Patent application number | Description | Published |
20080233903 | Selection of filter coefficients for tranceiver non-linearity signal cancellation - Embodiments of a method and apparatus for selecting coefficients of a non-linear filter are disclosed. The non-linear filter receives a transmit signal and generates a non-linear replica signal of a transmit DAC of a transceiver. The method include applying a plurality of periodic test pattern signals to inputs of the transmit DAC, wherein the periodic test pattern signals include a stream of symbols. Receive symbols are collected at an output of a receiver ADC of the transceiver resulting from the plurality of periodic test pattern signals. A non-linear map is generated that provides a value for each of n consecutive symbols input to the transmit DAC. Coefficients of the non-linear filter are selected based on the non-linear map. | 09-25-2008 |
20080304576 | Efficient decoding - Embodiments of a method and apparatus for decoding signals are disclosed. The method includes receiving modulated signals, generating bits representing the signals, and associated reliability of each bit. The method further includes executing a first stage of decoding the bits using a first component code, and simultaneously executing the first stage of decoding again using a second component code, and executing a second stage of decoding using the first component code. The first and second stages of decoding are used to generate the bit stream. Another method includes receiving modulated signals, generating bits representing the signals, and associated reliability of each bit. The method further includes executing a first stage of N stages for decoding the bits, the first stage using a first of M component codes, and simultaneously executing a plurality of the N stages of decoding, each of the plurality of N stages using a different one of the M component codes. The plurality of N stages of decoding are used to generate the bit stream. | 12-11-2008 |
20090238102 | Generating an estimated non-linear echo signal - Embodiments of a method and apparatus for generating an estimated non-linear echo signal are disclosed. One method includes receiving a plurality of data inputs. The plurality of data inputs are partitioned into subsets. A weight vector is computed for each of the subsets. A vector of addresses to memory locations is computed for each of the subsets. Values of interpolants are accessed at the memory locations (interpolation sites) based on the vector of addresses for each of the subsets. The estimated non-linear echo signal based is calculated on the values of the interpolants and the weight vector corresponding to each subset. | 09-24-2009 |
20100058143 | Efficient Decoding - Embodiments of a method and apparatus for decoding signals are disclosed. An embodiment of a decoder includes means for generating bits representing received signals, and beliefs representing an associated reliability of each bit. A bit node computation block receives the bits and associated beliefs, and generates a plurality of bit node messages. A plurality of M serially-connected pipeline stages receive the bit node messages and after M decoding cycles, and generate a plurality of check node messages once per decoding cycle, wherein for each iteration cycle, each of the M serially-connected pipeline stages performs check node computations using all of J component codes, wherein each one of the M serially-connected pipeline stages performs check node computations once per decoding cycle using a single component code that is different that component codes used for all other of the M serially-connected pipeline stages, wherein J is at least as great as M, and wherein each iteration includes M decoding cycles. | 03-04-2010 |
20110261863 | Reducing Transmit Signal Components of a Receive Signal of a Transceiver - Embodiments of a method and apparatus of reducing transmit signal components of a receive signal of a transceiver are disclosed. One method includes generating a transmit signal by passing a pre-driver transmit signal through a transmit driver. An echo cancellation signal is generated by passing the pre-driver transmit signal through an echo cancellation driver. A residual echo signal is generated by passing a pre-driver residual echo cancellation signal through a residual echo cancellation driver. The transceiver simultaneously transmits the transmit signal, and receiving the receive signal. At least a portion of an echo signal of the receive signal is canceled by summing the echo cancellation signal with the receive signal. At least another portion of the cancellation echo signal of the receive signal is canceled by summing the residual echo cancellation signal with the receive signal. | 10-27-2011 |
20120013398 | Adaptive Spectral Enhancement and Harmonic Separation - A circuit and method perform adaptive spectral enhancement at a frequency ω | 01-19-2012 |
20120014416 | Narrowband Interference Cancellation Method and Circuit - A narrowband interference (NBI) canceller is coupled to an A/D converter to receive an input signal and supply an NBI-canceled signal to an error correcting decoder. In the NBI canceller, a first arithmetic unit receives the input signal and a predicted-interference signal, and supplies a difference thereof as the interference-canceled signal. A slicer receives the interference-canceled signal and supplies a decision signal. A second arithmetic unit subtracts the decision signal from the input signal to generate a noise signal. A coarse frequency estimator receives the noise signal and analyzes the frequency spectrum to generate a coarse estimate of a fundamental frequency of the NBI. The coarse estimate is used by an adaptive narrowband interference predictor to generate the predicted-interference signal while adaptively tracking the narrowband interference. Use of the NBI canceller in a transceiver can eliminate link drop caused by operation of wireless devices that generate EMI in a cable. | 01-19-2012 |
20120014487 | Adaptive Narrowband Interference Prediction Circuit and Method - An input signal that includes narrowband interference is spectrally enhanced by an adaptive circuit that supplies as output signal(s), portion(s) of NBI at one or more frequencies that change adaptively. The output signal(s) are used in one or more tone predictor(s) to generate, based on prior values of the NBI portion, one or more predicted tone signals that are subtracted from a received signal containing the NBI, and the result is used in the normal manner, e.g. decoded. The adaptive circuit and the one or more tone predictor(s), form a feed-forward NBI predictor wherein the received signal is supplied as the input signal of the adaptive circuit. The result of subtraction may be supplied to a slicer that slices the result, yielding a sliced signal which is subtracted from the received signal to generate a signal can be used as the input signal, to implement a feedback NBI predictor. | 01-19-2012 |
20120126903 | Stabilized Digital Quadrature Oscillator - A stabilized quadrature oscillator providing consistently high signal quality is disclosed. The stabilized quadrature oscillator includes an iterative quadrature oscillator and a quadrature signal stabilizer. The iterative quadrature oscillator generates an iterative cosine signal and an iterative sine signal using a stabilized cosine signal and a stabilized sine signal from the quadrature signal stabilizer. The quadrature signal stabilizer generates the stabilized cosine signal and the stabilized sine signal based on an energy measure of the iterative cosine signal and the iterative sine signal. Specifically, if the energy measure is less than a low threshold then the quadrature signal stabilizer generates the stabilized sine signal and the stabilized cosine signal to have a greater magnitude than the iterative sine signal and the iterative cosine signal, respectively. Conversely, if the energy measure is greater than a high threshold then the quadrature signal stabilizer generates the stabilized sine signal and the stabilized cosine signal to have a lesser magnitude than the iterative sine signal and the iterative cosine signal, respectively. | 05-24-2012 |
20120128048 | Detection and Estimation of Narrowband Interference By Matrix Multiplication - One or more processing units are programmed to select from among M tones in a frequency domain representation of a signal, a set of tones including at least a strongest tone (relative to background noise) and a tone adjacent thereto. From among M complex numbers in the frequency domain representation of the signal, a set of complex numbers are identified and denoted as a vector Z, corresponding to the selected set of tones. Vector Z is then multiplied with each of M columns of a matrix G which is predetermined to identify a sub-resolution maxima in Z. The M products that result from the vector multiplication of Z and G are used to determine and store in memory at least one or both of: (A) a flag indicating presence or absence of narrowband interference in the signal; and (B) an estimate of a frequency of the narrowband interference. | 05-24-2012 |
20120128049 | Confirmation of Presence of Narrowband Interference By Harmonic Analysis - One or more processing units confirm existence of narrow band interference in a signal by using an estimate f of the frequency, to check for one or more harmonics. In illustrative embodiments, the estimate f is automatically identified as a second harmonic if a predetermined criterion is satisfied by the signal (in the frequency domain) at either of two frequencies namely (A) frequency f/2 and (B) frequency (M−f)/2 and whichever of these two frequencies is stronger is identified as the fundamental frequency. In several such embodiments, the estimate f is automatically identified as a third harmonic if a predetermined criterion is satisfied by the signal (in the frequency domain) at any of three frequencies namely (C) frequency f/3 and (D) frequency (M−t)/3 and (E) frequency (M+f)/3. If the predetermined criteria are not met at all five frequencies (A)-(E) then f is identified as the fundamental frequency. | 05-24-2012 |
20120131080 | Multi-Input IIR Filter with Error Feedback - Methods and systems for multi-input IIR filters with error feedback are disclosed. By using multiple-inputs to generate multiple outputs during each iteration, a multi-input IIR filter in accordance with the present invention has greatly increased throughput. Furthermore, the addition of a multi-variable error feedback unit in accordance with the present invention in a multiple-input IIR filter can greatly increase the accuracy of the multi-variable IIR Filter. | 05-24-2012 |
20130072143 | NARROWBAND INTERFERENCE CANCELLATION METHOD AND CIRCUIT - A narrowband interference (NBI) canceller is coupled to an A/D converter to receive an input signal and supply an NBI-canceled signal to an error correcting decoder. In the NBI canceller, a first arithmetic unit receives the input signal and a predicted- interference signal, and supplies a difference thereof as the interference-canceled signal. A slicer receives the interference-canceled signal and supplies a decision signal. A second arithmetic unit subtracts the decision signal from the input signal to generate a noise signal. A coarse frequency estimator receives the noise signal and analyzes the frequency spectrum to generate a coarse estimate of a fundamental frequency of the NBI. The coarse estimate is used by an adaptive narrowband interference predictor to generate the predicted-interference signal while adaptively tracking the narrowband interference. Use of the NBI canceller in a transceiver can eliminate link drop caused by operation of wireless devices that generate EMI in a cable. | 03-21-2013 |
20130215949 | DETECTION AND ESTIMATION OF NARROWBAND INTERFERENCE BY MATRIX MULTIPLICATION - One or more processing units are programmed to select from among M tones in a frequency domain representation of a signal, a set of tones including at least a strongest tone (relative to background noise) and a tone adjacent thereto. From among M complex numbers in the frequency domain representation of the signal, a set of complex numbers are identified and denoted as a vector Z, corresponding to the selected set of tones. Vector Z is then multiplied with each of M columns of a matrix G which is predetermined to identify a sub-resolution maxima in Z. The M products that result from the vector multiplication of Z and G are used to determine and store in memory at least one or both of: (A) a flag indicating presence or absence of narrowband interference in the signal; and (B) an estimate of a frequency of the narrowband interference. | 08-22-2013 |
20130272447 | ADAPTIVE SPECTRAL ENHANCEMENT AND HARMONIC SEPARATION - A circuit and method perform adaptive spectral enhancement at a frequency ω1 (also called “fundamental” frequency) on an input signal y which includes electromagnetic interference (EMI) at an unknown frequency, to generate a fundamental-enhanced signal φ1 (or its complement). The fundamental-enhanced signal φ1 (or complement) is thereafter used in a notching circuit (also called “fundamental notching” circuit) to generate a fundamental-notched signal y-φ1. The fundamental-notched signal y-φ1 is itself enhanced to generate a harmonic-enhanced signal φ2 that is used to notch the fundamental-notched signal y-φ1 again, in one or more additional notching circuits that are connected in series with the fundamental notching circuit. The result (“cascaded-harmonic-notched” signal) is relatively free of EMI noise (fundamental and harmonics), and is used as an error signal for an adaptation circuit that in turn identifies the fundamental frequency ω1. Use of a cascaded-harmonic-notched signal as the error signal improves speed of convergence of adaptation. | 10-17-2013 |