This 'remote' shows its users exactly where here is.

Every spring in years past, ecologists at the Joshua Tree National Monument would begin their annual study of the endangered California desert tortoise by marking with metal posts one square kilometer in the sand.

It would take five people using heavy surveying equipment five days to map out the kilometer, recalls Joshua Tree ecologist Jerry Freilich. The "grim" and "laborious" work was necessary because, in order to find out if the desert tortoise is disappearing, one must first know where they are, he says. By laying out a kilometer, scientists could count how many tortoises are found in that kilometer, Freilich explains.

This spring when the ecologists from Joshua Tree went out for their annual tortoise study, they did not bring the weighty survey equipment. Instead, they merely brought a hand-held device that weighs about a pound and can indicate, within 10 feet, a person's (or tortoise's) location on the earth.

Use of the new gadget has made Freilich's job "a million times" easier, he says.

"We're trying to find where the tortoises live. How do you find where they are in half a million acres of desert?" he says. "We can't imagine life without (the locator device)."

The locator is made by San Dimas-based Magellan Systems Corp. and works by receiving signals from the satellites in space. It is one of several products the company produces which receive signals from the Global Positioning System, says Jim White, Magellan spokesman.

The GPS is a network of 24 satellites orbiting the earth and transmitting exact time and position information to receivers on earth. Development of the system began in the 1970s, and the system became fully operational this year.

With a GPS receiver, a user tracks signals from three satellites at once and -- through an algorithm computation to the time and distance of the three satellites in relationship to the user -- can determine his or her own exact position on earth. The time it takes for the user to receive the signal is divided by the speed of light, which helps to determine distance, White explains.

Magellan is one of several companies working on GPS products. Notably, Seal Beach-based Rockwell International Corp. has been developing GPS receivers for the U.S. Department of Defense since the early 1970s and has produced GPS products for boats, planes, cars and buses.

In addition, Irvine-based Thomas Bros. Maps is working on a digitized computer map system of the U.S., says Glen Jansma, vice president of business development for Thomas Bros. That system may be used in the future as an electronic Thomas Bros. map capable of indicating drivers' locations and preferred routes to their desired destinations, by communicating with the satellites.

Magellan made a big news splash in October 1993, when it announced it had signed a five-year deal worth $100 million to build a GPS receiver for vehicle navigation for Xanavi Information Corp., a division of Nissan Motor Co. Ltd., Nippondenso, a major supplier of parts and systems for Toyota Motor Corp. and Toshiba Corp.

Commerce Secretary Ron Brown, who attended the news conference, contends that by the end of this decade as many as 100,000 Americans will be working in what will be a $5 billion electronic navigation industry.

Currently, about 500,000 Japanese motorists have GPS systems in their cars. Japan was faster than the U.S. in developing the maps, says Randy Hoffman, Magellan president and chief executive officer. In the U.S., "you'll start seeing them by the end of this year and in model year 1996," he adds.

Although GPS is not widely available in U.S. cars, Magellan began marketing a hand-held receiver for use by campers, hikers, hunters and fisherman a few months ago.

Called the "Trailblazer," the 1.4-pound device is available in several stores specializing in outdoor equipment, White says.

In its summer catalog, L.L. Bean, the sportswear and outdoor provider, plans to feature the Magellan Trailblazer for $500, according to Andy Shepard, product manager for sporting goods for the Freeport, Maine-based company.

"This is the first real opportunity for the general public to use GPS technology," Shepard says. "Up until now it has been used in military applications or in the aeronautics field."

Shepard says L.L. Bean has been watching the development of GPS hand-held receivers for three or four years now. "We have been tracking the technology and waiting for it to come down to a point that we thought the consumers would buy it," he says.

At $500, "I would say that this would be a product for the type of person who spends a fair amount of time outside or takes the time they spend outdoors fairly seriously," Shepard adds. He notes it would be especially helpful for someone who fishes seriously and is looking for a precise spot in a lake or in the ocean.

Ashley Ho, owner of the Euro Arms Enterprise in Alhambra, says he has had two Magellan Trailblazers for sale for the past two months in his shop, which specializes in selling guns to hunters.

So far, no one has been willing to pay $500 for the device, he says. "We have a lot of customers interested in it, but no one interested enough to pay the money to buy it."

Ho admits the lack of sales may be due to difficulties he and his salespeople have in explaining how to operate the device. "I'm not good with computers," he concedes.

Shepard of L.L. Bean says the company is "excited" about the product, but would not give sales projections. "We're looking for this program not being a huge business for us in the beginning. But the business will develop over the next few years," he says.

Before last year, the only people using Magellan GPS systems were hard-core adventurers.

Pierre Odier teaches fine arts at Herbert Hoover High School in Glendale for nine months a year and spends his summers traveling through the most remote parts of the world. He says he has used a Magellan navigational system for a few years and plans to use it again this summer when he treks from Beijing to Alaska by way of Siberia.

Odier says he used his Magellan system one summer a few years ago to find a rare bird called the black neck crane in the Alti-Gobi desert in Mongolia. When he first saw the bird, he didn't have a camera but was able to record its exact position and come back the next year and capture it on film, he says.

Diego Daniel Rodriguez, a Miami commodities broker and weekend fisherman, was off the coast of Key Largo, Fla., in November 1993 when his boat started taking on water.

"Before we knew it, the batteries were under water and we couldn't get the engine started," Rodriguez says. "We started to go down, and we didn't get a chance to grab any life jackets."

Before the boat completely sank, Rodriguez and the three other boaters did grab onto an Igloo ice chest, a hand-held radio and a Magellan locator device, Rodriguez says.

"We called the Coast Guard and I turned on the Magellan and told them our location," Rodriguez says. Because they had the Magellan device, "we had our exact position."

Within an hour, a Coast Guard helicopter was hovering over the four fisherman and their floating ice chest, Rodriguez notes. It took another hour for a Coast Guard cutter to pick them up.

Rodriguez says he thinks he and his friends still would have been found if they didn't have the Magellan, because the Coast Guard can locate with a device called a radio direction finder. But the rescue would have taken longer, he says.

The radio direction finder "is just not as precise as the Magellan," Rodriguez says.