Lab News

Brand New Measurement Facility Kicks off for Summer

June 22nd, 2008

The new measurement facility is located just down the hall from the original NEAR-Lab in suite 25-00. The new facility will hold acoustic and terahertz experiments, in addition to receiving and processing a stream of live sonar and radar data from sensors deployed in the Pacific Northwest for environmental monitoring.

Pulsed terahertz spectroscopy measurements will be taken with Picometrix's T-Ray 4000. We will have one colinear unit (emitter/detector combo able to make monostatic measurements) and a second detector for bistatic measurements. Our primary focus in this area is to experimentally characterize frequency-dependent scattering from rough surfaces in the terahertz regime.

Sonar experiments for wave propagation, target detection and scattering from sediments will be performed. The facility is equipped with two water tanks (748 gal and 1500 gal), ultrasound transducers and high speed data acquisition hardware (NI PCI-6110). The experimental work is oriented to validate mathematical models and sonar processing techniques developed at the NEAR-Lab.

Oceanographer Barry Ma to Join NEAR-Lab

June 13th, 2008

Dr Barry Ma will join the NEAR-Lab this summer after leaving his current position as an assistant professor at the Department of Marine Science, Taiwanese Naval Academy. He earned a PhD from University of Washington /Applied Physics Laboratory (UW/APL) in the field of Acoustic Oceanography with (advisor) Dr. Jeffrey Nystuen in 2004 and studied in the U.S. Naval Postgraduate School for his master degree in the program of Undersea Warfare with Dr. C.S. Chiu. His research interests include using the acoustic methods to study the ocean properties and various acoustic propagation problems. The NEAR-Lab looks forward to Barry's arrival this summer.

Congratulations to George Ogden

June 13th, 2008

George Ogden, a NEAR-Lab veteran and alumni, graduated from Portland State's ECE department on June 13th, 2008. George now plans to pursue his masters' degree here at PSU, while continuing to work for the NEAR-Lab. He will work on a RADAR/SONAR project, which is part of collaboration with Pacific Northwest National Laboratory (PNNL). As part of the project, George will be installing a passive sonar array in the Willamette River to monitor ship traffic.

NEAR Lab to Research "Deep Ocean Detection Performance"

February, 2008

The NEAR-Lab has been awarded $300k for a new ONR-sponsored research effort entitled "Deep Ocean Detection Performance ". The objective of the three year project is to improve the ability to passively detect targets at low frequencies in deep water environments by utilizing an advanced signal processing framework based upon accurate characterization of the signal and noise structure. The effort will support the ONR North Pacific Acoustic Laboratory (NPAL) program, including participation on the planned data collection in 2009/2010 in the North Philippine Sea.

Professor Zurk Honored with PECASE Award in Washington D.C.

November 1, 2007

Professor Lisa Zurk was honored by the White House as a winner of the 2006 Presidential Early Career Awards for Scientists and Engineers (PECASE).

PSU News Article

Photo of award winners (Prof. Zurk, 3rd row left) with President Bush (center).

Shallow Water Array Performance (SWAP) Calibration Operations in Ft. Lauderdale, FL

September, 2007

As part of my research for the NEAR Lab's involvement with the ONR-funded Shallow Water Array Performance (SWAP) project, I assisted in calibration operations aboard the RV Seward Johnson this September. This was a week-long sea test of the new shallow water array which was deployed off the coast of Florida near Ft Lauderdale over the summer. Going on this trip allowed me to meet and network with some of the project staff from other participating groups, such as OASIS, an acoustics research firm based in Massachusetts, and the Naval Underwater Warfare Center (NUWC).

The NEAR Lab at Portland State is tasked with determining the physical limits of array signal gain in this environment. One challenge for the processing is the length of observation time needed by traditional adaptive beamforming formulations - with an array of this size and element quantity, the resolution of range and bearing cells is such that a ship may move across many cells during the snapshot time, spreading the resulting eigenvector structure and decreasing effective signal gain. A central question is the trade-off between array gain and this spreading loss. I am presenting a lecture on this topic at the Acoustical Society of America (ASA) conference in New Orleans at the end of November.

The purpose of this specific sea test was to analyze transmission loss (TL) and horizontal wavefront coherence as a function of frequency and range in the vicinity of the SWAP array. The array is in about 140 fathoms (256 meters) of water, about seven nautical miles (13 km) off the east coast of Florida, just south of Ft Lauderdale and north of Miami. This is in the middle of the Gulf Stream current, which flows north at about 3 to 4 knots. The signal environment is dominated by ship noise, as Ft Lauderdale and Miami are active ports with cargo and passenger traffic arriving and departing from ports throughout the Caribbean.

We left the Harbor Branch Oceanographic Institute's dock in Fort Pierce, Florida on the evening of 6 September and headed south, deploying a towed acoustic source behind the ship during the night. For the next six days, we transmitted several different types of audio test sequences with the source at depths from 10 to 100 meters, while moving along well-defined paths extending up to 80 kilometers from the array. This allowed the team ashore at the Navy's South Florida Testing Facility (SFTF) to monitor our acoustic signature on the SWAP array.

In addition to towing the acoustic source, we also took a great many measurements. These were my specific duties aboard the ship, along with the two other environment team members, Dr. Kevin Heaney and Richard Stroop, both of OASIS. We each took four hour watches, with eight hours off in between. My watches were from 0400 to 0800 and 1600 to 2000, every day. This allowed us to have at least one environment team member active at all times, with a second person off-duty person usually awake to assist.

At hourly intervals we deployed expendable bathythermograph (XBT) sensors from a handheld launcher, which allowed us to sample the seawater temperature from the surface to the bottom at a total of 80 positions over the six days. Knowing the temperature allows you to get a good approximation of the sound speed, which is a dominating parameter in most ocean acoustics calculations. At roughly four hour intervals, we assisted in deploying a tethered sled containing conductivity, temperature, and depth (CTD) sensors. We also monitored a sub-bottom profiling sonar system, which continuously pinged the area under the ship and allowed us to see rocks, sediment pools, and other features up to 30 meters below the ocean floor.

While not operating this equipment, we spent our time working on various other problems related to the SWAP project, which included theoretical discussions, sharing and developing MATLAB code, and sending figures and data off to our shore-side counterparts. I took quite a few pictures. The experience of being at sea is always enjoyable. I race sailboats in my free time, occasionally offshore, so being out of sight of land is my natural element. We had somewhat heavy seas for the first two days, due to Tropical Storm Gabrielle, but no one was seasick and the weather stayed clear except for frequent distant thunderstorm during the night.

Overall, the sea test went very well - we had no serious equipment failures or emergencies, and we met all of our goals for the test. One of the verdicts was that the test should be re-run during the cold weather season when the water column temperature is nearly uniform - I'd definitely jump at the opportunity to do it again.

- Richard Campbell Jr. Click to see the picture gallery.

Sonar Field Experiment in San Pedro, Belize

August, 2007

Josef Lotz is an ECE student completing his Master degree with research in the Northwest Electromagnetics and Acoustics Research Laboratory (NEAR-Lab) at PSU. His thesis is titled 'Coral Fish Shoal Detection from Acoustic Echograms' and has been sponsored by The Nature Conservancy (TNC), the world's largest conservation organization. Josef is part of a research team that created a software package named EchoMap, a tool that processes raw sonar data and generates visualizations of coral reef surfaces and fish shoal detections. The sonar data is obtained through an inexpensive and portable single-beam echosounder, typically referred to as a “fish-finder.” The ability to visualize the underwater coral bathymetry and fish shoal locations helps ecologists and biologists in rapid reef assessment and fish Spawning and Aggregation Site (SPAGS) management. EchoMap incorporates the fish algorithms that were designed as part of Josef’s thesis research.

Josef recently traveled to San Pedro, Belize with a TNC team led by Jean-Louis Ecochard (TNC Chief Information Officer) and organized with TNC Meso-American Reef Program. The purpose of the trip was to test the EchoMap program by training reef specialists to use the program, than using it to provide SPAG mapping for the Hol Chan Marine Reserve. The field test was also part of the new five year effort between the Nature Conservancy and PSU called the Conservation Technology Initiative (CTI). The CTI will initially focus on continued research in underwater mapping and will grow to consider general technology needs for the environmental conservation community.
The field test established EchoMap as a successful tool for marine ecology, and was used to map a coral reef known as Rocky Point. The results will help ecologists determine morphological coral features that attract SPAGS, and provide science-based prioritization for choosing marine conservation sites.
Click to download this article with illustrations.
Click to see the picture gallery.

Experiments at UW-APL

April 07, 2007

Students from the NEAR lab met with Dr. Zhou and Mohammad Hassan Arbab at the University of Washington's Applied Physics Laboratory. During the visit George Ogden, Scott Schecklman, and Brian Orlowski obtained Terahertz reflection measurements at APL's THz laboratory. The NEAR lab is developing a Quasi-Crystalline Approximation (QCA) program to model scattering of THz energy from particles hidden inside composite materials. The students measured THz reflections from small spheres embedded in a special rubber slab provided by the Naval Research Laboratory. These measurements will be helpful in calibrating the QCA scattering algorithms, which could prove to be useful for the detection of concealed explosives.
Click to see the picture gallery.

Shallow Water 2006 (SW06) Experiment

August 20, 2006

A PhD student in the NEAR-Lab, Jorge Quijano, was invited to participate in the Navy sponsored Shallow Water 2006 (SW06) Experiment. SW06 is a large-scale at-sea experiment that brings together dozens of scientists from leading institutions across the country with the goal of acquiring high-quality data for underwater ocean acoustic research. The experiment will be conducted off the eastern seaboard of the United States and occur over a two week period during August, 2006. Jorge will be aboard the Research Vessel Knorr, which which is owned and operated by MIT Woods Hole Oceanographic Institute (WHOI). Participation in such an esteemed experiment is an honor for Portland State University, and will provide outstanding data for Jorge's thesis work in ocean acoustic bottom scattering. Jorge received received his Masters in Science at PSU in June, 2006 under a Fulbright award, and is currently pursuing a PhD.
Click to see the picture gallery.

BSP Lab and The Nature Conservancy Collaboration

July 10, 2006

The NEAR-Lab, in collaboration with the Biomedical Signal Processing Lab (BSP), has received a grant from the Nature Conservancy to investigate the use of a fish-finding sonar to map coral reef areas and fish aggregation. The year-long effort began in June 2006 and will involve the development of physics-based algorithms for processing of sonar returns for the reef conservation environment. NEAR-Lab Master's student, Joe Lotz, and BSP Master's student Tim Ellis are working jointly on the project.
Click to see the picture gallery.