A SPREAD SPECTRUM DEEP WATER PINGER SYSTEM

HIGH-VALUE TEST ITEMS ARE OFTEN LOST IN OPEN-OCEAN TEST AND PRACTICE RANGES. SUCH ITEMS INCLUDE WEAPONS, FLIGHT DATA RECORDERS, MISSILES, DRONES, AND MANNED TACTICAL AIRCRAFT. THE LOSS OF VALUABLE TEST DATA CAN BE A SERIOUS PROBLEM. IN ADDITION, RECOVERY OF SOME ITEMS BY FOREIGN GOVERNMENTS NOT ONLY COMPROMISES WEAPON TECHNOLOGY, BUT CAN RENDER AN ENTIRE WEAPON SYSTEM SUSCEPTIABLE TO FOREIGN COUNTERMEASURES. THIS PROPOSAL DESCRIBES A PHASE I SBIR PROJECT THAT WILL DEMONSTRATE THE FEASIBILITY OF AN ADVANCED UNDERWATER LOCATION DEVICE THAT USES SPREAD SPECTRUM SIGNAL CODING. CONVENTIONAL UNDERWATER LOCATION DEVICES, OR PINGERS, EMIT A PERIODIC ACOUSTIC PULSE WHICH IS DETECTABLE BY ANYONE WITH A ULD RECEIVER. WE PROPOSE TO REPLACE THE ACOUSTIC PULSE WITH A PSEUDO-NOISE, SPREAD SPECTRUM SIGNAL. DETECTING THIS SIGNAL REQUIRES AN EXACT REPLICA OF THE TRANSMITTED CODE. TO AN UNAUTHORIZED OBSERVER WITHOUT THE REPLICA, THE BEACON'S SIGNAL IS INDISTINGUISHABLE FROM BACKGROUND OCEAN NOISE.