Abstract: Provided is a permanent seafloor seismic recording system utilizing Micro Electro-Mechanical Systems seismic sensors. The system includes and expandable backbone, multiple hubs and sensor lines. The sensor lines include multiple sensor modules that include 3-C accelerometers and a hydrophone for providing a 4-C sensor module output signal.

Abstract: A method and apparatus is disclosed for performing a seismic survey below the surface of a body of water and on the seabed. In one embodiment, a plurality of seismic data receivers are removably loaded in a carrier located above the surface of the water and the carrier is lowered into the water and placed at a depth relatively close to the seabed. Each of the receivers has a memory for recording the vibrations of the seabed and has a switch for activating the memory. A ROV is used to unload the receivers from the carrier and to deposit each receiver on the seabed and along a survey line. In one embodiment, the receivers comprise a frame, a pressure vessel for housing the memory and remotely activated controls, and a geophone that is separately planted into the seabed at a relatively short distance from the frame.

Abstract: A staggered vertical marine seismic source contains upper and lower arrays (10, 11) of emitters of seismic energy (S11, S12; S21, S22). The upper array (10) is horizontally displaced relative to the lower array (11). The source is used in a marine seismic surveying arrangement that has means for moving the source and at least one seismic receiver. In use, the source is moved through the water in a direction parallel to the direction in which the two arrays are displaced. The arrays (10, 11) are fired sequentially, and the time delay between the firing of the first-fired array and firing of the second-fired array is chosen such that each seismic emitter in one array is fired at the same x- and y-co-ordinates as the corresponding emitter in the other array. The seismic wavefields generated by firing the two arrays are thus generated at the same x- and y-co-ordinates, but at different depths.

Abstract: A method and device for seismic exploration of a subsea geologic formation by pickups set on the sea bottom and intermittently connectable to active data acquisition stations (11) brought nearby. Permanent passive reception stations (1) comprising a heavy pedestal provided with housings for seismic pickups (geophones (6), hydrophone (7) which receive acoustic or seismic signals from the underlying formation are arranged at the bottom of the water body. When collection sessions for the signals received by the pickups are scheduled, mobile active acquisition stations (11) connected to permanent passive reception stations (1) are positioned at the bottom of the water body. The signals picked up are then recorded, for the time required to carry out at least one session of acquisition and recording of the acoustic or seismic signals received by the passive stations in response to the emission of seismic waves by one or more seismic sources.

Abstract: A method for making a time-lapse seismic survey in a marine environment, the method designed to eliminate multiple surface reflections and changes in sea state and conditions. Seismic sources and receivers are positioned at predetermined conditions for a first set of data in which at least two sets of seismic signals are recorded at each receiver, proximate in time, such that there are insignificant changes in the subsurface formation. At a later point in time the seismic source(s) and receiver(s) are positioned at the same place when the first seismic data set was generated. A seismic source emits a sound wave and the seismic receiver receives what will be called a “monitor signal” and the two-way water travel time is again determined. A model is then developed for the first and second seismic data sets in that includes the subsurface signal, changes in the subsurface signal and the effect of multiple reflections.

Abstract: An inner race for a streamer cable connector. The inner race includes first and second curved sections with a screwless fastener for clamping the two sections together about the streamer cable. The two curved sections may be hinged at first ends so that the inner race can be opened like a clam shell for placement about the cable. Cooperating teeth on the second ends of the inner race provide a screwless fastener for the two halves, with the teeth cooperatively arranged to ratchet by each other as the curved sections are closed around the cable.

Abstract: A standalone digital data recorder of site background noise, by seismological transducer, providing at least data H and V in the form of analog signals, includes an acquisition and analog/digital conversion card, which includes at least two analog channels and a digital output, each analog channel including an input, a programmable gain analog signal amplifier and a filter, an analog multiplexer being provided between the filters and an analog/digital converter; a user interface; a removable storage device for storing data, a drive unit for an operating program, which includes a unit for enabling recording conditions, recording and warning of the end of the recording.

Abstract: A multi-gimbal configured transition protectively interfaces a mooring and communication cable to a communication ocean buoy. The transition interface contains a segmented, flexible sheath formed of a plurality of pivotally interconnected gimbal rings having mutually adjacent interior apertures through which one or more communication link members pass. Successive gimbal rings are orthogonally pivotally interconnected with one another so as to make the flexible sheath flexible in three dimensions. Upper ends of one or more communication link members are connectable with a communication cable connection fixture of the buoy. Lower ends of the communication link members are connectable to communication cable terminal connectors of a terminal end of the mooring cable.

Abstract: The present invention provides a method for analyzing traces collected along a plurality of adjacent sail lines in a marine seismic survey area. The method comprises selecting a plurality of trace groups, at least one trace in each group sharing a common midpoint with at least one trace from another group, determining an initial zero-offset travel time for each trace in the trace groups, and generating a plurality of updated zero-offset travel times and a plurality of time corrections for the trace groups using a pre-selected function of the initial zero-offset travel times.

Abstract: A method and apparatus for slowing the rise of air bubbles for large-scale applications such as bubble curtains for suppressing noise in marine seismic surveys. Bubble rise time is increased by a chemical additive which either retards bubble coalescence or produces smaller bubbles through wetting agent properties, or a combination of both.

Abstract: A method and apparatus for controlling seismic sources. The method and apparatus enable firing of a seismic sources at either a precise time or a precise position of the seismic source. Controlling the firing of the seismic source facilitates more accurate seismic data and a more consistent seismic source signature.

Abstract: Seismic detection apparatus comprising seismic detection means capable of detecting a plurality of seismic components over a defined tetrahedral volume is provided. The seismic detection means comprises four three-component geophones. Seismic data acquired by the geophones is processed to separate P-wave components from S-wave components. The geophones are spaced apart by distances smaller than the wavelength of the detected seismic components. The apparatus may be used on surface or in a marine environment or transition zone. A method of processing seismic data is also provided comprising acquiring seismic data relating to a wavefield over a selected volume of acquisition, and measuring the curl and divergence of the wavefield from the seismic data, to thereby identify seismic components within the seismic data. Additionally, an apparatus and method for hydrocarbon exploration is disclosed for using three or more seismic receivers placed in a plane and spaced closely to each other.

Abstract: Provided is a permanent seafloor seismic recording system utilizing Micro Electro-Mechanical Systems seismic sensors. The system includes and expandable backbone, multiple hubs and sensor lines. The sensor lines include multiple sensor modules that include 3-C accelerometers and a hydrophone for providing a 4-C sensor module output signal.

Abstract: A method is disclosed for processing seismic data from concurrently recorded co-located pressure sensors and geophones. The seismic data are processed by first determining an upgoing wavefield and a downgoing wavefield in the seismic data. Adaptive subtraction is then applied to at least one of the upgoing wavefield and the downgoing wavefield to remove the noise from the signal. In alternative embodiments, the upgoing wavefield can be used as a noise model for the downgoing wavefield or the downgoing wavefield can be used as a noise model for the upgoing wavefield.

Abstract: In one embodiment the invention comprises a method for receiving an acoustic wavefield beneath the surface of the water in which at least a portion of an acoustic wavefield is received at a first position, at least a portion of an acoustic wavefield is received at a second position, and at least a portion of an acoustic wavefield is received at a third position. The first position, the second position and the third position are triangularly positioned relative to one another. The first position is not directly above or below the second position or the third position, and the second position is not directly above or below the third position.

Abstract: A method of determining seismic properties of a layer of the seabed, in particular a surface or near-surface layer (5), comprises directing seismic energy propagating in a first mode at a boundary face of the layer so as to cause partial mode conversion of the seismic energy at the boundary face. For example partial mode conversion may occur when seismic energy propagates upwards through the interface between a surface or near-surface layer (5) and the basement (6), owing to the difference in seismic properties between the surface or near-surface layer (5) and the basement (6). In the invention, the two modes of seismic energy—that is the initial mode and the mode generated by mode conversions at the interface—are received at a receiver. The difference in travel time of the two modes between the interface and the receiver is determined from the seismic data acquired by the receiver.

Abstract: A cable for towing marine devices is disclosed. The cable includes a strength member and at least one conduit associated with the strength member. The conduit has apertures therein at selected locations along the conduit. The apertures are adapted to conduct gas from a source into water in which the cable is disposed. Also disclosed is a method for improving the flow of a cable through water. The method includes releasing a gaseous bubble stream proximate an outer surface of said cable while the water is moving relative to the cable.

Abstract: In one embodiment the invention comprises a particle velocity sensor that includes a housing with a geophone mounted in the housing. A fluid that substantially surrounds the geophone is included within the housing. The particle velocity sensor has an acoustic impedance within the range of about 750,000 Newton seconds per cubic meter (Ns/m3) to about 3,000,000 Newton seconds per cubic meter (Ns/m3). In another embodiment the invention comprises method of geophysical exploration in which a seismic signal is generated in a body of water and detected with a plurality of co-located particle velocity sensors and pressure gradient sensors positioned within a seismic cable. The output signal of either or both of the particle velocity sensors or the pressure gradient sensors is modified to substantially equalize the output signals from the particle velocity sensors and the pressure gradient sensors. The output signals from particle velocity sensors and pressure gradient sensors are then combined.

Abstract: A preferred seismic survey system includes a cable having a sensor unit. The sensor unit includes sensors for detecting acoustical energy (e.g., shear and/or pressure waves) and is disposed in a decoupling device that substantially acoustically uncouples the sensor unit from the cable. One preferred decoupling device includes relatively flexible tension members that isolate the sensor unit from acoustical-energy related movement of the cable. A fastening member, which is optionally formed of vibration absorbing material, affixes the sensor unit to the flexible member. Optionally, a spacer adjusts the resonant frequency of the tension member and a resilient tube encloses the decoupling device. One preferred seismic survey method includes connecting the sensor unit to a cable with a decoupling device that substantially acoustically uncouples the sensor unit from the cable; and positioning a sensor unit on a seabed such that the sensor unit is acoustically coupled to the seabed.

Abstract: A method of processing seismic data, for example surface seismic data such as multi-component OBC (Ocean Bottom Cable) seismic data, comprises using vertical seismic profile (VSP) seismic data to determine a model of the relationship between depth within the earth and the velocity of seismic energy. In one embodiment, an model of the relationship between depth and velocity of seismic energy for P-waves is calibrated using VSP seismic data. Then, a model of the relationship between depth and velocity of seismic energy for S-waves is calibrated using VSP seismic data. Initially the models are calibrated for the vertical velocity of P-waves and S-waves, using zero-offset or low-offset VSP data. The models may then undergo further calibration steps, such as calibration for VTI anisotropy and anelastic attenuation. Once calibration is complete, the models are used to process surface seismic data.

Abstract: A method and apparatus is disclosed for performing a seismic survey below the surface of a body of water and on the seabed. In one embodiment, a plurality of seismic data receivers are removably loaded in a carrier located above the surface of the water and the carrier is lowered into the water and placed at a depth relatively close to the seabed. Each of the receivers has a memory for recording the vibrations of the seabed and has a switch for activating the memory. A ROV is used to unload the receivers from the carrier and to deposit each receiver on the seabed and along a survey line. In one embodiment, the receivers comprise a frame, a pressure vessel for housing the memory and remotely activated controls, and a geophone that is separately planted into the seabed at a relatively short distance from the frame.

Abstract: A method for making a time-lapse seismic survey in a marine environment, the method designed to eliminate multiple surface reflections and changes in sea state and conditions. Seismic sources and receivers are positioned at predetermined conditions for a first set of data in which at least two sets of seismic signals are recorded at each receiver, proximate in time, such that there are insignificant changes in the subsurface formation. At a later point in time the seismic source(s) and receiver(s) are positioned at the same place when the first seismic data set was generated. A seismic source emits a sound wave and the seismic receiver receives what will be called a “monitor signal” and the two-way water travel time is again determined. A model is then developed for the first and second seismic data sets in that includes the subsurface signal, changes in the subsurface signal and the effect of multiple reflections.

Abstract: A method and device for seismic exploration of an underwater subsurface zone using seismic receivers coupled with the bottom of the water mass. Acquisition units (1) comprising a spire (2) where seismic receivers (4) are arranged, a measuring compartment (5) for acquisition and storage of the data received by the receivers, as well as removable and selective floating devices (7) are used. The acquisition units (1) are launched and, under the effect of gravity, they attach to the bottom and couple the receivers with the underlying formations. The respective positions thereof are first detected, seismic acquisition operations are carried out using an underwater source so as to collect seismic data on the formation, then the floating devices (7) are actuated so as to bring all or part of acquisition units (1) back up to the surface or a data collection device (vehicle or passive collection unit) is lowered to the neighbourhood of the various units.

Abstract: System designed for acquisition of seismic data by means of acquisition stations set on the bottom of a water mass.

Abstract: An ultrasonic signal processor operated at multiple frequencies comprises a nonpiezoelectric plate, an input IDT, an output IDT, a first piezoelectric substrate, and a second piezoelectric substrate. The input IDT with a dispersive type of electrode-finger pattern has an overlap length L and interdigital periodicities Pl (i=1, 2, . . . , m). The output IDT with a dispersive-slant type of electrode-finger pattern has the electrode-finger direction slanting to that of the input IDT by an angle &thgr;, and also has an overlap length Lp along the electrode-finger direction of the output IDT and interdigital periodicities Ql (i=1, 2, . . . , m) along the orthogonal direction to the electrode-finger direction of the output IDT. The input- and output IDTs, and the first- and second piezoelectric substrates form a transducer-unit. If one of input electric signals Si (i=1, 2, . . . , m) with frequencies fl (i=1, 2, . . .

Abstract: A seismic cable (1) including a plurality of electrical/optical elements (5) which are arranged to be interconnected with a number of seismic sensor devices (24) arranged at intervals along the cable and installed in a housing (15) integrated in the cable (1). The sensor housing (15) is centrally arranged in the cable (1) and interconnected with a central strength element (2). The electrical/optical elements (5) are arranged over and around the central element (2) and over the housing (15).

Abstract: Seismic wave reception device comprising a hydrophone and/or a geophone and method for coupling it (or them) with a solid medium such as the subsoil.

Abstract: A multi component seismic sensor which utilises orthogonal accelerometers to determine its orientation. The accelerometers may be used to measure seismic signals directly, or the system may include geophones for this purpose.

Abstract: A deflector for towing behind a vessel, especially for use in relation to seismic surveys, being adapted to pull equipment to a transversal position in relation to the moving direction of the vessel, comprising at least one connection point for connecting, through wires or similar, to the vessel and the equipment to be towed. Two or more deflector wings are adapted to provide the deflector with a lifting force transversally in relation to the moving direction of the vessel, at least one of the wings being provided with a rotating cylinder positioned in front of the wing adapted to increase the lift of the deflector wing, and a drive unit for driving the rotating cylinder with corresponding devices for power supply.

Abstract: A variable length data packet in a seismic system includes a fixed-length data portion and a variable-length data portion, the amount of data in the variable-length portion depending on the number of active channels. The data packet identifies the number channels which are in operation in the system, which may be the same or fewer than the number of installed channels. This signals the central recorder as to the length of the block of data in the data packet which includes seismic data. This feature permits the scaling of the system to accommodate varying numbers of channels, without reconfiguring the system. In another aspect, a method of sending data in a data system having a plurality of installed channels includes the steps of determining the number of active channels; assembling a packet of data comprising a fixed-length field and a variable-length field, the number of data bytes in the variable-length field being a function of the number of active channels; and sending the packet of data.

Abstract: A system and method for periodically providing information about subsurface formations in a marine environment using a non-towed seismic signal source (3) and a static array of seismic signal receivers (4) is disclosed. The seismic signal source (3) comprises a support frame (10) and a line (7) attaching the support frame to a stationary platform (2), wherein the line (7) restrains the support frame (10) in a position that is static in relation to the formation (8). The seismic signal source (3) includes eight air guns (12) attached to the support frame (10) such that the air guns (12) are discharged to provide a tapered, heavy centered, point source seismic signal at a specific location relative to the formation (8) that is reflected to the static array of seismic signal receivers (4) such that changes in the formation characteristics may be observed over time.

Abstract: A marine seismic source for generating acoustic source energy. A housing has a continuous exterior perimeter which is moveable to displace water. Movement of the housing can be accomplished by providing alternating convex and concave exterior surfaces connected with inflection points. The composite shape provides movement inwardly or outwardly, and can be moved with different types of actuators. Piezoelectric elements can be activated to move the housing surfaces and to change the internal housing volume. The resulting pressure pulse provides acoustic source energy useful for the evaluation of subterranean geologic formations and for other purposes.

Abstract: A seismic vibrator system for imparting compressional and shear wave vibrations into the earth has an earth contacting base with a vertical post. A tubular hub is slidably received on the post in a piston/cylinder relationship. Spaced apart horizontal top and bottom plates are secured to the hub. A mass is slidably supported between the plates. Pistons interconnect the hub and the mass. Hydraulic energy is used to reciprocate the mass vertically on the post and horizontally between the plates.

Abstract: A system and method are disclosed for reducing flow-induced noise in an urwater towed system. The system includes at least one neutrally buoyant towed array, a tow platform for defining a towed direction of the at least one towed array, a neutrally buoyant tow cable connected to the at least one towed array and the tow platform, and a deploy and retrieve apparatus for deploying and retrieving the tow cable. The deploy and retrieve apparatus is connected to both the tow cable and the tow platform. Deployment of the tow cable from the deploy and retrieve apparatus correspondingly deploys the at least one towed array, and retrieval of the tow cable with the deploy and retrieve apparatus correspondingly retrieves the at least one towed array. The speed of deployment of the tow cable can be varied to decrease the velocity of the towed array relative to the surrounding water thus reducing flow-induced noise.

Abstract: Methods and apparatus are described for seismic signal acquisition utilizing an odd number of vibratory sources arranged in line and positioning the sources for one sweep cycle at positions occupied by other sources during the previous sweep cycle. The method has advantages in particular for marine seismic acquisitions.

Abstract: Ocean bottom seismic cables are subject to rolling motions due to seismic wave fields and current action which cause poor receiver ground-coupling and signal distortion, particularly along the cross-line and vertical axes. Two multi-axial receivers are mounted on opposite sides of the cable in a single cluster. When the cable rolls, the axial response of one receiver of the cluster cancels the axial response of the other receiver of that cluster.

Abstract: The objective of this invention is to provide a method for estimating, in the frequency domain, deconvolution operators for removing spurious resonant coupling responses from the cross-line and the vertical seismic signal components in OBC surveys. The purpose is to balance the spectral response of the respective signal component in amplitude and phase in a manner consistent with the field geometry.

Abstract: A system for supporting marine seismic equipment such as sensors and positioning equipment deployed behind a marine seismic vessel. The vessel tows a lattice like web instead of individual streamer cables to carry hydrophones, and can deploy a geophone supporting web from the vessel to rest on the sea floor. The web can be formed with individual conductor members for providing structural support and signal transmission capabilities. The lattice construction of the web provides for redundant signal transmission capabilities in the event of individual conductor failure. The web provides this enhanced signal transmission capability while permitting high density sensor placement.

Abstract: A method for determining ocean bottom reflectivities from dual sensor seismic data, whereby a first time windowed pressure signal and a first windowed velocity signal are summed to generate a first summed signal, and a second time windowed pressure signal and a second time windowed velocity signal are summed to generate a second summed signal. The first summed signal and the second summed signal are transformed from the time domain to the frequency domain to generate a first transformed sum and a second transformed sum, respectively. A value R for said ocean bottom reflectivity is selected and used to calculate an inverse Backus filter (1+Rz).sup.2, where Z is the Z-transform of the two-way travel time delay filter. The first transformed sum and the second transformed sum are multiplied by the inverse Backus filter to generate a first filtered sum and a second filtered sum, respectively. A cross spectrum is calculated from the first filtered sum and the second filtered sum to generate a trial cross spectrum.

Abstract: An apparatus and method for modifying the seismic source signal from air guns towed behind a marine seismic vessel. At least one conduit is towed behind the vessel to release bubbles into the water. The bubbles are formed with compressed air released from apertures in the conduit. The size and distribution of the bubbles is controlled by varying the aperture size, the compressed air pressure, the aperture position and orientation on the conduit, and the vessel speed. The bubbles attenuate side directional frequencies to reduce the outwardly directed seismic source signal and to improve the signal to noise ratio at the receivers. By controlling the bubble size and distribution, attenuation of selected frequencies can be controlled.

Abstract: An improved bottom cable for a seismic marine data acquisition system 10. The bottom cable 30 includes a cable section 30b having a bus 48. The cable, along with the cable section and bus, are used to electrically connect a master control unit 40 to first and second modules 32b and 32c, respectively. The bus 48 includes first and second switches 48b and 48c, respectively, located near opposite ends of the bus. In this way, if a leak R1 occurs in the bus, the first and second switches can be opened, thereby electrically isolating the bus and stopping the leak.

Abstract: An improved acoustic source array system is provided by the invention to generate acoustic signals underwater. The system has an array of acoustic signal sources, such as air guns, towable while underwater behind a surface vessel. The array includes a plurality of these sources, and spreader bar assemblies including these sources. The sources are attached by these assemblies at predetermined separation distances in the array. The spreader bar assemblies provide manifolds for storing and regulating energy, such as compressed air, to operate the sources. The array is connected to the vessel by an umbilical. The sources are controlled by a shipboard controller for firing the sources to provide acoustic signals underwater at selected times. The array may be towed from the ship with the flat side of the array assuming an angle of approximately 45.degree. or less with respect to a vertical axis. The flat side of the array includes a horizontal axis that is normal to the direction of tow.

Abstract: An acoustic classification system in which echoes from sediment-sediment or water-sediment interfaces are compared to model waveforms predicted by Biot's equations for a given set of acoustic material parameters. The selection of parameters are varied until a match occurs, indicating the correct parameters of the reflecting sediments. Preferably, the variation of selected test parameters is conducted by formal search algorithms, such as simulated annealing or genetic algorithms, to increase computational efficiency.

Abstract: A method and system are provided for use in marine seismic data surveys to increase fold and offset without increasing streamer length or drag on the streamer boat. Generally the method comprises the use of a second source boat positioned in the steamer path and firing the second source at a time before the recording of information from the first source is finished. By positioning the second source about one streamer length in front of the closest hydrophone, the fold is increased by two for the same length streamer.

Abstract: A marine seismic surveying method recording with a first sensor a first signal indicative of pressure and with a second sensor a second signal indicative of motion, calculating a coupling mechanism filter for the second signal substantially correcting for the imperfect coupling of the second sensor, and applying a filter based on the coupling mechanism filter to at least one of the signals.

Abstract: A method for acquiring seismic data, the method comprising: deploying a first ocean-bottom cable from a first cable-handling/recording vessel; generating first source waves with a source vessel for data acquisition; recording data from the first ocean-bottom cable with the first cable-handling/recording vessel during the generating first source waves; preparing a second ocean-bottom cable with a second cable-handling/recording vessel during the generating first source waves; generating second source waves with the source vessel for data acquisition; and recording data from the second ocean-bottom cable with the second cable-handling/recording vessel during the generating second source waves.

Abstract: Disclosed is a protocol for transmitting data in a towed hydrophone streamer, including a transmission method and a data frame. The method comprises the steps of (1) receiving a portion of the data frame into a data transmission circuit within a particular module of the streamer, the portion of the data frame representing telemetry data derived from an adjacent module, the transmission circuit transmitting the portion of the data frame to a desired destination, (2) receiving an end-of-data signal into the transmission circuit, the end-of-data signal commanding the transmission circuit to add telemetry data derived from the particular module to the portion of the data frame and (3) adding the data derived from the particular module to the portion of the data frame, the data frame thereby transmitted to the destination and including the data derived from the particular module, the telemetry data ordered within the frame as a function of an order of modules within the streamer.

Abstract: For marine seismic surveying using an array of airguns towed behind a survey ship, wherein a common high pressure hoseline supplies compressed air to a multitude of airguns, a method, system and apparatus selectively shut off air flow to any airgun for stopping leakage of compressed air from the common supply line. Shutoff valves are employed with a respective valve being upstream of each airgun to enable selectively shutting off compressed air flow from the common supply line to any airgun for stopping loss of compressed air from the common line caused by leakage from a leaking component downstream from any valve, such as a ruptured feeder hoseline to an airgun. Each shutoff valve has a spring whose spring force biases open its valve. Simultaneous electrical energization of windings in all shutoff valves electromagnetically overcomes the spring force for simultaneously closing all valves.

Abstract: A method for measuring the velocity of shear waves in a formation beneath a body of water. The shear wave velocity is derived from the parameters of water density, water-bottom reflection coefficient, formation compressional wave, velocity and the propagation velocity of a submarine ground-roll wave front.

Abstract: An interface module assembly for disposition between a marine tow cable and n 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.