Superimposed training low probability of detection underwater communications

Louza, Fábio B.; DeFerrari, Harry A.

http://hdl.handle.net/10400.1/14782

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Authors

Louza, Fábio B.

DeFerrari, Harry A.

Abstract(s)

This paper proposes a superimposed training method for low probability of detection underwater acoustic communications. A long pilot sequence was superimposed to the message for equalization and synchronization purposes. A fast Hadamard transform (FHT) estimated the channel impulse response and compressed the pilot energy. A Wiener filter performed equalization. The interference signal was removed using hyperslice cancellation by coordinate zeroing. An inverse FHT decompressed the remaining sequence energy and the message was retrieved. Results from a shallow water experiment presented bit error rates <10-2 for signal-to-noise ratios <-8 dB.