Abstract: Method for determining the characteristic impedance of a transmission line on a printed wiring board using time domain reflectometry. The method involves selecting a driving point in time, selecting an undisturbed interval, measuring voltage at predetermined time intervals across the undisturbed interval, determining from the measured voltages a curve representative of such voltages, and determining the voltage on the representative curve at the driving point. The characteristic impedance of the transmission line under test, denoted by Z.sub.0, is obtained by using the "driving point" of the transmission line as the reference plane for the impedance measurements.

Abstract: A calibration method and system for substantially reducing one of the components of timing error in automatic test systems. The timing associated with digital stimulus and response circuitry in a tester is different for positive and negative signal transitions. This inherent timing difference is normally measured and compensated for during the tester calibration process. The present method and system uses a short circuited transmission line as a pulse generator to achieve superior stability and accuracy when calibrating transition dependent timing in automatic test systems.

Abstract: A method for detecting impedance discontinuities in two-conductor cable includes the initial step of transmitting a pulse of energy onto the cable and receiving any reflected pulses at a base location. The distance to the discontinuity is calculated by measuring the elapsed time between the transmitted and received pulses. A waveform is created on a display screen to shown the transmitted and reflected pulses, by taking a plurality of horizontal samples along the cable, and calculating a vertical value for each horizontal sample taken. Each horizontal sample is then converted to digital form and displayed on the screen. Another step in the method includes determining the gauge of the cable and then subtracting the exponential decay of the transmitted pulse waveform based upon that determined cable gauge so as to create a modified transmitted pulse which is displayed on the screen.

Abstract: A flash waveform analyzer (10) includes a transmission line (12) for propagating a signal from an input (14). The transmission line (12) contains a plurality of samplers (16) located at different points along the transmission line (12). Each sampler (16) is activated by a strobe pulse from a strobe source (18) in order to measure a characteristic of the signal at the different points along the transmission line (12). The propagation velocity of the signal is made slower than the propagation velocity of the strobe pulse by using a different dielectric constant in the transmission line (12) than that of the strobe delay line (17). The characteristic measured by each sampler (16) is sent to a multiplexer (20) that selectively outputs the measured characteristic from each sampler (16) to an analog-to-digital converter (22) for processing and subsequent analysis.

Abstract: A dual time base, zero dead zone time domain reflectometer repetitively launches a predetermined number of stimulus pulses into a transmission system in synchronism with clock signals from a first time base, providing a measurement cycle. The duration of the launched stimulus pulses, determined by a predetermined number clock cycles from the first time base, exceeds the total propagation time of the system to be measured so that a time interval between a launch and a reflection may be measured within the launched pulse. A second time base, which has a predetermined period that differs from the period of the first time base and defines a measurement period divided into equal sub-periods, continuously produces clock signals, one or more of which may be counted during the time interval.

Abstract: A low cost method and apparatus for locating the site(s) of partial discharges in electrical distribution lines without use of reflectometry or a separate sensor-to-sensor communication channel.

Abstract: A dual time base, zero dead zone time domain reflectometer repetitively launches a predetermined number of stimulus pulses into a transmission system in synchronism with clock signals from a first time base, providing a measurement cycle. The duration of the launched stimulus pulses, determined by a predetermined number clock cycles from the first time base, exceeds the total propagation time of the system to be measured so that a time interval between a launch and a reflection may be measured within the launched pulse. A second time base, which has a predetermined period that differs from the period of the first time base and defines a measurement period divided into equal sub-periods, continuously produces clock signals, one or more of which may be counted during the time interval.

Abstract: A PN modulated signal is applied to a near end of a buried electrical cable. The signal produces an initial pulse, a second pulse of energy reflected from a fault and a third pulse representative of the far end of the cable. The time/distance between the second and third pulses is stored. As the PN signal is continuously applied an operator, using an antenna coupled monitor, walks along the cable noting the time/distance between the initial and third pulses. When this time/distance equals the stored time/distance the operator is standing over the fault. If the fault is a high resistance fault a high voltage pulse is applied to the near end of the cable. The PN signal is initially sensed at a time when the fault has a low resistance because of arcing due to the high voltage pulse. To reduce stress on the cable, the arc is initialized by a high voltage low current signal and is maintained by a low voltage high current signal.

Abstract: A method and apparatus for locating an incipient fault at a point along the length of an insulated power line includes the application of an excitation voltage at an open end of the power line, and the signal pulse transmitted along the power line to the open end is passed through a high pass filter to remove the portion of the signal which is at a frequency below the excitation voltage and its harmonics. The filtered signal is amplified and passed through a band pass filter to remove a high frequency portion of the signal containing a large proportion of noise relative to the frequency of the partial discharge frequency from the incipient fault. This filtered signal is passed to a digital storage device adapted to be triggered by a signal of a predetermined amplitude, and the triggered digital storage device receives the amplified signal directly from the amplifier and stores digital data concerning amplitude and time for the peaks of the amplified signal for a predetermined period of time.

Abstract: A system for analyzing electrically conductive members such as pipelines, in which electrical pulses are transmitted through said member to intersect at predetermined locations. At least one of the pulses which intersects the other pulse is analyzed to determine whether there is a variation in the intersecting pulses at locations along the length of the member. With the member being tested being a pipeline, in some embodiments, a direct current is applied to the pipeline and this also is used to analyze the condition of the pipeline and also the information provided by the intersecting pulses. Amplitude, frequency, and wave form variations of the intersecting pulses are analyzed to detect anomalies or other conditions along the pipeline or other member.

Abstract: An automotive electrical system including a wiring harness incorporates the dedicated test line passing through critical connectors and components for allowing detection and isolation of improperly connected connectors. The dedicated test line can feed through expansion connectors, termination connectors, and junction blocks. Connector fault detection and isolation is achieved using time-domain reflectometry after final assembly, during vehicle servicing, or on-board during vehicle usage. A large number of expensive and inconvenient vehicle quits and tow-in's are avoided that would otherwise occur.

Abstract: An automotive electrical system including a wiring harness incorporates a dedicated test line passing through critical connectors and components for allowing detection and isolation of improperly connected connectors. The dedicated test line can feed through expansion connectors, termination connectors, and junction blocks. Connector fault detection and isolation can be performed as a test after final assembly and during vehicle servicing. A large number of expensive and inconvenient vehicle quits and tow-in's are avoided that would otherwise occur.

Abstract: A system for measuring partial discharges comprises a plurality of acquisition circuits each including a signal shaping circuit delivering a signal value, a multiplexer enabling the signal values provided by the various acquisition circuits to be delivered in succession on a common path, an acquisition trigger circuit responding to the existence of an acquisition command signal provided when the input level of at least one of the acquisition circuits exceeds a defined threshold and defining an acquisition command signal, and a signal treatment and storage system responding to the acquisition command signal and then performing an acquisition cycle during which it stores the values of the signals provided by the various acquisition circuits via the multiplexer.

Abstract: A method and apparatus of detecting an anomoly along an elongate, electrically conductive member comprising the steps of. An electrical pulse is so sent along the member from each of two locations towards an intersecting location between the two locations that the pulses intersect and are modified at the intersecting location. At least one of the modified pulses is analyzed to determine whether an anomoly exists at the intersecting location. The timing of at least one of the pulses is based at least in part on the propagation delay of an electrical pulse propagating between the two locations.

Abstract: A simple and inexpensive device which is suited for real-time location of a fault occurring anywhere in a residential distribution system by analysis of the propogating fault signal considering the predetermined propagating velocity of the cable.

Abstract: A method of analyzing an electrically conductive member, such as a well casing, where one end of the member is more accessible, and a second end of the member is less accessible. A first electrical pulse is transmitted along the well casing toward a lower end of the well casing, where the first pulse is reflected as a reflected pulse to travel back up the casing. A second pulse is transmitted down through the well casing to intersect with the reflected pulse, after which the reflected pulse is detected and analyzed to determine conditions along the well casing. The timing of the pulses its synchronized so that the point of intersection is stepped along the well casing.

Abstract: A method of locating an intermittent electrical fault in an optical undersea transmission system, comprises measuring the time difference between two signals emanating from the fault along two different routes of the system. In one embodiment one of the signals is a voltage transient and the other signal is an optical error signal created in a repeater adjacent the fault as a result of surge protection in the repeater responding to the electrical fault, and in another embodiment both signals are optical signals, once again emanating from adjacent repeaters and caused by the effect of the electrical fault on the adjacent repeaters. It is envisaged that such a transmission system could be permanently provided with apparatus to detect such a fault in which synchronized counters are permanently running and frequently re-set and which stop in response to error signals being received from a fault when it occurs.

Abstract: A method and apparatus for locating an abnormality in a gas-insulated electric device, operative to locate the spot of an insulation abnormality, which emerges inside a metallic container, from outside of said metallic container. A plurality of detectors (S.sub.0 -S.sub.n) disposed at certain positions in the metallic container produce detected signals, from which spectrum strengths (YH) in a high frequency band of 500 MHz or above are evaluated, and a position which renders a maximum spectrum strength is calculated from the relation between the spectrum strengths and the installation positions of the detectors and is determined to be the spot (x) of partial discharge.

Abstract: A plurality of current detectors are provided in a plurality of prescribed spots of a transmission line for locating a fault caused, e.g. by lightning. A plurality of discriminators are provided in correspondence to the plurality of current detectors. Each discriminator receives detected signals from an arbitrary pair of the plurality of current detectors for detecting a relative difference between arrival times of the detected signals while extracting low-frequency components from the detected signals respectively and for detecting a phase difference between the extracted low-frequency components. A locator receives relative time difference data and phase difference data from the plurality of discriminators, to locate a faulty point in the transmission line on the basis of the received data.

Abstract: An apparatus for the deletion of extraneous signals to a radio frequency monitor is described having a first radio frequency sensor disposed at the neutral common ground of a dynamoelectric machine and delivering radio frequency signals from all sources to a switch at the input of a radio frequency monitor and further having auxiliary radio frequency sensors disposed at sources of normal radio frequency activity and providing signals of such normal activity to a deletion pulse generator which issues a blocking pulse to said switch thereby deleting RF noise from normal sources which otherwise may produce false warnings and restrict the diagnostic utility of radio frequency monitoring of an electric power generator or an electric motor.

Abstract: Apparatus and method for detecting a location of a break in a conductor of cable, the cable having a multiple number of conductors. The conductors that are not under investigation are connected to ground potential. The conductor that is under investigation is connected to a timer, a resistor, and a DC voltage source that in turn is connected to ground potential. Charging current flows into the conductor under investigation. The time that it takes for the current to decrease to (1/e) of the current's initial value is measured by the timer. Alternately, the conductor that is under investigation is connected to a resistor and a DC voltage source that in turn is connected to ground potential. This conductor is also connected to a voltage level timer that is connected to ground potential. The charging voltage of the conductor increases. The time that it takes for the charging voltage to increase to (1-1/e) of the voltage value of the DC voltage source, is measured by the timer.

Abstract: A system for ascertaining the existence and location of anomalies along the length of a member, such as an underground pipeline. Electrical pulses are imparted to the pipeline at opposite ends thereof, with these pulses being synchronized so that they meet at predetermined locations along the length of the pipeline. The wave form of one of the pulses which has passed through the point of intersection is analyzed to determine the possibility of an anomaly being present at the location of intersection. These readings can be correlated to half-cell readings which could be taken along the pipeline as a means of analyzing pipeline conditions.

Abstract: An apparatus and method for identifying individual conductors in a multi-conductor cable, which will also identify a short or open circuit condition. One end of the multi-conductor cable is connected to a battery powered transmitter unit which sequentially generates a unique pulse on each conductor. That is, the transmitter generates a pulse on a first conductor having a unique pulse width and after a small delay follows the pulse on the first conductor with a pulse on a second conductor having a unique pulse width, preferably twice the pulse width. The transmitter sequentially steps through each conductor in a cable to generate the unique pulses. The battery powered receiver unit is connected to the other end of the multi-conductor cable with a test probe and a reference probe connected to any two conductors.