Method for qualifying loops for data services and apparatus for making the same

摘要

A method and automatic test system for determining qualification of a twisted pair transmission line to propagate data signals. The method includes measuring phase imbalance in the twisted pair transmission line. The phase imbalance is determined by resistance imbalance in the twisted pair transmission line. The resistance imbalance is determined by applying a common mode voltage to the twisted pair transmission line; and, determining phase imbalance in the twisted pair in response to the applied common mode voltage. The method includes applying a common mode voltage to the twisted pair transmission line; determining phase imbalance if the twisted pair in response to the applied common mode voltage; detecting a peak in the determined phase imbalance; determining a frequency of the detected peak; determining line qualification in accordance with the determined frequency. Methods are provided using series resistive imbalance and phase measurements to discover the type of imbalance existing on a twisted pair transmission line which is unable to support data transmissions. Methods are provided using series resistive imbalance and phase measurements to determine where an imbalance occurs as well as the magnitude of the imbalance.