Ocean floor Images Sail Worldwide

Abstract

Leveraging the power of fiber-optic communications and Unix workstations, scientists of the Woods Hole Oceanographic Institution relay images from 20,000 feet below the ocean surface to a ship floating overhead. Woods Hole was assisted by Electronic Data Systems Corp. in extending Internet links down to the ocean floor. A factor in the slight delays in broadcasting the images is that the lab has not yet converted many of its Sun Microsystems Inc. SunOS applications to the new Solaris 2.X operating system.

When Woods Hole Oceanographic Institution scientists send a remotely operated vehicle (ROV) into the ocean depths, they use distributed computing technology to immediately view ocean-floor images. And, by extending a shipboard local-area network through the Internet, they now send those same images via satellite to other laboratories worldwide.

Leveraging the power of fiber-optic communications and Unix workstations, the scientists relay images from 20,000 feet below the ocean surface to a ship floating overhead. The Internet data feeds were tried for the first time this spring during an underwater survey in Mexico's Sea of Cortez, scientists here said.

Woods Hole was assisted by Electronic Data Systems Corp. in Plano, Texas, in extending the Internet links down to the ocean floor.

"We extended the Internet by realtime satellite link to the ship and down to the vehicle," explained W. Kenneth Stewart, head of Woods Hole's Deep Submergence Lab.

Using a technique called multicasting, the newly acquired data was broadcast to several sites around the world, he said. The images were broadcast in "near-real time" due to subsecond lags in processing the imaging signals, according to Stewart.

SUNOS APPS NOT READY

One factor in the sliht delay was the scientists' use of Sun Microsystems, Inc.'s SunOS operating system, Stewart said. The lab has not yet converted many of its SunOS applications to Sun's new Solaris 2.X operating system, which is compatible with Unix System V Release 4. Conversion work will start this fall, he said, after the lab's prime diving season is over.

One real-time Sun application is already in use: A shipboard Scalable Processor Architecture workstation uses a VXWorks real-time operating system for sonar processing. Sonar signals, critical for proper positioning of the ROV, require response time on the order of 100 microseconds, Stewart said.

Roving submersibles use a 100M bit/sec. fiber-optic datastream, which is split into 10 10M bit/sec. segments, Stewart said. That way, telemetry, digital data, digitized sonar and broadcast--quality video can share the total available bandwidth. The fiber-optic link is tethered to the institute's ship, which is outfitted with up to a dozen workstations.

The ROs remote-sensing system is comparable to limited data communications from Woods Hole's famed Alvin submersible, a pressurized vehicle that carries a pilot and two scientists. Alvin has an underwater telephone and can transfer data at 1,200 bit/sec., Stewart said.

"A typical dive cycle is eight to 10 hours, and you only get to spend three to four hours of that on the bottom," he said. "There's a lot of economics driving the use of unmanned submersibles."

HOOKED ON UNIX

Woods Hole's use of Unix workstations is extensive. The oceanographic lab has about 160 Unix workstations, including 25 Sun workstations (see story at right).

The new multicasting technique opens up possibilities for obal cooperation on oceanic research. But everyday work at the lsb also depends on networks of peered Unix workstations and the Internet.

"We use electronic mail for communications with colleagues, send source code over the [Internet] network and transfer files," Stewart said. "Most of our real-time systems are on the Internet, and we can do first-pass processing that way."

ALL WE WANT FOR CHRISTMAS

By year's end, one mainstay of the Woods Hole Oceanographic Institution's computing environment will be gone. A cluster of two Digital Equipment Corp. VAX 3000 machines will be unplugged in hopes of saving money and completing a transition to distributed computing.

"My expectation is that we will not have a chargeback, time-sharing system here after Dec. 31," said Robert C. Groman, director of the Information Systems Center (ISC). Planned for several years, the migration will cap a gradual move to data processing within research projects, he said.

Two factors have driven the change: increasing desktop capability and project-based purchases. "The improvements in PCs and workstations have outstripped the power of the central machine," Groman said. The VAXs have 300 accounts for 150 users--down from 700 accounts for 350 users several years ago.

The VAX shutdown will not mark the end of the ISC's support of the laboratory's 850-user community. More than 20 ISC staff members will shift their attention to supporting 160-plus Unix workstations--including 125 Sun workstations--and 800 PCs on campus. A growing number are Silicon Graphics, Inc. workstations used for high-resolution imaging.

"I talk about managing diversity," Groman said. "We have project-based funding, so it's counterproductive to have hard-and-fast rules that dictate what hardware people can buy."