Abstract: A physical layer device that is adapted to communicate with a cable medium and that includes an indicator comprises a first input/output terminal and a first transceiver that communicates with the first input/output terminal that is adapted to be connected to the cable medium. A detector detects a power over Ethernet (POE) device. A switching device selectively provides power from a power supply over the cable medium when the detector detects the POE device. A cable tester communicates with the first transceiver, tests the cable medium and determines a cable status, and delays testing of the cable medium when the detector detects the POE device until the switching device provides the power. The indicator indicates at least one of cable testing status during the test and the cable status after the test.

Abstract: A physical layer device communicates with a second physical layer device over a cable. The physical layer device includes a cable tester that identifies when the second physical layer device is disconnected from the cable. The cable tester includes a test initiating circuit that initiates a cable test when a link is lost, a test module that transmits test pulses on the pairs of the cable, measures reflection amplitudes, calculates cable lengths, and determines whether the pairs have said open status based on said measured amplitude and said calculated cable length, and a reporting circuit that generates a disconnect signal when at least one of the pairs has an open status.

Abstract: A physical layer device including a first port, a second port, and a cable that has one end that communicates with the first port and an opposite end that communicates with the second port. A cable tester tests the cable to determine a cable status, which includes an open status, a short status, and a normal status. A pretest module senses activity on the cable and selectively enables testing depending upon the sensed activity. A test module transmits a test pulse on the cable, measures a reflection amplitude, calculates a cable length, and determines the cable status based on the measured amplitude and the calculated cable length. A frequency synthesizer communicates with the cable and that selectively outputs a plurality of signals at a plurality of frequencies on the first port. An insertion loss calculator receives the signals on the second port and that estimates insertion loss.

Abstract: A cable tester tests cable and determines a cable pass/fail status. A pretest module senses activity on the cable and selectively enables testing based on the sensed activity. A test module is enabled by the pretest module, transmits a test pulse on the cable, measures a reflection amplitude, and calculates a cable length. The cable status includes an open status, a short status, and a normal status. The test module determines the cable status of the cable based on the cable at least one of passing and failing A out of B cable tests. The test module determines the cable status for each of the B tests based on the measured amplitude and the calculated cable length.

Abstract: A physical layer device that communicates over a cable comprises a cable tester that determines a cable status, which includes an open status, a short status, and a normal status. The cable tester includes a pretest module that senses activity on the cable and selectively enables testing based on the sensed activity. A test module is enabled by the pretest module, transmits a test pulse on the cable, measures a reflection amplitude, calculates a cable length, and determines the cable status based on the measured amplitude and the calculated cable length. An insertion loss estimator communicates with the cable tester and estimates insertion loss of the cable. A return loss estimator communicates with the cable tester and estimates return loss of the cable based on gain parameters of the physical layer device.

Abstract: A system comprises a physical layer device that is adapted to communicate with a cable medium and that includes a first input/output terminal. A first transceiver communicates with the first input/output terminal and the cable medium. A cable tester tests the cable medium and determines a cable status. An indicator communciates with the physical layer device and identifies at least one of link presence, link abscence, link activity, link duplex and or link speed of the first input/output terminal during normal operation. The cable tester also uses the indicator to indicate at least one of cable testing status during the test and/or the cable status after the test.

Abstract: An apparatus for monitoring the integrity of a wire is provided, which includes a TDR instrument for generating a pulse waveform for transmission through the wire. The apparatus also includes a function generator for generating an electrical or non-electrical forcing waveform for transmission through the wire. The pulse waveform is transmitted through the wire in combination with the forcing waveform and a detector measures a change in dissipation factor values along the wire.

Abstract: A system for determining characteristics associated with a communication channel includes a transmitter for transmitting a first signal via the communication channel. The system includes a receiver for receiving a second signal via the communication channel in response to the first signal. The second signal is associated with the first signal. The system includes a correlator for performing frequency domain correlation between a frequency domain representation of the second signal and frequency domain representations of a plurality of time-delayed versions of the first signal to generate frequency domain correlation information. The system includes an analyzer for identifying correlation peaks in a magnitude of the frequency domain correlation information to determine locations of discontinuities of the communication channel. The identified correlation peaks are associated with the locations of the discontinuities of the communication channel.

Abstract: An aircraft multi-function wire and low voltage insulation tester, having a time domain reflectometer, a digital multi-meter, and a matrix switch integrated in a computer, and a connector having a plurality of output pins allowing a plurality of wires to be hooked up simultaneously. The matrix switch connects the output pins to either the digital multi-meter or the time domain reflectometer perform the respective tests. Corresponding to the output pins, the matrix switch has a plurality of input/output channels, such that wire paths can be established between the output pins. The time domain reflectometry and characteristic tests can thus be performed on each line of a cable to be tested, and each wire path established between the output pins or the lines.

Abstract: In a system and method for testing and displaying the abnormalities, includes opens, shorts, bridged-taps and wet sections, of a copper pair line for xDSL service use, the abnormalities are amplified and normalized so as to be displayed within a predetermined observation range. The normalization steps include piecewise gaining and biasing the reflected pulse of various gains to create a first normalized reflected trace which match the reflected traces within a predetermined observation range and thereby constitute a total smooth curve; and amplifying the first normalized reflected trace according to a function of time to create a second normalized reflected trace so as to eliminate an exponential gain decay curve of a no-fault copper pair line with the same predetermined characteristic parameters from the first normalized reflected trace to thereby obtain a second normalized reflected trace showing any amplified abnormalities.

Abstract: Method is provided for testing electrically heated subsea pipelines that are “electrical-ready,” that is, equipped for applying electrical power when it is needed for heating the pipeline at any time during the life of the pipeline. Time domain reflectometer apparatus in a water-tight enclosure can be deployed subsea. Electrical connections are made with the pipeline using wet-mateable connectors. Reflected signals from the segment of the pipeline being tested are transmitted to an interface at the surface, where the time domain reflectometer is controlled to send a selected pulse. Reflected signals may be interpreted by observing pulse form and time of receipt or by comparison of pulse forms received at different times during the life of a pipeline. Apparatus for electrically connecting a time domain reflectometer to an electrical-ready pipeline is provided.

Abstract: A method and system for performing sequence time domain reflectometry to determine the location of line anomalies in a communication channel is disclosed. In one embodiment, the system generates a sequence signal and transmits the sequence signal over a channel that is the subject of the sequence time domain reflectometry analysis. The system monitors for and receives one or more reflections, collectively a reflection signal, and presents the reflection signal to a reflection processing module. In one embodiment, the reflection signal is correlated with the original sequence signal to generate a correlated signal. The system may perform signal analysis on the correlated signal to determine a time value between the start of the reflection signal and the subsequent points of correlation. Based on the time value and the rate of propagation of the signals through the channel, the reflection processing module determines a distance to a line anomaly.

Abstract: Disclosed herein is a method of measuring a dielectric constant of a Printed Circuit Board (PCB) for a Rambus Inline Memory Module (RIMM), which includes the steps of measuring a length of a Rambus product of a PCB, applying an input waveform to the Rambus product at a certain probing position and obtaining a cross point of rising times of the input waveform and an output waveform generated by reflection of the input waveform, obtaining time corresponding to the cross point, and calculating a dielectric constant by substituting the measured length of the Rambus product and the obtained time for corresponding variables of a dielectric constant calculating equation.

Abstract: In the case of the present-day trend of miniaturizing housed electronic devices, there is the problem that the contact spacings between the terminal pins becomes smaller and smaller and are no longer visible optically. As a result, it also becomes more difficult to solder the contacts of correspondingly designed contact bases, which for example, are designed as test bases, to the individual conductor tracks of the printed circuit board. Possible faulty soldering points, short circuits or interruptions have hitherto been tracked down by laborious manual measurement using the TDR method. The invention proposes producing a test device in which in each case two terminal pins are connected to a short-circuiting bridge. The test device is inserted into the contact base and connects two signal paths of the printed circuit board on which the propagation time of a reflected wave can be measured.

Abstract: The invention concerns a time domain reflectometry method for estimating properties of a transmission channel, for instance a channel for transmitting electric or acoustic signals. This method includes the steps of generating, at one end of the channel, a plurality of pulses (40, 42, 44) covering differency frequency bands, and processing the echoes provided by these pulses at the same end of the channel. The frequency bands of the generated pulses are preferably overlapping. The invention is particularly applicable to the testing of ADSL services.

Abstract: A method and system for performing integrated adjustable short-haul/long-haul time domain reflectometry (TDR). A TDR pulse count is set to a predetermined number. Next, a TDR pulse is transmitted through a cable. The width of the TDR pulse is a function of the multiplication of the TDR pulse count with the period of a TDR clock. It is then determined whether the TDR pulse has been reflected back. If the TDR pulse has not been reflected, the TDR pulse count is successively increased to successively increase the width of the transmitted TDR pulse until a reflection is detected—indicating an open in the cable. Furthermore, it eliminates false detections of cable opens. Moreover, the system can be combined into a line interface unit (LIU) integrated circuit such that TDR functionality can be performed automatically without the use of a technician.

Abstract: A method for isolating a fault in an aircraft circuit having a lead conductor and a plurality of branch conductors coupled to the lead conductor is disclosed. The method includes coupling a reference line of a device to a ground of the lead conductor, coupling a supply/return line of the device to the lead conductor, supplying an impulse signal to the supply/return line, and receiving a reflected signal that is produced from the impulse signal. The method also includes determining whether a fault exists in the plurality of branch conductors using the reflected signal, coupling the reference line of the device to a ground of the plurality of branch conductors, coupling the supply/return line of the device to one of the plurality of branch conductors, and supplying a signal to the supply/return line.

Abstract: A time domain reflectometer having a first impedance when in a first test mode and a second impedance when in a second test mode. The first impedance is substantially the same as the nominal characteristic impedance of a network link cable not connected to a network and the second impedance is substantially different from the impedance of a network link cable that is terminated into a network. A method for measuring the length of a terminated network cable includes the steps of determining that the network cable is terminated at a network, selecting a test mode suitable for testing the terminated network cable, and performing time domain reflectometry testing on the terminated network cable.

Abstract: A method for electrical cable testing by Pulse-Arrested Spark Discharge (PASD) uses the cable response to a short-duration high-voltage incident pulse to determine the location of an electrical breakdown that occurs at a defect site in the cable. The apparatus for cable testing by PASD includes a pulser for generating the short-duration high-voltage incident pulse, at least one diagnostic sensor to detect the incident pulse and the breakdown-induced reflected and/or transmitted pulses propagating from the electrical breakdown at the defect site, and a transient recorder to record the cable response. The method and apparatus are particularly useful to determine the location of defect sites in critical but inaccessible electrical cabling systems in aging aircraft, ships, nuclear power plants, and industrial complexes.

Abstract: Systems and methods are described for transmitting a waveform having a controllable attenuation and propagation velocity. An exemplary method comprises: generating an exponential waveform, the exponential waveform (a) being characterized by the equation Vin=De?ASD(x?vSDt), where D is a magnitude, Vin is a voltage, t is time, ASD is an attenuation coefficient, and VSD is a propagation velocity; and (b) being truncated at a maximum value. An exemplary apparatus comprises: an exponential waveform generator; an input recorder coupled to an output of the exponential waveform generator; a transmission line under test coupled to the output of the exponential waveform generator; an output recorder coupled to the transmission line under test; an additional transmission line coupled to the transmission line under test; and a termination impedance coupled to the additional transmission line and to a ground.

Abstract: A communication system uses a reflected signal to determine the location of an impedance mismatch along a transmission path. The system provides a forward signal through the transmission path, and obtains, using a feedback loop, forward signal samples and reflected signal samples from the forward signal and a reflected signal, respectively. Assuming a significant mismatch exists, the system identifies a time delay of any impedance mismatch from the forward signal samples and the reflected signal samples. The physical location of the mismatch along the transmission path is determined based on the time delay and a propagation velocity of the forward signal through the transmission path. The magnitude of the mismatch is determined based on a voltage gain calculation, a loss profile of the transmission path, the propagation velocity, and the time delay. In one embodiment, the method is carried out in a communications base station that includes an amplifier, a feedback loop, a feedback receiver, and a processor.

Abstract: A cable testing system and method tests cable and determines status, cable length and reflection amplitude. The test module includes a pretest state machine that senses activity on the cable and enables testing if activity is not detected for a first period. A test state machine is enabled by the pretest state machine, transmits a test pulse on the cable, measures a reflection amplitude and calculates a cable length. The test module determines the status based on the measured amplitude and the calculated cable length. A lookup table includes a plurality of sets of reflection amplitudes as a function of cable length. The test module determines the status using the lookup table, the reflection amplitude and the cable length.

Abstract: A non-intrusive, fully automated, variable Cable and impedance-based, multiplexed cable testing system is described that uses Time Domain Reflectometry techniques. The system can process more than one cable type, with varying characteristics, at any one time during which it confirms and processes both the characteristics of the cable type under test and any discontinuities encountered during its operational life due to the impedance variations defined and processed. Furthermore, the system provides an extensive range of Real-Time Diagnostic and Prognostic data together with accurate location and interpretation of any said data and or discontinuity including, but not limited to, the additional mapping of impedance variations along the length of the cable.

Abstract: A system for performing broadband differential time domain measurement on a subscriber loop. The system comprises a waveform generator coupled to a sampling head. The sampling head includes positive and negative pulse generators each coupled to one of the lines of the subscriber loop. The subscriber lines are in turn also coupled to two inputs of a differential amplifier, whose output is connected to an oscilloscope or other detector.

Abstract: An apparatus for monitoring the integrity of a wire is provided, which includes a TDR instrument for generating a pulse waveform for transmission through the wire. The apparatus also includes a function generator for generating an electrical or non-electrical forcing waveform for transmission through the wire. The pulse waveform is transmitted through the wire in combination with the forcing waveform and a detector measures a change in dissipation factor values along the wire.

Abstract: In an apparatus for determining the moisture content of a medium forming a dielectric of a measuring conduit of a probe, which apparatus includes an electronic evaluation unit, a signal generator providing a pulse signal to one end of the measuring conduit, a receiver for receiving a reflected signal returned to the one end of the measuring conduit and a time measuring device for determining the time elapsed between the supply of the signal and the return of the reflected signal, the electronic evaluation unit is arranged in close proximity to the one end of the measuring conduit and provided with temperature compensating means.

Abstract: A test device to isolate and locate problems in a wireless transmission antenna system by selectively inducing multiple faults in an independent integral configuration. The test device is used in conjunction with test analysis equipment allowing a technician to induce independent multiple faults system test configurations to detect, isolate and locate feed line and antenna system problems. By selectively connecting the test device at different points along the transmission path dependent on the test analysis outcome, the exact physical location of the problem can be determined within the transmission circuit.

Abstract: A timing adjusting circuit is mounted on a semiconductor device. A reference signal TREFIN and signals TPa to TPx to be adjusted are supplied from a tester via transmission lines on a test jig. By gradually advancing phases of the signals TPa to TPx with respect to a trigger signal TRIG generated on the basis of the reference signal, the differences of transition timings of driver waveforms are held in a plurality of registers corresponding to the transmission lines. The data held by the plurality of registers is sent to the tester via a storage result outputting circuit. On the basis of the data, output timings of the driver waveforms can be adjusted by the tester with high accuracy.

Abstract: A circuit for determining an indication of a length of a conductor. The circuit includes a terminal for connection to a conductor under test such as a cable. A pulse source is coupled to a sample-hold latch and a re-synchronizer, and the pulse source provides a signal to the terminal for testing the conductor. A voltage comparator is coupled to the terminal for providing a signal to the pulse source and the terminal. The circuit also includes a length error detector coupled to the sample-hold latch, the re-synchronizer, and the pulse source.

Abstract: A method for determining the make up of a subscriber loop via improved time-domain reflectometry techniques by analyzing the echo responses generated by transmittal of pulses onto the subscriber loop. In the method discontinuities along a loop are identified sequentially and in a step-by-step fashion by comparing the measured waveform to suitable waveforms generated on the basis of a hypothesized topology. Once the generated waveform that best matches the measured data has been found and a discontinuity identified, the waveform generated in correspondence of the loop topology identified so far is subtracted from the measured data to produce a compensated waveform, which, is more suitable for detection and location of the next echo.

Abstract: An integrated TDR for locating transmission line faults. An integrated circuit comprises a transmitter, a path coupled to the transmitter, and a TDR receiver integrated with the transmitter for analyzing a reflected signal from the path. The TDR receiver compares the reflected signal with a variable reference signal to generate a logic state at a sampling instant determined by a timebase generated by a sampling circuit. The reflected signal equals the variable reference signal when the logic state transitions. The reference signal and the corresponding timebase value are recorded at the logic state transition. A waveform is generated from the recorded reference signal and its corresponding timebase value. A reference point for the waveform is determined. The location of a fault on the transmission line can be determined from the timebase value difference between the reference point and the fault.

Abstract: A measuring method and a measuring apparatus which transmits to a transmission line a measuring signal, a part of which is reflected back to the measuring apparatus which comprises a processor which measures the reflected signal. The processor transmits a measuring signal to the transmission line and the processor measures the magnitude of the measuring signal before the measuring signal is transmitted and the processor compares the measuring result with the magnitude of the reflected measuring signal. In addition, the processor calculates a reflection coefficient for the transmission line in the frequency domain by means of the measuring results. Further, the processor calculates an impulse response for the transmission line by means of the refection coefficient in the frequency domain.

Abstract: An apparatus for monitoring integrity of a wire is provided, which includes a TDR instrument for generating a pulse waveform for transmission through the wire. The apparatus also includes a function generator for generating a forcing waveform for transmission through the wire. The pulse waveform is transmitted through the wire by itself, and then in combination with the forcing waveform.

Abstract: A method for measuring the attenuation in digital transmission lines between a switching center and a subscriber station, with a first pulse of a known frequency spectrum being sent from the switching center to the transmission line. From the multitude of the reflections received by the switching center in the time domain that pulse is selected which was caused by the total reflection at the end of the line of a certain subscriber station. The frequency spectrum of the selected pulse is determined and from the frequency spectra of the outgoing pulse and the selected received pulse, the attenuation of the transmission line is determined, depending on its frequency. To achieve the extremely high dynamics necessary for this and to obtain a pulse which is free of any overshoot, reflection measuring is carried out selectively in the frequency range and the pulse is calculated per Fourier transformation.

Abstract: A system for determining the locations of faults on a cable by determining the positions of transformers is described. The locations of transformers can be determined in a reflected signal trace resulting from a voltage pulse coupled into the cable. The reflected pulse signals on the reflected signal trace from the transformers follow a predictable attenuation pattern. Therefore, an algorithm executing on a computer system can be utilized to determine the location of transformers in a reflected signal trace. A fault can then be located by, for example, applying a high voltage to the cable and measuring a new reflected signal trace which shows reflection from the fault. The fault, then, can be located relative to neighboring transformers.

Abstract: Wiring defects are located by detecting a reflected signal that is developed when an arc occurs through the defect to a nearby ground. The time between the generation of the signal and the return of the reflected signal provides an indication of the distance of the arc (and therefore the defect) from the signal source. To ensure arcing, a signal is repeated at gradually increasing voltages while the wire being tested and a nearby ground are immersed in a conductive medium. In order to ensure that the arcing occurs at an identifiable time, the signal whose reflection is to be detected is always made to reach the highest potential yet seen by the system.

Abstract: In a system and method for testing and displaying the abnormalities, includes opens, shorts, bridged-taps and wet sections, of a copper pair line for xDSL service use, the abnormalities are amplified and normalized so as to be displayed within a predetermined observation range. The normalization steps include piecewise gaining and biasing the reflected pulse of various gains to create a first normalized reflected trace which match the reflected traces within a predetermined observation range and thereby constitute a total smooth curve; and amplifying the first normalized reflected trace according to a function of time to create a second normalized reflected trace so as to eliminate an exponential gain decay curve of a no-fault copper pair line with the same predetermined characteristic parameters from the first normalized reflected trace to thereby obtain a second normalized reflected trace showing any amplified abnormalities.

Abstract: A time domain reflectometer transmission line interface includes a pulse driver for generating a transmitted pulse signal. A coupling transformer coupled to the pulse driver couples the transmitted pulse signal to a transmission line and receives a reflected pulse signal from the transmission line. A differential amplifier is coupled to the pulse driver and to the coupling transformer through a network configured such that said transmitted pulse is balanced at the inverting and non-inverting inputs of the differential amplifier.

Abstract: Given the inventive electrical circuit with a device for testing connections in electrical circuits, the change of a test signal (27) due to the effect of a long line is used for determining the quality of an electrical connection (e.g., of a pin). In particular, a determination about the terminating impedance and, thus, about the quality of the connection, is made by defining a maximum value of the test signal (28) reflected at the line end. An existing boundary scan test implementation with appropriate expansions can thereby be used, including a test controller. Standard digital signals can be employed as test signal when their propagation time is lengthened by a delay element.

Abstract: A system is provided for detecting accumulation of material concurrently on multiple areas of a surface in real time. In one embodiment, it is used for detecting icing of airframes while in use or on the ground while awaiting use. It may use either Time Domain Reflectometry (TDR) or Frequency Modulated Continuous Wave (FM-CW) sources to provide a known energizing signal to a transmission line sensor. The system ascertains the signal's round trip travel time in the transmission line. As material accumulates around the transmission line sensor, the medium through which the signal propagates is indicated by the change in time for the signal to propagate in relation to propagation in a reference medium, e.g., air. By employing pre-specified spectral analysis algorithms and referencing to the dielectric constant of media of interest, a determination of the occurrence, location, and the rate and type of material accumulation can be made.

Abstract: The invention describes two alternative methods and corresponding devices for producing an energy signal yn whose amplitude values represent the energy of an electrical signal sn.

Abstract: A modem with built-in transmission line diagnostic capability is presented. Said built-in line diagnostics are capable of determining said transmission line's length and detecting the presence of any bridge taps. Said built-in diagnostics have an advantage of not requiring any specialized or expensive hardware and can be added to an existing modem without significant redesign work.

Abstract: In the case of the present-day trend of miniaturizing housed electronic devices, there is the problem that the contact spacings between the terminal pins becomes smaller and smaller and are no longer visible optically. As a result, it also becomes more difficult to solder the contacts of correspondingly designed contact bases, which for example, are designed as test bases, to the individual conductor tracks of the printed circuit board. Possible faulty soldering points, short circuits or interruptions have hitherto been tracked down by laborious manual measurement using the TDR method. The invention proposes producing a test device in which in each case two terminal pins are connected to a short-circuiting bridge. The test device is inserted into the contact base and connects two signal paths of the printed circuit board on which the propagation time of a reflected wave can be measured.

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: A system and method for characterizing a transmission line in a digital subscriber line (DSL) system. Broadly, the method uses DSL system components, which are configured to perform time domain reflectometry (TDR), in order to determine transmission line characteristics.

Abstract: Locating a fault of a transmission line in a system which performs bidirectional optical communication between a station-side device and plural subscriber devices and in which a transmission line 1 extending from the station-side device is branched by a branching/coupling device into plural transmission lines 2 each connected to the subscriber devices. The present invention provides a supervisory unit to the transmission line 1 and attenuators to respective transmission lines 2. The supervisory unit emits an optical test signal, observes a reflected signal of the test signal while changing the attenuation of the attenuators and locates the fault based on a return time and a return loss when the test signal returns as a reflected signal.

Abstract: The present invention relates to a via parasitics testing and extracting method for Gigabit multi-layered PCB boards. The method of the present invention is a unique test and extraction process that utilizes a TDR measurement and processes the output data therefrom externally. The testing aspect involves obtaining a TDR module waveform and obtaining a text file with output data, whereas the extraction aspect involves analysis of the data in the text file. This method can be used directly to ascertain a Gigabit via structure without the limitations that are imposed by the conventional methods discussed above, and has been theoretically proven to be highly accurate and much faster than any of the existing methods. The method of the present invention has the potential to be included as a built-in testing feature in high-speed TDR meters, and may also be used in order to design an optimized via.

Abstract: Methods and apparatus for determining the location of a fault or another region of interest in an electrical conductor such as an electrical cable. A preselected electrical signal is applied to the electrical conductor and a reflected signal produced thereby is generated. The reflected signal is compared to a plurality of preselected voltage values and time values are recorded representing times at which the voltage of the reflected signal crosses the preselected voltage values. Mathematical algorithms are applied using the recorded time and voltage values first to locate a suspected knee region in the reflected signal, then to confirm the presence of the knee within the suspected knee region. The location of the knee in the reflected signal is then used to calculate the distance to the fault or other region of interest. A further series of time values is recorded within the suspected knee region and used to more precisely determine the true location of the knee in the reflected signal.

Abstract: For measuring the operating properties of a subscriber line module (1) for high bit rate data transmission, a test signal is generated within the module and supplied into a test line (6) with a defined line termination (7) who line or terminating properties are known. The echo signal arising in the test line (6) as a result of the test signal is in turn detected in the subscriber line module (1) and interpreted for evaluating the operating properties.

Abstract: Test structure circuitry and apparatus, circuit boards, and testing systems are described, as well as methods to form such apparatus and circuit boards. The test structure apparatus is used for launching high frequency signals from a test instrument, such as a Time Domain Reflectometer (TDR), into circuitry under test, and includes a pair of launching conductors and a ground pad formed on the first surface of a substrate, or dielectric layer. A ground plane layer, formed on the second surface of the dielectric layer, is connected to the ground pad, which is typically formed so as to substantially surround some portion of the launching conductors. The test structure provides a matching impedance between the TDR probe tip, for example, and the circuit board or components under test.