197 results about "Crosstalk cancellation" patented technology

Signals propagating in one communication channel can generate crosstalk interference in another communication channel. A crosstalk cancellation device can process the signals causing the crosstalk interference and generate a crosstalk cancellation signal that can compensate for the crosstalk when applied to the channel receiving crosstalk interference. The crosstalk cancellation device can include a model of the crosstalk effect that generates a signal emulating the actual crosstalk both in form an in timing. The crosstalk cancellation device can include a controller that monitors crosstalk-compensated communication signals and adjusts the model to enhance crosstalk cancellation performance. The crosstalk cancellation device can have a mode of self configuration or calibration in which defined test signals can be transmitted on the crosstalk-generating channel and the crosstalk-receiving channel.

An apparatus and method of reproducing a 2-channel virtual sound while dynamically controlling a sweet spot and crosstalk cancellation are disclosed. The method includes: receiving broadband signals, setting compensation filter coefficients according to response characteristics of bands and setting stereophonic transfer functions according to spectrum analysis; down mixing an input multi-channel signal into two channel signals by adding head related transfer functions (HRTFs) measured in a near-field and a far-field to the input multi-channel signal, canceling crosstalk of the down mixed signals on the basis of compensation filter coefficients calculated using the set stereophonic transfer functions, and compensating levels and phases of the crosstalk cancelled signals on the basis of the set compensation filter coefficients for each of the bands.

A method and apparatus for evaluating and calibrating a signaling system is described. Evaluation is accomplished using the same circuits actually involved in normal operation of the signaling system. Capability for in-situ testing of a signaling system is provided, and information may be obtained from the actual perspective of a receive circuit in the system. A pattern of test information is generated in a transmit circuit of the system and is transmitted to a receive circuit. A similar pattern of information is generated in the receive circuit and used as a reference. The receive circuit compares the patterns. Any differences between the patterns are observable. Preferably, the patterns are repeating patterns that allow many iterations of testing to be performed. In one embodiment, a linear feedback shift register (LFSR) is implemented to produce patterns. Information obtained from testing may be used to assess the effects of various system parameters, including but not limited to output current, crosstalk cancellation coefficients, and self-equalization coefficients, and system parameters may be adjusted to optimize system performance. An embodiment of the invention may be practiced with various types of signaling systems, including those with single-ended signals and those with differential signals. An embodiment of the invention may be applied to systems communicating a single bit of information on a single conductor at a given time and to systems communicating multiple bits of information on a single conductor simultaneously.

System and method for canceling crosstalk in high-speed communications systems. An embodiment comprises precomputing channel pulse responses for a set of communications channels in a communications backplane, precomputing channel signal responses for the set of communications channels in the backplane with a training sequence, estimating noise coefficients using receiver training and the training sequence, storing noise coefficients for each communications channel in the set of communications channels, and canceling noise in a received transmission of a data sequence using the stored noise coefficients. The regularity of the communications backplane enables the precomputing of various values, which reduces computational requirements. Furthermore, it is often the case that a victim receiver has access to the digital data that is being transmitted by its dominant crosstalking transmitters, thereby simplifying noise cancellation.

A method and apparatus are disclosed for reducing crosstalk in a telecommunication system. Broadly, the present invention utilizes a common mode signal to obtain additional information that can be used to better approximate the transmitted signal (by approximating and canceling crosstalk or otherwise). In accordance with one embodiment of the invention, a modem is provided having improved crosstalk cancellation circuitry for canceling crosstalk received on a local loop (or otherwise estimating the remotely transmitted signal) carrying modem communications. The modem includes a first input for receiving a signal carried on the local loop and a second input for receiving a signal obtained from the common mode. The modem further includes processing circuitry configured to either reduce crosstalk present in the signal carried on the local loop, or to otherwise closely approximate the remotely transmitted signal. Using both the first and second signals allows the processing circuitry of the modem to obtain more accurate results.

Signals propagating in one communication channel can generate crosstalk interference in another communication channel. A crosstalk cancellation device can process the signals causing the crosstalk interference and generate a crosstalk cancellation signal that can compensate for the crosstalk when applied to the channel receiving crosstalk interference. The crosstalk cancellation device can include a model of the crosstalk effect that generates a signal emulating the actual crosstalk both in form an in timing. The crosstalk cancellation device can include a controller that monitors crosstalk-compensated communication signals and adjusts the model to enhance crosstalk cancellation performance. The crosstalk cancellation device can have a mode of self configuration or calibration in which defined test signals can be transmitted on the crosstalk-generating channel and the crosstalk-receiving channel.

A cancellation system comprises a channel circuit (11) for each noise source, such as echo in a particular cable pair. There are only eighty taps per channel, in two blocks (n_echo_a, f_echo_a). Each block is preceded by a variable delay line comprising blocks of registers cascaded so that a delay value of 0 to 40 clock cycles can be chosen. The delay value is determined by determining an optimum position for each tap block. This is achieved by determining a maximum coefficient sum for a number of windows. Taps from other channels are used during training, so that there is a total of 160 taps for each channel during training to enable the optimum positions to be determined.

A communication transmitting and receiving system in which the effects of near-end echo and near-end crosstalk signal from the communication medium are mitigated by adaptively reproducing the near-end echo and near-end crosstalk signal, which is then subtracted from the received signal. Filter coefficients for a Finite Impulse Response filter are adaptively generated to reproduce the near-end echo and near-end crosstalk. The filter coefficients are regenerated for the Finite Impulse Response filter in an adaptive correlator at the arrival of each received signal and whereby each new filter coefficient is a weighted sum of a previous coefficient and one received signal multiplied by a time delayed version of one transmitted signal.

The invention discloses a stereo playback method of a loudspeaker array. The stereo playback method of the loudspeaker array includes that positions and frequency ranges of loudspeaker pairs are determined in advance, sound signals are subjected to frequency division processing according to the frequency ranges, frequency division signals within corresponding frequency range of each loudspeaker are subjected to filtration through a crosstalk cancellation filter which corresponds to each loudspeaker, and result signals after filtration are played through the loudspeakers. The crosstalk cancellation filters are determined according to an optimum sound source distribution mode. By means of the stereo playback method of the loudspeaker array, good stereo surrounding effects can be achieved.

Systems and methods that use ultrasonic emitters for producing multi-dimensional parametric audio are provided. The systems and methods can be configured to determine HRTF filters for the left and right ears of a listener using an optical imaging system to scan a profile of a listener. Audio content may be encoded into a left and right channel for producing a three dimensional sound effect for the listener of the audio content by: processing the sound channel into left and right input channel signals; applying the HRTF filters and acoustic crosstalk cancellations filters to the left and right channel signals to generate output left and right channel signals; and modulating the left and right output channel signal frequencies onto an ultrasonic carrier.

Embodiments herein are primarily described in the context of a system, a method, and a non-transitory computer readable medium for producing a sound with enhanced spatial detectability and reduced crosstalk interference. The audio processing system receives an input audio signal, and performs an audio processing on the input audio signal to generate an output audio signal. In one aspect of the disclosed embodiments, the audio processing system divides the input audio signal into different frequency bands, and enhances a spatial component of the input audio signal with respect to a nonspatial component of the input audio signal for each frequency band.

A charge diffusion crosstalk reduction process is provided for image signals from, for example, a CMOS image sensor. Charge diffusion crosstalk processing can be used in accordance with aspects of the present invention to reduce charge diffusion crosstalk caused by electrons migrating from adjacent pixels. Crosstalk effects can be determined by color gain and color offset. By adjusting the color gain and color offset, crosstalk can be cancelled to the first order. Charge diffusion crosstalk processing in accordance with aspects of the present invention can be relatively easily integrated with color correction processing during the post processing of image sensors. Color correction and cross talk cancellation processing can use the same circuitry as previously used before by color correction process only. The input coefficients for color correction and cross talk cancellation processing can be determined from the results of the multiplication of color correction matrix C and crosstalk cancellation matrix K−1.

A system and method are shown for generation of at least one reference voltage level in a bus system. A reference voltage generator on a current driver includes at least one reference voltage level, at least one control signal, and an active device. The active device is coupled to the at least one control signal, such as a current control signal, and a selected reference voltage of the at least one reference voltage level. The active device is arranged to shift the at least one reference voltage level based on the at least one current control signal such as an equalization signal, a crosstalk signal, or the combination thereof, employed on the current driver.

A technique for canceling acoustic crosstalk is provided including a pre-processing filter and a crosstalk cancellation device. The pre-processing filter may be configured to obtain first and second channel signals and compensate or adjust the first and / or second channel signals for anticipated subsequent stage distortion by the crosstalk cancellation device. The crosstalk cancellation device maybe configured to receive the compensated first and second channel signals from the pre-processing filter. The crosstalk cancellation device then modifies the first channel signal to cancel anticipated acoustic crosstalk from the second channel signal, and modifies the second channel signal to cancel acoustic crosstalk from the first channel signal. The modified first channel signal is then transmitted over a first speaker and the modified second channel signal is transmitted over a second speaker. The first and second speakers may be closely spaced, yet provide a widened stereo image of the first and second channel signals.

A digital subscriber line (DSL) modem that has a canceller digital filter for cancelling crosstalk and RF interference in a received DSL signal is disclosed. The modem includes common-mode sense circuitry and also differential-mode sense circuitry. Samples of the common-mode signal are acquired during a “quiet” period of initialization of the DSL modem, and samples of the differential-mode signal are acquired during live transmission of a DSL signal. An estimate of an autocorrelation function is obtained from the common-mode samples, and a cross-correlation of the common-mode samples and differential-mode samples is also estimated. Digital filter coefficients are derived from these estimates, based on the assumption that the common-mode samples acquired during the “quiet” phase represent crosstalk and RF interference present during differential-mode communications. The digital filter coefficients can also be updated during showtime of the DSL link, using an expanded number of samples of the common-mode and differential-mode signals.

An apparatus for precoding multi-tone modulated transmissions of a plurality of communication channels over bundled subscriber lines. The apparatus includes a pseudo symbol controller and a precoder. The pseudo symbol controller detects a victim communication channel and an interferer communication channel having non-matching symbol rates, and transforms the interferor channel into a pseudo-symbol having both a substantially similar length as a corresponding symbol of the victim channel together with defined tonal characteristics expressed in terms of the interferor channel. The precoder assigns crosstalk coefficients to selected sub-channels or tones of the pseudo symbol and precodes the victim channel with the pseudo symbol using the crosstalk coefficients; thereby generating a precoded victim symbol which exhibits reduced crosstalk between the selected victim and interferor.

A system for performing a single ended line test (SELT) of a selected subscriber line within a bundle of in-service subscriber lines each supporting frequency division multiplexed multi-tone modulated XDSL communications. The system comprises: a crosstalk cancellation module and a SELT module. The crosstalk cancellation module is coupled to the subscriber lines and configured to cancel crosstalk between the selected subscriber line under test and the in-service subscriber lines. The SELT module couples to the crosstalk cancellation module and is configured to coordinate SELT testing with the crosstalk cancellation module to cancel crosstalk between the selected subscriber line and the in-service subscriber lines during testing.

The present invention effectively cancels echo, near-end crosstalk and far-end crosstalk. A FEXT canceller is placed at the transmitter rather than at the receiver according to an aspect of the invention. In some embodiment, a FEXT canceller can be placed at the receiver only or the combination of both ends. The FEXT canceller is continuously adapted with information sent back from a remote receiver and with data from a neighbor transmitter that causes the crosstalk at the remote receiver. This allows the FEXT canceller to quickly adapt to a change in crosstalk function or conditions with the surrounding environment, for example, aging, temperature, humidity, physical pressure, etc. In some embodiments, an adaptation control signal is sent back from the receiver to the transmitter by using an overhead bit in the frame format. In some embodiments, part of the FEXT canceller is built-in at the remote receiver.

A method and apparatus for reducing crosstalk in a multi-channel communication system is disclosed. In one embodiment, outgoing signals in a multi-channel environment are manipulated into a transform domain, such as the frequency domain. Thereafter, the signals may be combined and modified based on a weighting variable to create a cancellation signal. Combined processing greatly reduces system complexity and increases processing speed. After processing in the transform domain, the cancellation signal undergoes further processing to return the cancellation signal into the time domain. The cancellation signal may then be combined with received signals to cancel crosstalk or echo. A method and apparatus for crosstalk cancellation in the analog domain and digital domain is also disclosed. Cancellation at least partially in the analog domain reduces the dynamic range requirements for digital to analog converters within the front-end processing system of a receiver and thereby reducing clipping and increasing operating speed.

Crosstalk cancellation systems for left and right channel stereo audio signals that are played over left and right stereo loudspeakers include circuitry that is configured to apply more crosstalk cancellation delay to a difference signal between the left and right stereo audio signals, than to a sum signal of the left and right channel stereo signals. The circuitry may be configured to apply no crosstalk cancellation delay to the sum signal. Related crosstalk cancellation methods and electronic devices incorporating same are also disclosed.

A method of improving 3D sound reproduction is described, in which virtual sound sources to be positioned behind a listener 10 are filtered using an HF-cut filter in order to remove distracting high-frequency components caused by incomplete transaural crosstalk cancellation. Sound sources placed in the rearward hemisphere of reference sphere 30 are filtered by an amount dependent on the position of the sound source in order to provide a smooth transition between the filtered and unfiltered hemispheres. HF-cut filtering is at a maximum when the sound source is placed directly behind the listener, and is progressively reduced as the forward hemisphere is approached. The invention offers an advantage in that virtual sound images may be placed more effectively behind the listener, given improved realism of 3D effects.

This invention discloses a method and a device for eliminating crosstalk of xDSL, in which, the method includes: a, dividing multiple signals into two or more than two signal sets, b, connecting signals belonging to a same signal set to a same processor in a DSLAM for process, which reduces operations of transmission matrix on a processor and realizes elimination of crosstalk.

A method and apparatus for efficient filter structure for an enhanced operation of an ADSL-DMT modem on a subscriber loop with an environment consisting of ISDN interference. The method performs equalization of the channel by impulse response shortening and at the same time rejecting interference signals exhibiting cyclostationary properties. The method and apparatus for reducing the crosstalk involves a frequency-shifted versions of the received signal being filtered through frequency-shifted adaptive filters in the appropriate branches, and providing a joint time domain equalizer / crosstalk canceller to perform equalization of the channel and crosstalk cancellation in one instance and a separate crosstalk canceller to cancel crosstalk plus a time domain equalizer to equalize the channel. Downsampling the signal outputs of both the combined crosstalk equalizer and the frequency-shifted adaptive filters to reduce sampling rate; and subtracting the outputs of the combined crosstalk equalizer and the frequency-shifted adaptive filters to remove the cyclostationary interferer.

A method and apparatus for reducing crosstalk in a multi-channel communication system is disclosed. In one embodiment, outgoing signals in a multi-channel environment are manipulated into a transform domain, such as the frequency domain. Thereafter, the signals may be combined and modified based on a weighting variable to create a cancellation signal. Combined processing greatly reduces system complexity and increases processing speed. After processing in the transform domain, the cancellation signal undergoes further processing to return the cancellation signal into the time domain. The cancellation signal may then be combined with received signals to cancel crosstalk or echo. A method and apparatus for crosstalk cancellation in the analog domain and digital domain is also disclosed. Cancellation at least partially in the analog domain reduces the dynamic range requirements for digital to analog converters within the front-end processing system of a receiver and thereby reducing clipping and increasing operating speed.

A system and a method for crosstalk cancellation, the method includes: (i) generating estimated crosstalk cancellation matrices for each frequency bin of a group of adjacent frequency bins, wherein each estimated crosstalk cancellation matrix provides an estimation of a crosstalk cancellation that is expected to mitigate crosstalk that is generated at a single frequency bin by an array of transmitters that transmit information over different copper pairs that form a bonded digital subscriber line link; (ii) generating a group crosstalk cancellation matrix based on the estimated crosstalk cancellation matrices, wherein a size of the group crosstalk cancellation matrix is smaller that an aggregate size of the estimated crosstalk cancellation matrices; and (iii) cancelling crosstalk for each frequency bin of the group by utilizing the group crosstalk cancellation matrix.

A digital subscriber line (DSL) modem that has a canceller digital filter for cancelling crosstalk and RF interference in a received DSL signal is disclosed. The modem includes common-mode sense circuitry and also differential-mode sense circuitry. Samples of the common-mode signal are acquired during a “quiet” period of initialization of the DSL modem, and samples of the differential-mode signal are acquired during live transmission of a DSL signal. An estimate of an autocorrelation function is obtained from the common-mode samples, and a cross-correlation of the common-mode samples and differential-mode samples is also estimated. Digital filter coefficients are derived from these estimates, based on the assumption that the common-mode samples acquired during the “quiet” phase represent crosstalk and RF interference present during differential-mode communications. The digital filter coefficients can also be updated during showtime of the DSL link, using an expanded number of samples of the common-mode and differential-mode signals.

Data signals transmitted over transmission media suffer from attenuation caused by the transmission media. Equalization circuitry may be provided to compensate for attenuation caused by the transmission media. Equalization circuitry may include multiple stages arranged in series to allow the frequency responses of the stages to aggregate together. Each stage may be programmable to insert a zero, which causes the frequency response of the stage to increase in magnitude by 20 dB / decade. The frequency location of the zero may also be programmable to allow each stage to contribute a certain amount of gain for a specific frequency. Each stage may also be programmable to determine the location of poles for reduction of high frequency noise and cross-talk cancellation.

A computerized wagering game system has a gaming module comprising a processor and gaming code which is operable when executed on the processor to conduct a wagering game on which monetary value can be wagered. An audio module comprising a part of the computerized wagering game system is operable to play audio through two or more speakers, and is further operable to apply crosstalk cancellation to the audio played through the two or more speakers.

A signal processing system is disclosed. The signal processing system comprises an AGC and pre-echo cancellation system for receiving an analog signal, boosting it up (over all frequencies) to a pre-determined range by AGC, and removing the immediate transmit pulse from this received signal by pre-echo canceller to provide a second analog signal. The signal processing system further comprises a summer for receiving the analog signal; a feed forward equalization (FFE) unit for receiving a signal from the summer; and a slicer for receiving a signal from the FFE unit and providing an output signal. The signal processing system also comprises an Echo and NEXT cancellation system for receiving the output signal and for providing a signal to the summer for canceling the echo and crosstalk in the signal processing system. Accordingly, in a system and method in accordance with the present invention the Echo and crosstalk components associated with a signal processing system can be subtracted prior to the FFE. This allows for a practical analog implementation which has a good dynamic range of the signal through the FFE and subsequent analog elements. This system can be utilized to great advantage in low power CMOS designs where supply voltages are limited.