Abstract: A micro geophone having pole pieces do not extend out around the sides of the magnet, thereby allowing a reduced geophone diameter for a given magnet diameter. The pole pieces are adhesively bonded to the magnet using an adhesive, which may be made suitably electrically conductive by silver or nickel fillers or non-conductive by mica fillers such as borosilicate glass micro-spheres. Axial space is economized by eliminating traditional spider retaining rings. The spider springs are seated directly against the coil form and secured by adhesive fillets disposed on the outward-facing spring circumferences. The spider springs include circumferential notches to receive adhesive. A two-piece bimetallic coil form of aluminum and a heavier material, joined by adhesive, is provided. Headers are affixed to the housing within the seats by adhesive. A straight or rounded chamfer at each of the geophone ends allows the overall geophone dimensions to be maximized.

Abstract: A micro geophone having pole pieces do not extend out around the sides of the magnet, thereby allowing a reduced geophone diameter for a given magnet diameter. The pole pieces are adhesively bonded to the magnet using an adhesive, which may be made suitably electrically conductive by silver or nickel fillers or non-conductive by mica fillers such as borosilicate glass micro-spheres. Axial space is economized by eliminating traditional spider retaining rings. The spider springs are seated directly against the coil form and secured by adhesive fillets disposed on the outward-facing spring circumferences. The spider springs include circumferential notches to receive adhesive. A two-piece bimetallic coil form of aluminum and a heavier material, joined by adhesive, is provided. Headers are affixed to the housing within the seats by adhesive. A straight or rounded chamfer at each of the geophone ends allows the overall geophone dimensions to be maximized.

Abstract: A recording system and method for conducting seismic surveys including cordless battery-operated digital recorders, each employing an integral global positioning system receiver that is only periodically enabled for the purpose of establishing synchronized acquisition clock signals among all the recorders. The satellite receiver adjustment cycle is varied depending on past acquisition clock accuracy and temperature changes. A time stamp is recorded with the digitized seismic data in non-volatile memory. The memory is sized to allow extended periods of operation. Each recorder preferably includes a low-power system timer that may be used as a timer to remotely turn on and off the recorders according to a pre-programmed schedule to conserve power when the system is not in use. Electronic components are idled or de-energized when not needed.

Abstract: A new structure (FIG. 11) for a thick-film thermal printhead and a variety of implementation approaches for controlling such a printhead. In the structure of the invention, the conductive lead at each end of the heater element is switched to either the power supply (Vhd) or ground, depending on the corresponding nib data bit. The improvement over a traditional center-tap structure (FIG. 1) is the reduction of density of conductive leads to achieve the resolution of printed dots. Compared to the printhead structure of alternated conductive system, either with diodes (FIG. 2) or without diodes (FIG. 4), which both suffer from the introduction of undesirable leaking currents, the printhead structure of the invention provides the advantage of eliminating leakage current completely. Control of the thermal printhead according to the invention is based on the sequential exclusive-OR (XOR) logic operation applied to the shifted-in nib data bit stream.

Abstract: A micro geophone having pole pieces do not extend out around the sides of the magnet, thereby allowing a reduced geophone diameter for a given magnet diameter. The pole pieces are adhesively bonded to the magnet using an adhesive, which may be made suitably electrically conductive by silver or nickel fillers or non-conductive by mica fillers such as borosilicate glass micro-spheres. Axial space is economized by eliminating traditional spider retaining rings. The spider springs are seated directly against the coil form and secured by adhesive fillets disposed on the outward-facing spring circumferences. The spider springs include circumferential notches to receive adhesive. A two-piece bimetallic coil form of aluminum and a heavier material, joined by adhesive, is provided. Headers are affixed to the housing within the seats by adhesive. A straight or rounded chamfer at each of the geophone ends allows the overall geophone dimensions to be maximized.

Abstract: A micro geophone having pole pieces do not extend out around the sides of the magnet, thereby allowing a reduced geophone diameter for a given magnet diameter. The pole pieces are adhesively bonded to the magnet using an adhesive, which may be made suitably electrically conductive by silver or nickel fillers or non-conductive by mica fillers such as borosilicate glass micro-spheres. Axial space is economized by eliminating traditional spider retaining rings. The spider springs are seated directly against the coil form and secured by adhesive fillets disposed on the outward-facing spring circumferences. The spider springs include circumferential notches to receive adhesive. A two-piece bimetallic coil form of aluminum and a heavier material, joined by adhesive, is provided. Headers are affixed to the housing within the seats by adhesive. A straight or rounded chamfer at each of the geophone ends allows the overall geophone dimensions to be maximized.

Abstract: A recording system and method for conducting seismic surveys including cordless battery-operated digital recorders, each employing an integral global positioning system receiver that is only periodically enabled for the purpose of establishing synchronized acquisition clock signals among all the recorders. The satellite receiver adjustment cycle is varied depending on past acquisition clock accuracy and temperature changes. A time stamp is recorded with the digitized seismic data in non-volatile memory. The memory is sized to allow extended periods of operation. Each recorder preferably includes a low-power system timer that may be used as a timer to remotely turn on and off the recorders according to a pre-programmed schedule to conserve power when the system is not in use. Electronic components are idled or de-energized when not needed.

Abstract: A geophone in which a coil bobbin assembly ideally includes a provision for receiving a third coil winding between the upper and lower coils. A third mass-tuning coil is wound around the bobbin whose purpose is to adjust the overall mass of the bobbin assembly with greater accuracy and precision than can be achieved by machining techniques alone. Mass is adjusted by adding or subtracting one or more turns of wire in the tuning coil. The tuning coil is preferably electrically shorted for increasing geophone damping.

Abstract: A geophone utilizing an Alnico-9 magnet and having an improved sensitivity over Alnico-9 geophones of prior art through the lengthening of the parasitic air gap between the upper and lower pole pieces which, results in less magnetic flux leakage. The flux concentration through the geophone coils is increased and shifted towards the ends of the magnet. The increase of sensitivity of geophone of the present invention over prior art geophones may exceed 3 dB. The axial length of the coil bobbin is increased, and the positions of the electrical coils are moved towards the ends of the magnet to align with the shifted magnetic flux.

Abstract: A vertical geophone that includes a lower frequency spring, which forms part of the geophone electrical circuit, that is positioned directly on the lower end cap This arrangement eliminates the “spring supported by a spring” arrangement of prior art geophones to minimize geophone distortion and simplify tuning of the frequency springs. A contact spring is positioned between the lower frequency spring and the lower pole piece for forming part of the geophone electrical circuit. One surface of contact spring includes a plurality of wiper surfaces that ensure consistent sliding electrical contact against either the bottom surface of the lower pole piece or the upper surface of the lower frequency spring. The obverse surface of the contact spring is preferably spot welded to the other adjacent member.