Abstract: An improved hand-held sensor having a recessed LED array for indicating the location of an object behind a wall surface. The array displays in an arrow shaped format the location of the sensor relative to the object. The LED's can be offset both laterally and in depth from the surface of the sensor exterior case and are recessed from the surface. The sensor includes a soft feeling slip-resistant gripping surface for the user. One form of the sensor includes a slide switch actuator, which is retained in one wall of the sensor case to enable actuation of a switch mechanism without physical loading on the switch mechanism.

Abstract: A stud detector for detecting studs behind the surface of a wall, the stud detector having a measuring member with first and second ends and a preselected length that corresponds to a conventionally used stud configuration. A sensor is connected to the second end of the measuring member, the sensor including a magnet for detecting the presence of a stud behind a surface of a wall by detecting the presence of a metal object. The measuring member is adapted to permit identification of a surface portion of a wall behind which a stud might be located by measuring a preselected distance from a reference point.

Abstract: The present invention relates to an electronic system for identifying a single power line from a plurality of power lines having transmitting means for transmitting an identification signal on the single power line to produce a magnetic field with a strength around the single power line, sensing means for sensing the strength of a magnetic field around each of the plurality of power lines wherein the strengths of the magnetic fields range from a smallest value to a largest value, storing means for storing the largest value, and alert means for alerting a user when the sensing means senses the largest value. Also disclosed is a method of using the device.

Abstract: The present invention is a means of allowing continuous radio detection of underground utilities while maintaining cathodic insulation of metal utility conduits such as gas mains and pipes. By using a capacitor between a metal gas main and an old metal gas service line, the gas main is isolated from the service line. A short in the tracer line against the old metal gas service line will not result in an electrical connection with the metal gas line that increases the rate of deterioration of the cathodic protection anode. Using the capacitor in the tracer wire system eliminates check points isolating tracer wire sections. In the preferred embodiment of the present invention, the capacitor assembly comprises a ceramic nonpolar capacitor ranging from 0.01 microfarad to 1.0 microfarad encased in an epoxy plastic contained in a case. The tracer wire leads are of 14 gauge oxygen free copper.

Abstract: A portable device for selectively locating a wooden object, a metal object or a live AC wire positioned behind a wall surface covering when the device is moved along a wall surface is disclosed. Wood is detected by changes in effective dielectric constant, metal is detected by changes in magnetic reluctance and a live wire by detecting modulation signals at mains frequency. The device is controlled by a microcontroller to provide discriminating visual and audible signals when each of the kinds of objects are proximate the device.

Abstract: A hidden object sensor is described which senses and locates hidden objects hidden behind a surface of an architectural structure. The sensor includes sensing elements for sensing live wires behind the accessible surface, and separate sensing elements for respectively sensing metal and non-metallic objects behind the tested surface. A microprocessor alternates between the use of the various sensing elements and their associated circuits to detect live wires, metal objects, or wood studs. Visible and audible indicators are provided for indicating the device's mode of operation and the locations of sensed hidden objects. If a live wire is sensed, the processor may preclude an indication of a metal object or wood stud.

Abstract: A device for locating the edges of wall studs includes a comparison circuit connected to each of three capacitive elements. As the device is moved along a wall, the comparison circuit monitors the relative charge time associated with each capacitive element, the charge times providing an indication of the relative capacitances of the three capacitive elements. Changes in the relative capacitances of the three elements as the device is moved along a wall are due to a change in the dielectric constant of the wall, which normally results from the presence of a wall stud behind the surface over which the device is moved. The comparison circuit uses differences in the measured relative capacitances of the first, second, and third capacitive elements to locate the edges of the stud.

Abstract: A transmission enhancement system is used for strengthening low frequency cable locating signals on the metallic shields of long underground cables. The system includes equalization circuits on the cable armour or shield at regular intervals, for example at splice locations. The equalization circuit includes an inductor that significantly reduces the rate of attenuation of the low frequency tone signal and greatly enhances the strength of the signal at distances where the signal would otherwise be very weak or unusable. The equalization circuit may be a resonant circuit having a capacitor connected in parallel with the inductor. The capacitor compensates for the inductor's attenuation of high frequency tones for local location purposes. The preferred embodiments of the equalization circuit include a surge arrestor coupled in parallel with the inductor and capacitor.

Abstract: A composite tool and instrument is configured as a hammer having a metal striking head electrically coupled to capacitive sensing electronics disposed in a handle of the hammer. The head can thus serve as a sensing plate portion of a capacitive sensor responsive to a change in the effective dielectric constant of a building surface caused by the proximity of a structural member hidden behind that surface. The head can also serve as a sensing electrode portion of a sensor used to sense the proximity of AC power lines hidden behind the surface. In a preferred composite tool, the hammer has a handle made of an electrically insulating polymeric material and has an electrical conductor axially threaded through the handle so as to electrically couple the striking head to sensing electronics located in a cavity at the end of the handle distal from the head.

Abstract: A test system for distinguishing a particular AC distribution circuit interrupting device from among a plurality of AC distribution circuits interrupting devices. The test system comprises a transmitter for placing an identification signal on an AC power distribution circuit and a receiver for detecting the identification signal. The transmitter comprises means for generating an FM modulated identification signal, and means for coupling the identification signal to the AC power distribution circuit. The receiver comprises preselector means for selecting a predetermined band of frequencies for further processing, first detector means for detecting a signal within the predetermined band of frequencies, second detector means for detecting a modulating signal, and processor means for processing indications from the first and second detectors, and for activating a discernible indication of receiver operation.

Abstract: An electrical circuit finder has a transmitter which is plugged into one of the circuits of a building's electrical system and a receiver which is used to identify other elements of the circuit such as a circuit breaker, fuse, switch, electrical device or outlet. The transmitter induces in the circuit a high frequency current signal which is modulated at a lower frequency. The receiver, including a sensor wand and a receiver housing, is tuned to inductively detect the high frequency when placed in the magnetic field of the circuit and to produce visual and audible signals to the user which vary in intensity according to the detected signal. The user can thereby use his or her visual and/or audio senses to associate a circuit element proximate to the receiver with the circuit element connected to the transmitter.

Abstract: A system in which a boring tool is moved through the ground within a given region along a particular path in an orientation which includes pitch. A locating signal is transmitted from the boring tool which signal exhibits a field defined forward point within a reference surface which field defined forward point is vertically above an inground forward point on the particular path through which the boring tool is likely to pass. It establishes a predicted depth of the boring tool at the inground forward point by first identifying the field defined forward point with the use of a locator with two antennas. The signal strength of the locating signal is then measured at the field defined forward point as being representative of the depth of the boring tool at an inground upstream point which is the current location of the boring tool. With the boring tool at the upstream inground point, the pitch of the boring tool is determined.

Abstract: A method for tracking an object using energy fields, in the presence of interference due to introduction of an article responsive to the fields, in the vicinity of the object. One or more desired energy fields are produced in the vicinity of the object, and a characteristic of energy fields induced due to introduction of the article is determined. Signals are generated responsive to the energy fields at a plurality of locations of the object after introduction of the article. Spatial coordinates of the object are determined, responsive to the generated signals and the determined characteristic.

Abstract: An underground pipe and cable locator for continuous depth readings comprises a top and bottom receiver antenna sensor each connected to respective amplifier channels. A separate transmitter is used to stimulate electromagnetic radiations from a buried pipe, cable, or other electrical conductor. The bottom receiver antenna sensor is sampled and used to synchronize a phase locked loop controlled oscillator. The exceedingly faint and noise-riddled signals obtained from the top and bottom receiver antenna sensors are full-wave rectified without the use of rectifiers or diodes that can introduce distortions and offsets. Such signals are full-wave rectified by synchronously switching between inverted and non-inverted copies with an analog switch such that only the positive cycles of each are output in one pulse train. A continuous output is therefore obtainable from the top and bottom receiver antenna sensors, and this, in turn, permits a continuous display of the depth estimate of the buried conductor.

Abstract: A back-to-back locator instrument includes a first portion with an array of two or more magnetic sensors, and an indicator arrangement. A second portion of the instrument includes an array of correspondingly located magnets. Each of the first and second portions includes a marking arrangement, which either allows marking of the underlying surface, or viewing of a mark on the surface for properly locating the instrument portion thereon. When the two portions are congruent or registered, the indicator arrangement gives a maximum indication of corresponding locations. In a particular use, corresponding locations on the inside and outside of a tank are identified. The indicator arrangement may include a separate indicator for each magnetic sensor. A flux concentrator may be associated with each magnetic sensor.

Abstract: An automatic gain control (AGC) system for use in line locators that detect concealed conductors is presented. The AGC system includes determining an AGC signal from a reference sensor and processing signals from one or more observed sensors utilizing the AGC signal. The reference sensor is located farther from the concealed conductor than the observed sensors. The AGC system can be implemented in analog form or can include a digital AGC determination in a microprocessor.

Abstract: In order to identify a cable buried underground, a very low frequency voltage signal is applied to the cable and an electric field sensor is brought into proximity with the cable. The sensor thus detects the voltage signal on the cable and so identifies the cable. The sensor is unaffected by one or more additional cables carrying voltage signals, which are proximate the cable of interest, as the electric filters from such additional cables do not pass to the cable of interest. The sensor is mounted on a probe which is mounted into a bore in the soil around the cable of interest. The probes may also carry a magnetometer for detecting magnetic fields generated by low frequency alternating current signals on the cable of interest.

Abstract: A sensor system for use on drilling equipment to detect the presence of high voltages during horizontal or vertical drilling and providing an alarm signal corresponding to one of three possibilities: (1) the drilling tool hitting a high voltage line; (2) the drilling tool remaining in contact after hitting the high voltage line; and (3) an exposed or damaged high voltage line in close proximity to the drilling implement. The sensor system detects alternating current, converts the alternating current signal to a pseudo square waveform signal, compares the magnitude of the square waveform signal with a reference voltage, and sounds an alarm if the magnitude of the square waveform signal exceeds the reference voltage. The sensor system also incorporates a self-test circuit which allows an operator to check its functionality before use. The operator can also check the sensor at any time during drilling process.

Abstract: A nail locating device includes a seat, a coupling member and an indicating rod. The seat is adapted to be moved on a surface of a board into which a nail has been driven, and has an open upper end portion and an open lower end portion. The seat further has an intermediate portion between the upper and lower end portions and is formed with a ball socket therein. The coupling member has a ball portion hinged to the seat in the ball socket. The indicating rod is received in the seat and extends from the upper end portion, through the ball portion of the coupling member, and into the lower end portion of the seat. The indicating rod has a bottom end provided with a magnet that is adapted to be attracted to the nail such that the indicating rod pivots in the seat due to attraction of the magnet to the nail in order to indicate the location of the nail in the board.

Abstract: A flexible probe for insertion into an auxiliary pipe indicates the proximity of the auxiliary pipe to a device within a main pipe. The probe includes an apparatus for generating a magnetic field for detection within the main pipe. An indicator associated with the probe generates a signal when the probe is adjacent the main pipe. The magnetic field generating apparatus includes a coil with an electronic circuit for generating an alternating current signal and also includes a switch operable when the probe contacts the main pipe.

Abstract: A roof rib finder and fastening device using an inductive switch whereby ribs in a roofing structure can be located and a signal given to an operator to lower and actuate a screw loading device to enable the installation of a screw through an opening in a washer to achieve securement of the screw-washer combination to a rib in a roofing structure; the device includes a support frame, a screw loading device, a washer retaining device and an inductive proximity switch including an adjustable sensing distance potentiometer secured to a support frame as well as a light to indicate to the installer that the proper position on the roofing structure immediately above a rib has been located.

Abstract: A dual sensitivity stud sensor senses studs through both thick and thin surfaces. Studs are sensed by detecting a change in the capacitive loading of plates as they are moved along a surface and into proximity with a stud. The sensor informs the operator when the sensor has (incorrectly) been calibrated over a stud. The sensor also informs the operator if the sensor is placed against a surface either too thick or too thin for stud detection. Through use of a digital register, the sensor remains calibrated indefinitely while the sensor is powered on.

Abstract: A method is disclosed as part of an overall process in which a boring tool is moved through the ground within a given region along a particular path in an orientation which includes pitch. A locating signal is transmitted from the boring tool which signal exhibits a field defined forward point within a reference surface which field defined forward point is vertically above an inground forward point on the particular path through which the boring tool is likely to pass. The method establishes a predicted depth of the boring tool at the inground forward point by first identifying the field defined forward point. The signal strength of the locating signal is then measured at the field defined forward point as being representative of the depth of the boring tool at an inground upstream point which is the current location of the boring tool. With the boring tool at the upstream inground point, the pitch of the boring tool is determined.

Abstract: This invention relates to a carrier for a pipe and line locator which facilitates the use and operation of the locator in that the carrier includes a grounding rod for making it easy to connect a grounding output of the transmitter to ground, thereby enhancing the efficiency of using the locator. The grounding rod on the locator is associated with the handle that is used to lift and transport the carrier and to cause penetration of the ground with the grounding rod upon placing the carrier with the locator on the ground.

Abstract: To more accurately detect the position of a boring head (16) relative to a utility conveyance (22) during a boring operation, the conveyance carries a low power, pulsed signal. The signal is detectable only with a limited distance from the conveyance corresponding to a minimum allowable distance between the boring head and the conveyance. The boring head (16) carries at least one detector (28) for detecting the signal radiated by the cable. If the detector (28) detects the signal, then the boring head is too close and boring operation is interrupted.

Abstract: The present invention relates to an electronic system for identifying the circuit interrupter device associated with a particular power outlet receptacle on a power line, and to a method or means for identifying the circuit interrupter device.

Abstract: A compact hand-held metal detector that detects small ferrous and non-ferrous metal objects, that has a detection pattern in three planes, and that includes a plurality of detection alarm indications including visual, audio, and tactile detection alarm indications is provided. The invention includes a single small detection coil combined with an electronic control circuit that permits the coil and associated electronic components to be mounted adjacent each other in a compact enclosure. The coil provides a spherical detection pattern that is active in all three planes which detects metal objects in any orientation with respect to the coil. Upon detection of a metal object, the detector provides a visual and audio or tactile alarm indication.

Abstract: A process for detecting totally or partially hidden faults, such as cracks, and bubbles and the like in an opaque medium, by using microwave radiation. Microwaves from a transmitting antenna are directed against the surface of the medium which is to be inspected, and microwave radiation reflected or back scattered from the medium is detected and analyzed. In order to maximize the signal to noise ratio, minimizing the detection of radiation reflected by the surfaces of the medium itself, at least one of the transmitting antenna and the receiving antenna is oriented at an oblique angle relative to the surface of the medium.

Abstract: The invention relates to a method and apparatus for marking entrance and exit opening sites in opposite surfaces of a wall member of a perforation to extend therethrough and is provided, at one surface at a site corresponding to one of the entrance and exit openings with a wave signal transmitter and, at the other surface with a wave signal receiver responding to transmitted signals by rendering an indication of a maximum strength wave signal as a function of the location of the other of the entrance and exit opening. In a preferred embodiment, the receiver is mounted on a drill or the like at a predetermined distance from the axis thereof and the transmitter is provided with a cantilever provided with a marker spaced from the transmitter at a distance corresponding to the predetermined distance.

Abstract: A method of detecting the presence of an electric cable, the electric cable including conductive armoring and a conductive core that is electrically insulated from the armoring. In the method, the armoring is connected to ground, and a current pulse is emitted over the armoring by way of a current injector device connected to ground so that the return of the pulse to the injector device takes place via ground. The presence of the electric cable is detected in the proximity of a reception point by detecting, at the point, a signal that is representative of the pulse, by way of a detector.

Abstract: A locator such as a ground penetration probe (24) has spaced antennae (21,22,23) therein which detect electromagnetic signals from an object (26) such as a buried cable. By analyzing the electromagnetic signals using a suitable processor (25) it is possible to determine the separation of the locator and object (26), both in terms of the direction (X) corresponding to the spacing of the antennae (21,22,23) and the perpendicular direction (Y) to the object (26). This then permits a display to be generated showing visually the separation of the locator and the object (26). If the locator incorporates a tilt sensor, the processor (25) can then compensate for tilting of the locator, and determine the vertical and horizontal separation of the locator and the object (26).

Abstract: A device for locating the edges of wall studs includes a comparison circuit connected to each of three capacitive elements. As the device is moved along a wall, the comparison circuit monitors the relative charge time associated with each capacitive element, the charge times providing an indication of the relative capacitances of the three capacitive elements. Changes in the relative capacitances of the three elements as the device is moved along a wall are due to a change in the dielectric constant of the wall, which normally results from the presence of a wall stud behind the surface over which the device is moved. The comparison circuit uses differences in the measured relative capacitances of the first, second, and third capacitive elements to locate the edges of the stud.

Abstract: A method and apparatus are disclosed for applying a low strength, time varying magnetic field to a selected screening region of a host, and for sensing a responsive magnetic field from a retained ferrous body within the screening region. The excitation field coil is designed to create a region of finite magnetic field within the screening region, and a region of near zero magnetic field. The sensors are placed within the region of near zero magnetic field to minimize the effect of the applied field. The effects of the applied field are further reduced by use of a reference sensor, field compensation coils, and a feedback loop. The magnetic gradient measured by the sensors is processed to locate and characterize the ferrous body.

Abstract: A selected one of a plurality of underground utility conveyances(14--14) may be located in an enclosure (10) by providing each conveyance with an electronic marker (18). Each marker is responsive to a first RF signal from an electronic marker locator (32) operated by a utility worker. Upon receipt of the first RF signal, the electronic marker associated with the conveyance of interest responds by broadcasting a second RF signal containing information indicative of the conveyance. The second RF signal is received and processed by the electronic locator marker to locate the conveyance and ascertain information related thereto.

Abstract: A system for detecting faults in the insulation layer surrounding a concealed conducting pipe (10) includes a signal generator (12) for applying an alternating current with a frequency of around 4Hz to the pipe, a magnetometer (102) for detecting the alternating current from the pipe (10) and a CPU (115) for identifying changes in the gradient of the detected current along the length of the concealed conducting pipe (10) which are caused by the faults in the insulation layer. The magnetometer (102) is used in connection with a locator(100) which detects a second alternating current applied to the pipe (10) by the signal generator (12), this second alternating current having a frequency of around 128Hz. The system can also use both these signals to determine the direction of the signals emulating from the pipe (10).

Abstract: Precise location of a buried utility conveyance (10) is achieved by impressing on the conveyance low frequency conveyance-locating and conveyance confirmation signals, the later being pulsed in a particular pattern unique to the conveyance to be located. A first sensor (22) detects a first magnetic field radiated by the conveyance upon receipt of the conveyance-locating signal. An array (24) of sensors (26.sub.1 -26.sub.5) detects the second magnetic field radiated by the conveyance upon receipt of the conveyance-confirmation signal. A processor (32) coupled to the sensors (26.sub.1 -26.sub.5) precisely vectors the location of the conveyance from the second magnetic field strength sensed by each sensor (26.sub.1 -26.sub.5).

Abstract: An integrated circuit includes a first metal layer with first layer identification signal writing circuitry connections to produce first metal layer circuit identification signals. The integrated circuit also has a second metal layer with second layer identification signal writing circuitry connections to produce second metal layer circuit identification signals. Logic circuitry in the first metal layer has input connections to the first layer identification signal writing circuitry connections and the second layer identification signal writing circuitry connections. The logic circuitry combines the first metal layer circuit identification signals and the second metal layer circuit identification signals to produce a circuit identification number. The value of the circuit identification number can be changed by altering the first layer identification signal writing circuitry connectors or the second layer identification signal writing circuitry connections.

Abstract: A sensor device and method for finding the location of a conductor such as a wire, having an alternating voltage and which is not readily visible, i.e. hidden in the wall of a structure or buried. The detector device has four plates in two balanced pairs and arranged in a quadrilateral with a central reference plate. This reference plate provides a common mode rejection of the background electric field typically present for instance on the wall, which is induced by the alternating voltage in the wire. A sharp signal peak is detectable immediately over the wire from a differential signal of a pair of the balanced plates, when the plates of the pair are located on either side of the wire. Also a determination based on the sum and difference of the signals from the two plates allows one to determine the relative phase induced in the two plates of each pair, which indicates the direction in which the sensor device should be moved in order for the plates to be immediately over the target wire.

Abstract: The invention relates to a method and to a probe arrangement for the electromagnetic detection of metal objects. For this purpose several receiving loops are provided, which detect a secondary signal emitted by the sought object. The secondary signals received with the different loops are interconnected and evaluated in object-specific manner. This gives precise information on the position and location of the object to be detected.

Abstract: A system is disclosed in which a boring tool is moved through the ground in a region which includes at least one electrically conductive in-ground line. The system includes an arrangement for tracking a specific positional relationship between the boring tool and one or more in-ground lines. The arrangement generates a magnetic field from one of either the boring tool or the line. A particular characteristic of the generated field is detected at the boring tool if the field is generated from the line or is detected at the line if the field is generated from the boring tool. The characteristic varies as a function of the specific positional relationship between the boring tool and the line as the boring tool moves through the ground within the region.

Abstract: Buried conductors generally carry multi-frequency AC currents and are locatable by sensing the resulting varying magnetic flux. However the presence of several buried conductors makes location of individual conductors difficult. By investigating induced signals at a multiplicity of different frequencies it is possible to identify a frequency carried exclusively by a single conductor and use it to locate that conductor. E.g. an antenna array including three vertically spaced horizontal coils (A,B,C) is located over an apparent conductor position using vertical coils (D,E). For numerous frequencies, the terms SB/(A-B), 2SC/(A-C) and 2S (B-C)/?(A-B)-(B-C)! are determined (where S=coil spacing; X=signal strength of coil X). For an exclusive frequency the three values are identical and equal to the depth of the conductor.

Abstract: An antenna array has three horizontal coils (A,B,C) with equal spacings s, and two coplanar vertical coils (D,E) with a horizontal spacing 2f. When it is located over one or more current-bearing buried conductors, signal currents (A,B,C,D,E) are induced in the coils. The difference value D-E is measured and compared with a value "D-E" calculated from the equations:"(D-E)"=2f/("d".sup.2 +f.sup.2)"d"=2s(B-C)/?A-B)-(B-C)!.Identity indicates that the signal source is a single conductor. A larger calculated value indicates plural sources with mainly vertical separation. A small calculated value indicates plural sources with mainly horizontal separation.

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 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: An underground utility conveyance (10) may be precisely located by impressing both a locating tone and a confirmation tone on the conveyance. The locating tone is an RF signal that produces a first field that radiates above the earth that is sensed by a first, above-ground signal detector (22) to establish the general location of the conveyance. The confirmation tone is a near-DC signal that produces a second, field having a relatively limited radiation path. A second detector (24) is inserted into the earth at successive places in the region where the conveyance is located to establish its precise location.

Abstract: An apparatus and method is provided for determining if the signal received from an underground beacon (10) at a locator (22) is a true signal or a ghost signal. Orthogonal horizontal antenna (38) and vertical antenna (40) are used and a ratio is computed of the signal strengths measured by the two antennas. At the true location, the signal strength in the horizontal antenna (38) will be maximum and the signal strength of the vertical antenna (40) will be a null. If the ratio of the signal strength sensed by the horizontal antenna and vertical antenna is large, exceeding a predetermined value, the locator is receiving a valid signal from the beacon and a display of this fact is made on a display on the locator and the depth of the beacon is calculated. If the ratio is less than the predetermined value, a ghost signal is being received and this fact is displayed on the display on the locator (22).

Abstract: A dual sensitivity stud sensor senses studs through both thick and thin surfaces. Studs are sensed by detecting a change in the capacitive loading of plates as they are moved along a surface and into proximity with a stud. The sensor informs the operator when the sensor has (incorrectly) been calibrated over a stud. The sensor also informs the operator if the sensor is placed against a surface either too thick or too thin for stud detection. Through use of a digital register, the sensor remains calibrated indefinitely while the sensor is powered on.

Abstract: A pipe proximity warning device is operable for both cross-line and in-line digging operations to provide a warning to an operator that the bucket of a backhoe is in close proximity to a trace wire on a plastic pipe. The in-line system comprises two sensors located on the bottom of the bucket for detecting a signal on the trace wire. The distance to the wire is determined based upon a ratio of the signals detected by the two sensors. The cross-line system also has two sensors and also employs a ranging system that disables a geometry tracker when the bucket is outside an operable range of distances to the trace wire. From the angles of the boom, stick, and bucket, the geometry tracker determines the horizontal distance x and vertical distance z to the trace wire, both of which may be displayed to an operator in real-time.

Abstract: When identifying particular cable A among a plurality of cables housed in a trough, a signal applying section 10 compounds three different frequency signals, which are generated by an oscillating circuit section 11, by a potential signal compounding & applying circuit 15 and applies it to conductor A1 of the particular cable A. In a detecting section 20, a detecting circuit 22 detects the compound signal via an electrode 21, which is electrostatically coupled with particular cable A, an amplifying circuit 23 subjects the compound signal to gain adjustment, and a signal identifying circuit 24 identifies particular cable A from the compound signal.

Abstract: Apparatus for identifying faults within electrical power cables is provided. The apparatus allows a user to detect faults in cables regardless of the cable environment's noise content. Circuitry may be included for filtering the received test signal based on an understanding of a generic urban noise environment. The apparatus can provide the user with the size and direction of the test signal at a particular testing location.

Abstract: An electromagnetic tagging system is provided for remotely detecting and locating polymeric and other non-conductive structures situated behind barriers, such as underground plastic pipes or containers. The system comprises a fluctuating magnetic field source, a pattern of tags embedded in discrete regions of the wall of the polymeric structure, each tag including an amorphous magnetic metal target for generating a Barkhausen response when exposed to the fluctuating magnetic field source, and a portable detection circuit movable along the ground or other control surface for remotely detecting the Barkhausen response. The amorphous magnetic material in each tag is preferably in the form of a plurality of elongated particles having aspect ratios of at least 3 to 1 and arranged end-to-end.