Loop certification and measurement for ADSL

A method of testing a transmission line for a digital subscriber line service, comprising:

• transmitting a test waveform signal corresponding to the digital subscriber line service from a transmitting end of the transmission line to a receiving end of the transmission line;
• sampling the waveform signal from the receiving end of the transmission line;
• processing the sample of the received waveform signal to derive a plurality of eigenvalues characterizing a transfer function of the transmission line with respect to the digital subscriber line service;
• comparing the eigenvalues to threshold values representing an acceptable transfer function of a transmission line with respect to the digital subscriber line service;
• and
• from the comparison, determining a relationship of each of the eigenvalues to a respective one of the threshold values.

A system for testing a line of a communication network for a digital subscriber line service, comprising:

• a test waveform generator, for connection to a transmit-side of the line, wherein the test waveform generator comprises a generator for generating a waveform corresponding to the digital subscriber line service selected from waveforms corresponding to a plurality of digital subscriber line services available on the communication network;
• a waveform sampler, for connection to a receive-side of the line, for sampling a test waveform received through the line from the generator;
• and
• a processor, coupled to the waveform sampler and responsive to the sample of the received test waveform, for determining a set of eigenvalues characterizing a transfer function of the transmission line and for comparing the eigenvalues to threshold values corresponding to an acceptable transfer function of the transmission line, wherein the processor selects a set of threshold value corresponding to an acceptable transfer function of the transmission line from a plurality of sets of threshold values, each of the sets of the threshold values corresponding to one of the digital subscriber line services.

A line test unit comprising:

• a coupler, for connection to a line under test, having an output for a waveform signal received over the line under test;
• a waveform sampler responsive to the output of the coupler, for capturing digital samples of the received waveform signal;
• a storage device storing a plurality of sets of threshold values, each set of threshold values characterizing an acceptable transfer function of a line with respect to one of a plurality of digital subscriber line services;
• and
• a processor coupled to the waveform sampler and to the storage device, wherein:
• the processor processes a set of samples for a test waveform corresponding to a selected one of the digital subscriber line services and the captured digital samples, to determine a plurality of eigenvalues characterizing a transfer function of the transmission line with respect to the selected digital subscriber line service;
• and
• the processor compares the eigenvalues to a selected one of the sets of threshold values, the selected set of threshold values corresponding to an acceptable transfer function for the selected digital subscriber line service.