Abstract: An electric field sensor which may be used to detect the electromagnetic pulse (EMP) which accompanies a nuclear explosion, as well as other pulsed electric fields, is disclosed. One embodiment of this sensor has been constructed with an overall dimension of less than 5 cm. In general a sensor can be built to conform to an arbitrarily shaped conducting surface such as an airplane surface. Because of this conformity the sensor does not perturb the electric field being measured. By building the probe so that its RC time constant is much greater than the pulse rise time the probe output voltage is self integrated, and produces an output that is proportional to the signal itself rather than to its derivative. The nondifferentiating or self-integrating feature allows full utilization of the sensor/oscilloscope bandpass.

Abstract: A photographic film is adapted to provide visual record of the occurrence of a transient electrostatic or transient magnetic field by the inclusion of metallic patterns close to the film. The patterns are of a geometry to define gaps at which the fields are concentrated in a manner to interact with the film. The film exhibits a light spot at the gap, when it is developed, if a field of sufficient intensity is present during the test period. The film packet is intended primarily for inclusion in the shipping package for sensitive electronic devices to provide a visual record of exposures during shipment.

Abstract: A method and apparatus for locating and evaluating surface and subsurface anomalies by detecting, monitoring or measuring transient or local variations respectively which occur in an alternating component of a vertical current having a frequency characteristic which emanates from the earth'surface in the region being monitored or measured. For locating fixed anomalies, local variations which occur in the amplitude, frequency and frequency modulation of the alternating component of the vertical current are measured. For detecting the passage of moving or transient anomalies, a stationary detector is positioned to detect any change in the vertical alternating current leakage in the vicinity of the detector which is caused by a moving or transient anomaly such as a submerged submarine, seismic activity, or sustained severe wheather. For accuracy enhancement and redundancy, simultaneous measurements of the signal strength in multiple frequency bands may be used.

Abstract: Detection of lightning, storms, or the like via detecting means connected between an external antenna and ground, plus alerting means operatively connected to the detection means. An unpowered cascaded emitter-follower arrangement of at least a Darlington pair triggers a powered alerting circuit via an intervening gate opened when a fluctuation in ambient electric field causes the first transistor in such pair to conduct. A meter indicates such conduction even if the alerting means is not switched on, and alerting indicators in the alerting means may be tested in the absence of any detected field fluctuation.

Abstract: An apparatus for detecting the onset of a potential lightning discharge condition monitors the odd harmonics of an RF signal radiated from a conductive probe (antenna) for fluctuations that are representative of an electrostatic condition-induced corona. In response to the such fluctuations, an output signal representative of the onset of said condition is generated. This output signal may be employed to decouple communication equipment from its antenna until the lightning condition has subsided. In accordance with a further aspect of the present invention, there is provided a device for discharging static charge accumulation from a moving body (e.g. an aircraft) which is comprised of at least one discharging conductive wick arranged to be affixed to the trailing edge of a wing, so that charges may flow from the aircraft into the wick and be discharged therefrom.

Abstract: A non contact voltmeter includes a multilayered structure adapted to configure a plurality of coupled capacitors in a manner to permit high speed operation. A high frequency input signal is applied to a plate capacitivity coupled to both the test object and a sensor. The structure is also configured to capacitivity couple the sensor directly to the test object. The structure allows for circuit configurations with low time constants permitting outputs at the input frequency as well as a small and inexpensive solid state configuration.

Abstract: Offshore or onshore electrical surveys of buried or submerged structures such as pipeline are conducted in a fixed-cell-to-moving-cell fashion either before or after one or more established pipe-to-electrolyte potentials can be obtained. The results of the fixed-cell-to-moving-cell survey are then corrected by a summation of the fixed-to-moving-cell recorded potential and the established potential at the location of the established potential to obtain a reliable electrical survey of the structure. As indicated, the fixed-cell-to-moving-cell survey may be conducted either before or after the established potential is obtained or either before or after a disposable wire survey using a direct connection to the structure.

Abstract: The thunderstorm sensor of the present invention includes a pair of orthogonally positioned magnetic loop antennas to provide signals representative of the north-south and east-west components of the magnetic field produced by a lightning discharge. The system also includes an omni-directional electric field antenna to provide a signal representative of the electric field produced by a lightning discharge. The magnetic field and electric field signals from the antennas are coupled to an analog signal processor and digitizer which provides digital representations of the peak north-south and peak east-west components of the radiated magnetic field. The analog signal processor and digitizer also provides digital representations of the peak radiated electric field and the electric field sampled at a time subsequent to the time of occurrence of the peak radiated field wherein the second sampled electric field value represents the electrostatic field change due to the lightning discharge.

Abstract: This invention relates to a voltage sensor for sensing a voltage on an electrically charged object such as a distribution line or the like, the sensor being disposed with an insulation space to the object. The voltage sensor includes an amplifier circuit for outputting a signal having a waveform similar to that of a displacement current inflowing from the electrically charged object via the insulation space, and a filter circuit for extracting a signal having predetermined frequencies from the output of the amplifier circuit and outputting an alternating current waveform similar to the potential of the electrically charged object.

Abstract: An apparatus for providing a map-like display of weather phenomena such as lightning discharges, in which the distance from an observation location to the source of the discharge is determined from the ratio of the integrated intensity of two different components of lightning produced signals, the intensity of the first component varying as the inverse of the distance and the intensity of the second component varying as the inverse of the square of the distance.

Abstract: For evaluating the condition of a first lightning arrester of the gapless metal-oxide varistor type that is connected across the high voltage winding of a transformer, I connect externally of the transformer a second arrester of the same type, but with means for selectively changing its breakdown voltage between a first value that is higher than the normal breakdown voltage of the first arrester and a second value that is lower than said normal breakdown voltage. Pulses are applied to the low voltage winding of the transformer while the second arrester has its breakdown voltage set at the first value and while said breakdown voltage is set at said second value. By determining whether or not the second arrester conducts in response to each of these pulses, it can be established whether the first arrester is then undamaged, damaged in a shorted mode, or damaged in an open mode.

Abstract: A magnetic/electric field measuring device is disclosed, which is provided with an electron beam generator for generating an electron beam finely focused; a sample table, on which a sample is placed; electron beam deflectors for sweeping the electron beam two-dimensionally along an end surface of the sample; two-dimensional semiconductor position detection element using a photodiode for detecting the incident position of the electron beam, which has passed along the end surface of the sample; and a display section for displaying the position signal coming from said two-dimensional semiconductor position detection element in synchronism with a scan signal for the electron beam.

Abstract: Air ionization control apparatus comprising a plurality of emitter lines suspended in the atmosphere above a work space, each line comprising a plurality of ion emitting stations spaced therealong and emitting positive and negative ions into the atmosphere with an elongated electrical conductor averaging bar. insulatedly mounted in the atmoshere among said stations for receiving an induced charge representative of the average level of ionization of the atmosphere. An electrical charge sensing means connected to the averaging bar is employed to provide a signal indicative of the average level of ionization present in the room environment.

Abstract: There is disclosed a method for determining the location of an arc or corona as occurring in a high voltage power supply. The technique utilizes sheets of sensitive photographic film which are placed between printed circuit boards of the supply or between high voltage components and the metallic chassis walls of the power supply. During supply operation if an arc or corona occurs the film becomes exposed. The amount of exposure is determinative of the magnitude of the arc as well as indicative of the location of the arc or corona discharge which location and magnitude is determined by developing the film after supply operation. In this manner a comparative analysis of the amount of corona or arc as a function of time can be made by comparing the film density after photographic chemical development. The technique enables one to, therefore, accurately determine not only the magnitude of the arc or corona discharge but the exact location of the same.

Abstract: A sensor for an electrostatic voltmeter comprising an elongated vibratory element supported at one end in the manner of a cantilever beam, a sensitive electrode on the vibratory element near the other end and adapted to be disposed toward an electrical field or potential being measured, a driver chip on the vibratory element for vibrating the element in a direction to vary the capacitive coupling between the electrode and the electrical field or potential being measured, and an amplifier on the vibratory element in direct proximity to the sensitive electrode and having an input connected to the electrode and an output adapted for connection to the electrostatic voltmeter. The amplifier is mounted directly on the vibratory element so as to be in synchronous motion with the electrode. Preferably the electrode is mounted on one side of the vibratory element and the amplifier is mounted on the opposite side.

Abstract: A universal sensor includes a dielectric substrate, a curved surface capacitive plate mounted to the substrate and responsive to the electromagnetic field (EMF) of an integral coil ignition system, and a rotatable lever arm mounted to the substrate and having wire holders for receiving the EMF of spark plug wires of a distributorless ignition system (DIS)ignition, the arm operable in a closed position to conduct the DIS EMF to the plate, and operable in an open position for securing a standard ignition coil secondary wire between the arm and the plate allowing the standard wire EMF to be coupled to the capacitive plate.

Abstract: A surface potential detector of a non-contact type which comprises first and second detecting electrodes arranged in a separated manner from a measured surface so that charge variations are induced on the first and second detecting electrodes on the basis of the potential of the measured surface. The surface potential detector further comprises apparatus for making the amounts of charge variations induced on the first and second detecting electrodes different from each other, first and second detecting devices respectively detecting the amounts of charge variations induced on the first and second detecting electrodes and correction apparatus for performing arithmetic on the ratio between the outputs from the first and second detecting devices to correct the output of the first or second detecting devices on the basis of the ratio.

Abstract: The present invention relates to an apparatus for detecting magnetic and electromagnetic waves or fields through use of non-superconducting materials. The present invention relates to apparatus which are used to measure such fields in order to predict earthquakes, volcanic eruptions and other violent earth movements which generate substantial abberations in magnetic and electromagnetic fields. The present invention can be used to detect any fluctuating magnetic or electromagnetic fields regardless of their origin. The present invention incorporates the use of antennae for the electromagnetic components and coils to detect magnetic fields, in conjunction with electronic elements involving amplification, smoothing elements, frequency response networks, networks to make frequency response uniform within the band and notch filters where necessary.

Abstract: An instrument for non-contact measurement of electrostatic fields and related parameters, such as electrostatic potential, voltage and charge density of a charged object, includes a sensor for sensing the electrostatic field produced by the object and for producing an electrical signal, a display for producing a visual readout related to the electrical signal and a range scaling circuit for coupling the sensor to the display. The range scaling circuit is coupled to logic which switches the range scaling circuit and the display back and forth between two ranges, one for relatively higher strength field measurements and one for relatively lower strength field measurements. Because the distance at which the instrument is held from the charged object to achieve an accurate reading depends upon the strength of the field, the range scaling circuit is also coupled to circuitry which indicates the appropriate distance from the charged object at which the instrument must be held to provide an accurate measurement.

Abstract: Flow measuring apparatus comprising a probe (1) coupled via a coaxial cable (2) to control circuitry with a current to voltage convertor (10), absolute value circuit (12), auto zero switch and integration (11, 27) and voltage to current circuit (18) yielding an analog output, corresponding to flow at the probe.

Abstract: A process and apparatus for the day-or-night monitoring of weather phenomena by means of the analysis of the movements of air masses, wherein the movements are determined by monitoring and receiving the multi-band VLF electromagnetic radiation generated in the atmosphere with directionally selective receivers. The received frequencies are then compared with values which have been correlated with atmospheric events. Means are provided for displaying the predictive results for events occurring up to 500 km away from the VLF receivers--typically updatable within seconds--in at least two stages according to the (near or far) range desired or the type of electrical polarization.

Abstract: A safety system and method, for use with apparatus having a conductive member where the apparatus changes the attitude and/or altitude of the conductive member during the operation of the apparatus, includes an antenna mounted on the conductive member which senses an electric field and provides an AC signal representative of the strength of the electric field. The peaks of the AC signal are averaged over several cycles to provide an average peak signal. A reference signal circuit derives the reference signal from either the average peak signal prior to the change in the member's attitude and/or altitude or while the member's attitude and/or altitude is changing. A control device connected to the averaging circuit and to the reference signal circuit prevents further changing of the conductive member's attitude and/or altitude in accordance with the average peak signal and the reference signal when the electric field strength is greater than a safe value.

Abstract: The surface potential electrometer includes a reciprocating chopper, a measuring electrode on which a voltage is induced which is associated with the surface potential of a member to be measured, a shield member for shielding the measuring electrode and the chopper from electric field emanating from the member to be measured, and a driver for driving the chopper, thereby detecting the surface potential of the member in the form of an AC signal. The shield member is provided with an aperture for guiding the electric field emanating from the member to the measuring electrode.

Abstract: An indicator light apparatus having two terminals, one of the terminals being connected to the common or ground circuit of an electrostatic spray gun, preferably by connection to a grounded spray gun handle, the other terminal being placed in the proximity of the electrostatic field generated by the spray gun, so as to collect voltage charges emitted from the high voltage electrode of the spray gun and to conduct these charges to ground through the light indicator, which is typically a neon light or the like. The presence of electrostatic high voltage causes sufficient current flow through a light indicator to illuminate the light and provide an indication that the high voltage circuits are operating properly.

Abstract: Electric (E) and magnetic (H) field components of a lightning stroke are separately received in order to determine and display the location of regions of recently occuring lightning activity. Direction is determined by operating upon electrical signals associated with both the E and H field components. Range is determined by measuring the magnitude of the H field at two different frequencies. The range is then computed as a function of the ratio of the magnitude of the H field at a first frequency to the magnitude of the H field at a second frequency.

Abstract: An electrostatic field meter includes a field head which develops an electrical charge representative of the strength of an electrostatic field at the location of the field head. The electrical charge is converted to an AC signal which is then provided to metering apparatus. The metering apparatus provides an indication of the strength of the electrostatic field in accordance with the AC signal.

Abstract: A sensitive yet non-destructive method and apparatus for detecting the presence of voids contained within dielectric materials is disclosed which comprises applying a voltage across the dielectric material to create an electric field therethrough, increasing this voltage to create a partial electrical discharge and monitoring the field current to detect the voltage at which partial discharge occurs. When the partial discharge is detected, the voltage applied across the test material is recorded. Reference can then be made to mathematical charts and formulas readily available to determine the size and shape of the detected void.

Abstract: An electrostatic voltmeter with a microdeflector probe having a base, a flexible finger supported on the base in cantilever fashion, the finger deflecting in response to a potential difference thereacross, separate driven and variable capacitance electrodes on the finger sensing the charge voltage on the surface to be measured, the pickup electrode being electrically coupled to the driven electrode, the resulting charge voltage on the driven electrode changing finger deflection and altering the capacitive relationship between the base and the variable capacitance electrode; a predetermined reference voltage on the base; and a circuit for converting the change in capacitance between the base and the variable capacitance electrode to a signal representing the voltage on the surface. In an alternate embodiment, a second microdeflector is provided which changes capacitance between base and variable capacitance electrode in response to noise, and a control for adjusting the signal in response to the noise signal.

Abstract: An electrostatic system analyzer for checking the voltage at various test points in a high voltage electrostatic spray coating system. The analyzer includes an elongated analyzer body housing several elongated high voltage resistors making up a high resistance path. One end of the high resistance path is coupled to an ammeter mounted at a proximal end of the analyzer body, and the other end of the resistance path is coupled to an electrode mounted on a fitting at the distal end of the analyzer body. The fitting is rotatably mounted on the analyzer body and is generally L-shaped to position the electrode to be laterally offset from the distal end of the analyzer body. This positioning of the electrode facilitates viewing the electrode when it is placed at test points in the electrostatic coating system. The ammeter has a meter face which includes a different scale related to each test point, with the scales being offset from one another to compensate for resistance differences between the test points.

Abstract: A toroidal shaped metallic housing, mounted on and electrically connected with a high voltage transmission line, is adapted with a metal plate and an intervening dielectric sheet adhered to its exterior surface. The housing, tied to the transmission line voltage, and the metal plate constitute the electrodes of a first capacitor of a capacitive voltage divider, while the capacitive coupling of the metallic plate with the surrounding environment provides a second voltage divider capacitor. The voltage appearing on the plate is processed by circuitry within the housing to derive a signal indicative of the transmission line voltage.

Abstract: An optical voltage and electric field sensor for detecting the voltage or electric field applied to a device made of a single crystal of bismuth silicon oxide (Bi.sub.12 SiO.sub.20) or bismuth germanium oxide (Bi.sub.12 GeO.sub.20) is disclosed. The device comprises a plurality of crystal plates stacked in a direction perpendicular to the propagation direction of light, each plate having only one dimension reduced to a very small size.

Abstract: An apparatus and method for warning against lightning strikes, in which the rate of occurrence of ground flashes is determined and used as a criterion. The rate of occurrence of ground flashes in 0 to 5 kilometers, 5 to 10 kilometers and 10 to 20 kilometers is determined. In addition, the field intensity is used as a criterion. A series of time windows is generated, each time window starting when a ground flash occurs, and the number of flashes occurring in each time window is counted to determine the rate of occurrence. A criterion selection matrix is provided to select various criteria in different combinations to provide different alarm levels.

Abstract: The present invention relates to a wheel electrode suitable for use with a device for making an electrical survey of a structure contained in an electrolyte. The wheel electrode includes a chamber which contains electrolytic solution and a porous rim. The rim includes a dielectric rim structure having at least one recess in its axial surface, a plurality of apertures passing through the rim structure into the recess, and at least one porous member securable in the recess and having a predetermined rate of permeation. A metal electrode is positioned in the chamber in contact with the electrolytic solution. An elastic porous rim cover is securable about the rim for making contact with the electrolyte. The rim cover is adapted to carry an electrically conductive solution to the electrolyte during wheel rotation. Generating mechanisms are spaced about the wheel electrode at predetermined intervals for generating a series of electrical signals as the wheel electrode rotates.

Abstract: A metal oxide type surge arrester is provided with a plurality of arrester blocks in series within a housing having, in addition to line and ground terminals at the extremities, a bushing providing a tap voltage terminal intermediate the series stack such as between the bottom two arrester blocks. The provision of the voltage tap and a shunt resistance in series with the ground terminal permits respectively detecting the voltage and the current of the arrester so that they can be compared and their phase relation observed to determine if the arrester blocks are maintaining a capacitive characteristic or have become resistive. In addition, several other methods of use of such an arrester for monitoring line voltage, energy absorption, fault current and the like are disclosed.

Abstract: Apparatus and method for mapping an existing electric field involve exposing a field responsive element to the electric field to produce movement of the element in the path of a light beam, and detecting modulation of the light beam by the element. In a preferred embodiment the light beam is passed to and from the field responsive element by optical waveguides.

Abstract: A modular field strength measuring and indicating instrument that includes as one component a sensing module with a sensitive D'Arsonval meter movement and a receptacle for interchangeable plug-in type sensing modules for measuring an electrical condition, such as electrical power. The other component is a field strength sensing module that plugs into the receptacle and which includes a self-contained DC voltage source, a sensing antenna, a high-impedance, variable gain, linear DC amplifier operatively connected to the voltage source for amplifying the field strength voltage signal sensed by the antenna, and circuitry for transmitting the amplifier output voltage signal to the D'Arsonval meter movement for indicating the field strength detected by the instrument. The field strength sensing module may be used in the meter module interchangeable with other modules, such as modules for measuring RF power in RF transmission lines.

Abstract: In order to measure the values of the electrical charges (2) carried by a surface S of a dielectric sheet (1), one uses a device consisting of a first electrode or probe (S) facing the surface S, a second electrode (4) applied against the back surface of this sheet, means (F) to displace laterally the probe with respect to the sheet and means (5) to measure the charges (6) induced on this probe.In addition, by means of acoustical, optical or electrical methods, one subjects the surface S to deformation localized in very small spots p (of an area inferior to the one defining the spatial resolution of the measurement) during very short times and repeatly at frequence high enough and in such a way as to have some overlapping of the spots sequentially deformed.

Abstract: An electrostatic voltage sensor which includes a surface acoustic wave propagating medium and transmitting and receiving transducers coupled to the medium. The voltage sensor is provided with a separate voltage collecting member different from the electrode for applying a voltage or electric field, and the voltage obtained in the voltage collecting member is varied by a predetermined frequency for being applied to the electrode so as to detect external voltage by the variation component of the oscillating frequency.

Abstract: A fiber optic sensor system and associated technique is disclosed for measuring an electric field wherein a sensor arm of optical fiber cable is wound about a core member of piezoelectric material. A reference arm of optical fiber cable substantially equal in optical path length to the sensor arm is isolated and connected in parallel to the sensor arm so that coherent light generated by a single mode laser source may be split through the fiber-optic arms and recombined after passage therethrough for phase comparison. When subjected to a local electric field, the core member of piezoelectric material varies in dimensions and thereby causes a change in the strain in the optical fiber cable of the sensor arm. Relative phase changes in the coherent light caused by the resulting optical path length change of the strained sensor arm are detected by a passive homodyne demodulator and determinative of the value of the local electric field.

Abstract: An electric field strength indicator for use with high voltage conductors comprises a capacitive probe mounted within a tubular shield having an insulating spacer at one end for locating the unit with respect to a conductor under test. The probe is electrically coupled to a signalling circuit and is movable axially within the shield to a position at which a threshold response is obtained. Such position, which denotes the conductor voltage, is read on a scale provided. Because of the shield the device is directional, the probe being shielded from neighboring conductors.

Abstract: An E-Log I field computer includes a controlled power supply, timers, and a current level stepping relay for circulating cathodic current through a buried metal structure, interrupting the current to allow the decay of residual polarization of the structure and electrolytes within the surrounding ground, and measuring the circulated current and the voltage of structure relative to the ground. The circulated current, voltage of the structure to the ground, and other parameters of interest, such as, the output voltage of the power supply are printed. Then the current level is increased by the stepping relay, and the process is repeated. When a sufficient number of readings have been taken, the data is plotted as a semi-log graph, resulting in an E-log I curve from which the corrosion current and therefore the cathodic protection voltage can be determined.

Abstract: A method for locating and evaluating surface and subsurface anomalies. Solar wind results in a multi-frequency, high energy ionic impingement at the terrestrial poles of the earth. Monitoring the activity of the solar wind allows the determination as to when the activity produces a vertical alternating current leakage (solar alternating current) due to the ionic impingement. When the vertical current leakage is in a proper range which can be measured and which reflects and represents surface and subterranean anomalies, a predetermined region of the earth to be prospected is traversed. Local variations which occur in the amplitude, frequency and frequency modulation of the vertical alternating current leakage due to the ionic impingement of solar winds at the terrestrial poles (solar alternating current) is measured. The measurements are recorded in correlation with the spatial relation to the points of measurement to determine significant measurements indicative of surface and subterranean anomalies.

Abstract: An apparatus and method of detecting, tracking and displaying lightning activity is disclosed. A lightning stroke has associated therewith electric and magnetic field components characterized by maximum rise times and minimum power levels. The field signals comprise a plurality of sub pulses also. An electric field antenna and a pair of magnetic field antennas are disposed to receive the field components associated with lightning activity. Control circuitry cooperating with rise time and threshold measuring which operates on the field signals received by the antennas generates control signals including integration and sampling control signals for integrating the electric and magnetic field signals over a predetermined time interval (preferable one hundred microseconds) and for sampling and holding the field signals at each of the sub pulse peaks.

Abstract: To record significant discharges of a surge arrester, the energy dissipated in a separate varistor element equivalent to the varistor elements in the arrester and connected in the arrester discharge path is monitored. When an arrester discharge results in a temperature increase above a predetermined minimum in the separate varistor element, heat sensing means thermally coupled therewith triggers a counter to record the event.

Abstract: A surface potentiometer comprises a measuring electrode, a chopper for intermittently shielding the electric field between the measuring electrode and an object to be measured, a preamplifier circuit for converting an AC signal induced in the measuring electrode into a low impedance signal, and a printed substrate having the wiring pattern of the preamplifier circuit formed on one surface thereof and the electrode pattern of the measuring electrode formed on the other surface thereof.

Abstract: An electrical survey of buried structures such as underwater or underground pipelines utilizes the steps of connecting one end of an economically disposable wire from a wire supply to the structure, either directly or through a heavier lead, the opposite end being electrically connected to a cell. The cell is moved along the structure together with a wire supply and a meter to obtain periodic measured structure-to-electrolyte potential values. If the wire is accidentally or intentionally disconnected during the survey, a stationary electrode is positioned at the wire break or last valid measured reading, such electrode being reconnected to the free end of the wire from the supply. The survey then continues periodically obtaining electrode-to-cell potential values. A structure-to-electrolyte potential profile is obtained by summing the last valid recorded structure-to-electrolyte potential value with each electrode-to-cell values. The summing may be done after the survey is completed by computer.

Abstract: A partitioning circuit will partition into subintervals the time interval between two signals delivered by a recognition circuit, and will activate a gate circuit during one of these intervals which has been predetermined. In addition to the recognition circuit, the sequence of signals from a sensor responding to the occurrence of an at least approximately periodic event, is fed to a comparator circuit which will transmit a pulse to the gate circuit each time a certain signal level has been exceeded. If the gate is active, this pulse will be available for further processing.

Abstract: The apparatus and method of the present invention facilitate surveys of buried structures, such as pipelines or the like, in particular by substantially automatically measuring and indicating distance information. Preferably that information is obtained by a transducer that produces serial data representing the length of wire bailed out from a portable reel and a cyclical counter responsive to such data for counting the serial data. A signalling device, such as a horn, strobe light, etc., is activated each time the counter completes a cycle as an indication that a predetermined distance has been covered since the last measurement was made and that the next potential measurement should be made. The number of pulses of such serial data counted in each cycle of the counter can be manually adjusted to obtain small or large distance intervals between test locations at which potential or other measurements are to be made to obtain a substantially continuous survey of the pipeline.

Abstract: An automatic control system for the bias on a development electrode in which a plurality of ground-insulated, narrow floating electrodes are spaced along a line adjacent the entrance of a liquid developer applicator unit. The floating electrodes relatively scan image areas of the surface of an organic photoconductor carried by a conductive support moving through the developer unit. Owing to conduction of a charge from the photoconductive surface through the developer liquid to the floating electrodes, they assume potentials each of which is a function of the average potential of the image area subtended by the floating electrode. The potential of each floating electrode is sensed by a high input impedance measuring circuit which selects the potential of the lowest value, amplifies the selected potential and applies the amplified voltage to the biasing electrode or electrodes of the developer system.

Abstract: A sensor system is disclosed for measuring small physical perturbations in he environment using an optical fiber interferometer in the Fabry-Perot configuration operating at maximum sensitivity. A single frequency laser source is focused on one end of a single mode optical fiber with highly polished, highly reflective flat ends. An element responsive to the ambient magnetic or electric field alters the fiber's optical path length, thereby affecting the intensity of light transmitted through the fiber. A detection and feedback system detects the transmitted light and readjusts the optical path length to one which corresponds to maximum sensitivity.