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.
The transmitter sends out multiple signals to overcome this problem, he added.
After a predetermined number of days, the buoy either self-scuttles, and drops to the ocean floor, or the surface command center sends a message to the buoy ordering it to cease operations and allow itself to sink.
Before that, the submarine and command center can send hundreds of text messages if needed.
Ultra Electronics Maritime Systems and RRK Technologies Ltd. are partnering with Raytheon.
In April, an initial test demonstrated that a ship could deploy the buoy. The system works both ways. If a submarine has orders not to surface, but a command center wants to contact it, the buoy can be dropped from an aircraft or tossed over the side of a ship.
Once the transmitter is deployed, it can send out the pulse so the submarine can establish a communications link.
In June, a Navy submarine deployed 12 buoys at the Atlantic Undersea Test and Evaluation Center’s deep water range in the Bahamas, according to Raytheon. The buoy established a link between the submarine and a command center in Norfolk, Va.
A military utility assessment was conducted in August, and results from that test were expected in December.
“We would like to see it migrating from Iridium into other communications bands and other communications satellites,” Murphy added.
“It is a desirable capability and it’s the first capability for communications at speed or depth,” Murphy said.
It will be up to the Navy to fund the system and move the program forward, Murphy said.