Abstract: A method characterizes a customer line for data transmission. The method includes measuring electrical properties of the customer line from a central location, identifying a line model from the measurements, and identifying a modem model for a modem selected for use with the customer line. The modem model gives performance data for the selected modem. The method also predicts performance data for the customer line when operated with the selected modem by combining the line and modem models.

Abstract: A method characterizes a customer line for data transmission. The method includes measuring electrical properties of the customer line from a central location, identifying a line model from the measurements, and identifying a modem model for a modem selected for use with the customer line. The modem model gives performance data for the selected modem. The method also predicts performance data for the customer line when operated with the selected modem by combining the line and modem models.

Abstract: A method determines a structure of a subscriber line. The method includes searching a reference set for a match between the subscriber line and a model line of the reference set and identifying that the subscriber line has a specific physical structure. The match is based on electrical properties of the lines. The act of identifying is responsive to finding a match with one of the model lines that has the specific physical structure.

Abstract: Ad-hoc timing signals are transferred from a first circuit to a second circuit by determining a system transit delay, detecting an edge of an ad-hoc signal and the frame and timeslot that correspond with the edge, and regenerating the ad-hoc timing signal based on the system transit delay and the frame and timeslot that correspond with the edge.

Abstract: A method and apparatus to non-interactively test telephone networks and more specifically to localize faults such as resistive faults in the subscriber loop of the telephone network is presented. The method and apparatus determine whether the fault is in the tip line or ring line of a phone line. The existence of a fault voltage, if any, is also determined. The resistance of the tip line to ground and the resistance of the ring line to ground is measured. A fault resistance is calculated from this information, from which the location of the fault is determined.

Abstract: A method determines a structure of a subscriber line. The method includes searching a reference set for a match between the subscriber line and a model line of the reference set and identifying that the subscriber line has a specific physical structure. The match is based on electrical properties of the lines. The act of identifying is responsive to finding a match with one of the model lines that has the specific physical structure.

Abstract: A method detects a fault in a subscriber line having two wires with separate input impedances. The method includes driving the subscriber line from one end with an alternating voltage, making one-ended electrical measurements on the driven liner and determining from the measurements a quantity proportional to the phase difference of the two input impedances. The method also includes identifying a fault in response to the phase difference having a signature associated with presence of a fault in the line.

Abstract: 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.

Abstract: 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 if 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.

Abstract: An automated telephone line test system that is well suited for determining the location of faults within a telephone network. The telephone line test system uses time domain reflectometry to aid in locating the faults. The time domain reflectometry unit is connected through a switch in the network so that the time domain reflectometry unit can be connected to multiple lines without human intervention. Parameters of the time domain reflectometry signals are controlled so that reflections from the switch do not interfere with measurement of parameters on the faulty line.

Abstract: A line test system for diagnosing and segmenting faults in a switched telephone network. The system includes a remote measurement unit installed at a switch and a test system controller. The test system controller stores data about operating parameters of each of the subscriber lines when they are believed to be free of faults. When a fault is reported, the parameters are measured again. By comparison of the measured parameters with the stored parameters, the fault can be segmented between the premise and the network. Segmentation is performed using knowledge based analysis techniques. The actual source of the fault once it is repaired is also stored by the test system controller. This historical information is used to improve the accuracy of the knowledge based analysis techniques used for segmentation. The line test system is capable of detecting the presence of high impedance ringers.

Abstract: A line test system for diagnosing and segmenting faults in a switched telephone network. The system includes a remote measurement unit installed at a switch and a test system controller. The test system controller stores data about operating parameters of each of the subscriber lines when they are believed to be free of faults. When a fault is reported, the parameters are measured again. By comparison of the measured parameters with the stored parameters, the fault can be segmented between the premise and the network. Segmentation is performed using knowledge based analysis techniques. The actual source of the fault once it is repaired is also stored by the test system controller. This historical information is used to improve the accuracy of the knowledge based analysis techniques used for segmentation.

Abstract: Apparatus and method for testing lines. The apparatus is particularly useful for testing lines in a switched network, such as might be used to electronically route telephone and computer data lines to various offices in an office building. The apparatus includes an AC test source and a DC measurement device located at a near end switch. A DC transform circuit is located at a far end switch. According to the test method, an AC test signal is injected onto a line under test at the near end. At the far end, the received signal is converted to DC, which is sent to the near end. Line attenuation, and hence fault conditions, are detected by comparing the DC signal to the transmitted AC signal. Techniques to increase the signal to noise ratio of the DC signal are also disclosed.