Towed antenna system and method

A towable antenna system is deployable and retrievable from and tetherable to an underwater vehicle while the underwater vehicle is submerged under water. An underwater vehicle having a towable antenna system is capable of communicating with one or more remote communication systems, the towable antenna system acting as an intermediary for communications between a submerged underwater vehicle and the one or more remote communication systems.

BACKGROUND OF THE INVENTION

This application relates generally to towed antenna systems and methods, and more particularly to systems and methods for communicating data signals to and from underwater craft to and from one or more remote communication systems.

When any underwater vehicle (UV), such as, for example, an unmanned underwater vehicle (UUV) or a submarine, is submerged under water, it cannot receive a GPS signal from a GPS satellite, and it cannot transmit or receive data signals over the air using radio frequency (RF) or satellite communication techniques. This lack of connectivity to the world above the surface of the water when submerged may significantly impact or constrain UV operations, and ultimately, the mission the UV may perform. Consequently, the ability to transmit and receive data signals may be beneficial to UV operations while a UV is submerged.

Unmanned underwater vehicles (UUVs), which are also known as autonomous underwater vehicles (AUVs), have been in use for some time. In particular, UUVs are known to be used to carry out missions involving intelligence, surveillance, and reconnaissance (ISR), mine countermeasures (MCM), anti-submarine warfare (ASW), time critical strike (TCS), inspection and identification, oceanography, oil and gas, payload delivery, and information operations, to name a few. UUVs are autonomous in the sense that, once launched on a mission, they operate according to a preprogrammed mission profile.

UUVs are also known to be formed from a series of interchangeable segments to permit flexibility in adding, subtracting or replacing entire hull segments of the UUV to tailor the UUV to a particular mission. UUVs are further known to have standardized hull diameters of, for example, 9 inches, 12¾ inches, and 21 inches. However, deployable and retrievable towable antenna systems configured for use in connection with a submerged UUV and which are capable of receiving GPS signals and transmitting and receiving RF (e.g., Wi-Fi, cellular, spread spectrum, etc.) and satellite data signals to and from the UUV and to and from aircraft (e.g., fixed wing manned and unmanned aircraft (including unmanned aerial vehicles and unmanned combat vehicles), cruise missiles, helicopters, and lighter than air craft such as balloons, etc.), spacecraft, watercraft (e.g., ships, boats, hovercraft, pontoons, buoys, beacons, and relays, etc.), and terrestrial locations are not known to exist aside from the instant disclosure.

Consequently, a towable antenna system of the type herein disclosed, which may be deployable and retrievable from and tethered to a UUV while the UUV is submerged, and which bi-directionally (i.e., transmit and receive simultaneously or sequentially in packets or without packets) communicates to and from the UUV and to and from, for example, air, space, and terrestrial communication systems via, for example, RF and satellite communication systems, as well as have the ability to receive GPS signals via GPS communication systems, may greatly enhance UUV operability and flexibility by permitting the UUV to remain submersed for longer periods than currently known UUV systems. In addition, a UUV having these capabilities and which is coupled with a towed antenna system designed to carry out communication to and from the UUV may be more maneuverable and controllable underwater (e.g., 3 to 5 meters below the surface) than it would be if, for example, the UUV were floating on the surface and subjected to waves and wind. A submerged UUV coupled to a towed antenna system may also minimize visibility of the overall UUV-towed antenna system during clandestine operations while allowing the UUV to continue its mission without having to resurface to obtain, for example, updated GPS position information.

SUMMARY OF THE INVENTION

A communication system is disclosed comprising an underwater vehicle configured for communicating with at least one remote communication system while the underwater vehicle is submerged, the underwater vehicle being connected to and configured for communicating with a towable body that is configured to communicate data signals to and from the underwater vehicle and to and from the at least one remote communication system while the underwater vehicle is submerged under water and while the towable body is deployed at or near the surface of the water.

In one embodiment, the underwater vehicle is an unmanned underwater vehicle. The underwater vehicle may be in communication with the at least one remote communication system and the towable body while the underwater vehicle is submerged under water and towing the towable body at or near the surface of the water.

The towable body may receive data signals from a global positioning system (GPS) reflecting a real time geographical position of the underwater vehicle. The towable body may transmit and receive data signals to and from at least one of the remote communication systems via at least one of an RF connection, a Wi-Fi connection, and a satellite connection.

In an embodiment, the at least one remote communication system comprises at least one of a GPS communication system, a satellite communication system, a Wi-Fi communication system, and an RF communication system.

In another embodiment, the underwater vehicle comprises a removably insertable towable antenna system, comprising a hull segment for connecting with at least one adjacent hull segment of the underwater vehicle, a launch and recovery system removably secured to the hull segment, where the launch and recovery system deploys and retrieves the towable body from and to the underwater vehicle, and a cable connecting the towable body to the launch and recovery system and connecting the launch and recovery system to the underwater vehicle. The cable transmits electrical power from a power source in the underwater vehicle to the towable body and transports data signals between the underwater vehicle and the towable body.

In one embodiment, the cable comprises a coaxial cable. The coaxial cable may include an inner conducting member and an outer conducting member, where the inner conducting member transmits electrical power from the underwater vehicle to the towable body and the outer conducting member transports data signals between the underwater vehicle and the towable body.

In another embodiment, the cable comprises a fiber optic cable. The fiber optic cable may include at least two optical fibers, where one optical fiber transmits electrical power from the underwater vehicle to the towable body and another optical fiber transports data signals between the underwater vehicle and the towable body.

A towable antenna system for an unmanned underwater vehicle is disclosed, comprising a launch and recovery system removably secured to the unmanned underwater vehicle, and a towable body tetheringly connected to the launch and recovery system by a cable that transports data signals between the towable body and the unmanned underwater vehicle. The towable body is configured for communicating with at least one remote communication system. Using the cable, the launch and recovery system retrievably deploys the towable body from a first position to a second position while the unmanned underwater vehicle is submerged under water to enable the unmanned underwater vehicle to communicate with the at least one remote communication system.

A profile of the towable body may approximately conform to an outer portion of the unmanned underwater vehicle when the towable body is in the first position. The towable body may be located at or near or on the surface of the water when the towable body is in the second position.

The towable body may include at least one communication system that receives and transmits data signals to and from the unmanned underwater vehicle and to and from the at least one remote communication system. In one embodiment, the at least one remote communication system includes at least one of a GPS communication system, a satellite communication system, a Wi-Fi communication system, and an RF communication system.

The towable antenna system may further include a hull segment removably connected with at least one adjoining hull segment of the unmanned underwater vehicle for housing the launch and recovery system and the towable body aboard the unmanned underwater vehicle. The cable may transmit electrical power to the towable body from the unmanned underwater vehicle.

A towable body for an underwater vehicle is disclosed, comprising a top section including at least one antenna for communicating with at least one remote communication system, and a bottom section connected to the top section. The bottom section comprises a cavity having at least one communication system removably housed therein for communicating with the at least one remote communication system through the at least one antenna and for communicating with the underwater vehicle.

The top section may include a profile that approximately conforms with at least a portion of an outer profile of the underwater vehicle when the towable body is in a stowed position relative to the underwater vehicle. The towable body may further include an antenna housing extending from a top surface of the top section and housing the at least one antenna to assist the at least one antenna in acquiring and maintaining at least one communication link with the at least one remote communication system while the towable body is at or near the surface of the water and while the underwater vehicle is submerged under the surface of the water.

The towable body may be deployable from a stowed position relative to the underwater vehicle while the underwater vehicle is submerged under water to a deployed position at or near the surface of the water to form at least one communication link between the at least one remote communication system and the underwater vehicle.

The towable body may further include a keel. The towable body may further include a rudder. In one embodiment, the rudder comprises a fixed position. In another embodiment, at least a portion of the rudder is movable side to side via at least one servo motor.

In an embodiment, the towable body is buoyant. The towable body may comprise a hydrodynamic lift-to-drag ratio greater than approximately 1.0 to enable the towable body to rise to the surface of the water when deployed from the underwater vehicle. In one embodiment, the towable body includes a circumferentially swept airfoil cross section.

In an embodiment, the at least one remote communication system comprises at least one of a GPS communication system, a satellite communication system, a Wi-Fi communication system, and an RF communication system. In another embodiment, the top section includes an aperture covered by a removably replaceable cap for providing access to the cavity of the towable body.

The bottom section and the top section may be separable and recombinable with one another. Alternatively, the bottom section is integratingly formed with the top section.

A launch and recovery system for a towable antenna system for use with an unmanned underwater vehicle is disclosed, comprising a drive system for retrievably deploying a towable antenna system to and from a unmanned underwater vehicle, and a launch and recovery communication system connected to the drive system for communicating data signals to and from the towable antenna system and the unmanned underwater vehicle and for transmitting power from the unmanned underwater vehicle to the towable antenna system, where the launch and recovery system is operable when submersed in water.

The drive system may include an electric motor operable on commands received from the unmanned underwater vehicle or the towable antenna system to deploy and retrieve the towable antenna system from and to the unmanned underwater vehicle and to and from the surface of the water. The drive system may also include a first end block releasably connected to a baseplate, the first end block forming a mount for the electric motor. The drive system may further include a first end cap connected to the first end block for forming a water-tight seal therebetween. The drive system may additionally include a first connector for connecting the drive system to a power source of the unmanned underwater vehicle, the connector forming a water-tight seal with the first end cap.

The launch and recovery communication system may include a slip ring assembly for communicating data signals to and from the towable antenna system and the unmanned underwater vehicle and for transmitting power from the unmanned underwater vehicle to the towable antenna system. The launch and recovery communication system may also include a second end block releasably connected to a baseplate, the second end block forming a mount for the slip ring assembly. The launch and recovery communication system may further include a second end cap connected to the second end block for forming a water-tight seal therebetween. The launch and recovery communication system may additionally include a second connector for connecting the launch and recovery communication system to a communication system of the unmanned underwater vehicle, the second connector forming a water-tight seal with the second end cap.

The launch and recovery system may further comprise a drum driven by the drive system, the drum configured to reel and unreel a cable thereon, the cable being connectable to the launch and recovery communication system on one end and to the towable antenna system on the other end, the cable being configured for transmitting electrical power from a power source in the unmanned underwater vehicle to the towable antenna system and for transporting data signals between the unmanned underwater vehicle and the towable antenna system.

DETAILED DESCRIPTION

Although the figures and the following disclosure describes an embodiment involving an unmanned underwater vehicle (UUV), one of ordinary skill in the art would know that the teachings of the disclosure would not be limited to use solely in connection with UUVs, and instead would appreciate that the teachings of the following disclosure would also apply to any submersible craft.

Turning now to the figures, wherein like reference numerals refer to like elements, there is illustrated inFIG. 1system10incorporating an embodiment of the present invention.FIG. 1shows how an underwater vehicle, such as UUV20, which is submerged under the surface of the water, may deploy towed body60to the surface of the water to transmit and receive communication signals to and from various remotely located communication systems. System10ofFIG. 1includes UUV20and towed antenna system40. System10may also include watercraft13, which may comprise at least one ship, boat, hovercraft, pontoon, buoy, beacon, or relay, to name a few. System10may also include aircraft12, which may comprise at least one manned or unmanned aircraft or rotorcraft, cruise missile, or lighter-than-air craft, such as a balloon, for example. System10may further include satellite14, which may comprise at least one GPS satellite and at least one communications satellite, such as the Iridium constellation of satellites. System10may additionally include one or more terrestrial communication systems16,18. Terrestrial communication systems16,18may include, for example, one or more RF communication systems operating on one or a number of frequencies, including Wi-Fi, microwave, UHF, VHF, spread-spectrum, cellular, and PCS communication systems.

UUV20, through towed antenna system40, may initiate and bi-directionally communicate with one or more of aircraft12, watercraft13, satellite14, and terrestrial communication systems16,18. Similarly, one or more of aircraft12, watercraft13, satellite14, and terrestrial communication systems16,18may initiate and bi-directionally communicate with UUV20through towed antenna system40. Bi-directional communication may simultaneously occur between UUV20and one or more of any or all of aircraft12, watercraft13, satellite14, and terrestrial communication systems16,18.

Turning now toFIG. 2, there is shown a more detailed view of UUV20together with towed antenna system40, and further showing towed body60partially deployed. UUV20may include, for example, nose module30, propulsion and guidance module24, lift hoist22, and one or more interchangeable modules32that, when assembled together, form UUV20. One of modules32may include one or more electrical power sources, such as power supply157shown schematically on, for example,FIG. 27. In addition, UUV20may include one or more computers, such as computer155shown schematically on, for example,FIG. 27. Computer155executes preprogrammed computer instructions to autonomously direct UUV20to carry out a predetermined underwater mission as well as to direct the deployment and retrieval of towed body60and operation of towed antenna system40. Computer155is additionally configured to engage towed antenna system40to permit communication of UUV20with remote air, water, space, and terrestrial communication systems.

Turning toFIG. 3, towed antenna system40includes hull segment42, which may include receptacle44for receiving towed body60. In addition, as is shown in the figures, towed body60may be configured to conform with hull segment42and vice versa to minimize drag on UUV20during underwater operations of UUV20when towed body60is fully retracted and engaged with UUV20.

Turning toFIG. 4, there is shown a more detailed view of towed antenna system40shown with towed body60in a partially deployed configuration. Towed antenna system40includes, for example, hull segment42for interchangeably mounting to adjoining modules32. Hull segment42may additionally be configured as a platform upon which to attach and secure launch and recovery system46for deployment and retrieval of towed body60from UUV20to and from the surface of the water. The forward and aft ends of hull segment42may be configured, for example, to maintain a watertight connection with adjoining modules32.

Towed antenna system40also includes towed body60connected to cable system48, which is connected to launch and recovery system46, and which is ultimately connected at least electrically to the electronics and one or more power supplies housed in one or more modules32of UUV20. Accordingly, cable system48is configured not only to act as a tether for deployment and retrieval of towed body60to and from UUV20, but cable system48also serves the function of, for example, transporting electrical power to towed body60from UUV20and for transmitting data signals between towed body60and UUV20. Such data signals may include, for example, real-time digital or analog video and voice signals as well as digital or analog data signals. In one embodiment, towed body60includes a camera for taking digital photographs and digital video, which may, for example, be streamed real-time to at least one of the remote communication systems. The taking of digital photographs and digital video may be autonomously performed according to a preprogrammed mission, or may be the result of a user remotely operating the camera in real-time via a communications link with towed antenna system40.

Towed body60is further configured to house various antennas and associated electronics usable for receiving and transmitting data signals to and from UUV20and to and from aircraft12, watercraft13, satellite14, and terrestrial communication systems16,18while UUV20is permitted to be submersed below the surface of the water.

As is shown inFIG. 4, launch and recovery system46may comprise, for example, a powered underwater winch, usable for deploying and retrieving towed body60. Power for launch and recovery system46may be provided by one or more power sources contained in other modules32of UUV20. To deploy towed body60, launch and recovery system46may unwind, and therefore let out, a predetermined length of cable system48knowing, for example, the depth of UUV20below the surface of the water. Alternatively, launch and recovery system46may unwind, and therefore let out, a length of cable system48until, for example, a sensor senses slack in cable system48. Deployment and retrieval of towed body60may be performed at preprogrammed times or intervals, as may be programmed in and commanded by the computer connected to or part of UUV20.

Once towed body60is deployed at or near or on the surface of the water, towed antenna system40may autonomously attempt to open one or more communication channels to permit bi-directional communication with remote air, water, space, and terrestrial communication systems via, for example, RF and satellite methodologies. Once one or more communication channels are established between one or more remote air, water, space, and terrestrial communication systems, towed antenna system40may carry out bi-directional communication of data signals between such one or more remote air, water, space, and terrestrial communication systems and computer155onboard UUV20. In this way, UUV20may remain completely submersed and hidden from view. In one embodiment, UUV20is submersed approximately 3-5 meters below the surface of the water when towed body60is deployed at the surface of the water.

Alternatively or additionally, towed antenna system40may autonomously attempt to receive GPS position data to update computer155onboard UUV20with updated actual geographical position information of UUV20. Priority between one or more bi-directional communication channels or GPS data acquisition may be predetermined, such as, by knowing the predicted route that UUV20is programmed to make under water and knowing in advance what communication systems will likely be available at predetermined times of deploying towed body60. Alternatively, computer155or a computer of towed antenna system40may cycle through available communication options or attempt to open all available communication options simultaneously. If multiple communication options are available at a given point in time, computer155or towed antenna system40may open all available communication channels or any number less than all available communication channels. Once at least one communication link is made with at least one remote communication system, remote control and operation of UUV20and towable system40may be made by a remote user.

To retrieve towed body60from a deployed position, launch and recovery system46may reverse the process and wind cable system48until towed body60is once again seated against hull segment42of towed antenna system40. A locking mechanism may be provided to secure towed body60in its fully retracted position. To avoid overstretching cable system48during retrieval operations, launch and recovery system46may cease winding of cable system48when launch and recovery system senses, for example, a threshold resistance in cable system48or in launch and recovery system46. In one embodiment, towed antenna system40includes proximity switch214to sense retraction of towed body60against hull segment42. When proximity switch214is triggered, launch and recovery system46may cease winding of cable system48.FIG. 5illustrates towed antenna system40with towed body60in its fully retracted position.

To assist in the deployment and retraction of towed body60, towed antenna system40may include cable guide50to guide cable system48neatly onto a drum or spool of launch and recovery system46and to guide cable system48during deployment of towed body60. As shown inFIG. 6, cable guide50may include aperture52through which cable system48may be guided during deployment and retraction of towed body60. In addition, cable guide50may include one or more support members54, which may be fixedly mounted to an inner wall of hull segment42so as to suspend cable guide50, and aperture52, in a predetermined point and space within hull segment42. In the embodiment shown inFIGS. 4-5and7, cable guide50may be positioned directly underneath towed body60when towed body60is in its fully retracted position and engaged with hull segment42. Cable guide50may be made from any material that is lightweight, durable, and suitable for underwater use including salt water environments. In one embodiment, cable guide50is made from a plastic. In another embodiment cable guide50is made from a composite material.

Turning toFIG. 7, towed antenna system40is shown with towed body60in a fully retracted position. Launch and recovery system46is shown positioned underneath towed body60, and secured to hull segment42. Although launch and recovery system46is shown in the figures as being permanently secured to hull segment42, launch and recovery system46may alternatively be configured to be removeably secured to hull segment42.

Turning now toFIGS. 8-14, there is shown in detail an exemplary towed body60. InFIG. 8which shows a top perspective view of an exemplary towed body60, for example, towed body60includes antenna housing66, top section64, bottom section68, cavity65, and access cap84.

FIG. 9shows a bottom perspective view of an exemplary towed body60shown inFIG. 8, and shows towed body60may additionally include keel74, right and left pontoons78, rudder76, and cable system48positioned through an aperture formed in keel74. In addition, at the entrance point of cable system48through the aperture in keel74, there is shown seal70, which is configured for ensuring that the cable-keel interface forms a water-tight seal. In one embodiment, seal70includes a flexible epoxy and a flexible polysulfide strain relief.

Turning toFIG. 14, there is shown a cross-section of the exemplary towed body60shown inFIG. 13. For example, towed body60is shown as including a plurality of fasteners88for securing access cap84to top section64. In addition, there is shown seal90between cap84and top section64for forming a water-tight seal when fasteners88are secured to top section64. In another embodiment, towed body60is formed without aperture86. Top section64may be fastened or secured to bottom section68using any known means, such as, for example, by snapping the two sections together or by securing the two sections together with adhesive or with fasteners. Alternatively, top section64may be integrally formed with bottom section68to form towed body60.

Antenna housing66may include one or more antennas, including GPS antenna109and satellite antenna115, for example. Antenna housing66may also include an appropriate GPS receiver and/or an appropriate satellite receiver permanently potted within antenna housing66. Antenna housing66may also include Wi-Fi antenna127and/or RF antenna121. Antenna housing66may further include a Wi-Fi cable for connecting Wi-Fi antenna127to a Wi-Fi transceiver, which may be housed in electrical housing62secured in cavity65of bottom section68of towed body60. Alternatively or additionally, antenna housing66may include a GPS/satellite cable connected to a GPS receiver and/or a satellite transceiver, both of which may be housed in electrical housing62in cavity65of bottom section68of towed body60.

Top section64, as shown inFIG. 14, may be interchangeable with other top sections64having different configurations of GPS/satellite/Wi-Fi/RF antennae and receiver/transceiver hardware.

Seal92, which may be made from, for example, an elastomeric material, may be positioned between top section64and bottom section68to form a water-tight seal therebetween. In this way, top section64may be removably replaced with another top section64having a different antenna and communication hardware configuration stored therein.

Bottom section68also includes cavity65for positioning electrical housing62. Electrical housing62is optional if the communications package is merely installed in cavity65.

Antenna housing66, as shown inFIG. 14, is shown as extended above the top surface of top section64to best position GPS antenna109, satellite antenna115, or Wi-Fi antenna127as high above the surface of the water as possible without being easily visually detected. Antenna housing66may be in a fixed position and in a fixed length, or it may be deployable and retractable, in, for example, a telescoping manner. One of ordinary skill would appreciate that antenna housing66, and towed body60, may be configured in any number of ways. In one embodiment, antenna housing66is configured in the shape of a relatively small blister. In another embodiment, antenna housing66is non-existent, where the RF, Wi-Fi, GPS, satellite and cellular antennas are housed inside tow body60.

As shown in the figures, towed body60may comprise an airfoil shape to provide hydrodynamic lift during deployment under water. In one embodiment, the airfoil shape is based on a NACA5515 airfoil cross section. The airfoil cross sectional shape may be swept to match the shape of any diameter of UUV20to approximately conform towed body60to the contour of the outer surface of UUV20. In this way, towed body60will allow UUV20to function as close to normal as possible during periods when towed body60is stowed, which could be up to approximately 94%, for example, of an entire UUV20mission.

In one embodiment, towed body60is buoyant to cause towed body60to float to the surface of the water on deployment from UUV20and to operate at or on the surface of the water to communicate with the at least one remote communication system. Towed body60may additionally be configured with a lift-to-drag ratio of greater than approximately 1.0 to permit towed body60to hydrodynamically “fly” to the surface of the water on deployment from UUV20. In one embodiment, towed body60is configured with powered control surfaces that are movable via one or more servo motors, for example, to control towed body60while deployed under water and at or on the surface of the water. In another embodiment, towed body60is configured with powered control systems to propel and control towed body60while deployed under water and at or on the surface of the water. Towed body60may be made from any material that is lightweight, durable, and suitable for underwater use including salt water environments. In one embodiment, towed body60is made from a plastic. In another embodiment, towed body is made from a composite material. Rudder76of towed body60may be fixed or it may be moveable, for example, using one or more servo motors to permit additional directional control of towed body60during deployment under water and at or on the surface of the water. Access cap84may be removed from top section64to gain access to, for example, the electronics housed in cavity65of towed body60. In this way, quick access to such contents may be obtained without having to disturb the water-tight seal between top section64and bottom section68.

It should be understood by one of ordinary skill that a substantial portion of towed body60may be submerged, at least momentarily, while towed body60is at or on the surface of the water without causing loss of connectivity with the at least one remote communication system and without departing from the teachings of the instant disclosure. For example, top section64may be partially or completely submerged but, for example, the top of antenna housing66may remain above water thereby maintaining communications between the one or more antennae housed therein with the at least one remote communication system. In addition, towed body60may be completely submerged near the surface of the water and be in communication with the at least one remote communication system.

Turning now toFIGS. 15-19, there is shown various exemplary options for cable system48. Cable system48may comprise, for example, mini coaxial cable282. Cable282may comprise, for example, an approximately 0.046 inch diameter or an approximately 0.100 inch diameter, either of which is relatively small compared to many other cable system options. The relatively small diameter of cable282serves to minimize drag while towing deployed towed body60, yet still be large enough to transmit both power and data signals between towed body60and UUV20. In this way, a two-wire protocol may be employed to transmit data on, for example, conductor288and power on, for example, shield286, or vice versa.

In the embodiment ofFIGS. 15-16, cable282comprises cover284, shield286, and conductor288. Cover284may comprise an FEP jacket. Conductor288may comprise an approximately 34 AWG silver plated steel conductor. Shield286may comprise tinned copper. Tensile strength of cable282is anticipated to be approximately 10 lbs, which is well in excess of an approximately 3 lb. tensile load that is expected to be applied to cable system48during deployment of one embodiment of towed body60. Cable282may be capable of supporting up to approximately 600 volts and approximately 0.2 amps. However, since the electrical current is relatively low, the voltage may need to be increased to provide enough power for the electronics housed in towed body60. In addition, by adding an in-line filter, data and electrical power may be transmitted using a single cable282for cable system48.

In another embodiment, cable system48comprises cable252, as shown inFIG. 17. Cable252may comprise a fiber optic configuration having cover254, strength member256, and dual optical fibers258. Cover254may be made from a waterproof PVC material. Strength member256may be made from a strong yet lightweight material, such as Kevlar. Cable252may be desirable for long cable runs and/or extremely high bandwidth where multiple data streams may be multiplexed onto a single fiber258.

FIG. 18shows another embodiment of cable system48comprising cable262. Cable262may include, for example, cover264, strength member266, and three optical fibers268. Cover264may comprise, for example, a polyurethane material. Strength member266may comprise a relatively strong yet lightweight material such as Kevlar. Fibers268may be encased in a gel-filled stainless steel sheath surrounded by strength member266. Cable262may be approximately 0.12 inches in diameter, which may create more drag than, for example, cable282during deployment of towed body60, but may be more rugged in a rough marine environment than, for example, cable282.

FIG. 19shows yet another embodiment of cable system48comprising cable272. Cable272may include, for example, cover274, dual conductors276, and dual fibers278. In one embodiment, cable272is a M2-220 fiber optic cable having an approximately 0.26 in. diameter and which is available from Opticis Co. The relatively large diameter of cable272, as compared to, for example, cable282, may cause increased drag during deployment of towed body60thereby increasing the tensile loads on cable system46.

While all of the foregoing cable system48options would work in connection with towed antenna system40, testing has shown that cable282may provide the potential for deeper deployments and higher underwater speeds of UUV20than can be achieved using cable252or cable262, for example.FIG. 20illustrates the test results of a simulated UUV20submersed to approximately 3 meters using cable252or cable262to tow a simulated towed body60.FIG. 20, for example, shows the measured distance astern from a simulated UUV20traveling at approximately 1 to approximately 3 knots. By comparison,FIG. 21shows the measured distance astern from a simulated UUV20traveling at approximately 1 to approximately 3 knots when towing a simulated towed body60using cable282. As the velocity of the simulated UUV20increases,FIG. 21shows that using cable282results in a shorter distance astern as compared to using cable252or cable262having a diameter of approximately twice that of cable282—all other factors being approximately equal.

During experimental tests involving a simulated towed body60, attached to cable272, which has an approximately 0.26 inch diameter, it was shown that at 2 knots forward speed there was approximately 4 ounces of drag, while at 2.2 knots there were approximately 5 ounces of drag, and at 2.8 knots of forward speed, there was approximately 7 ounces of drag. These drag forces were in the range of what was predicted. Consequently, it is anticipated that cable282, which is just under approximately 22% of the diameter of cable272, would result in a fraction of these measured drag forces at these velocities. Consequently, while actual results in a real-life application may vary from the foregoing, the lower drag of cable282may provider operators of UUV20with a greater depth and speed envelope for UUV20. In addition, the electrical components may also be simpler and less expensive than their fiber optic counterparts. Durability of cable282is also expected to be more rugged than many other options, including many fiber optics options, which may result in less down time, less repair operations, and better monitoring of operational status of UUV20.

Turning now toFIGS. 22-23, there is shown an exemplary launch in recovery system46. As shown in the figures, launch and recovery system46may include drive system200and launch and recovery communication system170. Drive system200may include motor216, which may be a DC gear motor, for example, for driving drum210forward and in reverse to wind and unwind cable system48onto and from drum210. Drive system200may further include end cap204, which may be removable and replaceable to access, for example, motor216while maintaining a water-tight seal. Drive system200may further include underwater connector218for transmitting electrical power along conduit208from UUV20to motor216. Drive system200may further include end block206attached to base plate212for securing launch and recovery system46to hull segment42of towed antenna system40. Drive system200may additionally include one or more bearings180and one or more rotary seals182to permit drum210to rotate relative to end block206while maintaining a water-tight seal therebetween.

Launch and recovery communication system170of launch and recovery system46may be configured for transmitting data signals to and from UUV20and towed body60and for transmitting electrical power from UUV20to towed body60. Launch and recovery communication system170may include slip ring assembly174to electrically interface the stationary electrical components of launch and recovery communication system170of launch and recovery system46to the rotational electrical components of launch and recovery system46.

Launch and recovery communication system170may further include underwater connector184for connecting cable system48to drum210while maintaining a water-tight seal. Launch and recovery communication system170may further include one or more bearings180, and one or more rotary seals182, to enable drum210to rotate relative to end block186while maintaining a water-tight seal therebetween.

Launch and recovery communication system170may additionally include end cap178, which may be removable and replaceable to access internal components of launch and recovery communication system170, such as, for example, slip ring assembly174. Launch and recovery communication system170may also include end block186, attached to base plate212for securing launch and recovery communication system170to hull segment42of towed antenna system40. Launch and recovery communication system170may further include underwater connector176for transitioning cable system48from launch and recovery communication system170to connect with UUV20in a waterproof manner. In one embodiment, cable system48exiting underwater connector176comprises cable system188, which connects with UUV20. In another embodiment, cable system48comprises a continuous cable from originating at towed body60and terminating at UUV20.

Launch and recovery system46may be made from materials suitable for submersion in salt water environments. In one embodiment, at least some of the components of launch and recovery system46are made from a plastic. In another embodiment, at least some of the components of launch and recovery system46are made from a composite material.

FIGS. 24-26illustrate optional embodiments for launch and recovery system46to enable cable system48to be continuous from towed body60to UUV20without requiring slip ring assembly174.FIG. 24, for example, shows launch and recovery communication system220, including drive system226, and reel system224. As shown inFIG. 24, cable system48may be wound and unwound from a fixed spool with a bail-type sheave rotating around the spool. In this way, the spool does not turn thereby allowing cable system48to remain as one continuous line from towed body60to module32housing UUV communication system150of UUV20. A spring loaded retainer with foam on the inside may maintain pressure on that portion of cable system48that is wound on the fixed spool to keep cable system48from loosening and possibly becoming tangled in the event of loss of tension on cable system48when towed body60is deployed. Reel system224, as depicted inFIG. 24, may be designed for at least 100 feet of cable system48within a spool diameter of approximately 2.5 inches and a drum length of approximately 1 inch axially. Hull segment42incorporating launch and recovery communication system220may be less than 24 inches long from bulk head to bulk head to adjoining modules32with this configuration.

A simulated reel system224of launch and recovery communication system220was performed by modifying a fishing spool having a spool diameter of approximately 4.5 inches and adding approximately 30 sheet of a fiber optic tow cable, such as, for example, cable252or cable262. A simple bail was fabricated and was manually driven around the stationery spool. The cable was unwound from the spool and then rewound onto the spool during which it was discovered that there was approximately a one-half turn of twist induced in the cable. However, when the cable was fully unwound from the spool, the twist disappeared. Further tests indicated that this behavior was repeatable.

FIG. 25shows launch and recovery communication system230having drive system236and reel system234. Drive system236may include motor237, which may comprise a stepper motor, hydraulic motor, DC rotary actuator, or a modified servo. All of these options are capable of underwater use but their depth ratings may vary. In one embodiment, communication system230comprises a modified DA-22 sub servo available from Volz GmbH of Germany. A servo of this type may be designed for travel angles less than 330 degrees, but may easily be modified for continuous rotation as may be required by launch and recovery system46. The stall torque for the DA-22 sub servo is approximately 410 oz-in and continuous torque is expected to be approximately 230 oz-in, which translates to approximately 6-11 lbs of tension capacity of cable system48. A DA-22, for example, is approximately 1.75 inch by approximately 2.68 inch by approximately 1.0 inch, is rated to a depth of approximately 100 meters, and is controlled with a common RS 422 or RS 485 interface. Cable system188may be connected to motor237to transmit data signals to and from towed body60and UUV20and to transmit power to towed body60from UUV20.

In an embodiment, reel system234may be based on, for example, a Zeebaas ZX 27 fishing spool modified by removing the handle and adding coupling238for the spool to motor shaft interface. Reel system234, like reel system224, may comprise cable system48spun around a fixed spool with a bale type sheave rotating around the spool. In this way, cable system48may be coiled around the spool without the spool itself turning.

FIG. 26shows an exemplary towed antenna system40incorporating launch and recovery communication system230together with another embodiment of towed body60. As shown inFIG. 26, the relatively small size of launch and recovery system46having launch and recovery communication system230permits the total length of hull segment42to be just longer than the overall length of towed body60. This is because the small reeling mechanism can fit beneath towed body60instead of taking up space behind it.

Turning now toFIG. 27, there is shown an exemplary communication system100that is usable in connection with towed antenna system40of system10for bi-directionally transmitting and receiving data signals to and from one or more remote communication systems to and from UUV20. Communication system100includes towed body communication system102and UUV communication system150. Depending on the configuration of launch and recovery system46used in connection with towed antenna system40, communication system100may also include, for example, launch and recovery communication system170,220, or230.

Towed body communication system102, as shown inFIG. 27, includes computer105, which may include flash memory, ram memory, and means for permanent data storage, such as a hard drive. Computer105may also include a processor as well as various ports and interfaces to connect with peripheral devices and antennas. For example, computer105may include Bluetooth, USB, Wi-Fi, cellular, satellite, IEEE UART, and I2C ports and interfaces. Computer105may comprise an operating system for carrying out computer instructions, such as Linux, and operate on one or more wired or wireless networks, such as an intranet and the Internet. Towed body communication system102may use one or more encryption methods for privately communicating data signals to and from UUV20and to and from the at least one remote communication system.

As shown inFIG. 27, computer105is connected to Wi-Fi communication system125, GPS communication system107, satellite communication system113, and RF communication system119through, for example, interface111. To bi-directionally transmit and receive data signals to and from towed antenna system40to and from one or more remote communication systems via a Wi-Fi connection, Wi-Fi communication system125of towed antenna system40may include a Wi-Fi antenna connected to a Wi-Fi transceiver. The Wi-Fi transceiver may be connected to computer105using, for example, a USB, serial, or Ethernet cable. The Wi-Fi transceiver may alternatively be integrated with or directly connected to computer105.

To receive GPS data signals, GPS communication system107of towed antenna system40may include a GPS antenna connected to a GPS receiver. GPS receiver of GPS communication system107may be connected to computer105using, for example, a USB, serial, or Ethernet cable. The GPS receiver may alternatively be integrated with or directly connected to computer105.

To bi-directionally transmit and receive data signals to and from towed antenna system40to and from one or more remote communication systems via a satellite connection, satellite communication system113of towed antenna system40may include a satellite antenna connected to a satellite transceiver. The satellite transceiver of satellite communication system113may be connected to computer105via a serial cable, or a USB cable, for example. The satellite transceiver may alternatively be integrated with or directly connected to computer105. The satellite antenna and the GPS antenna may comprise a single antenna configured to receive GPS signals and to transmit and receive data signals to and from one or more satellites. Similarly, the satellite transceiver and the GPS receiver may be configured as part of a single module having both satellite and GPS communication capabilities.

To bi-directionally transmit and receive data signals to and from towed antenna system40to and from one or more remote communication systems via an RF connection, RF communication system119of towed antenna system40may include an RF antenna connected to an RF transceiver. The RF antenna may be configured to receive and transmit, for example, UHF radio signals, including spread spectrum radio signals, and cellular communication signals.

As shown inFIG. 27, computer105may be connected to Ethernet to Coax bridge103using, for example, an Ethernet cable, to convert the data signals from an Ethernet-based system to cable system48comprising, for example, mini coax cable282.

As further shown inFIG. 27, cable system48connects towed body communication system102with launch and recovery system46. Cable system48or, for example, cable system188, connects launch and recovery system46with computer155of UUV20contained in a module32of UUV20.

Cable system48(or cable system188, for example) may be connected with Ethernet to Coax bridge153of UUV communication system150to convert the data signals to and from an Ethernet-based system to or from a coax cable system, such as, for example, cable282. Ethernet to Coax bridge153may be connected with computer155either directly or, for example, using an Ethernet cable.

Also shown inFIG. 27is UUV power supply157which may supply UUV20electrical power to launch and recovery system46to power, for example, drive system200. Similarly, electrical power from UUV20may be supplied from UUV20through cable system48through, for example, launch and recovery communication system170of launch and recovery system46and ultimately to towed body60through cable system48. Alternatively, towed body60may house and carry its own power supply, such as a battery, to power computer105and all peripheral components in towed body60.

Computer155of UUV20may command launch and recovery system46to deploy and retrieve towed body60according to pre-programmed commands stored in computer155. UUV20may transmit and receive communication signals to and from one or more remote communication systems using towed antenna system40to do so.

Data signals to and from the remote communication system with towed antenna system40may be transmitted to and from computer155of UUV20in real time. Alternatively or in addition to, data signals to and from the remote communication system with towed antenna system40may be stored in memory associated with computer105. In this way, data signals from computer155of UUV20may be stored in memory associated with computer105for later transmission to the one or more remote communication systems. Similarly, data signals received from the one or more remote communication systems by towed antenna system40may be stored in memory associated with computer105for later transmission to computer155of UUV20.

In an embodiment cable system48comprises a mini coax-type cable, such as cable282, a Gumstix Verdex Pro XM4 or a Gumstix Verdex Pro XL6P may be employed. These devices, which are available at www.gumstix.com, are each a complete computer system that can accept multiple serial devices, has both wired and wireless Ethernet ports and runs the Linux operating system. It requires relatively low power to operate and it is literally the size of a stick of gum.

The Ethernet protocol is full duplex and high speed, but typically requires four conductor wires to transport data signals. To employ a two-wire protocol to permit cable system48to require only two conductors to transport data signals, an E-Linx Ethernet Extender may be employ. An E-Linx Ethernet Extender, which is available at www.www.bb-elec.com, permits Ethernet to operate over two wires and up to 50 MBPS for cable runs up to approximately 980 feet. An E-Linx Ethernet Extender may auto-negotiate its speed to maintain data integrity, eliminating the risk of data loss. In one embodiment, a Gumstix Verdex Pro XM4 may be connected to an E-Linx Ethernet Extender via the Ethernet port and housed in towed body60. Within UUV20, another E-Linx Ethernet Extender may be connected to computer155via its Ethernet port. A software bridge may be written to transport data signals between one or more serial ports and the Ethernet port.

In an embodiment cable system48comprises a fiber optic-type cable, such as cable252, a PRIZM Ultimate USB may be employed to transmit and receive data signals along a single fiber. The PRIZM Ultimate USB, which is available at www.moog.com, offers bi-directional fiber optic transmission of, for example, video and data signals, over a single fiber. The PRIZM Ultimate USB is designed for underwater applications, and includes a 4 port USB 1.1 hub. This device may require up to 7.5 watts of power to operate, which may or may not be significant depending on the power source availability in UUV20or in towed body60and the power transmission properties of the chosen cable system40. Two boards may be needed for the system to be complete: one board for each end of cable system48.

Another option for use in connection with cable system48comprising a fiber optic-type cable is the AXFT-1621 single fiber, bi-directional receptacle/transceiver. This device, which is available from Axcen Photonics Corp. at www.axcen.com.tw, can transmit and receive data signals at the serial TTL level enabling compatibility with virtually any type of communications hardware. A second multiplexer board may be needed to combine data signals to and from Wi-Fi communication system125, GPS communication system107, satellite communication system113, and RF communication system119. The AXFT-1621 transceiver may incorporate additional multiplexers and provide breakouts for communications ports to attach additional communication modules, but may require custom supporting circuitry in order to function in towed antenna system40.

In one embodiment, the Wi-Fi transceiver of Wi-Fi communication system125may be based on the RTL 8187B chipset found in, for example, a Trendnet TEW-424 UB Wi-Fi module, which is available at www.trendnet.com. This module operates with the standard IEEE 802.11g protocol, which may provide a range of approximately 100 meters for Wi-Fi communication. In addition, this particular module may connect directly into a USB port or a USB adaptor to computer105, and is configured together with a Wi-Fi antenna.

In a test using this module for Wi-Fi communications, a simulated towed body60was placed in the water and a battery powered Wi-Fi router was carried approximately 12 feet above the water at various distances from the simulated towed body60carrying the Trendnet TEW-424 UB Wi-Fi module.FIG. 28shows the signal to noise ratio for the signal that the handheld Wi-Fi router received from the Wi-Fi module.

In another embodiment, a NetWi-FiMicroSD Add-on board may be added to or be integrated with a Gumstix microcontroller to form a Wi-Fi transceiver. The NetWi-FiMicroSD, which is available at www.gumstix.com, features a 10/100 wired Ethernet port and a Marvell 88W8385 Wi-Fi transceiver module supporting IEEE 802.11b/g. This device also includes a MicroSD slot allowing up to 4 GB of flash memory to be used by the Gumstix microcontroller for logging or other file storage needs.

In an embodiment in which cable system48comprises a fiber optic-type cable, the Wi-Fi transceiver includes a WL-USB-RSMAP, which is available at www.jefatech.com. This module includes an SMA antenna jack to permit its use with a Wi-Fi amplifier to increase range.

In another embodiment, a Wi-Fi amplifier is connected between the Wi-Fi transceiver and the Wi-Fi antenna to amplify data signals received by and transmitted out from the Wi-Fi antenna. In an embodiment, the Wi-Fi amplifier comprises an RF-Linx 2400 CAE-1W, which is available at www.rflinx.com. This amplifier is a 1-watt amplifier, which uses automatic gain control to only use power when it needs to send or receive data, thereby conserving energy. Simulation testing has revealed that a Wi-Fi communications connection using this amplifier may result in a range of up to 1 mile over open water.

Turning to hardware options for GPS reception, in one embodiment, the GPS receiver of towed antenna system40includes one of the NovAtel OEMV 1/1G line of GPS receivers, which are available at www.novatel.com. The NovAtel OEMV 1/1G line offers centimeter-level positioning accuracy with RTK corrections and 2 meter or greater accuracy as well as high reliability using satellites in the GLONASS network. With 48+ satellites in the combined GPS-GLONASS networks, performance in high seas may be expected to be improved as more satellites are visible in the non-blocked portions of the sky. The OEMV-1 supports both RS232 and USB interfaces.

In one embodiment, the GPS antenna includes a PCtel WS3951-HR, which is available at www.canalgeomatics.com. This antenna provides high gain, low noise, low power and small size. It also has a high rejection, dual SAW filter, which is expected to decrease the risk of interference with any nearby Wi-Fi antenna.

In another embodiment, the GPS receiver includes a GlobalSat SiRF III transceiver module, which may track up to approximately 20 GPS satellites simultaneously. Data from this transceiver module is output in standard NMEA 0183 format over, for example, a USB interface.

When testing a simulated towed body60carrying this particular GPS transceiver module, the following results showed that the transceiver unit had a successful communications connection with one or more GPS satellites:$GPGGA,165837.000,4135.1941,N,07056.7651,W,2,11,0.9,6.4,M,−34.4,M,0.8,0000*4F$GPGSA,A,3,08,10,09,27,26,18,15,24,21,29,02,,1.3,0.9,1.0*38$GPRMC,165837.000,A,4135.1941,N,07056.7651,W,0.19,175.92,260309,,*1E$GPGGA,165838.000,4135.1941,N,07056.7651,W,2,11,0.9,6.4,M,−34.4,M,0.8,0000*40$GPGSA,A,3,08,10,09,27,26,18,15,24,21,29,02,,1.3,0.9,1.0*38$GPRMC,165838.000,A,4135.1941,N,07056.7651,W,0.07,65.49,260309,,*28$GPGGA,165839.000,4135.1941,N,07056.7651,W,2,11,0.9,6.4,M,−34.4,M, 0.8,0000*41$GPGSA,A,3,08,10,09,27,26,18,15,24,21,29,02,,1.3,0.9,1.0*38$GPRMC,165839.000,A,4135.1941,N,07056.7651,W,0.06,202.70,260309,,*11$GPGGA,165840.000,4135.1941,N,07056.7650,W,2,11,0.9,6.5,M,−34.4,M, 1.8,0000*4E
When the unit lost a GPS connection, the sentences had lots of empty fields like this.$GPGGA, 165837.000,,,,,0,0,99.99,,,,,,*5F$GPRMC,165837.000,A,,,,,,,,N,,,,,,,,,W,0.19,,,,,,260309,,*1E

During testing, it was also discovered that the GPS communication connection may be lost or interrupted when the GPS antenna109in the simulated towed body60is submerged more than 1 inch below the water. However, GPS signal reacquisition occurred in a matter of approximately 2 seconds once the simulated towed body60returned to the surface. In a test involving a simulated towed body60configured with antenna housing66comprising a relatively short dorsal extension extending from top surface64(see, e.g., the exemplary towed body60shown inFIG. 26), the Wi-Fi transceiver seemed to lose its effectiveness at approximately 225 feet from the simulated towed body60. To mitigate the possibility of incurring connectivity issues due to, for example, submersion, water spray from waves, or line-of-sight blockage as may occur from a wave, system10may include, for example, extending the height of antenna housing66and therefore any antennas therein, operating towed body60in calm seas, and having a number of available remote communication systems with which to make at least one communication connection. Components of system10may also include computer hardware and/or software designed to communicate data signals in packets to maximize available connection opportunities.

Turning to options to communicate with one or more satellites, in one embodiment, the satellite transceiver of towed antenna system40includes the Iridium 9601, which is available at www.iridium.com. The Iridium 9601 transceiver is an OEM solution designed for embedded systems. It offers global coverage for the short-burst-data (SBD) service. The SBD service allows 340 bytes per message which is expected to work well for “phone-home” messages containing GPS coordinates and simple status updates from UUV20. The Iridium 9601 interfaces with RS232 and uses an L-band antenna.

Turning now toFIG. 29, there is shown another exemplary communication system130that is usable in connection with towed antenna system40of system10for bi-directionally transmitting and receiving data signals to and from one or more remote communication systems to and from UUV20. Communication system130includes towed body communication system144and UUV communication system150. Towed body communication system144includes one or more of, for example, Wi-Fi communication system125, GPS communication system107, satellite communication system113, and RF communication system119.

Towed body communication system144may include Ethernet switch131to transmit and receive data signals to and from Wi-Fi communication system125, GPS communication system107, satellite communication system113, and RF communication system119to and from UUV communication system150of UUV20. Ethernet switch131of towed body communication system144may be connected to Ethernet to Coax bridge103via, for example, Ethernet cable159, to convert the data signals from an Ethernet-based system to cable system48comprising, for example, mini coax cable282. Ethernet switch131may alternatively be integrated with Ethernet to Coax bridge103thereby simplifying connectivity with Wi-Fi communication system125, GPS communication system107, satellite communication system113, and RF communication system119. Depending on the configuration of launch and recovery system46used in connection with towed antenna system40, towed body communication system144may also include, for example, launch and recovery communication system170,220, or230.

To bi-directionally transmit and receive data signals to and from towed antenna system40to and from one or more remote communication systems via a Wi-Fi connection, Wi-Fi communication system125of towed antenna system40may include Wi-Fi antenna127connected to Wi-Fi amplifier133for amplifying data signals received by and/or transmitted out from Wi-Fi antenna127. In one embodiment, Wi-Fi communication system125includes a Wi-Fi transceiver connected to Wi-Fi amplifier133. The Wi-Fi transceiver may be connected to Ethernet to Wi-Fi bridge139, which is usable for converting data signals to and from an Ethernet-based system. In another embodiment, UUV communication system150of UUV20includes a Wi-Fi transceiver for bi-directionally transmitting and receiving data signals to and from one or more remote communication systems to and from UUV20via a Wi-Fi connection.

As shown in the embodiment ofFIG. 29, Wi-Fi amplifier133is connected to Ethernet to Wi-Fi bridge139. Ethernet to Wi-Fi bridge139may be connected to Ethernet switch131using, for example, Ethernet cable159. As described above, Ethernet switch131may be connected to Ethernet to Coax bridge103using, for example, Ethernet cable159. Alternatively, Ethernet to Wi-Fi bridge139may be integrated with Ethernet switch131and/or Ethernet to Coax bridge103.

To bi-directionally transmit and receive data signals to and from towed antenna system40to and from one or more remote communication systems via a satellite connection, satellite communication system113of towed antenna system40may include satellite antenna115connected to satellite transceiver114. Satellite transceiver114may be connected to Serial to Ethernet bridge141using, for example, serial cable137. Serial to Ethernet bridge141may be connected to Ethernet switch131using, for example, Ethernet cable159. Alternatively, Serial to Ethernet bridge141of satellite communication system113may be integrated with Ethernet switch131and/or Ethernet to Coax bridge103.

To receive GPS data signals, GPS communication system107of towed antenna system40may include GPS antenna109connected to GPS receiver108. GPS receiver108may be connected to Serial to Ethernet bridge141using, for example, serial cable137. As shown inFIG. 29, GPS receiver108may alternatively be integrated with or directly connected with satellite transceiver114to form a single module having both satellite and GPS communication capabilities. In addition, satellite antenna115and GPS antenna109may comprise a single antenna configured to receive GPS signals and to transmit and receive data signals to and from one or more satellites.

To bi-directionally transmit and receive data signals via an RF connection to and from towed antenna system40to and from one or more remote communication systems via an RF connection, RF communication system119of towed antenna system40may include RF antenna121connected to RF amplifier135for amplifying data signals received by and transmitted out from RF antenna121. In one embodiment, RF communication system119includes an RF transceiver connected to RF amplifier135. The RF transceiver may be connected to Serial to Ethernet bridge141, which is usable for converting data signals to and from an Ethernet based system. In another embodiment, UUV communication system150of UUV20includes an RF transceiver for bi-directionally transmitting and receiving data signals to and from one or more remote communication systems to and from UUV20via an RF connection. The RF transceiver or RF amplifier135may be connected to Serial to Ethernet bridge141using, for example, serial cable137.

As shown in the embodiment ofFIG. 29, RF amplifier135is connected to Serial to Ethernet bridge141using, for example, serial cable137. Serial to Ethernet bridge141may be connected to Ethernet switch131using, for example, Ethernet cable159. As described above, Ethernet switch131may be connected to Ethernet to Coax bridge103using, for example, Ethernet cable159. Alternatively, Serial to Ethernet bridge141of RF communication system119may be integrated with Ethernet switch131and/or Ethernet to Coax bridge103.

Cable system48connects towed body communication system144with launch and recovery system46. Cable system48or, for example, cable system188, connects launch and recovery system46with computer155of UUV20contained in one of modules32of UUV20.

Cable system48(or cable system188, for example) may be connected with Ethernet to Coax bridge153of UUV communication system150to convert the data signals to and from an Ethernet-based system to or from a coax cable system, such as, for example, cable282. Ethernet to Coax bridge153may be connected with computer155using, for example, Ethernet cable159. Alternatively, Ethernet to Coax bridge153may be integrated with computer155.

Electrical power from UUV20may be supplied through cable system48(or cable system188, for example) through, for example, launch and recovery communication system170of launch and recovery system46, and ultimately to towed body60through cable system48. Alternatively, towed body60may house and carry its own power supply, such as a battery, to electrically power computer105and all peripheral computer and communication components and all servo motors in towed body60.

Computer155of UUV20may command launch and recovery system46to deploy and retrieve towed body60according to pre-programmed commands stored in computer155. UUV20may bi-directionally transmit and receive communication signals to and from one or more remote communication systems, in parallel or in series, using towed antenna system40to do so.

Data signals to and from the one or more remote communication system with towed antenna system40may be transmitted to and from computer155of UUV20in real time. Alternatively or in addition to, data signals to and from the one or more remote communication system with towed antenna system40may be stored in memory associated with computer105. In this way, data signals from computer155of UUV20may be stored in memory associated with computer105for later transmission to the one or more remote communication systems. Similarly, data signals received from the one or more remote communication system by towed antenna system40may be stored in memory associated with computer105for later transmission to computer155of UUV20.

In one embodiment, Ethernet to Wi-Fi bridge139comprises a Quatech Airborne Enterprise Class Ethernet bridge module, which is available at www.quatech.com. In another embodiment, GPS receiver108of GPS communication system107comprises, for example, a Hemisphere Crescent OEM module, which is available at www.hemispheregps.com. In a further embodiment, a GPS antenna109comprises a Wi-Sys WS3951-HR No-Interference Embedded GPS Antenna, which is available at www.antenna.com. In yet another embodiment, Serial to Ethernet bridge141comprises a Moxa NE-4100 Embedded Serial Device Server, which is available at www.moxa.com. In one embodiment, Ethernet switch131comprises a Moxa EOM-104 4-Port Embedded Managed Ethernet Switch, which is also available at www.moxa.com. In another embodiment, RF amplifier135comprises a Freewave MM2900MHz Spread Spectrum UHF Radio, which is available at www.freewave.com. In one embodiment, Ethernet to Coax bridge103comprises, for example, an Amplicon UCA-6120 Intelligent Ethernet to Coax Adaptor, which is available at www.amplicon.com. In another embodiment, satellite transceiver114of satellite communication system113comprises, for example, an Iridium 9602 SBD transceiver, which is available at www.iridium.com.

Typical UUV missions can last up to 18 hours in duration, during which towed antenna system40may be tasked with providing up to 50 deployments, each lasting from approximately 3 to approximately 8 minutes. In one embodiment, transmission and reception of data signals via satellite draws up to approximately 20 watts of power. The resulting energy capacity needed to operate an embodiment of towed antenna system40is approximately 133 watt-hours of energy. Therefore, an exemplary towed antenna system40may either require a battery with 133 watt-hour capacity, or cable system48must be sized to transmit approximately 20 watts from UUV20's own power supply.

In an embodiment involving cable system48comprising a fiber optic-type cable, to transmit electrical power over fiber, a JDSU Photovoltaic power converter may be used. This unit delivers 0.5 watts of energy at voltages ranging between 2 and 12 volts DC. Although this may not be enough energy to simultaneously power all of the electrical devices located in towed body60, this device may nevertheless be used to trickle charge a battery housed in towed body60between deployments.

In one embodiment having the hardware listed below for cable system48comprising a fiber optic-type cable, and assuming a deployment duration of approximately 8 minutes for towed antenna system40, each device may be expected to demand the following amounts of electrical energy:

To accommodate these electrical loads, in one embodiment, a 7.4 V Li—Po battery having 875 mAh of capacity may be employed. A battery of this type is expected to weigh only 1.6 oz. and would provide 6.5 W-hrs, which is expected to be more than three times the needed capacity.

A power control board may be used to regulate the charging of the battery and distribution of power to the different system components. If the Axcen AXFT-1621 fiber optic module were included in the system, charging circuitry could be incorporated into its circuit board as well. Otherwise, a small PCB incorporating a single chip charging regulator may be built.

In an embodiment having the hardware listed below for cable system48comprising a mini-coax-type cable, and assuming a deployment duration of approximately 8 minutes for towed antenna system40, each device may be expected to demand the following amounts of electrical energy:

In this embodiment, the maximum current required is therefore approximately 1.36 amps. Taking, for example, cable282, which may be rated to transmit only approximately 0.2 amps, the voltage may need to be stepped up to approximately 38.5 volts to provide enough power to system components. A DC-DC converter may be employed to step the voltage down to any level required by any electrical component of towed antenna system40. In addition, a passive filter located in towed body60may be employed to separate out the DC power from any data signals.

While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the disclosure herein is meant to be illustrative only and not limiting as to its scope and should be given the full breadth of the appended claims and any equivalents thereof.