Abstract: Crosstalk between subscriber loops used to transmit different broadband services through the same bundled telephone cable is a significant limitation to providing digital subscriber line services. A method for estimating the crosstalk, identifying the sources of the crosstalk and predicting additional sources of crosstalk are disclosed. The crosstalk sources are identified in the frequency domain by maximizing the correlation with a “basis set” of received crosstalk PSDs which consist of the cascade of a finite set of known transmit PSDs types times a representative set of crosstalk couplings. Multiple crosstalk types are identified with a technique of successive spectral subtraction. Once a type is identified the crosstalk disturber is compared against all other members of the complete set for that type. Additionally, Mutliple Regression (MR) techniques and a Matching Pursuit (MP) algorithm are used to increase the ability of the system and method to identify various crosstalk disturbers.

Abstract: A method and apparatus for testing telephone equipment for longitudinal balance. A signal generating circuit places a test signal at a certain frequency on the tip and ring wires of a telephone line. The telephone line is monitored and the signals on the tip and ring wires are measured and compared against each other. The frequency is gradually increased in set increments until the test frequency is in the megahertz range.

Abstract: A method and system for determining the make-up of a subscriber loop having sending pulses onto a loop and acquiring data based on received echo signals. Determining from the received echoes each discontinuity on the loop and, based on each discontinuity, determining a channel transfer function for each loop section preceding the discontinuity. The transfer function is then used to synthesize an inverse filter. The inverse filter and acquired data are convolved for all the loop sections preceding the discontinuity. The method may be further improved by modeling real and spurious echoes and subtracting these echoes from the echoes generated in the loop.

Abstract: Signature apparatus and techniques that make home networking devices, e.g., in-Home Phoneline Network (herein referred to as “HPN”) devices, isolation filters, network interface devices, etc., detectable by commercially available metallic loop termination (MLT) test equipment. The invention also provides a method of testing a telephone line for the existence of a signature circuit identifying a home network. The home network signature circuit includes a series combination of a voltage breakdown device (e.g., Zener diodes) and an impedance (e.g., 200K ohm resistor). In operation, the home network signature circuit shunts the tested subscriber line loop with a voltage-dependent impedance in the presence of an appropriate test voltage exceeding 80 volts. Different high voltage thresholds of the voltage breakdown portion and/or different resistance values of the shunt impedance can be implemented in the home network signature device to produce uniquely detectable signatures.

Abstract: An apparatus for testing the installation of Asymmetric Digital Subscriber Lines (ADSLs) that includes an ADSL Transceiver Unit - Central Office (ATU-C), an ADSL Transceiver Unit - Remote (ATU-R) and a load coil detector. The apparatus can test the operation of the Central Office ATU, the quality of the POTS cable pair connecting the end-user to the Central Office and the operation of the end-user's equipment. The tests can be carried out by using a standard main distribution frame test cord to connect the test apparatus to the existing test jacks and test shoes at the main distribution frame.

Abstract: A method for controlling transmission power from a customer premise equipment device over a local loop of a digital subscriber line involves determinating a maximum power level for transmissions over the local loop. The maximum power level is based on a response of the local loop to a test signal to allow a different loop in the binder group to have a different maximum power level to reduce potential for crosstalk in the binder group.

Abstract: A method and apparatus for qualifying a telephone transmission line for XDSL communication services is disclosed. The system includes a modem, located at the customer premises to be connected. The modem analyzes actual signals to determine the electrical characteristics of the communication channel associated with the customer premises. The modem includes a transmitter, receiver and controller to generate test signals and receive responses. The modem then analyzes the data to generate an output value indicative of the electrical characteristics of the communication channel being tested. This output value is then displayed to a user or transmitted over the communication channel to a network. The system thereby eliminates the necessity of dispatching a technician to test the telephone line, and provides more accurate test results than those achievable at the network-side of the connection alone.

Abstract: The present invention is related to a method and device for call-waiting signal to identify tolerant errors and particularly to a method and device for call-waiting signal on a telephone set with a call-waiting function to identify tolerant errors though making use of an amplitude detecting device to perform a reaffirming action so as to escalate the identification rate of the call-waiting signal..

Abstract: Metallic testing of a subscriber loop that provides voice and DSL services is provided by a voice switch and DSL services, each of which includes a metallic test unit. A voice line card has a connection to a first metallic test bus connected to the voice switch metallic test unit via a first relay set configured to connect the metallic test bus to the subscriber loop and to disconnect the subscriber loop from the line card during testing. The DSL line card has a connection to a second metallic test bus, which is also connected to the DSLAM metallic test unit, and to the subscriber loop. A second set of relays control the connection of the metallic test bus to the line card to the subscriber loop. A signal is sent from either metallic test unit to cause the relays to change to provide a clear path for metallic testing from DC to light.

Abstract: Test functions to test an operability of a subscriber circuit are integrated in the subscriber circuit. The test functions use existing components and do not significantly burden the signal processor of the subscriber circuit. The subscriber circuit is provided in a digital telephone exchange having connectable subscriber lines and has a high-voltage section and a low-voltage section. Once an alternating current, which is produced by a tone generator, has been fed into connecting paths, a frequency-selective current threshold-value comparison is carried out, by which the operability of the subscriber circuit can quickly be confirmed.

Abstract: In one embodiment, a test tone is placed in an outbound path of a full-duplex transmission system. An echo cancellation capability is disabled, enabling an echo signal of the test tone to pass through the inbound path of the full-duplex transmission system, which echo signal is analyzed to determine the condition of the full-duplex paths. In another embodiment a standard DSP generates DTMF tones which are looped-back and tested by the DSP, under control of a CPU. The DSP is a standard DSP avoiding the need for any hardware/software modification of the DSP to perform the test mode. The tests are performed the local level, i.e. at the subscriber's location, eliminating the need for central office intervention, for example.

Abstract: A method tests a subscriber line. The method includes providing a classifier to predict a performance characteristic of the line based at least in part on a value of an auxiliary variable. Each value of the auxiliary variable represents a property of the line. The method also includes performing electrical measurements on the subscriber line, using the measurements to predict a value of the auxiliary variable, and predicting the performance characteristic of the line. The act of predicting the characteristic applies the classifier to the predicted value of auxiliary variable.

Abstract: Telephone line service type identification is provided to a telephone technician in the field by the placement of one or more tuned circuit(s) across the telephone line. In one embodiment, an inexpensive tuned circuit such as a ceramic resonator forms a telecom service resonator ID device which is placed across a telephone line, either at the central office or at the customer premises. Injection of a test current at a predetermined frequency, and a suitable amplitude of the same indicates to the technician aspects of telecom service to that particular telephone line (e.g., the existence of POTS, ISDN, and/or xDSL) and or use of the telephone line by a home network such as HPNA. In another embodiment, a telecom service transponder ID device is formed to provide line service identification to an interrogating line technician. The telecom service transponder ID device is activated when the test signal including an appropriate frequency is present to cause excitation in the telecom service transponder ID device.

Abstract: Techniques for estimating distances to irregularities on a subscriber loop are described. A loop response is measured in the frequency domain. The loop response is weighted by a prolate spheroidal wave function to yield a weighted response. The weighted response is transformed to a spectral domain, and peaks in the spectral domain are identified as the distances to the irregularities.

Abstract: The system to pre-qualify copper subscriber loops for high bandwidth access service determines electrical characteristics of a subscriber line served by a central office switch from a location remote from said subscriber line absent a direct metallic connection exclusively to said subscriber line. This is accomplished where the subscriber line has subscriber equipment connected thereto at an end distant from said central office switch by establishing a communication connection through the central office switch between the service provider and the subscriber equipment connected to said subscriber line. In response to the establishment of this communication connection, electrical signals, comprising subscriber or network generated tone signals, are applied to the subscriber line to enable the service provider to determine the electrical characteristics of the subscriber line by analyzing the received tone signals.

Abstract: A method and system for determining the high speed data service capability of a subscriber line includes sending an embedded test signal to a subscriber line. A reflected signal received in response to the test signal is analyzed for determining transmission characteristics of the subscriber line. Based on the reflected signal, a determination about the high speed data service capabilities of the subscriber line is made and stored for future reference.

Abstract: An electronic relay matrix (22) is connectable between a plurality of customer telephone lines and a plurality of testers (2, 201-203). The electronic relay matrix (22) includes a line matrix (80) having a plurality of relay assemblies (821-8250). Each relay assembly (82) in a relaxed state connects together the line-side (12) and the drop-side (8) of one of the customer telephone lines. Each relay assembly (82) is adjustable to enable one of the plurality of testers (2, 201-203) to be connected to the drop-side (8) and/or the line-side (12) of a desired customer telephone line.

Abstract: A Digital Subscriber Line Access Multiplexer includes a set of line cards, a set of xDSL modem cards, a redundant xDSL modem card, a test and switching unit, a control unit, and a trunk unit. Each line card may include a switch, through which the control unit may selectively direct the line card to couple to a corresponding xDSL modem card or a redundancy bus. The test and switching unit is coupled to the redundancy bus, and includes a relay matrix and a Copper Loop Tester (CLT). In response to commands received from the control unit, the relay matrix may route redundancy bus signals to the CLT and/or the redundant xDSL modem card. The CLT performs tests to measure or determine subscriber loop electrical characteristics in response to control unit commands, and returns test results to the control unit.

Abstract: A system and method for measuring latency in voice communications is presented. In an exemplary embodiment, latency is measured by establishing a call between a first and a second telephony device, and measuring a latency between a signal originating at the first telephony device and the signal as it arrives at the second telephony device.

Abstract: A digital subscriber line (xDSL) communication system (10) is disclosed that allows xDSL communication across a local loop. The system (10) includes a local loop termination point (14) and customer premises equipment (12) connected to a twisted pair telephone line (16). Loop integrity test devices (22, 24) for xDSL communication are located at the local loop termination point (14) and the customer premises equipment (12) and are coupled to the telephone line (16). The loop integrity test devices (22, 24) are respectively operable to transmit test signatures across the telephone line (16), to receive and evaluate test signatures from the telephone line (16), and to indicate whether the telephone line (16) can support xDSL communication based upon evaluation of test signatures.

Abstract: A remote telephone testing device (22) includes a transmitter (30), a receiver (24), a controller (26) and a test circuit (28). In response to the receiver (24) receiving a test signal from a test system (20) via a telephone network (2, 4, 6, 8), the controller (26) communicatively isolates telephone equipment (10) of a subscriber (S) from the telephone network (2, 4, 6, 8) and connects the test circuit (28) to the telephone equipment (10). The test circuit (28) tests the telephone equipment (10) and conveys one or more results of such test to the controller (26) which relays the one or more results to the test system (20) via the transmitter (30). When testing is complete, the telephone equipment (10) is isolated from the test circuit (28) and is communicatively connected to the telephone network (2, 4, 6, 8).

Abstract: A communications system is tested to simulate a realistic conversation. A first measurement device make a call, through the system it is testing, to a second measurement device and the two devices converse using predetermined speech generated dynamically by each device in response to the signals received from the other, to simulate aspects of conversation over non-perfect communications system link. The progress of the conversation will therefore take different courses according to the quality of the link. For example, if an expected signal is detected by one device, it transmits an appropriate predetermined response to the other device. However, if the expected signal is corrupted, or not received at all, different predetermined responses (or no response at all) are transmitted to the other device. This in turn may cause the other device to repeat the original signal.

Abstract: A communication line tester system and method allows for effective measurement and presentation of communication line characteristics. The communication line tester includes a transmitter, an analog-to-digital converter and a main processor. The transmitter is electrically coupled to the communication line. The analog-to-digital converter is electrically coupled to the communication line. The main processor is electrically coupled to the analog-to-digital converter. The main processor include a pseudo-random code processor configured to generate pseudo-random coded signals for transmission by the transmitter on to the communication line and to decode pseudo-random coded signals received by the main processor from the analog-to-digital converter.

Abstract: A system and methodology for qualifying a twisted pair copper loop for digital subscriber loop services are described. The system automatically queries telecommunications provider database records and/or requests measurements from network switching equipment or testing systems to obtain data regarding the twisted pair copper loop, such as loop length, electrical characteristics, and other loop topology characteristics such as wire gauge, the presence of load coils, and the presence of bridge taps. The system determines which digital subscriber loop services are available for the copper loop based on the combination of all data obtained. The system may be implemented in part as an expert system with a knowledge base of qualification rules used in the decision-making process.

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.