Unlocking interoperability in the underwater domain: secure acoustic communications

New concepts of operations are emerging which look to increase lethality by leveraging additional sensing capabilities from remote and autonomous systems that operate alongside crewed ships and submarines. The aim is not simply to remove the sailor from the battlefield. Rather, the objective is to deliver increased mission success by providing sailors with additional tools that extend the range of their sensing capabilities, allowing them to gain quick and easy access to actionable data.

Autonomous systems provide a range of capabilities that can deliver persistent underwater surveillance. They can act as the spearhead to a strike group, they can enhance situational awareness by monitoring chokepoints, and they can scale and help extend our reach beyond our own sensing capability.

These concepts require an effective, low probability of intercept and secure network. The solution today is to standardise on one specific supplier using acoustic modems that use the same proprietary protocols. This is not only ineffective, it can compromise security.

Acoustic communication, whilst multifaceted and technically challenging, is both proven and mature. In solving the interoperability problem however, it’s not just about the underpinning technology, but also how industry-academia-government institutions collaborate at the national and international level to address the specific challenges of military communication in the subsea domain. Through this collaborative working, technologies can be developed that will enable interoperability across key operational requirements including secure transmission, multi-user networking, and achieving optimal situational awareness.

In other words, if you want your autonomous underwater vehicle (AUV) systems, divers and submarines to be truly effective and avoid vendor lock-in, you need to come up with a common language.

Dstl has pioneered a breakthrough – Phorcys

The UK Defence Science and Technology Laboratory (Dstl), in conjunction with UK industry partners, including our technology partner Sonardyne, academic partners such as Newcastle University, and the National Cyber Security Centre (NCSC), has been developing a UK government-owned acoustic communication waveform to address the challenges of open, secure and interoperable tactical acoustic communication. This technology, known as Phorcys, will be published as an open standard for worldwide use.

Phorcys works using cryptographic keys that provide two separate layers of encryption for both the waveforms and the data, making it nigh on impossible to break the code. The Phorcys waveform will allow Phorcys equipment vendors to certify equipment, and so provide truly secure and interoperable acoustic communication. Users will select their own keys thus ensuring only they can communicate with their assets.

There is no single operating frequency that meets the many and disparate user requirements for tactical acoustic communication. Acoustic frequency determines range, with lower frequencies providing longer ranges. The Phorcys waveform standard spans three frequency bands to provide a trade-off solution space spanning ultralong range, over 15 nautical miles, command, and control (C2) i.e., asset ‘paging’, medium range, up to 15 nautical miles, command control and communication (C3) applications, and short-range, up to three nautical miles, C3 applications. A key consideration in this multi-band approach to subsea acoustic communication is the fact that size, weight and complexity is driven by the acoustic transducer and not the software or hardware responsible for generating and receiving the acoustic signals.

Making Phorcys work requires a single consolidated software-defined modem (SDM) architecture, separably configurable for each band and transducer. This SDM needs to be hosted in a range of platforms. The integration of open secure waveforms and flexible SDM architectures is arguably the key step towards unlocking true interoperability in the underwater domain.

Where are we now? What’s next?

A recent trial off the coast of Portugal demonstrated a secure data exchange between a submarine and its support vessel at range. This was the first time an acoustic data exchange, using modern cryptographic principles, had been transmitted from a submarine.

At Forcys, our aim now, working alongside our technology partners, is to enable Phorcys certified systems to be supplied as standard on commercial-off-the-shelf (COTS) platforms. These systems are already integrated across the underwater domain on unmanned underwater vehicle (UUV) systems, diver hand-held devices and swimmer delivery systems. The benefits from upgrading them to this new standard will deliver immediate effect.

If you would like to find out more about acoustic communications or want to be a partner in delivering interoperability, please get in touch.