Abstract: A termination control circuit is coupled to a far end of a cable. A modulated test signal is reflected back to a near end of the cable at a different frequency but at substantially the same level of attenuation as the test signal. Signal attenuation in the reflected signal is then measured to determine the amount of attenuation in the test signal. A second embodiment of the termination control circuit measures crosstalk by enabling and disabling termination resistors at the far end of the cable. A DC bias voltage located at the near end of the cable selectively turns on switching diodes to enable the termination resistor. Alternatively, both the attenuation and crosstalk circuits are combined together allowing both signal attenuation and crosstalk measurements with the same termination control circuit.

Abstract: A method and apparatus is provided for monitoring and locating the presence of fluids leaking from a containment vessel. A multiplicity of probes having conductive affinity are strategically oriented adjacent the containment vessel and periodic surveillance is made relying on conductivity of the sub-surface media within which the probes have been placed, such that disturbances in the conductivity correlate with migration of the leaking fluid. The method and apparatus may be utilized to detect migration of salinated fluids into a region where previously less salination existed. The probes can be oriented adjacent a surface and yet determine a conductivity of the sub-surface media at a plurality of different pseudo-points having varying depths. The presence, location and extent of a leak can thus be monitored.

Abstract: Apparatus for sensing or measuring a magnetic field comprises a light source (10) for generating light having at least a component which is polarized, a sensing element (16) arranged to transmit light from the source and comprising material having a substantial Verdet constant which depends on the temperature of the material, means (14-19, 21) for combining light from the source with light from the sensing element to form an interference pattern, means (23) for providing a signal representative of the intensity of the light so combined, and means for deriving first and second signals dependent on the Verdet constant of the material and the temperature thereof, respectively, from the signal representative of light intensity, whereby the intensity of the magnetic field at the element, substantially independent of temperature, can be derived. The invention extends to a method of sensing or measuring magnetic field intensity, and to apparatus and a method for sensing or measuring electric current.

Abstract: A circuit board extractor particularly suitable for extracting "burn-in" boards from a test fixture is attached to the front of the test fixture between the tester connector assembly and the burn-in board, or burn-in board frame rails, for movement of a movable member between first and second positions. The first position of the movable member occurs when the pin connectors on the edge of the burn-in board are inserted into corresponding pin receptacles on the front of the test fixture. Movement of the movable member from the first position thereof to its second position pushes the burn-in board away from the front of the test fixture to cause withdrawal of the pin connectors on the edge of the burn-in board from the pin receptacles on the edge of the test fixture without damaging the burn-in board or the test fixture.

Abstract: A contactless sheet resistance measurement apparatus and a method for measuring the sheet resistance of a desired layer of a first conductivity type, formed upon a substrate of an opposite conductivity type, is disclosed. The apparatus comprises a junction capacitance establishing means, a point location alternating current AC photovoltage generating means for generating a laterally propagated AC photovoltage, an attenuation and phase shift monitoring means for monitoring the .laterally propagated AC photovoltage, and a sheet resistance signal generating means responsive to the-junction capacitance establishing means, the AC photovoltage generating means, and the attenuation and phase shift monitoring means for generating an output signal indicative of a sheet resistance R.sub.S of the desired layer according to a prescribed sheet resistance model.

Abstract: A method is disclosed for approximating the stem thrust during the operation of a motor operated valve combination including a valve having a valve stem, a valve disk, a valve seat, and a motor operator having a motor drive means interconnecting the motor to the valve stem for movement of the valve stem disk toward and into engagement with the valve seat to close the valve and a control switch for deactivating the motor.

Abstract: Apparatus and method for low cost monitoring the level of signal at a test point in a system for susceptibility to electromagnetic fields. A probe, including a detector diode, and a non-metallic, electrically overdamped conductor, which is transparent to the electromagnetic field, is used to monitor the signal level at a test point as an amplitude modulated radio frequency carrier. The carrier is transmitted to a monitor outside of the range of the electromagnetic field using a transmission link, such as an optical waveguide transmitter, that is transparent to the electromagnetic field when the system under test fails. The system under test can then be removed from the electromagnetic field and, for each frequency at which the system failed, a voltage can be injected, using a voltage injection probe, into the system at another point to recreate the detected level of signal at the test point that was coupled into the system from the electromagnetic field.

Abstract: A system and method for testing underground electric cables, while in service, for active corrosion and degree of neutral loss. The method is conducted by applying a non-harmonic selected frequency signal to the neutral(s) of the underground cable connecting a pair of structures, e.g., power transformers, from a variable frequency generator of the system. The test is conducted by a surveyor wearing foot electrodes which contact the earth as the surveyor walks along the earth over the cable in a close interval steps. At each step, direct current (DC) potentials are monitored by a voltmeter between a copper-copper sulfate electrode carried by the surveyor and brought into contact with the ground at each step and the transformer ground. The potential of the gradients between the foot electrodes at the selective frequency and at the native alternating current (AC) is also measured by the voltmeter. These measurements are recorded at a stationary location on a digital data logger and/or computer.

Abstract: A compact, hand-held electrical line tester includes a normally-open relay switch which is closed by connection of its relay portion to a line of a predetermined voltage level, and a piezoelectric tone generator, connected in series with the relay switch and a battery, which emits an audible sound to indicate that the tested line is electrified with the predetermined voltage level. The tester circuit can include a plurality of relay switches and/or tone generators for emitting different sounds in response to different line voltages, so that the user can determine the line voltage(s) without having to check a light indicator or read a dial.

Abstract: A system and method for detecting partial discharge of gas-insulated switchgear wherein a high-frequency component and the fundamental wave component of the voltage applied to the conductor of the gas-insulated switchgear are detected, the zero-cross point of the fundamental wave component is set as the starting point for the voltage, and the presence of partial discharge and the reason for the occurrence of partial discharge are ascertained based on the phase difference between the phase of the detected high-frequency component and the phase of the starting point of the voltage.

Abstract: A magnetic head tester has a popcorn noise detector for discriminating internally generated popcorn noise events from externally generated noise events. The popcorn noise detector includes a discriminator which receives the magnetic head output signal from the head and generates a comparator pulse for each popcorn noise event detected. A counter counts the number of pulses output from the detector. The discriminator includes a retriggerable noise detection gate circuit for producing a noise detection gate signal when triggered by a comparator pulse. The discriminator responds to a single comparator pulse during the gate period by indicating a popcorn noise event at the output of the discriminator. The discriminator responds to a plurality of comparator pulses during the gate period by indicating that no popcorn noise event has occurred.

Abstract: Nonintrusive sensors capable of measuring various storage cell parameters such as voltage, state-of-charge, electrolyte level, internal resistance, and temperature are attached to a monitoring module which gathers and processes signals representative of information concerning the condition of electrolytic storage cells and transmits the information to a central computer for further processing. In response to commands issued by the central computer, appropriate maintenance and/or repair operations can be initiated. Alternatively, the system described can be used to automatically perform such maintenance tasks as checking and adding electrolyte levels, reducing the voltage in cells whose output voltage is too high, and leveling the state-of-charge of each cell in an array of electrolytic storage cells. The system can monitor other functions of the electrolytic storage cells, including the evolution of hydrogen gas and the accumulation of sediments in individual electrolytic storage cells.

Abstract: An inductive displacement transducer is provided having a probe capable of being displaced within the hollow interior portion of a coil. The coil, which is typically uniformly wound, is connected electrically in parallel with a stable-frequency current-based oscillator which transmits an AC voltage oscillating signal relating to the inductance of the coil. A demodulating circuit, which is capable of converting the AC voltage oscillating signal to a DC voltage level, is connected in parallel with the oscillator. In one preferred embodiment, the coil is covered with a shield which is slit along its length. In operation, the probe is displaced within a hollow portion of the coil such that a change in inductance of the coil results. A corresponding change in the AC voltage amplitude of the signal output of the oscillator is communicated to the demodulating circuit which generates a change in DC voltage level corresponding to the change in the oscillating signal.

Abstract: A tester for semiconductor devices such as IC memory chips is provided with an improved test waveform simulating function. The test waveform simulating circuit comprises relays for selecting one of the outputs of a plurality of drivers. The driver output selected by a relay is compared by a comparator with reference levels at reference times recurring at short intervals, thereby producing information bits corresponding to the waveform of the driver output which is displayed as a two dimensional image through a memory and display.

Abstract: A system for the semiautomatic inspection of printed circuits on silicon wafers and other similar micro-electronic products which comprises in combination a floating table supporting a robot arm which has the function of grabbing a single wafer from a cassette in which it is housed, inverting same, or assuming a position with its axis defining the Y-axis of the scanning system, and of moving in this direction; and of placing after inspection such wafer in another cassette according to the grade it received; an optical inspection device, such as optical microscope combined with a TV camera or the like attached to said same table, said microscope being adapted to move in the direction of the X-coordinate of the inspection system, there being provided means for aligning the direction of the printed circuit with the X-Y coordinates of the scanning system. A sophisticated optoscanner system is used for the alignment of the wafer and for establishing its exact position.

Abstract: Radio frequency bridge techniques are used to parameterize the complex dielectric properties of solids, liquids, gasses and mixtures thereof. This parameterization is performed in an electrically isolated, physically open structure which allows continuous or batch monitoring of the materials and their mixtures. A method and apparatus are provided for measuring the composition of mutlicomponent process streams flowing in pipes or ducts. The method uses the pipe in which the mixture flows as a waveguide in which propagating radio frequency electromagnetic energy is induced through dielectric loaded apertures. The dielectric measurement is performed in an electrically isolated, flow through test section which induces constructive or destructive interference patterns at characteristics frequencies. The characteristic frequency determines the dielectric constant of the mixture. The dielectric properties are used in turn to determine mixture composition.

Abstract: A partial discharge detecting device for transformers includes an antenna disposed in a metallic insulation gas filled tank enclosing a core and coil assembly and a signal processing circuit for processing an output signal from the antenna. The antenna includes a magnetic core and a single coil or two coils differently operated. An electromagnetic wave due to the partial discharge is detected by the antenna. A detection signal from the antenna is supplied to the signal processing circuit, which determines whether or not the partial discharge has taken place, based on the detection signal.

Abstract: A single integrated circuit operable in either a single chip mode or a host dependent mode.

Abstract: Disclosed is a method for producing individual semiconductor chips which are singulated from larger wafers, and singulated wafers produced according to the method. Wafers from which the singulated dies are produced include scribe line area through which the wafer is cut by a saw or other method for singulating individual dies. In one aspect of the invention, test pads are provided within the scribe line area for testing of individual dies prior to severing of the wafer. In another aspect of the invention, conventional test circuitry is formed within the scribe line area and utilized in conjunction with text pads for testing operability of individual wafers prior to severing of the wafer into individual chips. Upon test, the scribe lines are severed effectively destroying the sacrificial test pads and circuitry.

Abstract: A magnetic and electric force sensing method uses a force responsive transducer made of a micromachined, solid state magnetic sensor consisting of a central silicon platform surrounded and supported by a thin silicon membrane. The silicon substrate is placed over an aluminum pad recessed into a well on a supporting glass substrate. The magnetic sensor responds to a static method of measuring force whereby the Earth's magnetic field or magnetic field or other origin acts as an attractive or repulsive force towards the magnetic material placed onto the silicon platform. The magnetic force mechanically displaces the silicon platform and diaphragm membrane which is transduced to an electrical signal where a change in capacitance is measured. Geometry of the silicon platform, diaphragm membrane and glass well depth are used to affect the linearity, sensitivity and range of measurements of the magnetic sensor.