When wireless-tracking devices making use of recent advances in "location" technology began to appear, many Americans weren't sure they wanted to be found.
However, that attitude may be changing in the wake of the Sept. 11 terrorist attacks, which have turned a spotlight on personal security.
From the early days of the technology, consumers have been intrigued by its much-promoted benefits, but uncomfortable with its potential for abuse. Locator technology depends on radio frequency or satellite signals to give approximate locations of the electronic devices in which it is implanted.
Commercial applications were motivated by a 1998 Federal Communications Commission mandate that wireless carriers must include such technology for enhanced 911 services on cell phones. Numbers for telephones at fixed locations can be matched with addresses, but determining the location of mobile phones confounds emergency services and slows response time.
The benefits seemed obvious: The location of an accident victim such as Tillie Tooter, whose car went off an overpass, then hung suspended in a mangrove swamp near Fort Lauderdale, Fla., for three days last year, could have been quickly pinpointed if she'd had access to a cell phone with enhanced 911 features.
But the risks of such intrusive technology are great as well. Records showing the location of a person or car could be compiled and used in court cases. Marketers have threatened to bombard cell phones with coupons as the user passes retail outlets. A car rental agency revived fears of Big Brother when it tracked the speed and location of drivers, then fined them for exceeding local speed limits.
Now, in the wake of the attacks, interest in the budding technologies has swelled. For now, concerns about privacy may take a back seat.
There are several tracking methods, none perfect. The FCC is requiring that the enhanced 911 features be capable of locating callers only within 50 to 300 meters (164 to 987 feet), depending on the system. Although Oct. 1 was the date set for the features to take effect, most wireless carriers applied for delays.
The most common include Global Positioning System, or GPS, which uses Defense Department satellites; signal triangulation, in which the caller's distance is plotted by the strength of the radio signals from three cellular towers; and assisted GPS, a combination of both systems - the most likely to be adopted by wireless providers, because it uses less power.
"You have to know with these devices where they will work and where they won't work," said Yosi Hoshen, an analyst who has done a study for the Justice Department on how such technologies can track criminals.
They work best in relatively open areas, he said. They won't work inside buildings unless the device is near a window, because the GPS antenna must have a view of the satellites. They are unreliable in the canyons formed by the high-rises of big cities.
Most cell phone tracking devices being developed will not be accurate enough to locate a victim buried in the rubble of a collapsed building, at least in their earliest versions. But despite current shortcomings, improvements in antennae and batteries promise to eventually boost their effectiveness.
Chapman Technologies, a Boca Raton, Fla., company that makes locator devices for car fleets, has developed a personal safety module that can be attached to an Ericsson cell phone set to come out this year. A new antenna will greatly improve the precision of the module's GPS, according to Chief Executive Robert Chapman.
Personal safety devices on the market or about to be introduced can do everything from contacting parents when teen-agers drive outside given boundaries to transmitting a warning when biosensors indicate changes in vital signs. The devices, which range from $300 to $400, notify a central command center. Monthly fees are $10 to $50.
The Chapman Personal Safeguard Companion has limited cell phone capabilities, along with GPS tracking and a 911 alert button. This first-generation product will eventually be phased out in favor of the cell phone add-on module.
"Our current device can address any kind of problem - if you are lost, if you are being followed, if you have a medical crisis, if your car breaks down, or if you just need directions," Chapman said.
The device can transmit a voice by cellular connection while the GPS system is operating. Also, it also allows the command center to turn on the device remotely if someone calls in and reports a user is missing, and permits three-way teleconferencing between the victim, central command and local emergency services.
The Digital Angel takes a slightly different approach. Under development by Digital Angel Corp., based in St. Paul, Minn., the first generation of the product consists of a wristwatch and pager and is set to hit the market around the holidays late this year. It will include built-in biosensors and a tracking chip.
The watch will determine pulse rate and skin temperature, and track the wearer's location through GPS. It can make distress calls to a central command center through the pager, and a family can track the location of a lost child or wandering senior citizen anywhere in the world in real time, over the Internet.
Ituran, an Israeli company with U.S. headquarters in Fort Lauderdale, Fla., uses a proprietary radio frequency tracking system developed to find downed pilots in the early 1980s. It makes a LifeTrak PAL handheld device designed to locate Alzheimer's patients.
The system works in places where GPS does not, such as in big cities, parking garages, under bridges and basically "any place you can hear a radio," said Ron Shamai, chief executive.
The network, however, works only in parts of Florida, Argentina, Brazil and Israel.