Abstract: An underwater navigation system comprising a transmitter having an electrically insulted magnetic coupled antenna for transmitting an electromagnetic and/or magneto-inductive signal, a receiver having an electrically insulated magnetic coupled antenna for receiving an electromagnetic and/or magneto-inductive signal from the transmitter, and determining means for determining the position of the receiver relative to the transmitter using the received electromagnetic and/or magneto-inductive signal.

Abstract: The present invention provides a wireless auxiliary system for monitoring and control of an underwater installation. The auxiliary system of the present invention sends data and control signals between an underwater installation—for example, a lower stack 26 in a hydrocarbon drilling or production facility—and an associated riser assembly 23. Data is collected by sensor network 208A, 208B and is transmitted from a first transceiver 201 to a second transceiver 203 by electromagnetic signals. First transceiver 201 is powered by a local power supply 205. To conserve power consumption, the first transceiver is designed to become active for a short time and then to switch to an inactive mode. For example, wireless data transfer may occur after the detachment or just prior to the reattachment of riser assembly 23 to the underwater installation. Wireless data transfer may also occur on receipt of a handshaking signal from second transceiver 203.

Abstract: A bi-directional asymmetric system is provided with a first node and a second node. The first node has a first transmitter that produces a modulated magnetic flux and a first exciter receiver that acts to receive data at the first node. The second node is coupled to the first node with a direct inductive communications downlink and a mutually inductive uplink. The second node includes a receiver that produces a signal induced by the first transmitter at the first node. The second node has a mutually inductive data transmitter that modules an exciter signal produced at the first node by the exciter receiver.

Abstract: An underwater system (10) comprising a transmitter (12) for broadcasting an electromagnetic synchronization signal and at least one node (14) that has a receiver for receiving that signal, the node being adapted to use the received signal for synchronization.

Abstract: The present invention relates to a system that provides flexible data access to a wired underwater communications network through an electromagnetic, non-conductive connection. An underwater data access point is described wherein data access to a cabled network is provided through an electromagnetic connection. An inductive connector system may also be provided to allow transfer of data and/or power between a data access point and a client system.

Abstract: A magnetic flux coupling transducer system comprising a primary coil (51) and primary coupling core (52) and a secondary coil (54) and secondary coupling core (55) for passing communications signals and/or electrical power from one side of an electrically conductive barrier to receiving equipment on the other side.

Abstract: A magnetic and/or magneto-electric antenna that has a plurality of conducting loops where each individual loop can be resonated at a frequency that is offset from the frequency of the other loops to provide a composite band-pass response that is broader than that of the individual loops. A receiving circuit acts to sum the signals from each of the antennas to provide a combined frequency response that is broader in bandwidth than any of the individual loops. Similarly a combination of multiple transmitter loops where a transmit circuit drives a common transmit waveform to each of the combined antennas to provide a combined transmitter frequency response that is broader in bandwidth than any of the individual loops.

Abstract: An environmental monitoring system including at least one underwater measurement device and a transmitter for transmitting data from the measurement device to an above water station using a magnetically coupled antenna.

Abstract: The present invention discloses a tagging and identification device and system for tracking and monitoring sea vessels as they enter sea ports, estuaries and/or other channels. The tagging device of the present invention comprises a receiver, for receiving an underwater electromagnetic signal transmitted by an underwater beacon. An acoustic transmitter is provided for transmitting an identification signal to an acoustic receiver deployed nearby. The acoustic identification signal is transmitted after an electromagnetic trigger signal is received from the underwater beacon. The tagging and device may further comprise a memory device which can store data relating to position and time of the see vessel to which it is attached. The tagging and identification device of the present invention is covert, compact and is capable of extended active deployment without replenishment of batteries etc.

Abstract: The present invention relates to an underwater guidance system for guiding an underwater apparatus, for example an underwater vehicle, towards a target structure, such as a docking station. The system comprises at least one system for capturing or sensing information on the relative position of the apparatus and the target structure and/or at least one imaging system for capturing an image of the target structure and a transmitter for wireless electromagnetic transmission of data indicative of the position information and/or captured image to the underwater apparatus or an underwater apparatus controller.

Abstract: An underwater remote sensing system comprising a transmitter for transmitting an electromagnetic signal, a receiver for receiving an electromagnetic signal reflected from an object and determining means for determining the location of the object, wherein at least one of the transmitter and receiver is underwater. The determining means may be operable to determine the location of the object using signals received at three or more receiver positions. To do this, three or more receiver antennas may be provided. Alternatively, a single receiver antenna may be provided and moved between three or more different measurement locations.

Abstract: An underwater communications system is provided that transmits electromagnetic and/or magnetic signals to a remote receiver. The transmitter includes a data input. A digital data compressor compresses data to be transmitted. A modulator modulates compressed data onto a carrier signal. An electrically insulated, magnetic coupled antenna transmits the compressed, modulated signals. The receiver that has an electrically insulated, magnetic coupled antenna for receiving a compressed, modulated signal. A demodulator is provided for demodulating the signal to reveal compressed data. A de-compressor de-compresses the data. An appropriate human interface is provided to present transmitted data into text/audio/visible form. Similarly, the transmit system comprises appropriate audio/visual/text entry mechanisms.

Abstract: An underwater communication method is provided. EM signals are transmitted via a seabed using an underwater electrically insulated magnetically coupled antenna. By making use of the low loss properties of the seabed, EM signal attenuation can be reduced and consequently the transmission range can be increased. The underwater electrically insulated magnetically coupled antenna may be located within a body of water or may be buried in the seabed.

Abstract: An underwater communications system is provided that transmits electromagnetic and/or magnetic signals to a remote receiver. The transmitter includes a data input. A digital data compressor compresses data to be transmitted. A modulator modulates compressed data onto a carrier signal. An electrically insulated, magnetic coupled antenna transmits the compressed, modulated signals. The receiver that has an electrically insulated, magnetic coupled antenna for receiving a compressed, modulated signal. A demodulator is provided for demodulating the signal to reveal compressed data. A de-compressor de-compresses the data. An appropriate human interface is provided to present transmitted data into text/audio/visible form. Similarly, the transmit system comprises appropriate audio/visual/text entry mechanisms.

Abstract: An underwater communications system is provided that transmits electromagnetic and/or magnetic signals to a remote receiver. The transmitter includes a data input. A digital data compressor compresses data to be transmitted. A modulator modulates compressed data onto a carrier signal. An electrically insulated, magnetic coupled antenna transmits the compressed, modulated signals. The receiver that has an electrically insulated, magnetic coupled antenna for receiving a compressed, modulated signal. A demodulator is provided for demodulating the signal to reveal compressed data. A de-compressor de-compresses the data. An appropriate human interface is provided to present transmitted data into text/audio/visible form. Similarly, the transmit system comprises appropriate audio/visual/text entry mechanisms.

Abstract: An underwater communications system is provided that transmits electromagnetic and/or magnetic signals to a remote receiver. The transmitter includes a data input. A digital data compressor compresses data to be transmitted. A modulator modulates compressed data onto a carrier signal. An electrically insulated, magnetic coupled antenna transmits the compressed, modulated signals. The receiver that has an electrically insulated, magnetic coupled antenna for receiving a compressed, modulated signal. A demodulator is provided for demodulating the signal to reveal compressed data. A de-compressor de-compresses the data. An appropriate human interface is provided to present transmitted data into text/audio/visible form. Similarly, the transmit system comprises appropriate audio/visual/text entry mechanisms.