RFID Helps Naval Ships Defend Themselves From Missile Attacks

Each Lockheed Martin decoy launcher (typically two, four or six launchers per combatant, depending on ship size) has a set of six tubes, allowing 12, 24 or 36 decoys per ship to be loaded and fired. Each launcher contains an Aviant low-frequency (LF) 125 kHz RFID reader with six channel options for redundancy. The reader is wired to six antennas, one at the base of each barrel. Naval personnel attach a small disk-shaped tag, compliant with the ISO 11784/5 standards and encoded with a unique ID number, to the bottom of each decoy cartridge. Sailors can then use a handheld Aviant interrogator to read the tag's ID number and link it to the type of decoy to which that tag is attached. When the tagged cartridge is loaded in the launch barrel, the reader identifies the tag's unique ID number and transmits that information to the ALEX system.

The ARID-enabled ALEX system operates in two modes—fully automatic and semi-automatic—though a manual override option exists at all times. When ALEX receives information regarding inbound threats (a potential threat's bearing and type), ship course and speed, and wind speed and direction, it selects the appropriate response from its database of stored tactics. In the fully automatic mode, the response requires no human interface, and the tactic will be deployed automatically. If the ideal decoy/launch barrel combination is unavailable, the system will utilize ARID to select the next best alternative and automatically deploy that tactic. In the semi-automatic mode, the system will suggest the proper tactics, and the ALEX system operator will be presented with those options and, upon receipt of proper authorization from the ship's commanding officer or his or her representative, make the decision to fire. In manual override mode, the ALEX operator takes control of the system and manually selects the launcher and barrel in order to launch a decoy.

To ensure the RFID system would operate properly in the rigorous environment of a vessel at sea, Lockheed Martin put the Aviant system through heavy testing, Porter says. This included vibration, shock, temperature and moisture exposure, as well as testing for electromagnetic interference (EMI) with other systems on a ship.

"The maritime environment is very rugged, so the testing had to be quite rigorous," Porter says. Lockheed Martin needed the ARID technology to last the lifetime of the ALEX system itself, he adds, and to be able to withstand the ship's highly wet and metallic environment, as well as sustain the shocks of repeated decoy firing. In creating a system capable of meeting these objectives, Aviant's engineers designed the antenna so that the antenna coil is insulated from the metal surface to which the tag is attached. "We're very happy with this system," he states. Lockheed Martin also considered several other technology options, he says, including bar-code labels. However, the company ultimately determined that bar codes would not operate as effectively as RFID in a naval vessel environment.