An underwater communication method, device, and system that enables bi-directional communication between and among under-water divers. In accordance with the present invention, messages may be transmitted and received between and among the divers in a network and/or between divers and a diving boat, buoy, or other reference point. The present invention also permits one or more divers to receive a homing signal and to move toward the source of that signal using an acquisition and tracking feature and functionality that utilizes a Doppler frequency shift and preferably a compass to determine the distance and direction of the source of the signal. The present invention also enables a diver in distress to broadcast a distress signal (i.e., SOS) that is received by every other diver within a predetermined distance from the distressed diver. The divers receiving the distress signal are then able to locate and rescue the distressed diver using the acquisition and tracking feature and functionality.

A relative positioning system enabling a user to return to a starting position or some other point on the user's path. The system may include an array of accelerometers. The output from the accelerometers may be integrated to quantify movement of the array. The various movements of the array may be reconstructed to determine a net two or three dimensional translation. The current location of the array may be compared to a reference point to derive at trajectory directing the user to the reference point The trajectory may be continuously or periodically updated. Another application may include an accelerometer array secured at various positions on a ski to monitor distortion of the ski and the skier's movements. Reconstructing the skier's movements may be accomplished by integrating the accelerometer output and transforming the integrated output into a two or three dimensional path or location.

An apparatus for providing Global Positioning System (GPS) position data to an underwater diver for use in navigation is comprised of a SCUBA Flag/Antenna Float, positioned on the surface of the water, containing a Spring-loaded Cable Reel which is connected via a Signal Umbilical Cable to a GPS Capsule carried by the underwater diver. A GPS Antenna and power supply provide a signal to a GPS Receiver/Display which is encased in the GPS Capsule. The diver views icons displayed on the GPS Receiver to determine his/her current position in relation to previously entered waypoints, or geographical coordinates, such as a wreck, dive boat, or locations of interest plotted by the diver during the dive. The position information displayed by the GPS receiver enables the diver to navigate to and from the various locations or geographical coordinates while submerged.

A multi-functional underwater device for use by scuba divers for communicating with and tracking the relative direction of one or more other divers. The device is configured to monitor and communicate with multiple other devices simultaneously and includes a transmitter and receiver assembly for transmitting location signals to and receiving location signals from other communication devices on frequencies defined by a communication channel setting for the device. A processor processes signals to determine separation distance between the devices and to compare separation distances to a safety distance. A display assembly indicates communication channel and safety distance for the communication device and indicates when the separation distance is exceeded. The display assembly includes an input portion operable to set the safety distance and/or the communication channel. The transmitter and receiver assembly transmits and receives communication signals, such as check diver and emergency signals, at frequencies defined by the communication channel.