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Tim Wen

Principal Engineer

Email

tim@apl.washington.edu

Phone

206-543-6860

Research Interests

Arctic Acoustics, Data Acquisition and Analysis, Software, Embedded Software

Biosketch

Timothy Wen is a research experimentalist, software designer, and data analyst. He has participated in many arctic field trips, measuring ice thickness with high-frequency sonar, acoustic absorption in the direction of ice growth, and the directional properties of acoustic reflections from ice surfaces. He has also provided data acquisition expertise for studies of air-sea interactions and has been involved in the design and coding of a software package to analyze shipboard sensor calibration for the Navy. Most recently, he has designed and implemented embedded software for unattended data acquisition and for controlling an autonomous underwater vehicle used to profile the ocean. Mr. Wen has been with the Laboratory since 1976.

Department Affiliation

Ocean Engineering

Education

B.S. Mechanical Engineering, University of Washington, 1974

M.S. Mechanical Engineering, University of Washington, 1976

Publications

2000-present and while at APL-UW

PhilSea10 APL-UW Cruise Report: 5-29 May 2010

Andrew, R.K., J.A. Mercer, B.M. Bell, A.A. Ganse, L. Buck, T. Wen, and T.M. McGinnis, "PhilSea10 APL-UW Cruise Report: 5-29 May 2010," APL-UW TR 1001, October 2010.

More Info

30 Oct 2010

A team from the Applied Physics Laboratory of the University of Washington (APL-UW) conducted underwater sound propagation exercises from 5 to 29 May 2010 aboard the R/V Roger Revelle in the Philippine Sea. This research cruise was part of a larger multi-cruise, multi-institution effort, the PhilSea10 Experiment, sponsored by the Office of Naval Research, to investigate the deterministic and stochastic properties of long-range deep ocean sound propagation in a region of energetic oceanographic processes. The primary objective of the APL-UW cruise was to transmit acoustic signals from electro-acoustic transducers suspended from the R/V Roger Revelle to an autonomous distributed vertical line array (DVLA) deployed in March by a team from the Scripps Institution of Oceanography (SIO.) The DVLA will be recovered in March 2011.

Two transmission events took place from a location designated SS500, approximately 509 km to the southeast of the DVLA: a 54-hr event using the HX554 transducer at 1000 m depth, and a 55-hr event using the MP200/TR1446 "multiport" transducer at 1000 m depth. A third event took place towing the HX554 at a depth of 150 m at roughly 1–2 kt for 10 hr on a radial line 25–43 km away from the DVLA. All acoustic events broadcasted low-frequency (61–300 Hz) m-sequences continuously except for a short gap each hour to synchronize transmitter computer files. An auxiliary cruise objective was to obtain high temporal and spatial resolution measurements of the sound speed field between SS500 and the DVLA.

Two methods were used: tows of an experimental "CTD chain" (TCTD) and periodic casts of the ship's CTD. The TCTD consisted of 88 CTD sensors on an inductive seacable 800 m long, and was designed to sample the water column to 500 m depth from all sensors every few seconds. Two tows were conducted, both starting near SS500 and following the path from SS500 towards the DVLA, for distances of 93 km and 124 km. Only several dozen sensors responded during sampling. While the temperature data appear reasonable, only about one-half the conductivity measurements and none of the pressure measurements can be used. Ship CTD casts were made to 1500 m depth every 10 km, with every fifth cast to full ocean depth.

On feature based automatic classification of single and multitone signals

Das, A.K., P. Arabshahi, T. Wen, and W. Su, "On feature based automatic classification of single and multitone signals," In Proceedings, Ninth IASTED International Conference on Wireless and Optical Communications, 6-8 July, Banff, Alberta (Acta Press, 2009).

More Info

6 Jul 2009

We consider the problem of feature based automatic classification of single and multitone signals. Our objective is to extend existing blind demodulation techniques to multitone waveforms such as MIL-STD-188-110B (Appendix B) and OFDM, developing a capability to identify signal types based on short data records, and maintaining robustness to channel effects. In this paper, we report on the first phase of our approach, namely, building a coarse classifier for a range of single tone and multitone signals. Among the features considered by the coarse classifier are those based on trigonometric moments and higher order statistics of the instantaneous frequencies of the received signal. No a priori information is assumed on the part of the received signal. The received signal of interest has not been previously observed; it is not part of a library of known signals; and no automated classifier has been built for it. Extensive simulation results based on real world signals are presented demonstrating the feasibility of the above features for automatic classification purposes of single and multitone signals.

Seaglider: a long-range autonomous underwater vehicle for oceanographic research

Eriksen, C.C., T.J. Osse, R.D. Light, T. Wen, T.W. Lehman, P.L. Sabin, J.W. Ballard, and A.M. Chiodi, "Seaglider: a long-range autonomous underwater vehicle for oceanographic research," IEEE J. Ocean. Eng., 26, 424 - 436, doi:10.1109/48.972073, 2001.

More Info

1 Oct 2001

Seagliders are small, reusable autonomous underwater vehicles designed to glide from the ocean surface to a programmed depth and back while measuring temperature, salinity, depth-averaged current, and other quantities along a sawtooth trajectory through the water. Their low hydrodynamic drag and wide pitch control range allow glide slopes in the range 0.2 to 3. They are designed for missions in a range of several thousand kilometers and durations of many months. Seagliders are commanded remotely and report their measurements in near real time via wireless telemetry. The development and operation of Seagliders and the results of field trials in Puget Sound are reported.

More Publications

Inventions

Underwater Sound Level Meter

Record of Invention Number: 46351

David Dall'Osto, Per Reinhall, Tim Wen, Peter Dahl

Disclosure

8 Jan 2013

Acoustics Air-Sea Interaction & Remote Sensing Center for Environmental & Information Systems Center for Industrial & Medical Ultrasound Electronic & Photonic Systems Ocean Engineering Ocean Physics Polar Science Center
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