Abstract: A method for obtaining far-field signatures of marine source arrays by the downward continuation of near-field data recorded along a short signature streamer of closely spaced hydrophones, located beneath the array. This method has several advantages over conventional far-field signature measurement techniques. The technique can be used in water depths as shallow as 50 meters, it does not require any precise knowledge of the array geometry or of the location of the recording sensors, and it may be used on a shot-by-shot basis to obtain signatures for use in a shot-by-shot signature deconvolution.

Abstract: Ribbon termination member has thread therein for connection to a coupling between sections of the towed array. First and second pins have cylindrically curved front surfaces upon which legs of the flexible ribbon tension member are engaged. The curved surfaces permit transfer of tension loads between the flexible tension ribbon and the pins. The second pin has an extended bearing surface 92 for preventing damage to the ribbon when loads are out-of-line.

Abstract: A device for supplying electric power to electronic apparatuses of a seismic streamer of great length, comprises an electric feeding assembly associated with each electronic apparatus and including three voltage transformers whose primary windings are respectively fed from a generator with a different phase of a three-phase current, and whose secondary windings are respectively connected to three rectifier bridges supplying the required DC voltage to the electronic apparatus.

Abstract: Transmitting information from a central receiver and recorder utilizes plural series-connected transmission modules, each connected to a respective data acquisition unit. The transmission modules are sequentially connected along plural transmission lines, at least two of which are outgoing data transmission lines for transmitting information from the central receiver and recorder to the acquisition units. At least two other lines are incoming data transmission units to the central receiver and recorder. Each transmission module has, for each outgoing line, respective line receivers, informaiton decoders, line transmitters and matrices of transmission line selectors controlled by individual information decoders, and a selector unit which ensures that a signal from a selected outgoing transmission line is transmitted to the next module on all outgoing transmission lines.

Abstract: A cable for towing air or water guns behind a seismic vessel is constructed with a reinforced air hose in the center region. The air hose (1) is a Kevlar fiber reinforced high pressure air hose with low air diffusion. Outside the hose, signal conductors are placed which are individually insulated with watertight coating and arranged substantially in a single layer of cylindrical elements (2) that are wound around the air hose (1). The interstices between the elements are filled with a water-repelling lubricant. Outside the layer of cylindrical elements (2) is a protective intermediate jacket (3) not intended primarily to have a water-sealing effect, and this is followed by tension-relieving elements (4) preferably disposed in two layers twisted in opposite directions around the intermediate jacket. An outer protective jacket (5) for the entire cable can be provided on the exterior. A cable constructed in this way provides a solution of the water-sealing problem.

Abstract: A method for maintaining a substantially constant tension on a towed seismic cable, wherein the instantaneous towing force and the instantaneous cable displacement relative to a fixed shipboard reference are continously measured and sampled. A microprocessor associated with a servo controlled capstan device, uses those measurements to pay out cable or to retrieve cable in response to an increase or decrease in the instantaneous towing force. The microprocessor also tries to minimize the average cable displacement.

Abstract: A method is disclosed for determining if sign-clipped variations of full-waveform traces can be used in subsequent cross-correlation processing without undue hardship. In accordance with one aspect, the present invention examines skewness of the amplitude spectrum of the full waveform. If the former significantly differs from conventional Gaussian distribution over the frequency range of interest, i.e., the amplitude spectrum is non-Gaussian, sign-clipped versions thereof can be used in subsequent cross-correlation processing without undue loss in processing accuracy. In another aspect, the present invention is used to edit a series of traces, one at a time, gathered by a large multichannel collection system. In this aspect, the different spectral noise estimates, including cross-correlation estimates generated from sign-clipped versions of the full-waveform traces, are advantageously used.

Abstract: A marine seismic cable comprising a plurality of universal sections, each section including a plurality of fundamental arrays, preferably positioned end-to-end. Each of the arrays are separately wired to a logic circuit in one of the connectors or cans between sections and wiring is provided for connections to each of the fundamental arrays in at least an adjoining section. The logic circuits are controlled by control signals to produce composite responses from a selected grouping of fundamental arrays and, preferably, also to produce weighted or tapered responses by connecting and emphasizing each of the fundamental responses in the desired weighted manner.

Abstract: Disclosed is a coupler for connecting together electrically and mechanically adjacent sections of a marine seismic streamer. The coupler includes a split cylindrical electrical connector housing assembly which establishes electrical interconnection between the adjacent streamer sections. The coupler includes an outer sleeve, which surrounds the electrical connector assembly and transmits tension forces across the coupler.

Abstract: Disclosed is test apparatus included in a cable transmission system having intermediate local data units spaced along a cable, one connection to the cable also being to a master or control station. At each data unit, there is an input differential amplifier with two input terminals for application of at least one local data signal. A test signal is applied to the data unit via a transmission connection from the master station to a first element of a voltage divider connected to one of the two input terminals of the differential amplifier. A switch at the data unit is connected for disconnecting the data connection from the other input terminal of the differential amplifier. A second switch at the data unit, provides a connection to a conductor leading to the master station for connecting earth ground to the data unit local circuit common.

Abstract: An armored umbilical and termination housing is disclosed for towing a sub-array of seismic air guns used in marine seismic surveying comprising a single air hose for supplying all the high pressure air to the individual air guns surrounded by all the electrical control cables needed to operate the air guns in the sub-array. Protective coatings are applied around the electrical control cables and stress members for carrying the laod of towing the sub-array are incorporated within the umbilical. A termination housing is provided on the end of the umbilical for terminating the single air hose and all the electrical control lines to common connectors so that individual electrical control lines and air hoses can run from the termination housing to each individual air gun in the sub-array. Air shut off valves are provided so that the high pressure air can be shut off to the individual air guns within the sub-array remotely from the survey vessel.

Abstract: A device is provided for interconnecting a series of data acquisition apparatuses. Each of the apparatuses collect signals and transmit them to a remote central receiving and recording system. In order to sequentially transmit the signals thereto on reception of an order from said central system, the apparatuses are subdivided into a plurality of groups having the same number m of apparatuses. The groups comprise cable sections of substantially equal length interconnecting the acquisition apparatuses in such a manner that the apparatuses of the same rank of each group are connected in parallel by the same transmission cable to the central system.

Abstract: A seismic data gathering system includes a seismic cable having a plurality of cable sections, each including a seismic detector and a pair of signal lines for carrying the seismic energy signals produced by the detector in response to seismic energy waves. A shunting resistance is located in each cable section with one end connected to one of the pair of signal lines and the other end connected through a mating connector to the other of the pair of signal lines in the next succeeding cable section so that a shunting resistance is added to the seismic cable each time a detector is added to the seismic cable. In this manner the electrical damping of each seismic detector remains constant when the seismic cable is coupled to a data acquisition unit regardless of the number of detectors included within the seismic cable.

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: A marine acoustical streamer cable having plural sections connected serially together with the streamer sections having connector couplers at opposite ends thereof adapted to be secured in mated relation without rotation to companion connector couplers of the same construction at the ends of adjacent streamer sections, each coupler comprising an axially elongated coupler body having a fully cylindrical anchoring head portion at one end and an axially elongated half cylindrical segment portion extending integrally from the anchoring head portion. The half cylindrical segment portions of the companion couplers when secured in mating relation collectively form a cylinder of the diameter of the streamer jacket.

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 hydrophone cable having a series of hydrophones (7) at spaced intervals along the cable and having strength members (1) and transmission line conductors (3) extending along the cable in which a braided construction (2, 3, 4 and 5) is used which can be loosened to insert the hydrophones (7) into cable, voids in the cable being filled with a buoyant gel and the assembly covered by an outer plastic sheet (6).

Abstract: This invention is an electrical connector held together by flexible magnetic substrates which also form the support for the connector's electrical contacts. The connector has many uses but is especially suitable for the connection between sections of hydrophone streamer cables.

Abstract: A method is disclosed for editing seismic traces gathered by large multichannel collection systems using a pattern analysis of the noise spectrum of each trace. Analysis is limited to only a small time window, say the last second of the trace. In that way a minimum number of quantitative variables and mathematical manipulations are required to carry out the invention. On-site as well as off-site, processing of the traces in accordance with the method of the present invention, is contemplated.

Abstract: A marine seismic streamer cable having both pressure responsive and acceleration responsive transducers disposed therein. The accelerometer responds to acceleration along one axis regardless of its orientation about the other axis. The accelerometer is mounted in the streamer cable and responds to accelerations produced by a seismic source but is insulated from the noise and motion produced as the streamer cable is towed through the water.

Abstract: A system for detecting and identifying acoustic sound sources using a pluity of identical data acquisition modules spaced at preselected intervals along a line array. Two small diameter coaxial cables provide intermodular connections for power, timing control and sequential data transmission to a remote receiver. A control clock waveform leading edge simultaneously triggers sampling and holding of sensor data at each module of the array while the waveform trailing edge is delayed for a preselected interval at each module to provide squential data output.

Abstract: A marine seismic cable is sectionalized with the individual cable sections being joined by articulated connector assemblies which permit relative bending movement between such individual cable sections.

Abstract: A device for transmitting seismic data informations from acquisition devices of a seismic streamer to a central recorder an a ship, comprises at least two outward, and at least tow inward transmission lines made up of line sections interconnected by interconnection systems including means for the reconfiguration of signals, means for detecting order signals receives at said interconnection systems and switching means, and controlled by the detection means to connect different line sections, previously tested, and to by-pass faulty sections so as to form one outward and one inward continuous transmission line in good operating condition.

Abstract: An apparatus for rejection of turbulence induced flow noise for towed hydhone arrays. Two adjacent hydrophones in the array are spaced less than flow noise coherence distance apart forming a flow noise cancelling module. The inverted acoustic/flow noise signal from the lead hydrophone of the pair is split, one side passing to the final stage of signal processing while the other side, filtered, amplified and inverted, is added to the combined signal from the lag hydrophone which has been filtered and amplified. The acoustic signal components cancel leaving only the lead hydrophone flow noise plus the lag hydrophone flow noise which has been shifted by a factor dependent upon tow vessel speed and hydrophone spacing.

Abstract: Marine seismic data is gathered by a single vessel beyond the range of a conventional towed seismic sensor cable through the use of expendable sensors and hard wire transmission cables. The vessel tows a submerged platform adapted to carry several inexpensive seismic sensors and very small diameter multiconductor cables which are controllably released from the platform by appropriate equipment on the towing vessel. Signals generated by each sensor are transmitted back to the towed, submerged platform through the small diameter cable connected to each sensor and are transmitted by other means from the platform to the towing vessel for retransmission, recording and/or display. Each sensor transmits a signal back to the platform until its small diameter cable is completely deployed at which time the cable breaks and is abandoned together with the sensor.

Abstract: A seismic streamer cable, composed of a plurality of cable sections includes a common transmission line and an internally mounted inductive element in each section. The inductive elements are coupled in parallel to the common transmission line. A plurality of depth transducers, each associated with an inductive pickup, are secured externally to the streamer cable at desired intervals, adjacent to one of the internal inductive elements. A control signal is periodically transmitted through the transmission line and is received, by inductive coupling, at each transducer after a selected delay. In response to the delayed control signal, the transducers inductively launch a depth-proportional signal into the transmission line for reception by a depth readout device.

Abstract: A hermaphroditic submarine cable connector link for a multisection seismic marine streamer cable includes identical end fittings mounted at each end of a pair of adjacent cable sections. Identical connector plates are coupled to electrical conductors at each end of the sections. The connector plates from the pair of adjacent cable sections are mated and then linked to the end fittings. A barrel is slipped over the end fittings and around the mated connector plates. The end fittings are locked by the barrel in spaced-apart relationship, employing a ball-and-detent locking arrangement.

Abstract: A hydrophone mounting in a cavity of the hydrophone cable and a method of mounting the hydrophone. The cavity which is provided in the hydrophone cable may be constructed so that it is free-flooding, that is, the construction allows the liquid in which the hydrophone cable is submerged to completely surround the hydrophone. The cavity serves to insulate the hydrophone from movements and perturbations to the cable so that the hydrophone response is not distorted by these sources of noise.

Abstract: A bulkhead for a marine seismic streamer section comprises a generally cylindrical body of rigid tough plastics material such as polycarbonate polymer, having an axial hole therethrough, through which passes the electric conductor bundle of the streamer section, and peripheral radial slots with hemicylindric bottoms receiving the tension lines of the streamer section. The bulkhead has an annular circumferential groove which is radially as deep as the axes of the bottoms of the slots and in which is disposed a belt of phosphor bronze, or stainless steel, or other strong corrosion resistant metal. The belt holds the tension lines in the slots and holds together the bulkhead, which is made of two sectors. One sector is greater than 180 degrees in extent and the other is less than 180 degrees in extent, e.g. the one sector may extend 240 degrees and the other 120 degrees.

Abstract: A linear acoustic array for use in oceanographic work in either a towed or a vertically suspended configuration utilizes a flexible cable in which strands are woven or braided into a tube, the strands of which can be separated sufficiently to insert a hydrophone and multiplexer assembly at each of a plurality of specified locations therealong. Each hydrophone and multiplexer assembly is adapted to be readily connected into or removed from a two wire system.

Abstract: A condition responsive line array cable having pairs of conductor contain, hollow braided strands plaited into a hollow braid in which transducer mounts are enmeshed and gripped. The mounts comprise a rigid plastic tubular housing in which a rubber jacketed transducer is resiliently suspended by elastomeric projections. Resiliently flexible, hollow, tapered, rubber fairings extend from each end of the housing and are slit to admit wires pulled from a cable strand. The fairings are long relative to the housing diameter and are retained assembled with the housing by cooperating ribs and grooves.

Abstract: A marine seismic streamer-cable section includes a plastic tubular jacket reinforced by tough, braided-fiber tapes embedded in the jacket wall. A termination fixture is fastened to each end of the cable section. The termination fixture includes a bulkhead, an untapered end of which fits snugly into the plastic jacket. The other end of the bulkhead is tapered and protrudes from the end of the jacket. Short lengths of the reinforcing tapes are exposed by stripping away some of the jacket wall. A cylindrical wedge grips the exposed tapes between the inner wall of the wedge and the tapered portion of the bulkhead. The tapes are doubled back over the outside of the wedge and are bound to the jacket and to the untapered end of the bulkhead by bands.