Abstract: A system is provided for identifying service affecting conditions in an access portion of a network through which a number of subscribers are connected to an exchange. The access network includes subscriber lines connected to DSL subscriber modems. The system includes a receiver for receiving pilot signals from a modem connected to one of the subscriber lines. A measuring unit is operatively associated with the receiver for measuring electrical characteristics of the received pilot signals. A controller is operatively associated with the measuring unit and uses the measured electrical characteristics to identify a service affecting condition. The subscriber modem pilot signals include differential mode signals and the measuring unit measures common mode of each wire of the subscriber line. By using combinations of measurements and deductive logic, the system can detect one or more service affecting conditions.

Abstract: A system is provided for identifying service affecting conditions in an access portion of a network through which a number of subscribers are connected to an exchange. The access network includes subscriber lines connected to DSL subscriber modems. The system includes a receiver for receiving pilot signals from a modem connected to one of the subscriber lines. A measuring unit is operatively associated with the receiver for measuring electrical characteristics of the received pilot signals. A controller is operatively associated with the measuring unit and uses the measured electrical characteristics to identify a service affecting condition. The subscriber modem pilot signals include differential mode signals and the measuring unit measures common mode of each wire of the subscriber line. By using combinations of measurements and deductive logic, the system can detect one or more service affecting conditions.

Abstract: A telephone line test system that may be used to compute line length of subscriber lines connected to a central office or other distribution point. When initially installed, the test system may automatically compute CO limits. The CO limits are computed from single-ended measurements on subscriber lines and represent electrical effects of the path between a test head and the distribution point. These CO limits are used to more accurately compute the length of lines connected to the distribution point using measurements made by the test system. Because the process uses single-ended measurements, it may be run in background mode during the initial installation of the test system or at any subsequent time it is desired to update the CO limits.

Abstract: A system for identifying service affecting conditions on a subscriber line in the access portion of a broadband network, particularly an ADSL network. A measurement unit provides information on the line that aids in identifying projected performance. Information from a modem on the subscriber line indicative of actual performance is obtained and compared to the predicted values. Deviations are used to identify service affecting conditions and, depending on the nature of the deviations, the type of condition affecting service on the line. The physical measurements are used to identify the length of the subscriber line. Modem information is obtained through the MIB and allows determination of the bit loading on the line. Interference sources are identified by comparing the actual bit loading to bit loading expected for a line corresponding to the measured length.