Abstract: Methods and apparatus to perform and/or analyze communication channels are described. In one embodiment, a test signal may be generated and transferred using a first signal route to a line-under-test in response to line qualification mode. The first signal route may include a compensation device to modify the test signal. In some embodiments, a reflected signal from the line-under-test may be received in response to the test signal. A second signal route may be utilized to route the reflected signal in response to line qualification mode.

Abstract: A system for determining whether a telephone loop is capable of carrying a Digital Subscriber Line (DSL) signal. A Constant Amplitude Zero Auto Correlation (CAZAC) sequence signal is generated and transmitted through the loop plant to a central office and the received echo signal is processed using second-order statistics. The second-order statistics calculation permits determination of the echo signal amplitude and time between the echo signal and sequence signal. The echo signal amplitude and time may be used to obtain telephone loop characteristics such as loop length.

Abstract: An apparatus and technique for determining whether a telephone loop is capable of carrying a Digital Subscriber Line (DSL) signal. Time domain reflected (TDR) signals that are echoes of transmit impulse signals are processed using time domain echo averaging and echo enhancement using second-order statistics. Each technique allows clearer visualization of the TDR echo signal by reducing the noise and distortion present in the TDR signals. These statistical signal processing techniques allow determination of telephone loop characteristics such as loop length once the TDR echo signal amplitude and time index are calculated.

Abstract: A system for determining whether a telephone loop is capable of carrying a Digital Subscriber Line (DSL) signal. A Constant Amplitude Zero Auto Correlation (CAZAC) sequence signal is generated and transmitted through the loop plant to a central office and the received echo signal is processed using second-order statistics. The second-order statistics calculation permits determination of the echo signal amplitude and time between the echo signal and sequence signal. The echo signal amplitude and time may be used to obtain telephone loop characteristics such as loop length.

Abstract: An apparatus and technique for determining whether a telephone loop is capable of carrying a Digital Subscriber Line (DSL) signal. Time domain reflected (TDR) signals that are echoes of transmit impulse signals are processed using time domain echo averaging and echo enhancement using second-order statistics. Each technique allows clearer visualization of the TDR echo signal by reducing the noise and distortion present in the TDR signals. These statistical signal processing techniques allow determination of telephone loop characteristics such as loop length once the TDR echo signal amplitude and time index are calculated.

Abstract: An apparatus and technique for Digital Subscriber Line (DSL) telephone loop qualification that includes a fuzzy logic impedance mismatch network. The impedance mismatch network is used to increase the received echo of a transmit pulse signal to determine the telephone loop characteristics.

Abstract: Briefly, a system that may perform line qualification within a mass-manufacturable modem.