Abstract: A method and system for performing sequence time domain reflectometry to determine the location of line anomalies in a communication channel is disclosed. In one embodiment, the system generates a sequence signal and transmits the sequence signal over a channel that is the subject of the sequence time domain reflectometry analysis. The system monitors for and receives one or more reflections, collectively a reflection signal, and presents the reflection signal to a reflection processing module. In one embodiment, the reflection signal is correlated with the original sequence signal to generate a correlated signal. The system may perform signal analysis on the correlated signal to determine a time value between the start of the reflection signal and the subsequent points of correlation. Based on the time value and the rate of propagation of the signals through the channel, the reflection processing module determines a distance to a line anomaly.

Abstract: A method and apparatus for noise cancellation in a multi-channel communication system is disclosed. In one embodiment this system is configured to cancel FEXT on a victim channel utilizing the signals received on the other channels. The processing benefits gained by a receiver's other filters, such as for example, the FFE and DFE filters, is utilized when generating a FEXT cancellation signal. As a result, the complexity of the apparatus that generates the FEXT cancellation signal may be made less complex since part of the processing burden is performed by other filter apparatus. In one configuration pre-code FEXT cancellation occurs in that a pre-code FEXT filter generates one or more pre-code FEXT cancellation signals corresponding to each of the other channels. The pre-code FEXT cancellation signals are combined, prior to transmission, with the signals associated with each of the other channels, to thereby pre-cancel FEXT prior to transmission.

Abstract: A method and system for performing sequence time domain reflectometry over a communication channel to determine the location of line anomalies in the communication channel is disclosed. In one embodiment, the system generates a sequence signal and transmits the sequence signal over an optical channel. The system receives one or more reflection signals over the optical channel and performs reflection signal processing on the reflection signal. In one embodiment, the optical reflection is transformed to an electrical signal and correlated with the original sequence signal to generate a correlated signal. The time between the start of the reflection signal and a subsequent point of correlation and the rate of propagation reveals a line anomaly location. A circulator, beam splitter, or any other similar device may direct the reflection signal to the apparatus configured to perform reflection signal processing.

Abstract: A method and apparatus is disclosed for adaptively determining threshold values in a decision device, such as a decision slicer. In one embodiment, a slicer receives one or more updated threshold values during operation to adaptively accommodate changes in the received signal or the channel that may occur over time. The updated threshold value is based on a MIN value and a MAX value. The MIN values represent a value related to a recently received input that was determined to qualify for a particular slicer output and was less than the particular slicer output value. The MAX values represent a value related to a recently received input that was determined to qualify for a particular slicer output and was greater than the particular slicer output value. In one embodiment, the MAX and MIN value computation is based on scaling factors that dampen the rate of change of the threshold value.

Abstract: A method and apparatus is disclosed for adaptively determining threshold values in a decision device, such as a decision slicer. In one embodiment, a slicer receives one or more updated threshold values during operation to adaptively accommodate changes in the received signal or the channel that may occur over time. The updated threshold value is based on a MIN value and a MAX value. The MIN values represent a-value related to a recently received input that was determined to qualify for a particular slicer output and was less than the particular slicer output value. The MAX values represent a value related to a recently received input that was determined to qualify for a particular slicer output and was greater than the particular slicer output value. In one embodiment, the MAX and MIN value computation is based on scaling factors that dampen the rate of change of the threshold value.

Abstract: A system, method, and signal are disclosed for line probing. The invention provides an improved signal for line probing having desirable characteristics. In various embodiments the signal comprises a periodic sequence having good autocorrelation characteristics. The periodic sequence of the invention provides a faster and more accurate evaluation of the channel. Another embodiment of the invention comprises processing of the received sequence to determine a desired or maximum data rate for the line or channel. The invention also provides an evaluation and calculation of the noise on the line or channel.

Abstract: 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.

Abstract: 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 are also disclosed.

Abstract: A method and apparatus for noise cancellation in a multi-channel communication system is disclosed. In one embodiment this system is configured to cancel FEXT on a victim channel utilizing the signals received on the other channels. The processing benefits gained by a receiver's other filters, such as for example, the FFE and DFE filters, is utilized when generating a FEXT cancellation signal. As a result, the complexity of the apparatus that generates the FEXT cancellation signal may be made less complex since part of the processing burden is performed by other filter apparatus. In one configuration pre-code FEXT cancellation occurs in that a pre-code FEXT filter generates one or more pre-code FEXT cancellation signals corresponding to each of the other channels. The pre-code FEXT cancellation signals are combined, prior to transmission, with the signals associated with each of the other channels, to thereby pre-cancel FEXT prior to transmission.

Abstract: Adaptive analog equalization. The present invention provides an analog equalization solution that is assured to converge irrespective of the initial conditions of the adaptation. For very high frequency communication applications, including DS3 or E3 line code applications operating at frequencies approaching 45 MHz, the analog adaptive equalization employs double sampling. One of the samples is used to make the decision if a transition actually goes to zero, and the other of the samples is used to drive the adaptation loop to converge. The present invention employs a high pass network and an adaptable gain to control an adaptive analog equalizer structure. There are two different feedback paths to ensure convergence of the present invention. In one embodiment, one feedback path is the gain control feedback path that is provided to the adaptive analog equalizer structure. The other feedback path is provided to a variable gain amplifier.

Abstract: A method and apparatus for noise cancellation in a multi-channel communication system is disclosed. In one embodiment this system is configured to cancel FEXT on a victim channel utilizing the signals received on the other channels. The processing benefits gained by a receiver's other filters, such as for example, the FFE and DFE filters, is utilized when generating a FEXT cancellation signal. As a result, the complexity of the apparatus that generates the FEXT cancellation signal may be made less complex since part of the processing burden is performed by other filter apparatus. In one configuration pre-code FEXT cancellation occurs in that a pre-code FEXT filter generates one or more pre-code FEXT cancellation signals corresponding to each of the other channels. The pre-code FEXT cancellation signals are combined, prior to transmission, with the signals associated with each of the other channels, to thereby pre-cancel FEXT prior to transmission.

Abstract: A method and system for performing sequence time domain reflectometry over a communication channel to determine the location of line anomalies in the communication channel is disclosed. In one embodiment, the system generates a sequence signal and transmits the sequence signal over an optical channel. The system receives one or more reflection signals over the optical channel and performs reflection signal processing on the reflection signal. In one embodiment, the optical reflection is transformed to an electrical signal and correlated with the original sequence signal to generate a correlated signal. The time between the start of the reflection signal and a subsequent point of correlation and the rate of propagation reveals a line anomaly location. In one or more embodiments sequence signal time domain reflectometry occurs during data transmission.

Abstract: A method and system for performing sequence time domain reflectometry to determine the location of line anomalies in a communication channel is disclosed. In one embodiment, the system generates a sequence signal and transmits the sequence signal over a channel. The system receives one or more reflection signals, and performs reflection signal processing on the reflection. In one embodiment, the reflection signal is correlated with the original sequence signal to generate a correlated signal. The system determines a time value between the start of the reflection signal and the subsequent points of correlation to determine a location of a line anomaly. In one embodiment preprocessing and post-processing occurs to counter the effects of a communication device, such as a DMT modulator/demodulator. In one embodiment sampling of the sequence and reflection signal may occur at different times or at a different phase to provide greater resolution of the line anomaly location.

Abstract: A system, method, and signal are disclosed for line probing. The invention provides an improved signal for line probing having desirable characteristics. In various embodiments the signal comprises a periodic sequence having good autocorrelation characteristics. The periodic sequence of the invention provides a faster and more accurate evaluation of the channel. Another embodiment of the invention comprises processing of the received sequence to determine a desired or maximum data rate for the line or channel. The invention also provides an evaluation and calculation of the noise on the line or channel.

Abstract: A method and system for performing sequence time domain reflectometry over a communication channel to determine the location of line anomalies in the communication channel is disclosed. In one embodiment, the system generates a sequence signal and transmits the sequence signal over an optical channel. The system receives one or more reflection signals over the optical channel and performs reflection signal processing on the reflection signal. In one embodiment, the optical reflection is transformed to an electrical signal and correlated with the original sequence signal to generate a correlated signal. The time between the start of the reflection signal and a subsequent point of correlation and the rate of propagation reveals a line anomaly location. A circulator, beam splitter, or any other similar device may direct the reflection signal to the apparatus configured to perform reflection signal processing.

Abstract: A method and apparatus is provided for processing a signal to remove or reduce the unwanted effects of transmission through the transmission line. To reverse, negate or counter the attenuating properties of transmission through a transmission line the method and apparatus described herein determines the amount of amplification or a gain value required to restore one or more aspect of the signal to a desired or a pre-transmission level. Characterization of the line, based on the gain value, determines one or more filter coefficients. Based on the one or more coefficients, a filtered modifies the signal to reverse the effects of the channel. In one embodiment the peak value or an average magnitude of the received signal is detected to determine the gain value. Dampening may optionally be included to limit the amount of filter modification that may occur on the signal in a clock cycle.

Abstract: Modem start-up delay reduced by measuring condition of communications line upon connection termination. Variation between termination and start-up line conditions determines if cold or warm start is required. Warm-start may use original condition descriptors. Condition represented by ambient noise, echo or spectral response of channel.

Abstract: A system, method, and signal are disclosed for line probing. The invention provides an improved signal for line probing having desirable characteristics. In various embodiments the signal comprises a periodic sequence having good autocorrelation characteristics. The periodic sequence of the invention provides a faster and more accurate evaluation of the channel. Another embodiment of the invention comprises processing of the received sequence to determine a desired or maximum data rate for the line or channel. The invention also provides an evaluation and calculation of the noise on the line or channel.

Abstract: In one embodiment a communication device activation system is provided to restore activation of one or more communication devices that are in a powered-down mode to conserve power usage during a period of inactivity. The activation signal, also referred to as a warm start signal, comprises a sequence signal. A sequence generator generates a desired sequence signal. It is contemplated that one or more sequence signals may be selected for use by the activation system. The sequence signal may be generated or stored and retrieved. To resume communication, a wake-up sequence signal is generated and transmitted to a remote communication device. Upon receipt the received signal is filtered, correlated and analyzed. Analysis may compare one or more aspects of the signal to a threshold signal. If the signal is determined to comprise a wake-up signal, i.e. a request for communication, then a warm-start operation may occur. An acknowledgement signal may optionally be generated to acknowledge receipt of the signal.

Abstract: A method and system for performing sequence time domain reflectometry to determine the location of line anomalies in a communication channel is disclosed. In one embodiment, the system generates a sequence signal and transmits the sequence signal over a channel. The system receives one or more reflection signals, and performs reflection signal processing on the reflection. In one embodiment, the reflection signal is correlated with the original sequence signal to generate a correlated signal. The system determines a time value between the start of the reflection signal and the subsequent points of correlation to determine a location of a line anomaly. In one embodiment preprocessing and post-processing occurs to counter the effects of a communication device, such as a DMT modulator/demodulator. In one embodiment sampling of the sequence and reflection signal may occur at different times or at a different phase to provide greater resolution of the line anomaly location.