Abstract: A wand-type magnetic metal detector has a telescoping wand which shortens the wand sufficiently for the detector to be comfortably carried in a holster carried on the user's body. The user's hands are thereby freed for other tasks than carrying the detector.

Abstract: A magnetic core, for use in fluxgate magnetometers or gradiometers, for example, comprises a pair of coaxial coils constituted by strips of permeable magnetic material oppositely wound on a non-magnetic cylindrical tube. At each of their opposite ends, the coils terminate in planes perpendicular to the length of the tube. In the manufacture of a core, the strips at each end of the coils may be joined to each other to form a lap extending along the length of the tube. In one embodiment, strip portions extending beyond the respective planes, including a portion of each lap, are cut off and removed. In another embodiment, the entire lap at each end is removed after the strips at each end are welded to each other. By virtue of the core construction, the signal-to-noise ratio of saturable core measuring devices using the cores is substantially improved.

Abstract: A magnetic marker serving to locate, trace, and identify an elongated hidden object, such as a buried utility pipe, duct, conduit, or fiber optic cable, is manufactured by applying magnetic material to a substrate that is elongated and by forming from the material a helical or twisted permanent magnet pattern extending along the length of the substrate. The magnetic material, which may be coextensive with the substrate or applied to a portion only of the substrate, may be formed as a strip coextruded with the substrate and magnetized in the direction of the width of the strip. Alternatively, magnetic material may be mixed with the material from which the substrate is extruded or may be coated on the substrate. A strip may also be preformed and applied to an elongated object as the object is buried, or the strip may form a separate warning tape that is buried with the object and that is provided with a desired magnetic signature by twisting the strip lengthwise as it is advanced for burial.

Abstract: A magnetic marker serving to locate, trace, and identify an elongated hidden object, such as a buried utility pipe, duct, conduit, or fiber optic cable, is manufactured by applying magnetic material to a substrate that is elongated and by forming from the material a helical or twisted permanent magnet pattern extending along the length of the substrate. The magnetic material, which may be coextensive with the substrate or applied to a portion only of the substrate, may be formed as a strip coextruded with the substrate and magnetized in the direction of the width of the strip. Alternatively, magnetic material may be mixed with the material from which the substrate is extruded or may be coated on the substrate. A strip may also be preformed and applied to an elongated object as the object is buried, or the strip may form a separate warning tape that is buried with the object and that is provided with a desired magnetic signature by twisting the strip lengthwise as it is advanced for burial.

Abstract: A magnetic detection apparatus (magnetic locator) comprises a housing constituted by a first integral molded plastic unit and a second integral molded plastic unit that are joined. The first unit has a tube with a plate at one end thereof transverse to the length of the tube, the plate having an opening through which a magnetic sensor assembly is inserted into the tube. The second unit has a cover open at one end and having a tubular handle at the opposite end, by which the user may grasp the apparatus. Attachment of the cover to the plate closes the open end of the cover to provide a casing. Magnetic sensors are mounted on a channel or angle structural member that is rigidly attached to the chassis of an electrical unit mounted in the casing. Sound from a loudspeaker mounted on the chassis is transmitted through the handle to the exterior of the apparatus. The chassis also supports a meter that is visible through an opening in an end wall of the cover adjacent to the handle.

Abstract: A magnetic detection apparatus (magnetic locator) comprises a housing constituted by a first integral molded plastic unit and a second integral molded plastic unit that are joined. The first unit has a tube with a plate at one end thereof transverse to the length of the tube, the plate having an opening through which a magnetic sensor assembly is inserted into the tube. The second unit has a cover open at one end and having a tubular handle at the opposite end, by which the user may grasp the apparatus. Attachment of the cover to the plate closes the open end of the cover to provide a casing. Magnetic sensors are mounted on a channel or angle structural member that is rigidly attached to the chassis of an electrical unit mounted in the casing. Sound from a loudspeaker mounted on the chassis is transmitted through the handle to the exterior of the apparatus. The chassis also supports a meter that is visible through an opening in an end wall of the cover adjacent to the handle.

Abstract: In order to locate, trace, and identify hidden elongated objects, such as buried fiber optic cables, the objects are provided with elongated permanent magnet identifier devices having magnetic fields that may be detected at a distance from the objects. In one embodiment the identifier device comprises an elongated strip magnetized in the direction of its width and formed into a long-pitch helix, producing a characteristic "magnetic field signature" that enhances detection and identification of the object, as by a portable gradiometer that is moved over the surface of the earth along a line generally parallel to the length of the object. This embodiment may provide a magnetic field that diminishes as the square of the distance from the identifier device (rather than the usual cube of the distance), thereby enabling detection at substantial distances.

Abstract: A magnetic marker serving to locate, trace, and identify an elongated hidden object, such as a buried utility pipe, duct, conduit, or fiber optic cable, is manufactured by applying magnetic material to a substrate that is elongated and by forming from the material a helical or twisted permanent magnet pattern extending along the length of the substrate. The magnetic material, which may be coextensive with the substrate or applied to a portion only of the substrate, may be formed as a strip coextruded with the substrate and magnetized in the direction of the width of the strip. Alternatively, magnetic material may be mixed with the material from which the substrate is extruded or may be coated on the substrate. A strip may also be preformed and applied to an elongated object as the object is buried, or the strip may form a separate warning tape that is buried with the object and that is provided with a desired magnetic signature by twisting the strip lengthwise as it is advanced for burial.

Abstract: A magnetic detection apparatus (magnetic locator) comprises a housing constituted by a first integral molded plastic unit and a second integral molded plastic unit that are joined. The first unit has a tube with a plate at one end thereof transverse to the length of the tube, the plate having an opening through which a magnetic sensor assembly is inserted into the tube. The second unit has a cover open at one end and having a tubular handle at the opposite end, by which the user may grasp the apparatus. Attachment of the cover to the plate closes the open end of the cover to provide a casing. Magnetic sensors are mounted on a channel or angle structural member that is rigidly attached to the chassis of an electrical unit mounted in the casing. Sound from a loudspeaker mounted on the chassis is transmitted through the handle to the exterior of the apparatus. The chassis also supports a meter that is visible through an opening in an end wall of the cover adjacent to the handle.

Abstract: In order to locate, trace, and identify hidden elongated objects, such as buried fiber optic cables, the objects are provided with elongated permanent magnet identifier devices having magnetic fields that may be detected at a distance from the objects. In one embodiment the identifier device comprises an elongated strip magnetized in the direction of its width and formed into a long-pitch helix, producing a characteristic "magnetic field signature" that enhances detection and identification of the object, as by a portable gradiometer that is moved over the surface of the earth along a line generally parallel to the length of the object. This embodiment may provide a magnetic field that diminishes as the square of the distance from the identifier device (rather than the usual cube of the distance), thereby enabling detection at substantial distances.

Abstract: In order to locate, trace, and identify hidden elongated objects, such as buried fiber optic cables, the objects are provided with elongated permanent magnet identifier devices having magnetic fields that may be detected at a distance from the objects. In one embodiment the identifier device comprises an elongated strip magnetized in the direction of its width and formed into a long-pitch helix, producing a characteristic "magnetic field signature" that enhances detection and identification of the object, as by a portable gradiometer that is moved over the surface of the earth along a line generally parallel to the length of the object. This embodiment may provide a magnetic field that diminishes as the square of the distance from the identifier device (rather than the usual cube of the distance), thereby enabling detection at substantial distances.

Abstract: Magnetic cores are manufactured from preforms of magnetically permeable strip material wrapped about non-magnetic supports. The preforms have configurations, such as an X-configuration, that determine the placement and helix angle of convolutions of the strip material that constitute the cores. In a preferred embodiment, corresponding ends of the legs of an X-configuration preform are placed upon a support, and the preform is wrapped about the support so as to form two superposed layers of convolutions, with the convolutions of corresponding portions of the layers having opposite helix angles.

Abstract: Magnetic cores are manufactured from blanks of magnetically permeable sheet material that have core preforms including strip elements that are partially separated from adjacent portions of the blank. Stabilizer strip elements are provided at opposite sides of the preform and are partially separated from adjacent portions of the blank. A tube is attached to one end of the blank and a weight to an opposite end of the blank. After removal of portions of the blank adjacent to the strip elements, the strip elements are wound upon the tube while tension is applied to the strip elements by virtue of the weight. After the winding, the strip elements of the core preform define a core configuration, and the remainder of the blank is removed.

Abstract: Locating and tracing of a concealed, elongated, conductive object, such as a buried pipe or cable, is enhanced, when a second such object is adjacent to the first, by employing a transmitter having a pair of antennae that induce distinguishable currents in the respective objects. A receiver movable with respect to the transmitter and with respect to the objects produces an output signal dependent upon the sensing of fields associated with both currents. The position of the transmitter relative to the objects is adjusted to optimize the output signal.

Abstract: Magnetic cores are manufactured from preforms of magnetically permeable strip material wrapped about non-magnetic supports. The preforms have configurations, such as an X-configuration, that determine the placement and helix angle of convolutions of the strip material that constitute the cores. In a preferred embodiment, corresponding ends of the legs of an X-configuration preform are placed upon a support, and the preform is wrapped about the support so as to form two superposed layers of convolutions, with the convolutions of corresponding portions of the layers having opposite helix angles.

Abstract: Magnetic cores are manufactured from blanks of magnetically permeable sheet material that have core preforms including strip elements that are partially separated from adjacent portions of the blank. Stabilizer strip elements are provided at opposite sides of the preform and are partially separated from adjacent portions of the blank. A tube is attached to one end of the blank and a weight to an opposite end of the blank. After removal of portions of the blank adjacent to the strip elements, the strip elements are wound upon the tube while tension is applied to the strip elements by virtue of the weight. After the winding, the strip elements of the core preform define a core configuration, and the remainder of the blank is removed.

Abstract: In locating current-carrying objects, such as buried pipes in the presence of extraneous magnetic fields by detecting the magnetic field produced by the current, first and second spaced primary sensors measure the magnetic field at first and second locations, and a compensating sensor measures the extraneous field at a location midway between the first and second locations. The signal from the compensating sensor is combined with the signals from both of the primary sensors so as to compensate for the extraneous magnetic field at the primary sensors. The invention compensates for ambient magnetic fields associated with propagating electromagnetic energy that induces current in an object, and compensates for extraneous magnetic fields produced by current flow in an adjacent object.

Abstract: Magnetic detector apparatus comprises a pair of electrically matched magnetic sensor assemblies supported at opposite ends of a titanium sensor tube of significant length. The sensor tube is supported in a liquid bath so as to resist gravitational forces tending to distort the sensor tube and thereby misalign the magnetic axes of the sensors. The excitation conductors of the sensors are connected in series with an electrically conducting path formed through the sensor tube by spider members in electrical contact with the tube interior and connected to the respective excitation conductors.

Abstract: Magnetic detector apparatus comprises a pair of electrically matched magnetic sensor assemblies supported at opposite ends of a titanium sensor tube of significant length. The sensor tube is supported in a liquid bath so as to resist gravitational forces tending to distort the sensor tube and thereby misalign the magnetic axes of the sensors. The excitation conductors of the sensors are connected in series with an electrically conducting path formed through the sensor tube by spider members in electrical contact with the tube interior and connected to the respective excitation conductors.