Channel characterization using FSK wave forms

Automatic characterization of underwater acoustic communication channels can support connectivity over a wide range of operational ocean environments. With quantitative measures of the prevailing channel, adaptive modems may optimize the modulation and initialize the demodulation equalizer. A novel channel-estimation technique involving noncoherent processing of received FSK wave forms has been described recently by Green and Rice (Proc. IEEE Oceans’98) and Rice and Green (Proc. MTS Ocean Community Conference, 1998). This technique uses received handshake signals to measure temporal and spectral spreading and signal excess directly, and to estimate coherence parameters. This effort will focus on applying this channel-estimation technique to received and autonomously recorded 8–13 kHz MFSK signals using shallow horizontal channels. [Work supported by ONR 32 and SPAWARSYSCEN.]