AuthorIltis, Ronald A.
AffiliationUniversity of California, Santa Barbara
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RightsCopyright © International Foundation for Telemetering
Collection InformationProceedings from the International Telemetering Conference are made available by the International Foundation for Telemetering and the University of Arizona Libraries. Visit http://www.telemetry.org/index.php/contact-us if you have questions about items in this collection.
AbstractUnderwater acoustic (UWA) telemetry requires wideband waveforms for anti-multipath which are simultaneously easy to equalize and demodulate. The Walsh/m-sequence waveforms proposed here are robust to multipath and with appropriate time-guard bands do not require equalization. For example, in the UCSB prototype acoustic modem, a data rate of 133 bps is achieved using 8-ary Walsh signaling with an 11.2 msec. symbol duration. Demodulation is performed using noncoherent detection, and hence accurate phase tracking, which is difficult to achieve in the UWA channel, is not required. However, telemetry from unmanned underwater vehicles (UUVs) is more problematic due to large Doppler shifts resulting from platform motion. A new receiver algorithm based on Matching Pursuits is proposed which combines channel and Doppler shift estimation. Symbol-error rate (SER) simulation results are presented for the UWA modem under realistic Doppler/multipath conditions.
SponsorsInternational Foundation for Telemetering