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Virtual Reality
Under the Sea

USS Oklahoma City (SSN-723)
Shoots Torpedoes in the Bahamas
that Run in Newport

by Will Canto

 

“Firing Point Procedures, Sierra One, ADCAP torpedo, Tube 2,” barks Lieutenant Brian Roth, Officer of the Deck on the USS Oklahoma City (SSN-723). He’s driven the ship to the optimum firing position against a live target on the Atlantic Undersea Test and Evaluation Center (AUTEC) range in the Bahamas.

LTJG Wade Cole, the Junior Officer of the Deck (JOOD), directs final adjustments and announces, “Solution Ready.”

“Ship Ready,” Roth confirms, properly continuing the litany prior to torpedo launch.

“Weapon Ready!” returns FT3(SS) Mike Brodbeck.

Satisfied all is well, Roth orders “Shoot on generated bearings.”

“Set…standby…shoot!

This is a familiar scene for many submariners, but today on Oklahoma City, there’s a difference. The submarine is not launching an exercise torpedo, nor is its crew practicing only on the ship’s on-board test equipment. Oklahoma City is plugged into a digital network established by engineers and scientists at the Naval Undersea Warfare Center Division Newport (NUWCDIVNPT) that permits real-time connectivity among submerged submarines on the AUTEC range and test facilities on the beach in the Bahamas and Newport, Rhode Island. Oklahoma City, submerged in the Bahamas, has just launched a “virtual torpedo,” which runs inside the “mind” of a computer – and whose guidance hardware is on a test stand – at NUWC’s Weapons Analysis Facility (WAF) in Newport. After launch, the torpedo’s simulated location and corresponding wire-guidance telemetry data are transmitted across the network between the WAF at Newport and the Oklahoma City. The still submerged Oklahoma City “sees” the torpedo in real-time, thus allowing the generation of wire guidance commands on board to compensate for target evasion.

Oklahoma City’s first test shot demonstrated the full capability of this system. Roth’s shot on Cole’s solution was slightly off, but the team properly analyzed the torpedo run after launching, and FT Brodbeck inserted steering commands to turn the weapon around, and acquire and hit the target. Roth’s watchsection successfully launched two more “virtual torpedoes,” thus completing the first test period. LT Brent Rodgers had the conn for the second series. His watchsection, guided by his JOOD, LTJG Chris Hoehn,
performed superbly, successfully launching five more virtual torpedoes, including a “Snapshot” – a rapid
torpedo firing in response to a close-aboard “enemy” contact.

Bringing Modeling and Simulation to the Fleet
This large-scale simulation project is called Synthetic Environment Tactical Integration, or SETI. It establishes the systems, processes, and capabilities that give the Fleet access to NUWC’s models and simulations for undersea warfare. SETI’s goals are to reduce cost and increase the value of testing and training through synthetic torpedoes (as used by Oklahoma City), synthetic targets (to supplement live target services on range), and integration of on-board trainers with external environments. With additional connectivity enhancements, SETI will provide simulated targets, countermeasures, and range- correlated ocean environments. Expected additions include simulations of undersea weapons for surface and air anti-submarine platforms. The benefits of connecting NUWCDIVNPT’s undersea weapons simulations to live ASW platforms include:

  • Allowing crews to train on their own platforms, sensors, and fire control systems
  • Unlimited availability of virtual weapons
  • High confidence hit-or-miss assessment and analysis
  • Re-prosecution and re-attack support
  • Actual target evasion and weapon interaction with countermeasures
  • Avoiding some of the artificiality of exercise constraints

Thus, SETI expands the applications of high fidelity simulation capabilities far beyond the walls of the laboratory, enhancing the reusability, accessibility, and versatility of these land-bound simulators. By coupling an operational SSN to modeling and simulation assets, the Fleet can become an at-sea contributor to the life cycle support of existing weapons and an integral part of research and development for new weapon technology.

How it Works
For the SETI Virtual Torpedo program, submarines operating at depth and speed at AUTEC can constructively launch virtual torpedoes that “run” at NUWC’s Weapons Analysis Facility in Newport, Rhode Island. The SETI network integrates three major facilities into a single, coordinated system.

Atlantic Undersea Test and Evaluation Center (AUTEC)
The AUTEC range systems provide accurate underwater and in-air tracking for both firing platforms and targets using a variety of acoustic beacons and sensors. By taking advantage of the growing maturity of underwater acoustic telemetry, AUTEC can also provide two-way digital data communications with submarines operating at speed and depth. Systems already under test have demonstrated reliable, secure, two-way data transmission over several nautical miles at data rates exceeding one kilobit per second (Kbps). While this is neither wide-band nor long range, it adequately supports the current requirement, and expected advancements will bring higher data rates and longer ranges in the future.

Exercise Communication Center (ECC)
The ECC connects the simulation facilities at NUWC, Newport to the range infrastructure at AUTEC via encrypted land line and satellite data links. It also provides a gateway to other high fidelity modeling and simulation centers operated by the Army, Navy, and Air Force through similar classified communication links.

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An OKLAHOMA CITY Officer of the Deck directs his watchsection
through the final stages of virtual torpedo launch.

Weapons Analysis Facility (WAF)
The actual Mk 48 ADCAP torpedo guidance and control hardware and its embedded software reside at the WAF and constitute an OPTEVFOR-certified simulation. A nearby supercomputer simulates the torpedo-target geometry and the underwater acoustic environment, and generates a high fidelity representation of what the torpedo would “hear” at every moment of the evolving scenario. These acoustic inputs stimulate the torpedo guidance system on the bench, which interprets the data and responds with steering commands. These, in turn, are fed back to the computer simulation to move the scenario forward in time. Similarly, wire commands from the submarine are received and acted upon also. This hardware-in-the-loop setup permits testing the latest torpedo hardware and software more quickly, at lower cost, and with minimal risk. Further, it allows for more rapid Fleet feedback and familiarization.

The Future
The SETI system design allows for extension of virtual reality to other instrumented ranges, such as Atlantic Fleet Weapons Training Facility (AFWTF), Southern California Off-Shore Range (SCORE), and the Pacific Missile Range Facility (PMRF). With additional development in acoustic telemetry, this capability could be extended to open-ocean exercises.

Efforts are already underway to apply the already developed Mk 48 ADCAP virtual torpedo concept to airborne platform lightweight torpedoes launched from aircraft, such as the Mk 46 and Mk 50. A partnership between NUWCDIVNPT and the Naval Aviation Warfare Center Aircraft Division (NAWCAD) Patuxent River, Maryland, is currently addressing the benefits of air-dropped virtual torpedoes.

The first test of this capability will have a live Light Airborne Multi-Purpose System (LAMPS) helicopter launching virtual torpedoes against simulated targets. Deployed on surface ships, LAMPS helicopters perform their mission by localizing submerged threats, downloading weapons presets into air-launched torpedoes, and dropping the weapons to find and destroy the target. The scenario provides for real-time testing of probability of kill, insertion of countermeasures by the threat, simulation of threat evasive maneuvers, and test of LAMPS re-attack capabilities. This same technology can be applied to other air ASW assets, with substantial reuse of our current capabilities for future platforms.

SETI is an example of how Navy support organizations are harnessing the electronics revolution to improve the quality and flexibility of at-sea training, while reducing costs. It allows leveraging laboratory resources created for long-term research and development to support other applications, such as training and readiness. Continuing improvements in high performance computers allow engineers to simulate complex ocean environments and predict sound-ray paths with ever greater accuracy. Advancements in communication network architectures for simulation, such as DoD’s High Level Architecture (HLA), are supporting high-speed transmission and integration of data from an array of platforms, sensors, and modeling and simulation devices. Future developments in data processing and transmission, with improved human-computer interface, will undoubtedly change the way sailors train to fight their ships and aircraft. Twenty-first century sailors are likely to train more efficiently with the aid of virtual systems, allowing them to “stay-up” on their warfighting skills, instead of “working-up” for deployments as we do today.

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Will Canto is the project manager of the SETI system at NUWC, Newport.

 

Underwater Acoustic Telemetry

The SETI Virtual Torpedo Program makes use of a growing body of techniques for underwater acoustic digital communications that have been under study for several decades in both academia and industry. Specifically, AUTEC uses the NUWC-developed Underwater Digital Acoustic Telemetry (UDAT) modem system to provide robust bi-directional communications between the facility’s Command/Control Center ashore and submerged submarines on the range. At the transmitting end, a modem (modulator-demodulator) transforms digital data streams into acoustic signaling waveforms that are transmitted through the water to a waiting receiver. There, a second modem converts the acoustic signals back into digital data. On submarines at AUTEC, the incoming acoustic telemetry signals are received on the WLR-9 sensors, while outgoing data is transmitted on the broadband low frequency transducer that also serves as the standard range “pinger” for acoustic tracking.

Using acoustic signals with carrier frequencies between 10 and 20 kilohertz, data rates on the order of 900 -1800 bits per second are routinely achieved at 10,000 yards in deep water.