Underwater navigation system

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 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.

Description

CROSS-REFERENCE TO RELATED APPLICATION[0001]This application claims the benefit of Ser. No. 60 / 690,964, 60 / 690,966, and 60 / 690,959, all filed Jun. 15, 2005, and is a continuation in part of GB0602398.0, filed Feb. 7, 2006, which applications are fully incorporated herein by reference.FIELD OF USE[0002]The present invention relates generally to an underwater communications system, and its methods of use, and more particularly to an underwater communications system that uses electromagnetic propagation and magnetic induction transmission, and optimizes the distance which can be achieved by digital transmission of information.DESCRIPTION OF THE RELATED ART[0003]Various underwater communication systems are known. One of the most common is based on acoustic techniques. A problem with such systems is that they are degraded by noise and interference from a number of sources. They are also subject to multi-path effects and in some environments are virtually unusable. Other underwater commun...

AI Technical Summary

Benefits of technology

[0009]Accordingly, an object of the present invention is to provide an improved underwater communication systems, and its methods of use, that uses electromagnetic waves for communication and propagation.

[0010]Another object of the present invention is an underwater communication system, and its methods of use, for communication and propagation that increases the distance over which information can be transmitted.

[0011]Another object of the present invention is an underwater communication systems, and its methods of use, for communication and propagation that increases the useful information rate.

[0012]Another object of the present invention is an underwater communication systems, and its methods of use, for communication and propagation with improved data compression by reducing the transmitted bit rate.

[0013]Another object of the present invention is an underwater communication systems, and its methods of use, for communication and propagation where the transmitted bit rate is reduced when there are a number of types of information sources.

[0014]Another object of the present invention is an underwater communication systems, and its methods of use, for communication and propagation that has a resultant reduced bit rate that allows lower transmitted signal frequencies to be adopted.

Problems solved by technology

A problem with such systems is that they are degraded by noise and interference from a number of sources.

They are also subject to multi-path effects and in some environments are virtually unusable.

Whilst the communications systems of WO01 / 95529 and GB2163029 have some technical advantages over more conventional acoustic or radio link systems, the functionality described is limited, and for many practical applications the available bandwidth is highly restrictive, as is distance over which data can be transmitted.

However, for propagating electromagnetic waves the energy is continually cycling between magnetic and electric field and this results in attenuation of propagating waves due to conduction losses.

The attenuation losses, the bandwidth restrictions and the limited distances over which data can be transmitted all pose significant practical problems for underwater communications.

Existing methods of acoustic communication are inherently restricted in the distance they can achieve at effective data rates.

The existing art of electromagnetic communication under water fails to recognize measures that can be taken to maximize the distance and / or useful information rate which can be achieved by adapting the devices sourcing and using the information so that more effective signal frequencies can be adopted.

Images