Underwater remote sensing

• US 20100109933A1
• Filed: 01/13/2010
• Published: 05/06/2010
• Est. Priority Date: 06/15/2005
• Status: Active Grant

• Current Assignee: Wfs Technologies Ltd.
• Original Assignee: Wfs Technologies Ltd.
• Inventors: Hyland, Brendan, Rhodes, Mark, Wolfe, Derek
• Granted Patent: US 8,055,193 B2
• Time in Patent Office: Days
• US Class Current: 342/22
• 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
• CPC Class Codes: Y10S 367/901 Noise or unwanted signal reduction in nonseismic receiving system
• CPC Class Codes: Y10S 367/904 Doppler compensation systems
• CPC Class Codes: Y10S 367/91 Portable sonar devices

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.

Claims

1. 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 using the received signal, wherein at least one of the transmitter and receiver is underwater.

2. An underwater remote sensing system as claimed in claim 1 wherein the determining means are operable to determine the location of the object using the field strength at three or more receiver positions.

3. An underwater remote sensing system as claimed in claim 2 wherein three or more receiver antennas are provided and the determining means are operable to determine the location of the object by comparison of the field strength of the signal received at each antenna.

4. An underwater remote sensing system as claimed in claim 2 wherein a single receiver antenna is provided and the determining means are operable to determine the location of the object by comparison of the field strength of the signal received at three or more different receiver locations.

5. An underwater remote sensing system as claimed in claim 1 wherein at least one of the receiver and transmitter has a magnetic coupled antenna.

6. An underwater remote sensing system as claimed in claim 1 wherein at least one of the receiver and transmitter has an electrically insulated antenna.

7. An underwater remote sensing system as claimed in claim 6 wherein each insulated antenna is surrounded by an impedance-matched low conductivity medium, for example distilled water.

8. An underwater remote sensing system as claimed in claim 1 wherein the receiver antenna is a directional antenna and the means for determining are operable to use the directionality of the receiver to determine the relative directional position of the reflecting target.

9. An underwater remote sensing system as claimed in claim 1 wherein means are provided for varying the frequency of the transmitter signal.

10. An underwater remote sensing system as claimed in claim 1 wherein the transmitter and receiver are operable to implement a communications link.

11. An underwater remote sensing system as claimed in claim 1 wherein the receiver shares an antenna with the transmitter.

12. An underwater remote sensing system as claimed in claim 1 wherein the receiver is remotely located from the transmitter.

13. An underwater remote sensing system as claimed in claim 1 wherein the transmitter and receiver are substantially co located.

14. An underwater remote sensing system as claimed in claim 1 wherein the location of the object is determined relative to at least one of the receiver, the transmitter or a pre-determined reference.

15. An underwater remote sensing system as claimed in claim 1 wherein the transmitted signal has a frequency of below 3 MHz.

16. An underwater remote sensing system as claimed in claim 15 wherein the transmitted signal has a frequency in the range of 1 MHz to 3 MHz.

17. A system for determining underwater electromagnetic signal propagation direction comprising at least one receiver for receiving the electromagnetic signal and determining means for determining the direction of propagation using field strength at three or more receiver locations.

18. A system as claimed in claim 17 wherein three or more receiver antennas are provided and the determining means are operable to determine the location of the object by comparison of the field strength received at each antenna.

19. A system as claimed in claim 17 wherein a single receiver antenna is provided and the determining means are operable to determine the location of the object by comparison of the field strength received at three or more different receiver locations.