GSM Link Provides Underwater Communications

France Telecom R&D, in partnership with Amphicom, has invented a system that allows telephone communications with a diver working underwater. The system comprises a buoy fitted with a GSM phone relay that handles two-way communications with an underwater terminal - almost like a personal underwater phone booth. The terminal is connected to the buoy by a wire, and is equipped with a dial pad (like a telephone keyboard), a special mouthpiece, a light and a buzzer.

The buzzer and a flashing light alert the diver of an incoming call. The parties are able to talk because of the ability of bones to conduct sound underwater. The sound wave from the surface transits through the system to the mouthpiece. The diver merely has to bite down on the mouthpiece and push a button to "unhook the handset". Sound vibrations propagate to his ear via his skull, which acts as a resonance chamber. He can then clearly hear the incoming call and also talk back, in half duplex mode.

This innovative system is primarily designed for professionals working underwater, and significantly improves safety. Since the end of last year, it has been tested by archeologists at the Alexandrine Research Center, in charge of underwater excavations at the presumed site of the Alexandria Lighthouse, in Egypt.

The new underwater communications system should be commercialized by the end of 2002. France Telecom's research teams are already looking at ways to eliminate the wire link between the buoy and the submerged terminal, so that divers are totally independent. This also means that members of a team diving in the same area can call each other whenever they want. Two possible solutions to transmit voices under water are now under study: ultrasound waves, or weak electrical currents."

Posted to the site on 26th November 2001