Ocean Server Technology, Inc.

Digital Equipment Corporation

Compaq Computer Corporation, Inc.

Other

Hewlett-packard Development Company, L.p.

L3 Technologies, Inc.

Trackserver, Inc.

Jonathan C Crowell

David William Maruska

Joseph Ervin

Jeffrey P Copeland

Kevin W Ludlam

David Charles

A system where a large number of underwater devices can transmit their precise position relative to a fixed underwater beacon, by transmitting two short duration, precisely timed acoustic tones (pings). The arrival time of the pulses at the fixed underwater transceiver beacon will relay the transmitter's precise position relative to that beacon. The two pings code for two numbers; either the range and bearing or an X, Y coordinate of each object with respect to the beacon. Data messages can be sent to and received from the beacon, used for command, control and status. The pulses can be a single frequency and have duration of around a 1 ms and operate one or many frequencies to allow multiple cycles to be overlapped in time. This coding scheme allows many devices to send the data simultaneously in the cycle for group tracking from last position or as independent cycles for unambiguous tracking. The transducers used in the system can be omni-directional hydrophones. The tracking grid size is a function of the acoustic frequency chosen and range from 1000 m for 40 KHz and 6000 m for 8 kHz. The system requires that all nodes in the system keep precise synchronized time.

Underwater acoustic tracking and two way messaging system

Systems and methods are disclosed allowing for spatially separated nodes to transmit data to a single remote master receiver node in a synchronized way. Slave nodes can send acoustic data so that it travels through water and arrives at the master node exactly timed so that the data bit appears in a predetermined time slot. The next time slot could be a data bit coming from another remote or slave node in another direction and at a different distance. This can be repeated for many nodes and the incoming bits will be received in a time division multiplexed fashion at the receiver or master node. The senders address and bit meaning are implicit due to the time slot in which they arrive. The assumption is that all nodes have accurate synchronized time as well as the ability to accurately estimate sound travel time between itself and any master node.

Method and apparatus for underwater acoustic communication

Methods and systems for synchronizing clocks used in underwater devices is described. All clocks have some drift due to frequency accuracy and this disclosure provides a method for periodically synchronizing clocks to an accurate master clock to remove long term drift. A synchronization device can use an accurate clock and hardware to transmit both a sound wave and light pulse at the same point in time. Remote slave clocks can detect the light first, and later the sound, allowing them to calculate the distance the pulse had to travel. The clocks can then synchronize their time to the master clock canceling out any drift. The synchronization device can be packaged in a waterproof housing and can be moved around on a periodic basis between the clock on an underwater robot or any other means.

Method and apparatus for synchronizing clocks underwater using light and sound

A system and a method are provided for determining the position of an underwater vehicle while the vehicle is operating underwater. A buoyant float stays on or near the surface of the water and is attached to the vehicle by thin tether that can include insulated wires. The vehicle moves under the water and pulls the float behind it. The float can receive a localization signal, such as a signal indicating its GPS position, and so can determine its position precisely. The position can be transmitted to the underwater vehicle over the wires located in the tether. The underwater vehicle can use sensors and/or calculations to determine the positional offset of the vehicle from the float buoy and generates its true position based on the known position of the float and the positional offset. The float can be constructed with attributes that will allow the float it operate with a greater tether length, and in turn allow the underwater vehicle to operate at greater depths. The float may also generally carry a radio system for high speed communication of signals from the vehicle while the vehicle is submerged.

System and method for determining the position of an underwater vehicle

A system and a method are provided that allow load sharing between two or more DC output power supplies that are connected in parallel to scale the output power. As the temperature of the critical components in a power supply rises, the output voltage from that power supply will be lowered, so that the coolest supply will have the highest voltage and thus the highest current to the load. The systems and methods can operate without any additional wires connecting the supplies other than those supplying the power to the load.

Load balancing method and system to scale DC output power by temperature of parallel DC power supplies

Methods and devices are provided for rescuing and recovering underwater vehicles. In one embodiment, a system is provided that includes a modular rescue device configured to attach to an underwater vehicle, such as with a tow line. The rescue device can include one or more emergency mechanisms that can be automatically and/or manually activated to aid in detecting the location of the underwater vehicle in the event of an emergency. One exemplary emergency mechanism includes a buoyancy mechanism, e.g., an expandable lift bag, configured to be inflated with a fluid to add buoyancy force to the system to pull the underwater vehicle toward a water surface. Another exemplary emergency mechanism includes a signaling mechanism configured to signal the underwater vehicle's location.

External rescue and recovery devices and methods for underwater vehicles

A method for determining the position of an underwater device includes placement of a plurality of station keeping devices on or below the surface of the water in known positions. A device to locate is provided for placement below the surface of the water, and the device to locate and the station keeping devices are provided with a synchronized time base and a common acoustic pulse time schedule. Each station keeping device sends an acoustic pulse at a time according to the common acoustic pulse schedule. The device to locate receives pulses sent by the station keeping devices and calculates a distance between itself and each station keeping device based upon the time that the acoustic pulse is sent and the time that the pulse is received. The device to locate then calculates its position based upon the distances between the device to locate and the station keeping devices.

Underwater acoustic positioning system and method

A method for determining the position of an underwater device includes placement of a plurality of station keeping devices on or below the surface of the water in known positions. A device to locate is provided for placement below the surface of the water, and the device to locate and the station keeping devices are provided with a synchronized time base and a common acoustic pulse time schedule. Each station keeping device sends an acoustic pulse at a time according to the common acoustic pulse schedule. The device to locate receives pulses sent by the station keeping devices and calculates a distance between itself and each station keeping device based upon the time that the acoustic pulse is sent and the time that the pulse is received. The device to locate then calculates its position based upon the distances between the device to locate and the station keeping devices. Systems and devices are also disclosed.

A general purpose computer apparatus including a central processing unit, a main memory and a system bus. The general purpose computer apparatus further includes means for interfacing the central processing unit to the system bus and means for interfacing the central processing unit to an I/O bus. A housing encloses the central processing unit, the main memory and the means for interfacing, with the housing having a mechanical form factor corresponding to a disk drive housing.

Apparatus for providing a CPU cluster via a disk I/O bus using a CPU brick which fits into a disk cavity

An apparatus is provided for reducing read latency for an I/O device residing on a bus having a short read latency timeout period. The apparatus includes a I/O bridge on an I/O bus having a longer read latency timeout which modifies read transactions into two separate transactions, a write transaction to the same address requested by the read transaction which will force a write-back if the address hits in the CPU's write-back cache, and then performing the read transaction which is performed after a predetermined period of time following initiation of the write transaction. This removes the possibility of a device on the I/O bus having a short read latency timeout period from exceeding it's read latency timeout limit.

Method and apparatus for reducing the apparent read latency when connecting busses with fixed read replay timeouts to CPU'S with write-back caches

An apparatus is provided for reducing read latency for an I/O device residing on a first bus having a first, short read latency timeout period. The apparatus includes a I/O bridge on a second bus having a second, longer read latency timeout compared to that of first bus which modifies read transactions into two separate transactions. A first transaction is a write transaction to the same address requested by the read transaction. This transaction forces a write-back if the address hits in a CPU's write-back cache. Thereafter the read transaction is performed after a predetermined period of time following initiation of the write transaction. This removes the possibility of a device on the first bus having a short read latency timeout period from exceeding it's read latency timeout limit.

Method and apparatus for reducing the apparent read latency when

A computer system includes a housing, a motherboard, a first module and a second module. An electrical connector on the motherboard is joined to and in electrical communication with an electrical connector on one of two opposing surfaces of the first module, and an electrical connector on the second module is joined to and in electrical communication with another electrical connector on the other of the opposing surfaces of the first module. An electrically conductive path connects the two electrical connectors on the opposing surfaces of the first module. The motherboard transmits electrical signals corresponding to a module identifier to the first module through the motherboard's joined electrical connector. An electrical device on the first module in the electrically conductive path modifies the electrical signals so that they correspond to a second module identifier. The modified electrical signals corresponding to the second module identifier are transmitted to the second module via the electrically conductive path through the electrical connector on the first module that is joined to the electrical connector on the second module.

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Dorchester, MA, United States of America

Jonathan C Crowell