Systems and techniques relating to channel degradation detection for communication systems are described. A described system includes a processor and an interface to transmit signals and receive signals via a channel that includes a cable. The processor can be configured to perform echo cancellation based on echo tap values to remove portions of the transmitted signals that appear as echoes within the received signals, signal equalization based on equalizer tap values, or both. The processor can be configured to determine a channel quality indicator of the channel based on one or more of the echo tap values, one or more of the equalizer tap values, or both. The processor can be configured to generate a warning indication based on the channel quality indicator indicating a degradation of the cable or the channel.

Systems and techniques relating to channel degradation detection for communication systems are described. A described system includes a processor and an interface to transmit signals and receive signals via a channel that includes a cable. The processor can be configured to perform echo cancellation based on echo tap values to remove portions of the transmitted signals that appear as echoes within the received signals, signal equalization based on equalizer tap values, or both. The processor can be configured to determine a channel quality indicator of the channel based on one or more of the echo tap values, one or more of the equalizer tap values, or both. The processor can be configured to generate a warning indication based on the channel quality indicator indicating a degradation of the cable or the channel.

A method of determining when there has been a change in the modem power state of a modem connected to a digital subscriber line. An Uncalibrated Echo Response (UER) trace is obtained from the digital subscriber line by running a Single Ended Line Test (SELT) on the line. This UER trace is compared to a historical (baseline) UER trace from the same line. A difference in the two traces in a higher frequency range (for example, DS3 for a VDSL line), is indicative of a possible modem power state change.

A method of determining when there has been a change in the modem power state of a modem connected to a digital subscriber line. An Uncalibrated Echo Response (UER) trace is obtained from the digital subscriber line by running a Single Ended Line Test (SELT) on the line. This UER trace is compared to a historical (baseline) UER trace from the same line. A difference in the two traces in a higher frequency range (for example, DS3 for a VDSL line), is indicative of a possible modem power state change.

A detection apparatus is provided for a signal transmission apparatus, the signal transmission apparatus being configured to receive a reception signal via a transmission line and including an adaptive filter to be applied to the reception signal. The detection apparatus includes an acquisition unit configured to acquire a filter coefficient of the adaptive filter, and a detection unit configured to detect an abnormality in the transmission line, based on an amount of change over time in the filter coefficient acquired by the acquisition unit.

A detection apparatus is provided for a signal transmission apparatus, the signal transmission apparatus being configured to receive a reception signal via a transmission line and including an adaptive filter to be applied to the reception signal. The detection apparatus includes an acquisition unit configured to acquire a filter coefficient of the adaptive filter, and a detection unit configured to detect an abnormality in the transmission line, based on an amount of change over time in the filter coefficient acquired by the acquisition unit.

A transmission-path degradation detection apparatus comprises a transmission path of a transmission system, plural communication devices connected to the transmission path, a signal generation part provided in one communication device of the plural communication devices for generating a pseudo-communication signal, and a degradation detection part provided in one communication device of the plural communication devices for detecting a degradation of the transmission path based on a reception of the pseudo-communication signal passing through the transmission path.

A transmission-path degradation detection apparatus comprises a transmission path of a transmission system, plural communication devices connected to the transmission path, a signal generation part provided in one communication device of the plural communication devices for generating a pseudo-communication signal, and a degradation detection part provided in one communication device of the plural communication devices for detecting a degradation of the transmission path based on a reception of the pseudo-communication signal passing through the transmission path.

A communication device includes: a signal generator configured to generate a first signal and supply the first signal to a telephone line; a terminator having a variable terminal impedance as seen from the telephone line; a detector configured to detect a difference between the terminal impedance and a line impedance of the telephone line; and a controller configured to determine the terminal impedance so that the difference is reduced.

A communication device includes: a signal generator configured to generate a first signal and supply the first signal to a telephone line; a terminator having a variable terminal impedance as seen from the telephone line; a detector configured to detect a difference between the terminal impedance and a line impedance of the telephone line; and a controller configured to determine the terminal impedance so that the difference is reduced.