Martin Siderius

Electromagnetic waves attenuate rapidly in the ocean, which has led to acoustic waves being the most practical way to sense and communicate in marine environments. Many of the everyday technologies we use for navigating and communicating in terrestrial environments (in air) are extremely difficult to duplicate when operating under the ocean. As an example, off-the-shelf aerial drones can easily navigate using GPS and communicate using radio-frequencies (RF) capable of transmitting real-time video. Underwater drones are much more limited due to the difficulties in both navigation and having to use acoustic communications. The issues for underwater acoustic communications are numerous. The acoustic propagation speed is many orders of magnitude slower than for RF signals and the acoustic channel is severely band-limited due to frequency dependent attenuation. For communications over 1-10 km, commercial modems typically operate below 50 kHz and use bandwidths less than 10 kHz. Further, acoustic signals suffer from multipath interference as well as boundary reflections and scattering. If a modem is on an underwater vehicle, the motion can introduce not only Doppler shifts in the received signal but also multipath Doppler spread. In this presentation, the underwater acoustic channel will be described to illustrate the many complexities that can distort signals. Modeling techniques have been developed to better understand the acoustic propagation physics and these will also be discussed.

Biography:

Martin Siderius received his Ph.D. degree in Electrical Engineering from the University of Washington, Seattle, WA, in 1996. After graduating, he joined the NATO Undersea Research Centre in La Spezia, Italy where he stayed until 2001. From there, he joined Science Applications International Corporation (SAIC) as a Senior Scientist and remained there until 2004 when he left to co-found HLS Research Inc. (San Diego, CA). At HLS Research, he was the Vice-President and a Principal Scientist. In 2008, he joined the faculty of the Department of Electrical and Computer Engineering at Portland State University where he currently holds the rank of Professor. His teaching includes courses in electromagnetics, acoustics and signal processing. His research interests are in underwater acoustic propagation and scattering, signal processing, ambient noise, geoacoustic inversion, computational acoustics, acoustic communications and marine mammal acoustics.