Underwater Navigation

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.

1 . An underwater navigation system comprising:
 a transmitter having an electrically insulated magnetic coupled antenna for transmitting an underwater electromagnetic signal from the transmitter;   a receiver having at least one electrically insulated magnetic coupled directional antenna for receiving the electromagnetic signal underwater;   and a determining means for directly determining the position of the receiver relative to the transmitter using the received underwater electromagnetic signal,   wherein at least one of the transmitter and receiver is underwater and the determining means are operable to use the directionality of the at least one directional antenna of the receiver is used to determine the directional position of the transmitter.   
     
     
         2 . An underwater navigation system as claimed in  claim 1  where the receiver directional antenna is operable to rotate until a received signal strength minimum is received from the transmitter. 
     
     
         3 . An underwater navigation system as claimed in  claim 1  comprising a receiver having two directional antennas operable to receive an electromagnetic signal underwater. 
     
     
         4 . An underwater navigation system as claimed in  claim 3  wherein each directional antenna is spaced apart and operable to rotate until a received signal strength minimum is received from the transmitter at each directional antenna. 
     
     
         5 . An underwater navigation system as claimed in  claim 1  wherein the determining means uses direction of loss gradient of received signal data to determine the position of the receiver relative to the transmitter. 
     
     
         6 . An underwater navigation system as claimed in  claim 1  wherein the at least one directional antenna is provided on a rotatable arm. 
     
     
         7 . An underwater navigation system as claimed in  claim 3  wherein each directional antenna is provided on a rotatable arm.