The application of spread spectrum signaling techniques to underwater acoustic navigation

There are three standard techniques of tracking underwater vehicles; long baseline acoustic navigation, short baseline acoustic navigation, and ultra-short baseline acoustic navigation. All three techniques require accurate detection of a known signal which may be corrupted by additive noise and multipaths. In the particular case of ultra-short baseline navigation, an accurate phase measurement of the signal must be made in order to compute the bearing estimate. Significant improvements in the resolution of underwater navigation systems are possible with the use of coded wideband signals, as compared to conventional tone bursts. An ultra-short baseline acoustic tracking system has been developed at Woods Hole Oceanographic Institution based on the use of spread spectrum signaling techniques. Simulations and expressions are presented which demonstrate the application of wideband signaling to the problem of underwater acoustic navigation.