Navy can text stealthy submarines 24/7.

• Author: Magnuson, Stew
• Position: Battlefield Communications

* SAN DIEGO -- For years, the Navy has wanted to communicate with its submarines as they travel underwater at great depths.

On some missions, a commander can be ordered to run silent and deep for months without any way to send or receive messages.

Communicating with a command center often means rising to shallow depths where a periscope with an antenna can be raised above water.

That makes the ship vulnerable and can expose its presence to the enemy.

The Space and Naval Warfare Systems Center and Raytheon recently tested a new system that will allow a submarine to "send a page" to surface ships or command and control centers or vice versa without having to surface or stop its engines.

Raytheon Co.'s Deep Siren tactical paging system is part of the Navy's communications at speed and depth program. The contractor and SPAWAR conducted a series of tests this year that uses a buoy ejected from the submarine's trash chute to establish a communications link to the outside world.

"Employing this technology enables the submarine fleet to be connected to the network while actively participating in military operations," said Jerry Powlen, Raytheon vice president of network centric system's integrated communications system division.

After the buoy is ejected from the trash chute, it hovers at a predetermined depth as the submarine continues its journey, explained Barry Murphy, director of undersea networked communications at Raytheon.

When the submarine is far enough away, the buoy ascends to the surface, deploys floatation devices and sends a message to a command and control center through an Iridium satellite.

Once a link between the buoy and the command center is established, it then lowers an antenna deep into the water.

A transducer takes messages, translates them into acoustic energy and sends a pulse out through the water in an area greater than 50 nautical square miles.

How many miles and how deep the transmitter operates are classified, Murphy said.

Sending these pulses through ocean waters that have different thermal layers, with different consistencies was one of the challenges.

"Adjustments on the fly are the tricky part," he said.

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