Abstract: The current density versus voltage characteristics of integrated circuit processing equipment such as a plasma etcher are determined using a passive probe including a semiconductor wafer in which one or more clusters of individual passive charge monitors are fabricated. Each monitor includes an EEPROM device having a control electrode and a floating electrode over a channel region connecting source and drain regions, a charge collecting electrode connected to the control electrode, and a current sensing resistor connecting the charge collection electrode to the substrate for developing a threshold varying voltage. By determining changes in device threshold voltage, a corresponding surface-substrate potential is determined which can be divided by the value of the current-sensing resistor to yield a current. The current can then be divided by the area of the charge collecting electrode to yield a value of the current density.

Abstract: A voltage monitor which uses the shift in absorption edge of crystalline material to measure strain resulting from electric field-induced deformation of piezoelectric or electrostrictive material, providing a simple and accurate means for measuring voltage applied either by direct contact with the crystalline material or by subjecting the material to an electric field.

Abstract: A distance measuring system for measuring a distance between two objects has a transmitter assembly mounted on one of the two objects, for transmitting a plurality of electromagnetic waves having respective wavelengths different from each other at respective levels toward the other of the two objects, a receiver assembly mounted on the other object, for receiving the electromagnetic waves transmitted from the transmitting means, and a distance detector for detecting a ratio of levels at which at least one set of electromagnetic waves of the electromagnetic waves is received by the receiving means, as corresponding to a distance between the two objects, and determining the distance between the two objects from the ratio.

Abstract: A system evaluates occurrences of low level electrostatic discharge events in a manufacturing or processing environment or the like by encapsulating each of a plurality of a MOSFETs in a corresponding package having conductive first and second groups of leads coupled to the gate and source and/or drain electrodes of the MOSFET, respectively. The encapsulated MOSFET then is moved through the environment, wherein an electrostatic discharge causes current to flow into the first external electrode, stressing the gate oxide of the MOSFET and producing a permanent low resistance condition therein. The encapsulated MOSFET then is removed from the environment and tested by measuring an electrical parameter indicative of the low resistance condition between the first and second electrodes of the MOSFET. A statistical analysis then is performed on the data obtained by testing all of the MOSFETs to determine how to reduce or avoid ESD in the environment.

Abstract: An electromagnetic field frequency and image magnetic forms quantum analyzer apparatus for collecting and evaluating magnetic field waves, which includes a sensor, a tape recorder for recording the waveforms, an oscilloscope for displaying the waveforms, film and video cameras to record the locations and wave images, a cassette recorder for recording and playback for studying the waveforms and can include a computer to display and dissect the waveforms.

Abstract: Apparatus 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 storm monitoring apparatus and method is described wherein two H-field antennas are oriented with respect to the heading axis of an aircraft or the like at an angle of 45.degree.. The signals developed by these two antennas are picked-up by small R-F transformers which serve the inherent function of integrating the signals and extracting the H-field current component. A printed circuit board structuring of the two antennas provides for consistency of fabrication and reliability as well as compactness. The monitoring apparatus exhibits broad band frequency response to evaluate lightning strike rate to determine storm range and intensity. A computer control test utilizing diagnostic coils at the antenna carries out periodic testing of the performance of the device and a component such as a gravity switch provides an indication to the control system as to the orientation of mounting of the antenna on an aircraft.

Abstract: A lightning ranging device which utilizes two frequencies in the field generated by a lightning discharge to determine range. The relative amplitudes of the outputs from two tuned receiver channels varies with distance from the lightning stroke. A two-dimensioned look-up table with two inputs and one output can be utilized to output the range. The original ratio of the amplitudes of the two frequencies can be determined empirically from experimental data and amplification factors on the two frequency channels are pre-set at different levels to compensate for this difference in the original energy level.

Abstract: A hand-held detector for determining whether the exposure to electromagnetic fields resulting from electric power lines, faulty wiring, and electrical and electronic appliances is within acceptable limits. The device includes a shielded pickup coil, a filter circuit having a transfer function which provides a distinct response in two frequency bands, a summing circuit which provides a voltage indicative of the detected levels of electromagnetic flux density in the two frequency bands, and a display circuit, to provide a visual indication of the detected energy level. The filtering circuit preferably includes a first, extremely low frequency (ELF) amplifier having an upper cutoff frequency of approximately 2 kHz, and a second, very low frequency (VLF) amplifier having a lower cutoff at approximately 6 kHz.

Abstract: There is disclosed a surge discriminating and locating system having at least one master station and at least one slave station. The system comprises surge receiving means for receiving surges which occur on a power transmission line, locating means for locating a point where the surge occurs, digitizing means for digitizing said surge into a digital signal, extraction means for extracting from said digital signal the characterized portions thereof as information representative of the surge waveform, memory means for storing predetermined reference information concerning the nature of surges, and discriminating means for comparing said information representative of the surge wave form with said reference information stored in said memory means to discriminate the kind of surge.

Abstract: A storm monitoring apparatus and method is described wherein two H-field antennas are oriented with respect to the heading axis of an aircraft or the like at an angle of 45.degree.. The signals developed by these two antennas are picked-up by small R-F transformers which serve the inherent function of integrating the signals and extracting the H-field current component. A printed circuit board structuring of the two antennas provides for consistency of fabrication and reliability as well as compactness. The monitoring apparatus exhibits broad band frequency response to evaluate lightning strike rate to determine storm range and intensity. A computer control test utilizing diagnostic coils at the antenna carries out periodic testing of the performance of the device and a component such as a gravity switch provides an indication to the control system as to the orientation of mounting of the antenna on an aircraft.

Abstract: A storm monitoring apparatus and method is described wherein two H-field antennas are oriented with respect to the heading axis of an aircraft or the like at an angle of 45.degree.. The signals developed by these two antennas are picked-up by small R-F transformers which serve the inherent function of integrating the signals and extracting the H-field current component. A printed circuit board structuring of the two antennas provides for consistency of fabrication and reliability as well as compactness. The monitoring apparatus exhibits broad band frequency response to evaluate lightning strike rate to determine storm range and intensity. A computer control test utilizing diagnostic coils at the antenna carries out periodic testing of the performance of the device and a component such as a gravity switch provides an indication to the control system as to the orientation of mounting of the antenna on an aircraft.

Abstract: A storm monitoring apparatus and method is described wherein two H-field antennas are oriented with respect to the heading axis of an aircraft or the like at an angle of 45.degree.. The signals developed by these two antennas are picked-up by small R-F transformers which serve the inherent function of integrating the signals and extracting the H-field current component. A printed circuit board structuring of the two antennas provides for consistency of fabrication and reliability as well as compactness. The monitoring apparatus exhibits broad band frequency response to evaluate lightning strike rate to determine storm range and intensity. A computer control test utilizing diagnostic coils at the antenna carries out periodic testing of the performance of the device and a component such as a gravity switch provides an indication to the control system as to the orientation of mounting of the antenna on an aircraft.

Abstract: A storm monitoring apparatus and method is described wherein two H-field antennas are oriented with respect to the heading axis of an aircraft or the like at an angle of 45.degree.. The signals developed by these two antennas are picked-up by small R-F transformers which serve the inherent function of integrating the signals and extracting the H-field current component. A printed circuit board structuring of the two antennas provides for consistency of fabrication and reliability as well as compactness. The monitoring apparatus exhibits broad band frequency response to evaluate lightning strike rate to determine storm range and intensity. A computer control test utilizing diagnostic coils at the antenna carries out periodic testing of the performance of the device and a component such as a gravity switch provides an indication to the control system as to the orientation of mounting of the antenna on an aircraft.

Abstract: The apparatus for measuring pulse energy includes integration means and serves to measure high-current disturbances carried by a cable. The apparatus is characterized in that it further includes a current-to-voltage converter (2) mounted on the cable (1), attenuation means (3, 4) coupling said converter to the integration means (5, 6), and a processing and storage assembly (12) coupled to the integration means and to an output display (20). Application: monitoring lightning protection equipment.

Abstract: An electrostatic voltmeter suitable for use in a non-contacting, positive or negative potential sensing, type electrostatic voltmeter. The invention enables a flexible, low cost electrostatic voltmeter to be produced using high-voltage field-effect transistors in the circuit design. The invention further includes input conditioning components that enable high-voltage sensing and high-voltage feedback in such a manner that processing of the input signal from the sensor is accomplished without producing a variation in the current passing through the field-effect transistor in response to voltage variations. Elimination of this variation further reduces the susceptibility of the remaining signal processing circuitry to transient direct current signals. A differential cascode as the input stage is the preferred configuration for the input conditioning components.

Abstract: A test system 100 for performing electrical testing in a high voltage or inhospitable or inconvenient environment 150 electrically isolates a measurement detector 130 located within the environment from an externally located measurement result display and selector 110. Electrical isolation is accomplished using a non-conducting fiber optic link 120 for communicating the measurement results.

Abstract: A motor assembly (A) cyclically moves a sample (34) longitudinally through the longitudinally aligned central bores (16, 18) of a pair of hollow electrodes (12, 14). One of the electrodes (14) is connected with a Faraday shield (10) which electrically shields the electrodes and the sample and the other electrode (12) is electrically insulated from the Faraday shield. Preferably, the Faraday shield structure further serves as a hermetic seal for sealing the hollow electrodes against adverse effects of the ambient atmosphere. An electrical instrument (C) is connected across the two hollow electrodes to measure the induced charge transfer or potential difference as the sample cyclically moves back and forth between the hollow bores of the two electrodes.

Abstract: The present invention concerns a method and apparatus for determining average particle size of silver halide grains in a solution or emulsion containing silver ions and excess halide ions. The potential of the silver ion in solution (E.sub.d) is measured using a silver electrode and the potential of the silver ion in solution with infinitely large silver halide particles (E.sub.e) is measured using a silver electrode coated with silver halide. The molecular volume (v) of the solute is calculated and the average particle size (d) is calculated from the following formula: ##EQU1## wherein F is the Faraday constant and (s) is the surface energy of the average particle size per unit area.

Abstract: With a view to enabling errors in the space potential to be automatically corrected by detecting a floating potential in each of a plurality of probes and to remove the errors in measurement based on the corrected space potential to thereby realize the accurate measurement of the space potential, there is provided a triple-probe plasma measuring apparatus, which comprises: a circuit for measuring electron temperature and electron density of a plasma with use of triple probes; a circuit for detecting and holding a floating potential difference; a differential voltage adding circuit; a fixed voltage source; and a change-over switch, the apparatus being capable of determining a difference in the floating potentials at the position of said probes, and superimposing the potential difference determined on the fixed voltage.

Abstract: An efficient optical radiation detector for lightning or other light signals such as pulses, bursts, flashes, and steady fluctuations. A silicon photodiode (or similar light-sensitive silicon device) is arranged to receive light signals (infrared, visible, ultraviolet, broadband, etc.) of interest. The photodiode is connected across the primary winding of a properly-designed transformer. The transformer-coupled photodiode circuit gives AC coupling, photodiode bias, voltage gain, and several other desirable detector characteristics. Light fluctuations on the photodiode produce variations of photocurrent in the transformer primary circuit which, in turn, induce current in the secondary winding and circuit of the transformer. The current induced in the secondary circuit of the transformer is used to do useful work (such as energize an audible alarm, increment a counter, latch a relay, etc.

Abstract: The apparatus includes a pair of electrodes which makes it possible to channel a current density creating the current which induces a magnetic field in one or more induction coils. This magnetic field is measured with the aid of one or more magnetometric transducers. The electric/magnetic transfer rate of the coils and the conductivity of the conductive medium are known, so that the value of the electric field is deduced on the basis of Ohm's law. The local magnetic field is previously measured so as to take account thereof when measuring the induced magnetic field.

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: An E-field sensing apparatus detects the energization of high voltage utility transmission and distribution lines. An external housing substantially shields internal components of the apparatus from the detected E-field. A conductive wire extends from the housing where it is exposed to the E-field. A signal is induced onto the exposed wire and sensed by the apparatus. The length of exposed wire and the distance of the apparatus from the high voltage line attenuate the E-field so the induced signal is within operational parameters of internal sensing components. Adjustments to the wire length and apparatus distance enable detection of E-fields surrounding power lines carrying voltage levels of a predetermined voltage level (i.e. approximately 2000 volts and higher). In response to the E-field the apparatus generates an analog output signal and a line isolation control (one-bit digital) signal. The analog output signal drives a meter, LED or other indicating device serving to aid maintenance engineers.

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 storm monitoring apparatus and method is described wherein two H-field antennas are oriented with respect to the heading axis of an aircraft or the like at an angle of 45.degree.. The signals developed by these two antennas are picked-up by small R-F transformers which serve the inherent function of integrating the signals and extracting the H-field current component. A printed circuit board structuring of the two antennas provides for consistency of fabrication and reliability as well as compactness. The monitoring apparatus exhibits broad band frequency response to evaluate lightning strike rate to determine storm range and intensity. A computer control test utilizing diagnostic coils at the antenna carries out periodic testing of the performance of the device and a component such as a gravity switch provides an indication to the control system as to the orientation of mounting of the antenna on an aircraft.

Abstract: A maximum voltage detecting apparatus for measuring the output maximum voltage, such as of an optical sensor, a thermal sensor or a wind sensor, utilizing a ferroelectric substance. A d.c. power source of a reset circuit applies a d.c. voltage to a ferroelectric device to generate a maximum spontaneous polarization, the ferroelectric device including metal electrodes and a PZT ferroelectric substance held therebetween. The output voltage such as from the wind sensor is applied to the ferroelectric device so as to have an opposite polarity. A polarization measuring circuit measures a residual polarization in the ferroelectric device by this output voltage and measures a maximum output voltage value from the residual polarization value.

Abstract: An apparatus for detecting damped wave disturbances includes a hollow tubular housing of electrically nonconductive material with a pair of electrodes extending through apertures in each end of the housing such that the inner ends of the electrodes are spaced apart a predetermined distance within the housing. Ferro-magnetic electrically conductive particles are disposed loosely within the housing of sufficient quantity to form an electrical bridge between the electrodes when the particles are influenced by a magnetic field. A pair of annular collars of electrically conductive material are fastened to the housing and spaced coaxially apart, with one collar electrically connected to an antenna and the second collar electrically connected to ground. The particles within the housing have a very low electrical resistance when influenced by a magnetic field, so as to form an electrically conductive bridge. The particles also have a very high electrical resistance when not influenced by a magnetic field.

Abstract: A lightning and storm warning system capable of distinguishing lightning flashes from other light flashes and indicating to an operator of the existence of a lightning flash even under high ambient illumination conditions. The device may include a visual display indicating the severity and location of the storm and providing an indication of the time progression of the lightning rate.

Abstract: An apparatus for measuring transient earth current includes a detection electrode and a second electrode disposed beneath the surface of the earth in vertical alignment with one another at depths greater than those to which electromagnetic waves generated above the surface of the earth having commercial power line frequencies penetrate, such that the electrical resistance between the detection electrode and the second electrode is on the order of several tens of thousands of ohms, and a charge detector for detecting only high frequency components of a current flowing between the detection electrode and the second electrode. On the basis of these detected high frequency components, the likelihood of an occurance of an earthquake may be determined.

Abstract: A system evaluates occurrences of low level electrostatic discharge events in a manufacturing or processing environment or the like by encapsulating each of a plurality of a MOSFETs in a corresponding package having conductive first and second groups of leads coupled to the gate and source and/or drain electrodes of the MOSFET, respectively. The encapsulated MOSFET then is moved through the environment, wherein an electrostatic discharge causes current to flow into the first external electrode, stressing the gate oxide of the MOSFET and producing a permanent low resistance condition therein. The encapsulated MOSFET then is removed from the environment and tested by measuring an electrical parameter indicative of the low resistance condition between the first and second electrodes of the MOSFET. A statistical analysis then is performed on the data obtained by testing all of the MOSFETs to determine how to reduce or avoid ESD in the environment.

Abstract: A measurement system and method for determining the amount of radiation absorbed by living beings includes a measurement device capable of measuring the amount of radiation emanating from power lines and any other source of radiation of electromagnetic energy (non-ionizing) at a particular location and electrically conductive contact devices for connecting the measurement device to a living being and to a ground and requires that a reference reading be taken and then a second reading obtained by connecting the measurement device to an appendage on a living being with the other end of the meter being connected to ground, a subtraction device indicates the amount of radiation being absorbed by the living being.

Abstract: A peak voltage detector to measure the peak output voltage of light sensors, heat sensors and the like without the need for a reference voltage. In a ferroelectric element, the ferroelectric body is positioned between PT electrodes. The ferroelectric body has a thickness that progressively varies from one end to the other. A D.C. voltage dependent upon the direct current power supply is applied to generate a maximum spontaneous polarization Pr. The output voltage from light sensors, heat sensors and the like is of a reverse polarity with respect to that of the power supply. The output voltage is applied to the ferroelectric element. Depending on this external voltage, reverse polarization will be generated in either one part, certain parts, or all of the ferroelectric element. By measuring this reverse polarization with the polarization measuring circuit, the peak value of the external voltage is measured.

Abstract: A voltage monitoring apparatus for monitoring a value of a rectified AC voltage applied across a capacitive load is disclosed. The voltage has an AC component and a DC component. The apparatus monitors the value of the rectified cyclical AC voltage at a selected portion of the cycle. The voltage to be measured can either be the instantaneous value of the voltage at a predetermined time in the cycle, or the RMS value of the entire cycle. The apparatus is especially useful for monitoring a cathodic protection voltage applied to a metallic structure in contact with the ground and subject to corrosion, such as often applied to an underground pipeline. Such voltage is typically full wave rectified AC, and it is beneficial to know if the minimum voltage value of each cycle applied to the pipeline is below a predetermined value.

Abstract: An electrostatic measurement apparatus for generating a modified electrical signal in proportion to an electrostatic potential present on a surface. The apparatus includes a sensor for producing a signal representative of the electrostatic potential on the surface. The apparatus also includes a high-voltage level shifter and a converter to transform the sensor signal into a low-voltage signal indicative of the surface potential. The electrostatic measurement apparatus is implemented using high-voltage and low-voltage integrated circuit technology.

Abstract: A system for measuring and recording DC electric field data at multiple locations using field mill sensors having periodically exposed sensing electrodes to provide cyclic signals, relating to the field amplitude and polarity, which are demodulated by phase synchronous detection to provide measurement of the field at an indicator which is calibrated and checked by intermittently applying to a rotor electrode a DC voltage determine calibration data for sensor indicators. Phase and frequency adjusting circuits control sensor motor/rotor speed and the signals generated for optimum polarity and amplitude measurement. Motor speed is controlled to minimize effects of external noise. Contamination degradation of sense electrode insulators is measured by comparing output signals as the rotor is changed between rotating and stopped conditions. Metal modulator parts are finished with extremely smooth polished surfaces.

Abstract: A small, portable, non-intrusive device that detects the occurrence of an electrostatic discharge (ESD) during the handling, transporting, and testing of static sensitive electronic parts. It can be used to locate grounding problems in assembly equipment and is useful during repairs and assembly of electronic equipment. A preferred use is in the manufacture of semiconductor devices and the equipment containing these devices which are sensitive to ESD occurrences.

Abstract: In order to take into account the effect of load resistance applied to an electromagnetic field in analyzing an electromagnetic wave oscillator, the present invention arranges a resistance equivalent to the load resistance in the analytical region, and converts a voltage applied to the load and the current flowing therein into an electric field component and a magnetic field component to analyze the electromagnetic field distribution of the entire analytical region. The motion of an electrical charge is thus analyzed taking into account a force applied to the electric charge by the electromagnetic field distribution. This compound analysis of both the electric charge motion and the electromagnetic field is alternately and repeatedly performed.

Abstract: A multi-channel electromagnetically transparent voltage probe transmission link system for monitoring a plurality of voltage signals at a plurality of test points of a device under test that is subjected to a radiation field. Each channel includes two voltage probes, an electrical to optical signal transmitter, an optical signal transmission line and a receiver located out of the radiation field. The voltage probes contact and sense the voltage signals at the test point. The electrical to optical transmitters are removably mounted in a common base and are powered by either a common (or shared) power supply and/or by dedicated power supplies, such as rechargeable batteries. The receivers process the optical signals and provide display signals corresponding to the sensed voltage signal at the plurality of test points for evaluating the effect of the test radiation field.

Abstract: An electromagnetically complete field vector field probe has a set of three dipoles extending along three mutually perpendicular axes, and three loops situated in mutually orthogonal planes defined by different pairs of said axes. The dipoles and loops are all disposed about a common center. Each dipole has a central element and two end elements, separated by gaps. Each loop has four conducting elements each extending from a point adjacent to one of the three axes to a point adjacent to another of the three axes. The conducting elements of each loop are separated from one another by gaps at the axes, so that each gap of each loop is substantially coincident with a gap of another loop and with a gap of a dipole. Coaxial lines extending through the central conducting elements of the dipoles are connected directly to the ends of the loop elements and need not extend through parts of the loop elements themselves.

Abstract: The apparatus which predicts the onset of thunderstorm and the occurrence of close thunderbolts, includes a composite sensor with several metal pipes radially installed with equal separation on a hemispherical electrode. A plurality of corona needles are provided on the insulator at the end of each metal pipes, and the needles are electrically connected together within the composite sensor. The hemispherical electrode is connected to a circuit that counts the number of electric field-changes for certain time intervals. In case the receiving frequency exceeds the pre-determined level, it issues a first alarm. The groups of corona needles are connected to the circuit that measures the corona current, and issues a second alarm, in case the current a pre-determined level. In addition, the circuit includes circuitry that picks up the large amplitude corona current changes that the polarity change and issues the thunderbolt warning.

Abstract: A sensor for electrical charge fabricated as an integrated circuit and including an electrode (1) for receiving charge, a potential-sensitive switching device (2) for generating a pulse whenever the charge received on the electrode (1) is sufficiently great, a counting device (4) for counting the number of times the switching device operates, and a member (3) for restoring the potential on the electrode (1) to its initial potential each time the switching device (3) operates and/or continuously towards its initial potential. An integrated circuit having an array of such sensors and digital logic for controlling their operation is included. The array may be used as a multiple-channel detector for charged particles, particularly as a detector for electrons emerging from a channel plate electron multiplier. Dispersive particle and photon spectrometers, especially mass spectrometers, using such a detector are also provided.

Abstract: An electrostatic measurement apparatus for generating a modified electrical signal in proportion to an electrostatic potential present on a surface. The apparatus includes a sensor for producing a signal representative of the electrostatic potential on the surface. The apparatus also includes high-voltage and low-voltage devices combined to produce an amplifier which transforms the sensor signal into a low-voltage signal indicative the surface potential. The electrostatic measurement apparatus is implemented using high-voltage and low-voltage integrated circuit technology.

Abstract: A hand-held electronic apparatus for the detection and ranging of lightning strikes wherein radio frequency signals from lightning activity are filtered to allow selected low frequency emissions to be compared with standard voltages in order to activate light emitting diodes which correspond to distances to lightning activity: 0-10 miles, 10-20 miles, etc. The device only the electrostatic field component of the radio signals from lightning activity. The electrostatic component typically dominates over the electromagnetic component at comparatively short distances of 40 miles or less.

Abstract: The invention discloses a magnetic field radiation monitor which comprises at least one sense coil adapted to sense magnetic flux from the electromagnetic field to be measured for both ELF and VLF type of fields. The sense coil is coupled to a detection circuit wherein an EMF generated in the sense coil will be amplified and frequency compensated in the circuit to give an extremely flat frequency response allowing accurate detection of complex magnetic fields. The circuit consists of an ELF and VLF stage, both selectively coupled to the sense coil and incorporated into the circuit by a user activated switch. The output of either the ELF or VLF stages is further processed and the output is provided to a display to indicate the magnetic field strength measured. The magnetic field radiation monitor may be calibrated to yield a true RMS measuring platform using a RMS detector circuit which will give an accurate indication of magnetic energy content for complex waveforms.

Abstract: Method and apparatus for sensing electric fields with a dipole antenna, wherein the antenna generates an antenna signal representative of electric field potential, includes a signal generator for generating mixing signals having known characteristics, variable capacitors for generating first output signals representative of the antenna signal, wherein the capacitance of the variable capacitors is varied by the mixing signals such that the antenna signal is frequency translated. A signal processor processes the first output signals to generate a second output signal representative of the electric field. In a preferred embodiment of the invention, the mixing signals are a quadrature pair of sine waves. In an especially preferred embodiment, the variable capacitors are each a frame, a speaker mounted to the frame. The speaker cones move in response to a signal applied to each speaker.

Abstract: A detector for use on board an aircraft traveling along a path of movement to detect a power line comprises an antenna for sensing the electric field associated with the power line and producing an electric field signal, and a signal processor for receiving the electric field signal and generating a time-to-impact signal representative of the time for the aircraft to reach the power line if it continues on its path of movement. Sensors are used to determine the direction of the power line.

Abstract: An apparatus for determining the particle charge and size distribution of particles in suspensions of arbitrary concentration is provided. The apparatus includes a cell for application of an unsteady electric field or an unsteady mechanical force across the suspension of at least two different frequencies for accelerating the particles. The resulting acoustic wave generated by application of the electric field applied to the electrodes, or the electrical response and the acoustic pressure at the electrodes generated by application of the mechanical force is measured. Transducers convert the mechanical forces to electrical forces.

Abstract: A storm monitoring apparatus and method is described wherein two H-field antennas are oriented with respect to the heading axis of an aircraft or the like at an angle of 45.degree.. The signals developed by these two antennas are picked-up by small R-F transformers which serve the inherent function of integrating the signals and extracting the H-field current component. A printed circuit board structuring of the two antennas provides for consistency of fabrication and reliability as well as compactness. The monitoring apparatus exhibits broad band frequency response to evaluate lightning strike rate to determine storm range and intensity. A computer control test utilizing diagnostic coils at the antenna carries out periodic testing of the performance of the device and a component such as a gravity switch provides an indication to the control system as to the orientation of mounting of the antenna on an aircraft.

Abstract: A field strength measuring instrument for simultaneously measuring E and H fields is described. A loop antenna is formed by a half-loop (1) which is terminated by a metal surface (2). Due to the mirror effect of the metal surface (2), this arrangement, in field theory, is equivalent to a loop antenna which is divided into a first and a second half-loop (1, 5) by two load resistors (4a, 4b) arranged at opposite ends of the loop antenna. A circuit (8) for determining the field strengths of the E and H fields by means of the voltages (V.sub.1, V.sub.2) measured across the load resistors (4a, 4b) is arranged in a part-space shielded from the first half-loop (1) by the metal surface (2).