Underwater synchronisation system

• US 8,279,710 B2
• Filed: 01/31/2007
• Issued: 10/02/2012
• Est. Priority Date: 01/31/2006
• Status: Expired due to Fees

• Current Assignee: Wfs Technologies Ltd.
• Original Assignee: Wfs Technologies Ltd.
• Inventors: Rhodes, Mark, Hyland, Brendan Peter
• Primary Examiner(s): PIHULIC, DANIEL T
• Application Number:
  US12/160,903
• Publication Number:
  US 20100278014A1
• Time in Patent Office: 2,071 Days
• Field of Search: 367/131, 367/134
• US Class Current: 367/134
• CPC Class Codes: H04B 13/02 Transmission systems in which the medium consists of the earth or a large mass of water thereon, e.g. earth telegraphy

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.

Claims

1. An underwater system comprising a transmitter, the transmitter including a clock and transmitting an electromagnetic clock reference synchronisation signal, and at least one node in close proximity to the seabed, the node including a receiver for receiving the signal, the node being adapted to use the received signal for clock synchronisation.

2. An underwater system as claimed in claim 1 wherein the transmitter has an electrically insulated, magnetically coupled antenna for broadcasting the electromagnetic synchronisation signal.

3. An underwater system as claimed in claim 1 or claim 2 wherein the receiver has an electrically insulated magnetically coupled antenna.

4. An underwater system as claimed in claim 1 wherein the transmitter is operable to transmit a synchronisation signal that is indicative of an absolute timing event.

5. An underwater system as claimed in claim 1 wherein the transmitter is operable to transmit a synchronisation signal that is indicative of relative timing.

6. An underwater system as claimed in claim 5 wherein the synchronisation signal is a time varying signal, such as a sinusoidal signal.

7. An underwater system as claimed in claim 6 wherein a receiver is operable to phase lock the received synchronisation signal to an internal system clock to synchronise clock phase.

8. An underwater system as claimed in claim 1 wherein synchronisation occurs substantially continuously.

9. An underwater system as claimed in claim 1 wherein synchronisation occurs periodically.

10. An underwater system as claimed in claim 1 wherein the antennas use the seabed as a transmission path.

11. An underwater system as claimed in claim 1 wherein at least one of the transmitter and receiver(s) is above water and at least one is below water.

12. An underwater system as claimed in claim 1 wherein at least one receiver is operable to re-transmit the synchronisation signal to another more remote receiver.

13. A receiver for use in an underwater system comprising a transmitter, the transmitter including a clock and transmitting an electromagnetic clock reference synchronisation signal, and at least one node in close proximity to the seabed, the node including a receiver for receiving the signal, the node being adapted to use the received signal for clock synchronisation.