Abstract:
A drag antenna for a sonar system for detecting and/or locating sources of sound in water includes at least two acoustically sensitive lines positioned side-by-side and laterally spaced apart during a trailing operation. The lines are secured to each other at the leading ends and at the trailing ends by respective connecting element in order to lower the production costs for the drag antenna and to achieve a sufficiently constant lateral spacing between the acoustically sensitive lines.
Abstract:
Methods for making linear acoustic antennas designed to be towed behind a boat, wherein open-cell foam cylinders (101) are opened lengthwise (103) and electroacoustic receiver modules (101) are placed therein. After closing the cylinders, they are arranged end-to-end and a series of layers of porous nonwoven material, reinforcing nets (111) and wiring cables are wound around the cylinder surfaces. Finally, a protective sheath is extruded onto the cylinders and their end portions are joined together. The manufacture of such antennas may thus be mechanised using cable technologies.
Abstract:
A system for transmitting signals between a plurality of towed sensor streamers and a seismic vessel, the system comprising: a plurality of seismic streamers, wherein each streamer of the plurality of seismic streamers comprises: a leading end, a trailing end, a plurality of sensors located therein and a transmitter of seismic signals received by the plurality of sensors to a terminal located in the leading end of the streamer; at least one spreader located between the leading ends of two streamers of the plurality of seismic streamers, the spreader comprising: connectors for connection to the terminals of the streamers, a spreader terminal, and a spreader transmitter of signals between the connectors and the spreader terminal; a lead-in having a lead-in connector for connecting to the spreader terminal and a transmitter of signals between the lead-in connector and the seismic vessel. A seismic streamer system comprising: a lead-in, and multiple streamers; wherein the multiple streamers are signal-connected to the lead-in, and wherein at least two of the streamers are signal-connected by at least one spreader. A process comprising: transmitting signals between at least two streamers of a plurality of streamers; transmitting signals between a first lead-in and the plurality of streamers; and transmitting signals between the first lead-in and the vessel. A process comprising: transmitting signals between each streamer of the plurality of streamers and a spreader bus; transmitting signals between the spreader bus and at least one lead-in, wherein the number of streamers of the plurality of streamers is greater than the number of lead-ins; and transmitting signals through at least one lead-in to the vessel.
Abstract:
A telemetry system for receiving data from large arrays of sensors, in which the sensors are located in an unprotected environment, is implemented using fiber optic components. Laser sources, located in a protected environment, transmit light through the boundary separating the protected environment from the unprotected one. The light is then split into a number of beams and fed to electro-optical modulators, where it is modulated in response to electrical signals received from the sensors. The modulated light signals are then wavelength-division multiplexed and transmitted back through the environment boundary, where they are amplified, demultiplexed and converted to electrical signals. Multiplexing reduces the number of boundary penetrations, and the use of highly stable electro-optical modulators eliminates the need for signal conditioning electronics at each sensor. This optical approach is particularly beneficial in an underwater application, such as a submarine receiving data from a large array of acoustic sensors, where it is desired that hull penetrations be minimized and the underwater components be highly reliable and stable.
Abstract:
A method of computing the location of air guns and hydrophones within a seismic spread utilizes a navigation network having a plurality of stations. The network provides a plurality of navigation observations. A number of the observations consist of magnetic bearings which are used to derive the hydrophone locations. The method includes the steps of: a. obtaining a set of observations from the network, each observation being obtained by using navigation devices whose origin system moves independent of the navigation reference point; and b. forming a design matrix wherein the magnetic bearings are modeled based on the equation: ##EQU1##
Abstract:
A piezoelectric transducer hydrophone comprised of a plurality of longitudinal segments is described. The longitudinal segments allow the transducers to be readily attached to cables to form hydrophone arrays. Should a particular transducer become faulty following testing or use of the hydrophone array, the longitudinal segments allow the transducer to be accessed without the need to remove all of the acoustic transducers on the cable between the end of the cable and the one that is faulty.
Abstract:
A hydrophone retrieval system is described, which includes: a) a case having an interior chamber adapted to house an anchor fixture within the chamber, the case having at least one sealable opening therein adapted to accept therethrough an electric leader cable and a retrieval cable, in a water-tight manner; b) an anchor fixture disposed within the chamber, where the anchor fixture includes an anchor member portion, wherein a first end of the electric leader cable passes through a first aperture formed in the anchor member portion; c) a first end of the retrieval cable passing through a second aperture formed in the anchor member portion; d) a retrieval cable termination element attached to the first end of the retrieval cable within an interior portion of the fixture, wherein the diameter of the retrieval cable termination element is greater than the diameter of the second aperture; and e) a base member portion, wherein the anchor member and base member portions are rigidly separated from each other at a fixed distance.
Abstract:
A hydrophone carrier for mounting a hydrophone in a streamer. The carrier consists of a pair of end plates spaced apart axially by at least one rigid or semi-rigid central member, thus defining a zone between the end plates which is isolated from structural stress and strain induced by streamer borne vibration, yet admitting externally induced pressure fluctuations such as result from acoustic waves present in the environment. The at least one rigid or semi-rigid central member may be arranged in a variety of configurations to allow the at least one streamer strength members and wires to pass through the carrier.
Abstract:
An interface module assembly for disposition between a marine tow cable andn array of acoustic receivers includes a plurality of bodies interconnected in series by flexible tethers. A proximal one of the bodies is adapted for connection to the tow cable and a distal one of the bodies is adapted for connection to the array. An external coaxial cable extends between each two of the bodies and is in communication with other external coaxial cables by way of internal coaxial cables within the bodies.
Abstract:
Sonar array cable is typically provided in lengths comprising hydrophone ays and associated electronics and transmitter can components, each cable length or section having one of each of these components housed therein. These sections are relatively stiff and unbendable, requiring that they be connected with relatively bendable intermediate segments. These intermediate segments are susceptible to excessive bending that can lead to failure of the wiring provided therebetween. The wiring in these intermediate bendable segments is provided in the form of a coil, each of which coils is rigidly connected to the transmitter and electronics in one cable section, and the other end of the coil being connected electrically to the wiring associated with the hydrophone array in an adjacent cable section. Each coil is encased in relatively soft urethane material, preferably in one portion of the bendable segment, another portion of the bendable segment having the coil connected at its other end to a relatively stiff urethane material associated with the transmitter can and associated electronics.