Improved crosstalk identification for spectrum management in broadband telecommunications systems

In a system for identifying the source of crosstalk disturbance in a subscriber loop wherein the measured power spectral density of the noise on the subscriber loop is compared with a predetermined set of power spectral densities for a group of possible disturbers, the method of determining the predetermined set of power spectral densities for a group of possible disturbers comprising the steps of:

• transmitting a signal over a test loop in a bundle of test loops;
• measuring the -pair-to-pair crosstalk -couplings to generate a set of canonical crosstalk couplings;
• repeating the transmitting and measuring steps for each test loop;
• multiplying the power spectral density for each type of DSL by the set of canonical crosstalk couplings to generate the set of power spectral densities for a possible disturber;

A method for identifying crosstalk disturbers on a subscriber loop based on the availability of a crosstalk basis set comprising the steps of:

• measuring the power spectral density of the noise present on a subscriber loop;
• performing a singular value decomposition on the matrix of the crosstalk basis set to reduce its size;
• identifying the disturbers for said subscriber loop with said reduced size crosstalk basis set using a first mathematical technique;
• identifying the closest pair-to-pair coupling pertaining to the disturber using a second mathematical technique on the portion of the original crosstalk basis set pertaining to said identified disturber types