Abstract: A two-port fiber optic repeater includes means for receiving and restoring command word signals and means for receiving and restoring return data signals. A periodically actuated power supply supplies power to circuitry for sensing valid signal inputs to the repeater. When valid signal inputs are sensed, a main power supply is enabled to supply constant power to signal restoration circuitry. The pulse width of the command word signals are adjusted. The return data signals are restored using a fixed-frequency oscillator and a counter.

Abstract: An apparatus for implanting and positioning a geophone assembly into the earth is disclosed. The geophone implanting apparatus includes a receptacle for receiving and retaining a geophone assembly. A magnetic compass and a cylindrical bubble level are mounted concentrically approximately one meter from the receptacle so that the ferromagnetic properties of the geophone do not induce errors in the azimuth measurement. A pair of radially disposed handles are utilized to rotationally manipulate the geophone into a proper orientation during implantation. After the geophone assembly has been implanted and leveled a release mechanism is utilized to release the geophone from the receptacle by deforming a spring grip mechanism which is utilized to retain the geophone. In the depicted embodiment, a geophone assembly having a radially non-symmetric case is utilized in conjunction with a matching receptacle so that a unique orientation of the geophone may be accomplished.

Abstract: A high capacity continuous solid bowl centrifuge is disclosed having longitudinal vanes which cooperate with helical flights to form longitudinal channels. The longitudinal vanes may be curved vanes or they may be planar vanes disposed either radially or at an acute angle relative to a radius from the longitudinal axis of the centrifuge. In operation, the solids/liquid mixture fed into the centrifuge is separated, and the liquids move in a "plug-flow" manner in the longitudinal channels parallel to the axis of rotation, toward effluent discharge ports disposed at one end of the centrifuge. The separated heavier solids are moved by the flights toward the opposite end of the centrifuge where they exit through a solids discharge port.

Abstract: A method and apparatus for driving a seismic hydraulic vibrator in which a conventional sinusoidal drive signal in modified in such a manner as to improve vibrator response parameters. The sinusoidal drive signal is modified such that in the regions of the signal proximate the reference axis, the signal will abruptly pass from one side of the reference axis to the other side of the reference axis. This modification is accomplished by summing a square wave signal with the sinusoidal signal to form a composite drive signal.

Abstract: An improvement for the drive control system of a vibratory sound source used in seismic exploration comprising apparatus for generating a feedback signal proportional to the instantaneous acceleration of the reaction mass structure of the sound source's hydraulic drive system. Degenerative feedback of the signal so developed is used to reduce distortion of the vibratory seismic signal imparted into the earth.

Abstract: The present invention provides a method and apparatus for controlling the response of a seismic vibrator during its actuation period. The sweep input signal is modified in response to an average of the force applied to the earth by the vibrator over at least one cycle of the sweep signal. Additionally, this modified drive signal may be further adjusted by selective adjustment of the amplitude of the signal within selected frequency ranges.

Abstract: A spring system for use with a geophone for suspending a reference mass axially and laterally. One spring of the spring system flexes more axially than laterally, and the other spring of the spring system flexes more laterally, although heavily damped, than axially.

Abstract: A method and apparatus for generating a nonlinear sweep signal to be supplied to a seismic vibrator. A seismic sweep time is determined and is divided into a plurality of preselected time intervals. The rate of change of the frequency is determined for each of these time intervals to generate an output signal of a desired shape. The rate of change of the frequency for each time interval is calculated in response to the starting frequency of the sweep, the range of the sweep, the sweep time, and the desired shape of the output signal. The rate of change is supplied to a frequency generator which generates a signal to be supplied to the vibrator.

Abstract: For use in geophones to support either the coil or the permanent magnet, a spring formed from a disc, said spring having an outer ring, an inner ring, and three legs connecting the outer and inner rings. The legs are equidistant from one another and substantially equal in length. The inner edge of each leg lies on an arc having a radius at least 1.25 times greater than the distance from the center of the spring to the inner edge of the leg at the point where the leg joins the inner ring. For each leg, the straight-line distance between the points where a leg joins the inner and outer rings is equal to or greater than the distance from the center of the spring to an outer edge of the outer ring.

Abstract: A clamping apparatus for locking tools in a well is disclosed. A first piston sealably engages a hollow body member to form a chamber, which is filled with a working fluid. A bias member or spring moves the first piston, extending a clamping arm connected to the first piston against the well wall. A second piston is sealably engaged in a bore in the first piston; the bore is in fluid communication with the chamber. The second piston is driven into the bore by a motor, increasing the pressure in the chamber through a passage in the first piston between the bore and the chamber. This increased pressure further urges the first piston and locks the clamping arm against the well wall. The hydraulic pressure is released, and the clamping arm is unlocked, by opening a valve in a line between the chamber and a reservoir. The clamping arm is retracted by driving the second piston into the bore into contact with the first piston, forcing the first piston back against the spring.

Abstract: An electronic roll-a-long switch for use in a seismic exploration system and method of seismic exploration are disclosed. For a group of N sequentially numbered receiver points, N/2 input channels are provided. Each input channel receives input from one of two receiver points which are spaced N/2 receiver points apart. The input channels are multiplexed to a data bus in an order corresponding to the sequential numbers of the receiver points comprising the input channels.

Abstract: The claimed invention is directed to seismic exploration wherein an earth surface vibrator sweeps through a frequency range with varies with time as a function of frequency.

Abstract: An improved duty cycle controlled filter, wherein a resistance is included in every circuit path that exists between a switch terminal and an amplifier terminal. Such improved filter produces low distortion and has been found to be especially useful in data acquisition circuits of seismic exploration systems.

Abstract: Solids mixing well structure and methods are disclosed for mixing a solid having a first specific gravity with a fluid having a second specific gravity to produce a slurry having an intermediate specific gravity and a resultant pressure greater than atmospheric pressure. The solids can then be transported in the form of a slurry using the resultant pressure. At no time do the solids come in contact with a pump member. The apparatus and methods are particularly suited for transporting coal and solid waste material. No moving parts are required other than a pump to supply fluid pressure. A first cylindrical member receives at its inlet fluid at a pressure greater than atmospheric pressure and delivers the fluid at a first pre-determined pressure to a mixing region. A second structure receives at its inlet solids at atmospheric pressure and delivers the solids at the first pre-determined pressure to the mixing region down stream of the fluid.

Abstract: A transducer apparatus utilizing fiber optics for data transmission is disclosed in which an output optical signal is encoded with information representative of a parameter being measured and the encoded optical signal transmitted to a remote measurement and control apparatus site for decoding. The transducer is adapted to receive an input optical signal, and converts the input optical signal into electrical energy to power a driver. An electrical drive signal, generated by the driver, has a selectively variable frequency representative of the parameter being measured. Using the electrical drive signal, the output optical signal is generated. The driver includes a variable frequency oscillator whose frequency of oscillation is dependent upon the parameter being measured.

Abstract: A transducer for optical data transmission is disclosed in which an optical signal is encoded with information representative of a parameter being measured and transmitted to a remote measurement and control apparatus site for decoding. An input optical signal is received by the transducer and separated into first and second portions. The first portion of the optical input signal is converted to electrical energy and is used to power the transducer. The second portion of the input optical signal is modulated in response to the measured parameter and the modulated signal transmitted back to the remote site.

Abstract: A geophone spring is disclosed in which an inner ring member and an outer ring member are connected by a plurality of leg members. Each leg member includes a tapered segment that is wider at its middle than it is at either end. The tapered segment is connected to the inner ring by an inner segment, and to the outer ring by an outer segment. The inner and outer segments may also be tapered.

Abstract: An apparatus and method for testing a geophone during assembly is disclosed. The apparatus includes a light source cooperating with a photocell for generating a voltage signal in response to light. A member for support of the geophone to be tested is located in a defined path between the light source and the photocell for generating a voltage signal. The apparatus further includes a display unit for indicating the voltage signal generated, which is representative of the resilient characteristics of the geophone springs, characterizing the position of the geophone coil and its resonant frequency.

Abstract: Method and apparatus for determining the location of a break in a pair of wires of a multi-wire cable are disclosed. The method and apparatus permit such breaks to be found with a high degree of accuracy. The method and apparatus are especially useful in connection with locating breaks in seismic cables.

Abstract: A multistage volumetric feeder has a storage hopper for storing a mass of semi-flowable material, such as strand fiberglass, asbestos, or titanium dioxide. The material is bottom unloaded and passed through several stages of pressure reduction, aeration, and conditioning to loosen the material and place it in a state of substantially constant density. The conditioned material is further prevented from bridging and compacting as it is volumetrically delivered to a metering stage through a segregation stage. Because the semi-flowable material is placed in an uncompacted state of substantially constant density, the feeder is capable of delivering a precise mass of material over a wide range of flow rates.