Patent ID: 8682244

Claim:
An underwater communications system comprising: an electromagnetic transmitter which transmits electromagnetic and/or magnetic signals to a remote receiver, an optical transmitter which transmits optical signals to said remote receiver; a data input and a device for selecting one of said electromagnetic transmitter and said optical transmitter; said electromagnetic transmitter comprising a modulator for modulating input data onto a carrier signal wherein at least one of said electromagnetic transmitter and said remote receiver is underwater and said electromagnetic transmitter and said remote receiver are operable to communicate within a near field of said electromagnetic and/or magnetic signals, said near field of said electromagnetic and/or magnetic signals corresponding to the region around said electromagnetic transmitter where at least one of inverse distance squared (1/r 2 ) and inverse distance cubed (1/r 3 ) field components of said electromagnetic and/or magnetic signals is greater than an inverse distance (1/r) field component thereof.