Submarine Comms At Depth And Speed

To me, one of the most fascinating areas related to submarine operations is how to communicate securely with the outside world when the submarine is at depth. Unfortunately, this topic is shrouded by secrecy, so we really can't discuss it in an UNCLAS forum like this. That being said, here's some information on a new initiative that looks like it might have some promise:

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...
...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...
...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.

Interesting stuff...