Abstract: A remotely operated downhole switching apparatus, particularly adapted to selectively connect a downhole device such as a sensor circuit to a cable which supplies power to a downhole motor includes a switch for connecting the downhole device to a neutral node of the motor, a latch coil responsive to a latching signal carried by the cable for closing the switch, and a delatch coil connected to the cable through a frequency responsive circuit which is responsive to a delatching signal carried by the cable for passing current through the delatch coil. A diode connected to the delatch coil prevents current flow through the delatch coil in a direction which causes the switch to close. An AC signal may be employed for closing the switch, and a voltage pulse may be employed for opening the switch.

Abstract: A method and system for detecting objects having preferential polarization plane reflection characteristics. The method includes the steps of: (a) transmitting from a first given location, a first plane-polarized electromagnetic wave that is oriented in a predetermined reference plane; (b) transmitting from the first given location a second electromagnetic wave having the same frequency and intensity as the first wave and not being oriented in the predetermined reference plane: (c) receiving at a second given location, reflections of the first transmitted wave to provide a first received signal; (d) receiving at the second given location, reflections of the second transmitted wave to provide a second received signal; and (e) comparing the first received signal to the second received signal for detecting an object that preferentially reflects the transmitted radiation in a distinct plane so as to distinguish such object from other objects not having such characteristics.

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: A group-complementary codes provide sets of binary word groups which have the combined properties of optimized aperiodic autocorrelation and optimized cross-correlation between word sets. The optimized aperiodic autocorrelation property allows the implementation of pulse compression processing in sensor systems to achieve zero value temporal or range sidelobes within the principal interpulse period without resorting to weighting techniques for sidelobe reduction. The orthogonal nature of group-complementary codes, apparent from their absence of cross-correlation between sets, allows sensors to be deployed in close proximity, using the same carrier frequency without direct path mutual interference when synchronized.

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: A system for storing and transmitting pulse count information is disclosed wherein electrical pulses produced by logging tools, such as thermal neutron, are counted and stored downhole to remove the effect of lengthly transmission lines. In a further embodiment a coded multiplexed signal is transmitted uphole indicating the tool from which the transmitted data was received and the total count for a predetermined time period.

Abstract: A method and apparatus for use in marine seismic data gathering comprises a vessel (1) is equipped for deploying and retrieving trailer cables and tows a plurality of cables (3) which are provided with at least one array of transmitters (5), which array constitutes a point source for a transmitter, and an acoustic cable, over the region to be investigated. The transmitter cables (3) are caused to become distributed laterally in relation to the tow direction, the distance between them, the firing power and firing timing being controlled from the vessel in accordance with data collected previously regarding the nature of the sea bed. The point source-formed transmitter arrays can be distributed both laterally and longitudinally in relation to the tow direction. The transmitter cables (3) are distributed laterally with the aid of otterboards (8).

Abstract: Water inflow inside a seismic streamer may create parasitic electric connections between lines supplying current to the electronic devices of the streamer and lines transmitting seismic informations, thus damaging the electronic apparatus and making these informations inaccurate. In accordance with the invention streamer sections including sections of supply lines and transmission lines are provided with water inflow detection assemblies, each comprising a closed circuit element surrounding the supply lines, a conducting line connected to a DC voltage generator, and means for detecting any DC voltage therebetween resulting from parasitic connections between the supply lines and the closed circuit element, created by a water inflow.

Abstract: The method uses a combination monopulse and sequential lobing system to guide a vehicle, such as a missile, aircraft, auto, etc., toward a target. The target is tracked with conventional monopulse techniques while at the same time the vehicle is provided with coded data forming a cluster so as to provide spatial resolution information. The vehicle sequentially receives this information, stores the information until the sequence is complete and processes the information for guidance.

Abstract: An apparatus for the remote transmission of information from a borehole (1) to the surface of the earth is disposed in a drilling pipe string (4) of a drilling device. The drilling device further comprises a rotary drill bit (3) and a pump (5) which pumps the flushing liquid (6) downwards in the flow passage (11) of the drilling pipe string, through the rotary drill bit (3) and upwards in an annular space (7) surrounding the pipe string. The apparatus has devices for ascertaining information data (8), for converting the information data into electrical control signals (9) and for producing pressure pulses (10) in the downwardly directed flow of the flushing liquid (6). The devices are disposed in a chamber (13) which is bounded internally by the flow passage (11) and externally by an outer tube (12).

Abstract: A seismic wave generator and method of using it, which comprises a vertical array of sources at known spacings, for detonation in a seismic wave propagating medium of known seismic velocity; means to initiate the sources in time sequence in a selected series of known different time intervals and recording the seismic waves at a distant location to provide a first electrical signal; and correlating the first electrical signal with a second electrical signal derived from the pattern of initiation, as modified by the travel times of the waves between the several separate charges.

Abstract: A cable system for carrying out seismic operations, comprising a multi-conductor cable built with multiple segments, each segment terminated with identical connector plugs. Each segment having a selected number P of take-outs for accepting P seismic signals. The group of P seismic signals from the take-outs are multiplexed in each cable segment, and travel over a single conductor pair in the successive segments to the recording truck, where they are demultiplexed, and as reconstituted signals, are processed and recorded.

Abstract: A radar of the MTI type has a transmitter connected to a source of outgoing pulses whose carrier frequency is variable under the control of a mode selector for selective operation with fixed frequency, frequency diversity or frequency agility, depending on detected environmental conditions. A multiweight Doppler filter serves for the detection of mobile targets in each of these three modes. With frequency-agility operation, samples of echoes of an outgoing pulse received during a given sweep are stored in a memory in accordance with the carrier frequency used for that pulse, this frequency changing in random fashion from one pulse to the next among a certain number of predetermined values.

Abstract: Acoustic signals are transmitted in a direction substantially perpendicular to the borehole axis, from different levels of at least three determined generatrices of the borehole wall. Reflected acoustic signals are received from the same direction at different levels of these generatrices. A train of signals is derived from each reflected acoustic signal and at least a group of significant elements of this signal train is selected. The groups of significant elements of the signals obtained for the different generatrices are correlated. The interval between signal trains corresponding to the maximum correlation corresponds to one and the same geological formation and is representative of the dip angle of this formation.

Abstract: Method and apparatus are provided for measuring acoustic signals having amplitudes of widely varying magnitude during one traversal of the borehole corresponding to indications of cement bonding along a casing as well as acoustic travel time through an increment of the formation. Variable attenuators are provided associated with acoustic receivers disposed within the logging sonde wherein attenuation may be automatically adjusted as a function of acoustic transmitter-receiver trigger pulses transmitted downhole, depending upon whether a cement bond or other log of acoustic signal information having a substantially different magnitude is desired.

Abstract: A carrier mounted seismic vibrator system that is primarily adapted for generation of high force, high frequency seismic energy into an earth medium. The apparatus includes first and second vibrators (12F and R) as supported by first and second lift systems (28F and R) disposed in tandem juxtaposition generally centrally in said vehicle (10), and the lift systems (28F and R) are designed to maintain equal hold-down force on the vibrator coupling baseplates (32F and R) without exceeding the weight of the carrier vehicle. The juxtaposed vibrators are then energized in synchronized relationship to propagate increased amounts of higher frequency seismic energy into an earth medium.

Abstract: A device for deciphering encoded information is disclosed which comprises logic elements which combine a key input to implement a predetermined set of boolean transformations thereby yielding a corresponding set of translation terms. The translation terms are subsequently combined with corresponding encoded information to yield deciphered information.

Abstract: A method for marine seismic exploration, comprising the steps of first discharging simultaneously a set number of seismic sources having a known volume V.sub.1, resulting in several seismic waves with substantially identical form which after reflection by a same series of reflection points are detected by hydrophones as a sum signal of the individual emitted source waves having a frequency range f.sub.1. The sum signal is subsequently filtered by means of a suitable filter operation having a frequency range f.sub.1, resulting in a sum signal having substantially equal phase of the individual components in the frequency range f.sub.1, next discharging simultaneously a set number of seismic sources having a known volume V.sub.2, different from volume V.sub.1, resulting in several seismic waves with substantially identical form which after reflection are detected by hydrophones as a sum signal of the individual emitted source waves having a frequency range f.sub.2.

Abstract: A movable inner cylindrical valve member is rigidly attached to the upper end of an air powered impact projectile designed for striking a target to produce an acoustic pulse. By seating upwardly within the bore of a fixed outer valve member against spaced apart tapered valve faces, the cylindrical wall of the inner valve member covers intermediate air pressure ports in the bore wall. In operation, the axial separating movement between the inner and outer valve members will instantly admit air pressure adjacent the closed end of the bore of the outer valve member in order to exert an accelerating force to drive the projectile. At the same time, the operation of this valve can be made essentially pressure independent by proper selection and placement of the annular seals which contact the valve faces.

Abstract: Pressure and velocity detectors produce outputs which are combined to substantially cancel ghost reflections. The pressure detector produces a positive output in response to upwardly travelling compressional waves and a negative output in response to downwardly travelling rarefaction waves. The velocity detector for this is a positive output in response to upwardly travelling compressional waves and a positive output in response to downwardly travelling rarefaction waves. These outputs are filtered so that the impulse response of the rarefaction waves cancels. The filtered outputs are combined to produce an output in which the ghost reflection is substantially suppressed.