Voices
From the Deep

The New Age of
Submarine Communications

The Submarine Force is rising to the challenge of Forward…From the Sea by seizing numerous revolutionary opportunities offered by the Information Age.

by Jacob Longacre, Gerald Exley, and Craig McMillan

It has begun to transform itself from a “Silent Service” – with a tradition of operating independently – into a full participant in Network-Centric Warfare. With networked computers linked together by a variety of communications paths, submarines will soon be able to transmit and receive information at unprecedented rates. The Navy needs these new capabilities to establish information superiority over future adversaries as a major factor in achieving battlespace dominance.

A key element in this new architecture is the Submarine Communications Support System (SCSS), which adapts Navy-wide communications components and capabilities, while minimizing dependence on submarine-unique equipment. The SCSS will use industry-standard protocols and commercial technology in hardware ruggedized for the rigors of the shipboard environment. Its architecture will phase out today’s “stovepipe” systems to implement a client-server environment for exchanging information by means of seamless and comprehensive connectivity on shared, common-user communication links.

Vision and Roles
The Navy’s Network-Centric Warfare vision relies on sharing information to gain both strategic and tactical advantage. Information Technology for the 21st Century (IT-21) is the key initiative for creating the global information infrastructure required by that vision. For the submarine force to be a capable player in Network-Centric Warfare, it will need to be a full participant in the underlying information networks that enable interoperability with Joint forces. These networks will provide not only the Common Operational Picture (COP) for force coordination, but also the information-handling capabilities the warfighter needs to make better-informed decisions, execute cooperative engagements, allocate forces more effectively, and reduce tactical response times. The network will also transfer intelligence, weather, logistics, and disbursing information to improve operational effectiveness, as well as personal e-mail for better quality of life. For the submarine, the price of admission is a new communications infrastructure to support orders-of-magnitude more data than is possible even today. This infrastructure includes the antennas, transceivers, internal switching, system control, and data distribution elements that will facilitate submarine communications comparable to those of large surface combatants. Further, submarines must achieve these new capabilities without compromising their inherent stealth.

A New Age of Connectivity
The next decade will produce major changes in submarine communications. Increases in data rate, changes in the number and type of links supported, the use of link protocols that allow efficient sharing of the Radio Frequency (RF) spectrum, and improved traffic handling are all under development by the Space and Naval Warfare Systems Command (SPAWAR).

Antenna Developments
The greatest technical challenge facing submarine communications is fielding antennas capable of the high data rates future broadcast circuits will require. Current plans call for phasing out the current AN/BRA-34s in favor of two new antennas: the OE-538 Multi-Function Mast and the submarine High Data Rate (HDR) antenna. The OE-538 will cover all the bands of today’s AN/BRA-34, including Identification Friend or Foe (IFF) and Global Positioning System (GPS), add broadband HF, VHF, and L-band UHF for Link 16, and provide significant reliability improvements. The submarine HDR antenna/terminal features a 16-inch dish antenna, capable of satellite data rates ranging from 128 Kilobits per second (kbps) to 8 megabits per second (Mbps). It will access EHF Low Data Rate/Medium Data Rate (LDR/MDR) transmissions, SHF, and the Global Broadcast Service (GBS).

Further into the future, the next generation of submarine communication masts will be configured as multi-function, broadband antenna systems. They will incorporate electronic support measures (ESM) and offer sufficient aperture and gain to close the satellite links needed for sending and receiving imagery and other high-data-rate traffic.

To gain full benefit from tomorrow’s information infrastructure, the periodic and intermittent nature of traditional submarine connectivity must be supplanted, itself a major change in the way submarines do business. Fundamentally, this requires improving the submarine’s ability to communicate at depth. Submarines will still be able to receive bellringer and short emergency messages throughout most of their speed and depth envelope, but additional capabilities will be added. With the introduction of ELF on-hull antennas and enhanced-data-rate ELF transmissions, submarines will soon be able to receive ELF messages with fewer operating constraints. Also, the Advanced Buoyant Cable Antenna (ABCA), currently an Advanced Technology Demonstration, will allow two-way UHF satellite communications with submarines at depth, to rates of tens of kilobits per second or greater, and with UHF line-of-sight capability to more than 1.5 Mbps. Short-range communications between submarines, from submarines to unmanned undersea vehicles, and from submarines to surface ships will also be possible at depth using advanced underwater acoustic communications. This will provide data rates of several kbps over tens of nautical miles. The ultimate goal is to develop an RF and acoustic communications network for linking undersea forces seamlessly with each other and with air and surface units.

Internal Information Distribution
To take full advantage of these advances in external submarine communications, corresponding enhancements in on-board information processing and distribution are needed. The Submarine Communications Program Office (SPAWAR PMW173) is working with the Joint Maritime Communications Strategy (JMCOMS) Program Office (SPAWAR PMW176) to adapt the Advanced Digital Network System (ADNS) to submarines. ADNS integrates packet switching, Internet-Protocol message routing, and centralized equipment control functions into a suite of Navy-standard components. Operator aids and software automation will streamline the implementation of communication plans, simplify routine operations, and reduce manual maintenance requirements. Similarly, the submarine-unique equipment currently used for message processing will soon be replaced by a message handler based on commercial subsystems and incorporate automatic header recognition and integrated traffic management, as well as archiving and text processing.

The Undersea Network: A Future Vision

The transformation of today’s submarine radio room will occur incrementally over the next decade. During this time, the radio room will be automated increasingly for distribution of both baseband and RF signals. For RF, the Submarine Antenna Distribution System (SADS) will provide automatic switching and routing, as well as antenna system control and signal conditioning. SADS will be operated from a computer workstation that eliminates manual patch panels. Correspondingly, the Submarine Baseband Circuit Switch (SBCS) will use processor control to route baseband signals, as a major step toward achieving a fully automated radio room that can be operated from a workstation located either in the radio room itself or in the ship’s control spaces.

Affordability
In this era of diminishing defense budgets, the affordability of new systems is a key issue. These new communication systems minimize up-front investment by leveraging commercial telecommunications research and technology to the fullest extent possible, particularly in the areas of baseband equipment, data compression techniques, and satellite services. Off-the-shelf and Navy-common and Joint hardware and software will be employed extensively, tailored for submarine applications when necessary. The use of an open architecture will allow subsystems to be upgraded easily with state-of-the-art commercial components. Additionally, the automation of both routine operations and the preparation of communication plans, as well as paperless message distribution, will reduce the cost of training and manning.

Submarine Mast Antenna Progression

From right to left: OE-538 Multi-functional Mast, HDR Antenna, SHF Phased Array Antenna ATD, and Future Antenna Conceptual Designs

Impact on Future Submarine Operations
When fully realized, the enhancements now in development will integrate the Submarine Force more closely than ever into the mainstream of Fleet operations and permit the submarine to operate as a fully-connected member of the Battle Group. This will dramatically enlarge the submarine’s already central role in coordinated undersea warfare, and will improve its already robust capabilities in Intelligence, Surveillance, and Reconnaissance (ISR), land attack, and power projection ashore. This revolutionary connectivity will be central to the ability to respond rapidly to calls for fire from ashore and to participate in cooperative engagements with surface, air, and land assets. Over-the-horizon ISR with offboard sensors on unmanned underwater vehicles and unmanned aerial vehicles will become routine. With the submarine then able to act as a full participant in the Network-Centric Warfare envisioned for the Navy’s future, its former days as a “Lone Ranger” – “out of sight and out of mind” – will be over.

— The authors are scientists and engineers in the Submarine Electromagnetic Department at the Naval Undersea Warfare Center/Newport Division.