 at the center frequency fc of a frequency band used to transmit the data channel 33, on the radio receiving apparatus side, the frequencies of a local signal by which the received signal is multiplied share the same value, thereby speeding up the switching between the control channel and the data channel.

Abstract: For eigenmode transmission with minimum mean square error (MMSE) receiver spatial processing, a transmitter performs spatial processing on NS data symbol streams with steering vectors to transmit the streams on NS spatial channels of a MIMO channel. The steering vectors are estimates of transmitter steering vectors required to orthogonalize the spatial channels. A receiver derives a spatial filter based on an MMSE criterion and with an estimate of the MIMO channel response and the steering vectors. The receiver (1) obtains NR received symbol streams from NR receive antennas, (2) performs spatial processing on the received symbol streams with the spatial filter to obtain NS filtered symbol streams, (3) performs signal scaling on the filtered symbol streams with a scaling matrix to obtain NS recovered symbol streams, and (4) processes the NS recovered symbol streams to obtain NS decoded data streams for the NS data streams sent by the transmitter.

Abstract: An apparatus is disclosed to compensate for non-linear effects resulting from the transmitter, the receiver, and/or the communication channel in a communication system. A receiver of the communication system contains an image cancellation module that compensates for images generated during the modulation and/or demodulation process. The image cancellation module includes a fine carrier correction loop to correct for frequency offsets between the transmitter and receiver. The image cancellation module includes a coarse acquisition mode and a decision directed mode. The decision directed mode allows for a larger signal-to-noise ratio for the receiver when compared against the coarse acquisition mode.

Abstract: A non-linear detector for detecting signals with signal-dependent noise is disclosed. The detector may choose a data sequence that maximizes the conditional probability of detecting the channel data. Since the channel may be time-varying and the precise channel characteristics may be unknown, the detector may adapt one or more branch metric parameters before sending the parameters to a loading block. In the loading block, the branch metric parameters may be normalized and part of the branch metric may be pre-computed to reduce the complexity of the detector. The loading block may then provide the branch metric parameters and any pre-computation to the detector. The detector may then calculate the branch metric associated with the input signal and output the channel data.

Abstract: Received signal measurements are calibrated in a communication device by measuring a received signal level for each of one or more subcarriers of a transmitted signal received from another communication device, converting the measured received signal level for each of the one or more subcarriers into a corresponding measured power level, estimating a terminal-to-terminal impedance between the communication devices and calculating a corrected power level for each of the one or more subcarriers as a function of the measured power level for the subcarrier, a known reference input impedance for the communication device and the estimated terminal-to-terminal impedance.

Abstract: An asymmetric DFE receiver circuit is disclosed. The receiver circuit includes a voltage measuring unit configured to determine a signal voltage of a received signal, and a comparator unit configured to calculate a difference between the signal voltage and an evaluation threshold voltage and to compare the difference to the value of a midpoint voltage. The comparator unit is configured to generate a first control signal if the difference is greater than the midpoint voltage value or a second control signal if the signal voltage is less than the midpoint voltage value. The receiver includes an adjustment circuit configured to adjust the evaluation threshold voltage toward the signal voltage if the first control signal is generated and away from the signal voltage if the second control signal is generated. The rates of adjustment may vary depending upon whether the received signal is a transition bit or a non-transition bit.

Abstract: An adaptive cable equalizer includes a data signal input unit, a clock signal input unit, a variable equalizer that inputs a data signal input from the data signal input unit, and a transition time measuring portion that measures a transition time of a data signal output from the variable equalizer, with an equalizer control loop being configured that controls characteristics of the variable equalizer based on the output signal of the transition time measuring portion. The adaptive cable equalizer further includes a control circuit that controls response characteristics of the control loop according to the frequency of a clock signal input from the clock signal input unit. This enables a quick response at fast transfer rates by making the relationship between the response time of the control loop and the number of data bits substantially constant even when the transfer rate changes from a slow transfer rate to a fast transfer rate.

Abstract: A filter is created by sampling noise during an inter-frame gap (110) of a received signal, sampling a data frame preamble (115) from within a data frame (105) of the received signal, and computing filter coefficients based on the noise sampled during the inter-frame gap (110) and the data frame preamble (115) sampled from within the data frame (105).

Abstract: In connection with transmitted space-time, trellis encoded, signals that pass through a transmission channel that is characterized by memory, improved performance is realized with a receiver that combines a decoder with an equalizer that selects the trellis transition, s, that minimizes the metric ? j ? ( k ) = ? r ? ( k ) - ? l = 0 L 1 ? h ~ j ? ( l ) ? s ~ ? ( k - l ) - ? l = L 1 + 1 L + 1 ? h ~ j ? ( l ) ? s ^ ? ( k - l ) ? 2 where {tilde over (h)}j(l) is related to both the transmission channel and to the encoding structure in the transmitter, {tilde over (s)}(k) are the (trial) symbols according to a certain transition and ?(k) are the symbols that were previously decided.

Abstract: A multi-mode receiver system for processing signals based on a plurality of systems is disclosed. Embodiments of the invention provide for a shared architecture for processing baseband signals corresponding to a plurality of systems.

Abstract: An efficient baseband predistortion linearization method for reducing the spectral regrowth and compensating memory effects in wideband communication systems using effective multiplexing modulation technique such as wideband code division multiple access and orthogonal frequency division multiplexing is disclosed. The present invention is based on the method of piecewise pre-equalized lookup table based predistortion, which is a cascade of a lookup table predistortion and piecewise pre-equalizers, to reduce the computational complexity and numerical instability for desired linearity performance with memory effects compensation for wideband transmitter systems.

Abstract: A semiconductor integrated circuit equipped with an equalizer which has a circuit structure simpler than that of a related equalizer according to an FFE scheme or a DFE scheme and is capable of preventing a noise component from being amplified. The data receiver includes a plurality of receiver units, wherein each receiver unit includes a plurality of level detectors which detect different levels, and an encoder, in which the level detectors receive data according to a clock signal having a predetermined phase difference and perform an amplification operation including an equalization function based on feedback data, thereby outputting an amplification signal, and wherein level detectors of one receiver unit receive an amplification signal, as the feedback data, from level detectors of another receiver unit that receives a first clock signal having a phase more advanced than a phase of a second clock signal received in one receiver unit.

Abstract: A receiver and a method to process signals from one or more transmission sources. The receives includes a front-end having: an input coupling path to route an analog input signal received from one or more transmission sources; an equalizer to generate an equalized signal from the analog input signal; and an ADC to generate a digitized signal from the equalized signal. The method includes routing the analog input signal through an input coupling path; equalizing the analog input signal to generate an equalized signal therefrom; and digitizing the equalized signal to generate a digitized signal therefrom.

Abstract: A close-loop power calibration algorithm is performed on a wireless communication device to correct power amplifier pre-distortion or PADR correction curves. In addition to peak to average power ratio or PAPR detection techniques, an algorithm or process is implemented that uses a transmitted reference packet, such as an orthogonal frequency domain multiplexing (OFDM) packet. The reference packet is used to learn the linear response of a detector that measures output of the power amplifier. The transmitted packet can include a linear response. The included linear response can determined by subtracting a normal packet from the reference packet.

Abstract: A method for inverting telecommunication channel distortion by adaptive wavelet lifting. The distortion signal is analyzed using wavelet lifting and the inverse filter is computed. Coefficients of the inverse filter are used to either compute a transmission pre-filter or to update the transmitted message.

Abstract: A transmission line equalizer includes multiple signal paths connected in parallel between an equalizer input signal and an output amplifier where each signal path has a network implementing a specific frequency dependent response and each signal path implements current gain amplification with one or more of the signal paths having a variable gain programmed through a time invariant, DC programming signal. Furthermore, one or more of the signal paths implements linear-to-nonlinear signal transformations and compensating nonlinear-to-linear signal transformations to generate linearized output signals at the one or more signal paths. The equalizer further includes the output amplifier summing output signals from the multiple signal paths to generate an equalized output signal. In operation, the gain of the one or more signal paths is varied to establish the relative proportions of the output signals generated by each signal path and summed at the output amplifier.

Abstract: A method and device for compensating for undesirable signal characteristics such as baseline wander that includes a linear equalization filter responsive to receive an input, a combiner responsive to an output of the linear equalization filter, and a decision feedback equalization filter responsive to an output of the combiner, where the combiner is further responsive to an output of the decision feedback equalizer. Additionally, an error feedback circuit is responsive to the output of the combiner, and the combiner is further responsive to an output of the error feedback circuit to form a compensated signal having reduced distortion relative to the distorted signal.

Abstract: A scheme for deducing a DC offset in a received signal burst acquired through a particular channel, wherein the received signal burst corresponds to a transmitted signal burst. An impulse response estimate of the channel is used to model how a known or recovered part of the transmitted burst would have been affected by passage through said channel in place of the corresponding part of the transmitted signal burst. The modelled part of the transmitted burst is then compared with the corresponding part of the received signal burst to deduce a DC offset present in the received signal burst.

Abstract: A multi-tone system includes a data transmission circuit with an interface for receiving a data stream for transmission, a data steam splitter that splits the data stream to produce multiple substreams and a plurality of parallel data preparation circuits. Each data preparation circuit prepares a respective substream for transmission and generates a respective sub-channel signal. At least a first data preparation circuit of the plurality of parallel data preparation circuits includes a first analog filter for filtering a first substream. The first analog filter operates at a sample rate greater than the respective symbol rate of the first substream. The first analog filter provides pre-emphasis of the respective sub-channel signal and attenuation of signals outside of a respective band of frequencies corresponding to the respective sub-channel signal. The data transmission circuit also includes a combiner for combining respective sub-channel signals to generate a data transmission signal.

Abstract: A method for processing a stream of a digital broadcast transmitter, the digital broadcast transmitter, a method of processing a stream of a digital broadcast receiver, and the digital broadcast receiver are provided. The method includes: configuring a stream including a slot to which mobile data is allocated; and encoding and interleaving the configured stream and outputting the encoded and interleaved stream. Each slot of the stream includes signaling data, and the signaling data includes a slot indicator indicating a type of a slot, and may include at least one of a backward training indicator and a forward training indicator according to a value of the slot indicator. Accordingly, information on an adjacent slot is efficiently used.

Abstract: An update mechanism and approach are provided for configuring a communications receiver. According to the approach, a time domain equalizer and a frequency domain equalizer in a communications receiver are dynamically updated based upon performance data that indicates the performance of a communications channel from which the communications receiver receives data. This approach accounts for changes in the communications channel attributable to changes in the transmission medium or changes in interference sources.