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: 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: 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.

Abstract: A structure is disclosed for mounting separate magnetic sensor assemblies in a magnetometer and the like with the axes of the respective assemblies disposed in mutually orthogonal planes. In a preferred form, the structure comprises three separate elongated housings of rectangular cross section for carrying three separate sensor assemblies. The housings are connected together so that two housings cross one another at right angles and are centered lengthwise with respect to one another. The third housing is connected to one of the first or second housings with its axis disposed at right angles to each and being centered lengthwise with respect to each. Also disclosed is a suspension assembly for suspending the structure in an outer casing, the suspension assembly including a gimbal arrangement whereby the structure is free to swing about a pair of mutually perpendicular gimbal axes.

Abstract: A magnetic sensor assembly including an elongated support is supported in a tubular housing by a pair of tapered foam sleeves that space the support from the inner surface of the housing and that resist movement of the assembly in the housing in a direction opposite to the direction of insertion of the assembly into the housing. The sleeves, which are either continuous hollow cylinders or are formed of wound strips, are attached to the support by adhesive tape at the leading end of each sleeve.

Abstract: A magnetic locator employs a loudspeaker to produce an audible signal which indicates detection of a magnetic object. The loudspeaker is mounted on a frame in a housing and is spring biased against an end wall of a cover part of the housing. Openings through the housing wall for passage of sound are protected by a shield which, together with a plateau on the exterior of the housing wall, provides an annular space for omnidirectional radiation of acoustic energy. Mounting screws for the loudspeaker project from the frame through holes in the housing wall and receive nuts for securing the cover part of the housing to the frame. When the cover part is secured to the frame, elastomeric washers on the screws inside the housing are positioned automatically, and biasing springs on the screws are partially compressed.