Abstract: An adaptive equalizer. Implementations of adaptive equalizers may include implementations of 8-QAM adaptive equalizers that may include a signal filter, an adaptive processor coupled to the signal filter and a slicer coupled to the signal filter and the adaptive processor. The slicer may be configured to utilize a plurality of desired signals corresponding to an 8-QAM signal constellation having four quadrants, four levels disposed along the I-axis, and three levels disposed along the Q-axis. The slicer may also be configured to output an error signal by receiving an equalized output signal, processing the equalized output signal by correlating the equalized output signal with a decision region within one of the four quadrants, selecting one of a plurality of desired signals corresponding to the decision region, and calculating the error signal using the desired signal and the equalized output signal.

Abstract: Methods and apparatuses for blind equalizers with a hybrid adaptation error. In one embodiment, a Quadrature Amplitude Modulation (QAM) signal receiver, includes: a filter to reduce error in equalization, the filter to output a QAM signal; a decision engine coupled to the filter to determine a symbol based on the QAM signal; a first error generator coupled to the filter to compute a first error signal based on the QAM signal and a constant; a second error generator coupled to the filter and the decision engine to compute a second error signal based on the QAM signal and the determined symbol; an error combinator coupled to the first and second error generators to generate a combined error signal from the first and second error signals; and an adaptation engine coupled with the error combinator and the filter to reduce a equalization error according to the combined error signal.

Abstract: Described are methods and circuits for margin testing receivers equipped with Decision Feedback Equalization (DFE) or other forms of feedback that employ historical data to reduce intersymbol interference (ISI). In one example, a high-speed serial receiver with DFE injects the correct received data (i.e., the “expected data”) into the feedback path irrespective of whether the receiver produces the correct output data. The margins are therefore maintained in the presence of receiver errors, allowing in-system margin tests to probe the margin boundaries without collapsing the margin limits. Some receivers include local expected-data sources that either store or generate expected data for margin tests. Other embodiments derive the expected data from test data applied to the receiver input terminals.

Abstract: In a high-fidelity digital modulator, a mapper is provided to minimize quantization noise, jitter, and cross-talk between multiple digital-to-analog or analog-to-digital converters. The mapper receives a quantized level from a quantizer and maps the quantized level to an output sequence. The mapper includes a table defining multiple sequences corresponding to each quantized level. Each sequence includes two or more symbols, having one of multiple values. The mapper also includes a generator that selects one of the multiple sequences as the output sequence. The last symbol of a first output sequence is equal to the first symbol of the next output sequence and so on. The generator selects the output sequence by alternating between a first and a second sequence for each quantized level received. The generator selects the output sequence by alternating between sequences having a positive and a negative common mode energy for each odd valued quantized level received.

Abstract: Described are methods and circuits for margin testing digital receivers. These methods and circuits prevent margins from collapsing in response to erroneously received data, and can thus be used in receivers that employ historical data to reduce intersymbol interference (ISI). Some embodiments allows feedback timing to be adjusted independent of the sample timing to measure the effects of some forms of phase misalignment and jitter.

Abstract: A method and a device for generating a modulated navigation signal which is intended to be used to position a downlink receiver. Four pseudorandom navigation codes of chip rhythms greater than 0.5 MHz are modulated onto a carrier of frequency greater than 500 MHz according to an 8-PSK modulation of constant amplitude with a modulation frequency fM such that: 8fc?fM where fc=Max(fci), and fci designates the chip rhythms.

Abstract: A quadrature transmitter and receiver have configurable I and Q channel paths that facilitate the application of selected test signals to determine gain and phase imbalances introduced by the transmitter and receiver. In a first ‘normal’ configuration, the I and Q channels are independently tested by applying an I-only test signal, followed by a Q-only test signal. In a second ‘switched transmitter’ configuration, the Q-only test signal is again applied. In a third ‘switched receiver’ configuration, the I-only test signal is again applied. By combining the results, gain and phase imbalances of the transmitter and the receiver can be determined. In a preferred embodiment, these configurations and test signals are applied within a single transceiver that has the output of its transmitter closed-loop coupled to the input of its receiver.

Abstract: A system for balancing a signal having I and Q components includes means for cross correlating the I and Q components to produce a cross correlation product; means for adjusting the gain of each I and Q signal component in accordance with said cross correlation product; and means for adding one component with the adjustable gain of the other component to produce a phase-balanced signal.

Abstract: Provided is a direct-conversion frequency mixer for down converting a radio frequency (RF) signal into a baseband signal, in which a single phase RF signal and a quadrature location oscillation (quadrature LO) signal are used to generate the baseband signal, the frequency mixer comprising a first frequency mixing unit that uses quadrature LO signals having respective phases of 0 degrees and 180 degrees to directly down-convert the single phase RF signal into the in-phase baseband signal, and a second frequency mixing unit that uses quadrature LO signals having respective phases of 90 degrees and 270 degrees to directly down-convert the single phase RF signal into the quadrature-phase baseband signal, whereby drains and sources of the transistor for receiving the quadrature LO signal and the transistor for receiving the RF signal are connected in common, thus enabling low power source voltage driving.

Abstract: A continuous-time domain Decision Feedback Equalizer (DFE) for use in a serial communication channel comprises in one embodiment a summer, a decision circuit, a capture flip-flop (FF) and an N-th order active filter. The DFE and its active filter operate in continuous time to give improved performance over a discrete-time DFE. In one embodiment involving a first-order active filter, the capture FF is outside the continuous-time negative feedback loop of the DFE and involves a differential signal amplifier. In another embodiment, the capture flip-flop is inside the DFE loop, and in a third embodiment the decision circuit comprises a comparator.

Abstract: A normalized least means square (NLMS) equalizer including two equalizer filters is disclosed. In one embodiment, a single correction term generator is used to generate correction terms for tap coefficient updates of each of the equalizer filters based on a pilot signal. In another embodiment, two different correction term generators are used to generate correction terms for each of the equalizer filters, whereby one of the correction term generators uses data received from a hard decision unit at the output of one of the equalizer filters to generate correction terms for both of the equalizer filters.

Abstract: A system for providing multi-channel multi-mode QAM equalization and carrier recovery is provided. According to one exemplary embodiment, the system includes an equalization circuit and a carrier recovery circuit operating in a concurrent manner to provide equalization and carrier recovery. The equalization circuit and the carrier recovery circuit each have two operating modes, namely, an acquisition mode and a tracking mode. The carrier recovery circuit evaluates a phase detection error calculated based on signals obtained from the equalization circuit. Based on the evaluation of the phase detection error, the equalization circuit and the carrier recovery circuit are respectively directed to switch operating mode, if appropriate.

Abstract: In a multi-carrier system employing OFDM, for example DMT, an adaptive channel equalizer is normally used, operating in the frequency domain. The sampling clock is controlled so that the time delay between the transmitter and the receiver is effectively eliminated. If the information used to control the sampling clock is received from the equalized data stream, it will introduce an ambiguity between the operation of the channel equalizer and the mechanism used to control the sampling clock. Operation of the equalizer can mask an increasing time difference, between transmitter and receiver, which the sample clock controller should be tracking. The present invention eliminates the ambiguities in the operation of the equalizer and sample clock controller by preventing the equalizer accepting time differences which should be corrected by operation of the sample clock controller.

Abstract: Data is recovered in an asynchronous environment where a sampling clock is generated internally, and is not externally frequency locked, by using programmable delay modules each providing a number of delay tap outputs. To recover data, two of the delay modules are used with a first delay module designated as a monitor delay module to monitor the clock edge transitions, while a second delay module is designated as a data delay module that provides a data output. A controller provides for incrementing or decrementing the tap delay of both delay modules to assure clock data falls at the center of the monitoring window as determined using the monitor delay module. The controller further selects between the two delay modules as to which provides data and which is used as for clock edge monitoring when the clock edge transitions drifts to an edge of the monitoring window.

Abstract: Distortion due to transmission characteristics of a transmission medium is corrected by measuring leakage in a signal orthogonal to a received signal. The frequency response of an equalizer is adaptively adjusted until the measured leakage is at a local minimum.

Abstract: In preferred embodiments, an adaptive equalization circuit including at least two equalization filters (each for equalizing a signal transmitted over a multi-channel serial link) and control circuitry for generating an equalization control signal for use by all the filters. The control circuitry generates the control signal in response to an equalized signal produced by one of the filters, and asserts the control signal to all the filters. Preferably, one filter generates an equalized fixed pattern signal in response to a fixed pattern signal (e.g., a clock signal), each other filter equalizes a data signal, and the control circuitry generates the control signal in response to the equalized fixed pattern signal.

Abstract: An apparatus for compensating nonlinearly distorted multicarrier signals, a multicarrier signal receiver using the same, and a method therefor are provided, where the apparatus for compensating multicarrier signals and the multicarrier signal receiver using the apparatus extract parameter information on the HPA mode from the received signal so that nonlinear distortion of the received multicarrier signal is compensated for even though an accurate transfer function of a high power amplifier (HPA) is not known and side information or a special training signal is not transmitted when a signal is transmitted, such that nonlinearly distorted multicarrier signals such as OFDM signals transmitted by an HPA having a variety of transfer functions can be adaptively compensated and therefore a demodulated signal with an improved symbol error rate (SER) can be obtained.

Abstract: Method in a diversity antenna GMSK receiver of determining interference canceling equalizers and corresponding equalizers are described. The method includes providing a plurality of GMSK received signals; de-rotating and splitting each of the plurality of received signals into in phase and quadrature parts to provide a multiplicity of real valued branches; calculating linear equalizers for each of a multiplicity of subsets of the multiplicity of real valued branches; and providing an interference canceling equalizer for each of the multiplicity of real valued branches, each interference canceling equalizer corresponding to a weighted combination of the linear equalizers.

Abstract: A system for balancing a signal having I and Q components includes means for cross correlating the I and Q components to produce a cross correlation product; means for adjusting the gain of each I and Q signal component in accordance with said cross correlation product; and means for adding one component with the adjustable gain of the other component to produce a phase-balanced signal.

Abstract: Methods, apparatuses, and systems are presented for dynamically overclocking a processor comprising operating the processor at a clock rate to run an executable program by using the processor to carry out a plurality of instructions associated with the executable program, while the processor is running the executable program, repeatedly monitoring at least one activity measure associated with a specific operation of the processor, wherein the at least one activity measure is generated from within the processor, evaluating the at least one activity measure to determine whether a predefined condition representing processor activity level is met, and, if the predefined condition is met, dynamically adjusting the clock rate of the processor to modify execution speed at which the processor carries out instructions.

Abstract: There is provided a signal generation circuit for generating an output signal including jitter injected thereto. The signal generation circuit includes a jitter output section that outputs a first jitter signal and a second jitter signal which have different frequencies from each other, a carrier output section that outputs a carrier signal having a frequency positioned in substantially the middle between the frequencies of the first and second jitter signals, and an adding section that adds together the first jitter signal, second jitter signal and carrier signal so as to generate the output signal.

Abstract: A system and method are disclosed for determining the minimum required processing speed for a quadrature decoder using measurements of encoder performance, and to assess the safety factor of a particular decoder processing speed. The system and method may also be used to indicate proper adjustment direction by displaying real-time error measurements during encoder alignment. The system measures a logic state width error and calculates alignment parameters, processing speed and a safety factor. The method allows a measured logic state width error to be used to calculate a minimum required processing speed and safety factor.

Abstract: A testing apparatus for testing a device under test is provided, wherein the testing apparatus includes: a comparator for receiving a signal output from the device under test and converting the signal into a logic signal by comparing the signal with a first reference voltage; a driver for amplifying a logic signal to be output to the device under test on the basis of a second reference voltage and outputting to the device under test; a comparator setting unit for determining the first reference voltage so as to compensate for a delay amount of a reception signal received from the device under test and setting the comparator to be the first reference voltage; and a driver setting unit for determining the second reference voltage on the basis of the reference voltage of the comparator and setting the driver to be the second reference voltage.

Abstract: A method having enhanced decoding operations associated with receiving multiple Radio Frequency (RF) Burst(s) is provided. Multiple RF burst(s) are received where the multiple RF Burst(s) include first RF bursts and second RF Burst(s). The second RF bursts may be transmitted in parallel or in response to a decoding error associated with the first RF burst. The received RF burst(s) are equalized and deinterleaved to yield extracted soft samples. Then the first estimated bit sequences and second estimated bit sequences are decoded from the extracted soft samples. A set of possible bit sequences may then be pruned based on based on combined knowledge of the first estimated bit sequence and the second estimated bit sequences. This pruned set may be compared using a sequence detector and the combined first estimated bit sequences and second estimated bit sequences to select a decoded bit sequence.

Abstract: Receiving downlink CDMA signals in a fast-fading environment is facilitated at higher receiver velocities by updating the block-adaptive linear minimum mean square error (LMMSE) downlink CDMA equalizer. The autocorrelation matrix of the observed data is updated by passing block-wise autocorrelation slides through a filter. Each autocorrelation slide is an autocorrelation matrix estimated from a short block of observed data over which the channel can be considered constant. This method achieves a reliable estimate for the autocorrelation matrix when the block size must be small to ensure that the block-wise stationarity assumption holds in cases of fast fading channels. In addition, small block sizes make it possible to satisfy the equalizer delay constraint imposed by hardware and certain voice transmission standards such as CDMA2000 1X where demodulated data must be delivered within only several symbol periods of the signal arrival time.

Abstract: Some embodiments store a training sequence in a communications system. The stored training sequence exhibits certain desirable characteristics when used by a peak to average power constrained modulation format. In one embodiment, a set of original ordered sequences is selected to have at least one desired property. A set of extended sequences is created from the original sequences by beginning with an element of an original sequence and cyclically appending elements of the original sequence in order to obtain a desired extended sequence length. Each extended sequence is modified using a corresponding modifying sequence, such that a training sequence can be generated from any one of the modified extended sequences. Each modifying sequence is selected so that the generated training sequence when modulated by a selected modulation format has the at least one desired property of the corresponding original ordered sequence.

Abstract: Systems and methods for receiving non-coherent layered modulation signals are presented. An exemplary apparatus comprises a tuner for receiving a layered signal and producing a layered in-phase signal and a layered quadrature signal therefrom, an analog-to-digital converter for digitizing the layered in-phase signal and the layered quadrature signal, a processor for decoding the layered in-phase signal and the layered quadrature signal to produce a single layer in-phase signal and a single layer quadrature signal, a digital-to-analog encoder for converting the single layer in-phase signal and the single layer quadrature signal to a single layer in-phase analog signal and a single layer quadrature analog signal and a modulator for modulating the single layer in-phase analog signal and the single layer quadrature analog signal to produce a single layer signal.

Abstract: An apparatus and a method to estimate the channel response for a set of subcarriers in an OFDM receiver. The receiver receives a packet of information that includes a known transmitted part having known subcarrier values, and includes a signal-to-tone transformer to determine the subcarriers of a signal corresponding to a received packet. For each subcarrier, the method stores a function of an initial estimate of the channel response for the subcarrier, and accepts a post-channel correction pre-decision constellation point value for the subcarrier. The method further includes making a decision using the pre-decision constellation point value, re-modulating the decision to form a post-decision constellation point value, and forming a complex valued product of the function of the first estimate for the subcarrier and the complex-valued ratio of the pre-decision and post-decision values to forms a measure of the current channel estimate to use for updating the stored quantity.

Abstract: A radio receiver includes a low noise amplifier, a down conversion module, an analog to digital converter, and a digital demodulator. The digital demodulator is operably coupled to convert the digital low IF signals into inbound digital symbols and includes a baseband conversion module, a filtering module, a programmable equalizer, a CORDIC module, and a demodulation module. The programmable equalizer is operably coupled to equalize phase and frequency response of filtered digital baseband signals from the filtering module such that the phase and frequency response of the filtered digital baseband signals approximates phase and frequency response of a square root raised cosine filter to produce adjusted digital baseband signals. The CORDIC module is operably coupled to produce phase and magnitude information from the adjusted digital baseband signals. The demodulation module is operably coupled to produce the inbound digital symbols from the phase and magnitude information.

Abstract: An equalization method and apparatus for a Time domain synchronous orthogonal frequency division multiplexing (TDS-OFDM) receiver. The equalization method includes estimating a channel impulse response (CIR) based on a baseband sampled complex signal and locally stored pseudo-noise; eliminating the pseudo-noise from the baseband sampled complex signal based on the CIR; computing channel information including first channel information and second channel information from the CIR; performing pre-fast Fourier transform (FFT) compensation of a pseudo-noise eliminated signal based on the first channel information; performing FFT of a pre-FFT compensated signal; and equalizing a fast Fourier transformed signal based on the second channel information.

Abstract: A method is provided for performing a clear channel assessment in a local device. The local device receives signal energy in a wireless channel and splits the received signal energy into a real portion and an imaginary portion. It determines a real portion of a squared signal energy by subtracting a squared imaginary portion of the signal energy from a squared real portion of the signal energy, and determines an imaginary portion of the squared signal energy by calculating twice the product of the real and imaginary portions of the signal energy. It can perform a signal detection function on the real and imaginary portions of the squared signal energy to produce a clear channel assessment signal that indicates whether a set signal type is present in the wireless channel. This clear channel assessment signal can be used to determine whether the local device should remain in a low-power mode.

Abstract: Digital signal processing for television signals includes digital feedback loops. Analog information signals are oversampled to provide digital signals. The digital signals are introduced to a digital carrier recovery loop and a digital symbol recovery loop. The gain of the digital signals is also regulated in a feedback loop. The digital signals are processed to recover the data in the data signals. The use of digital feedback loops allows information recovered from the digital signals to be precise. Carrier signals can be directly demodulated to produce baseband inphase and quadrature signals, or first downconverted to produce intermediate frequency signals.

Abstract: A parallel orthogonal frequency division multiplexed (OFDM) communications system includes a transmitter and receiver, the transmitter having a parallel fast Fourier transform (FFT) module operating in parallel to a conventional inverse fast Fourier transform (IFFT) module for providing respective orthogonal outputs received by the receiver. The receiver has a parallel IFFT module and a conventional FFT module for providing respective orthogonal outputs. The respective orthogonal outputs are combined to form a composite signal that provides improved insensitivity to relative frequency offsets and Doppler frequency offsets. The parallel FFT and IFFT modules in the OFDM communication system provides improved signal diversity and performance in the presence of relative frequency offsets and Doppler frequency offsets, and provides improved tracking capability for the receiver with backward compatibility.

Abstract: A method and apparatus for compensating I/Q imbalance in receivers is described. The method includes determining a difference between energies of two quadratures, correcting an amplitude imbalance using the difference between the energies of two quadratures, determining a cross-correlation between the two quadratures, and correcting a phase imbalance using the cross-correlation between the two quadratures.

Abstract: Methods and apparatus for performing channel estimate updates in frequency division multiplexed, e.g., (OFDM), systems are described. After generation of initial channel estimates from received pilots, channel estimates corresponding to individual tones are updated using any one of a plurality of update techniques including, e.g., a constant modulus based method and a reduced constellation decision directed update method. The channel estimate update technique to be used with for an individual tone is selected based on a comparison of a signal noise measurement to one or more thresholds. The channel estimate update technique applied to different tones of the OFDM signal at the same time may vary. Over time, as the level of noise is reduced, the channel estimate update technique will switch from an interpolated pilot method, to a constant modulus algorithm based method, to a reduced constellation decision directed method, to a full constellation decision directed update method.

Abstract: A method of canceling gain and phase imbalance including estimating a cancellation parameter based on the signal divided by its complex conjugate, calculating a correction value for the signal using the cancellation parameter, and correcting the signal by subtracting the correction value from the signal. Estimate the cancellation parameter may include performing a stochastic gradient algorithm or a least squares estimate. A cancellation system including a conjugate conversion unit, an estimator, a combiner, a converter, and a subtractor. The estimator estimates a cancellation parameter and the combiner combines the cancellation parameter and the complex conjugate signal to provide a cancellation signal. The converter converts the cancellation signal to a correction signal, and the subtractor subtracts the correction signal from the imbalanced signal to provide a corrected signal. The combiner may be an adaptable tap of a digital signal processing circuit.

Abstract: An IQ modulator and method for modulating a signal in accordance with I and Q symbols using derivative FIR's operating at the symbol rate and programmable multi-accumulators for waveform generator. This provides advantages that reduced complexity is produced compared with traditional FIR's by a factor equal to the quotient of oversampling ratio and derivative order; programmability to Digital Very Low IF mode transmission is possible; the same circuit may perform interpolation for narrow band MA's; and reduced sets of coefficients enable implementation of two sets of coefficients for MA's, allowing fast handover between MA's such as EDGE and IS136.

Abstract: A number of basic equalization and demodulation structures have been shown to be appropriate for DMT systems depending on the channel, noise, and system parameters. These include single path, dual path, oversampled, and double rate structures. Using the fundamental computation units of two TEQs (FIR filters) and two FFTs, in conjunction with simple delays, downsampling and routing, single path, dual path, oversampled and double rate equalization structures can be realized from a common equalization structure.

Abstract: A method of processing an AM radio signal comprises the step of receiving an AM radio signal including an upper sideband portion and a lower sideband portion, demodulating the upper sideband portion and the lower sideband portion to produce a demodulated upper sideband signal and a demodulated lower sideband signal, weighting the demodulated upper sideband signal and the demodulated lower sideband signal in response to noise power to produce a weighted demodulated upper sideband signal and a weighted demodulated lower sideband signal, and combining the weighted demodulated upper sideband signal and the weighted demodulated lower sideband signal to produce an output signal. Demodulators which process AM radio signals in accordance with the method, and receivers incorporating the demodulators, are also included.

Abstract: A channel equalizer includes an equalizer filter for correcting an error upon receipt of a signal transmitted by a sending end, a DD slicer for calculating a first error upon receipt of the corrected signal from the equalizer filter, a Sato slicer for calculating a second error upon receipt of the corrected signal from the equalizer filter, and a DD error size calculation unit for taking the absolute value of the real part and imaginary part of the first error calculated from the DD slicer and summing these absolute values.

Abstract: An apparatus and method is disclosed for using adaptive algorithms to exploit sparsity in target weight vectors in an adaptive channel equalizer. An adaptive algorithm comprises a selected value of a prior and a selected value of a cost function. The present invention comprises algorithms adapted for calculating adaptive equalizer coefficients for sparse transmission channels. The present invention provides sparse algorithms in the form of a Sparse Least Mean Squares (LMS) algorithm and a Sparse Constant Modulus Algorithm (CMA) and a Sparse Decision Directed (DD) algorithm.

Abstract: A method and apparatus for a decision feedback equalizer wherein a correction term is used to compensate for slicer errors, thus avoiding error propagation. Filter coefficients for the equalizer are selected so as to minimize a cost function for the equalizer. The cost function calculation includes a correction term. The correction term is a function of the energy of the filter coefficients. In one embodiment, the cost function includes a Mean Squared Error (MSE) calculation. The equalizer includes a coefficient generator responsive to the correction term. The correction term may depend on the Signal-to-Interference-and-Noise Ratio (SINR) at the output of the equalizer.

Abstract: Analog signals encoded with quadrature amplitude modulation (QAM) pass through a coaxial cable at a particular baud rate. These signals have a carrier frequency individual to the TV station being received. They are mixed with signals from a variable frequency oscillator to produce signals at a particular intermediate frequency (IF). An analog-digital converter (ADC) converts the IF signals to corresponding digital signals which are demodulated to produce two digital signals having a quadrature phase relationship. After being filtered and derotated, the digital signals pass to a symmetrical equalizer including a feed forward equalizer (FFE) and a decision feedback equalizer (DFE) connected to the FFE in a feedback relationship. The DFE may include a slicer providing amplitude approximations of increasing sensitivity at progressive times. Additional slicers in the equalizer combine the FFE and DFE outputs to provide the output data without any of the coaxial cable noise or distortions.

Abstract: A method and system are disclosed that provide a more efficient decoder for decoding block codes such as a complementary code keying (CCK) code. A receiver receives a signal containing at least one block codeword. A decoder decodes the block codeword contained in the received signal by finding a path in a trellis diagram with a calculated path metric that accounts for intersymbol interference (ISI). The path metric can be based on a branch metric that is calculated according to a decision feedback sequence estimation algorithm.

Abstract: A decision feed back equalizer provides two feedback routines for one symbol-preceding decided data. The signal space is separated into decidable areas and uncertainty areas. Within each of decidable area the distance between any point and the signal point is small. Within each uncertainty area the distance between any point and the signal point is large. If the symbol-preceding equalized signal is in a decidable area, the piece of decided data is fed back, as it is presumed to be correct. If the symbol-preceding equalized signal exists in an uncertainty area, the piece of decided data is not fed back, as it is presumed to be in error. Here the one piece data is selected from all the predicted symbol-preceding decided data so that the instant equalized data is now in the decidable area. This piece of decided data is now fed back.

Abstract: A packet-switched multiple-access network system with a distributed fair priority queuing media access control protocol that provides multiple levels of priority of access and fair collision resolution with improved performance is disclosed. In one embodiment, the system provides high-speed transport of multimedia information on a shared channel. Further, in one embodiment, MAC level side-band signaling that is useful to other levels of the network protocol (e.g., the physical layer) is also provided.

Abstract: Distortion due to transmission characteristics of a transmission medium is corrected by measuring leakage in a signal orthogonal to a received signal. The frequency response of an equalizer is adaptively adjusted until the measured leakage is at a local minimum.

Abstract: The digital communications receiver receives an analog signal, modulated with digital information. The receiver converts the analogue signal to a digital signal, and demodulates the digital signal to recover the complex valued components of the transmitted digital signal. The complex valued components are low pass filtered and passed through an adaptive pre-equalizer filter, to reduce eigen value spread. The filtered complex valued signal is then subject to a decision feedback equalization, which operates using a series of adaptive filters additionally to remove artifacts of inter-symbol interference. The resulting filtered and equalized complex valued signal is the converted to a digital signal to recover the digital information.

Abstract: A receiver includes an equalizer and a decoder which decodes data from a signal. The signal is based upon an output of the equalizer. The receiver also includes an encoder, which re-encodes the decoded data, and an error generator, which generates an error vector based upon the signal and the encoded data and which weights the error vector according to a reliability that the decoder accurately decoded the data from the signal. A controller controls the equalizer in response to the weighted error vector.

Abstract: Analog signals encoded with quadrature amplitude modulation (QAM) pass through a coaxial cable at a particular baud rate. These signals have a carrier frequency individual to the TV station being received. They are mixed with signals from a variable frequency oscillator to produce signals at a particular intermediate frequency (IF). An analog-digital converter (ADC) converts the IF signals to corresponding digital signals which are demodulated to produce two digital signals having a quadrature phase relationship. After being filtered and derotated, the digital signals pass to a symmetrical equalizer including a feed forward equalizer (FFE) and a decision feedback equalizer (DFE) connected to the FFE in a feedback relationship. The DFE may include a slicer providing amplitude approximations of increasing sensitivity at progressive times. Additional slicers in the equalizer combine the FFE and DFE outputs to provide the output data without any of the coaxial cable noise or distortions.