Keeping Loved Ones on the Grid

Children wearing the Amber Alert GPS on lanyards.Â
THEY say if you love something, set it free. Good advice, but you still might want to keep your eye on it.

The Amber Alert GPS.
So the other day, I slipped a GPS tracking device into my wife's car before she headed off to work. I put another tracker in my 2-year-old's diaper bag and sent him off to the nanny for the day. I still had a few trackers left, and my parents were in town, so I also threw one into their vehicle while they took my son out to the park.
Of course, I had never suspected any wrongdoing and, later on, when I reviewed the trails left by these GPS devices, they turned up nothing untoward. My spying was meant only as an experiment, but I still felt like a heel.
As well I should have. It's precisely because of mischief like mine that tracking devices get a bad rap. These small gadgets work by connecting to GPS satellites and cellular networks to follow subjects and report back their locations to their masters. Once I sent them out into the world, I could look up the trackers online, either on the Web or through a smartphone app. They could also be configured to send me alerts based on various criteria. If my wife's car left her office parking lot during the day or my parents' vehicle broke the speed limit, I might get a text alert. If your mind reels at the universe of Maury Povichian possibilities contained within these gadgets, you're not alone.
Yet after chatting with representatives at several GPS tracking companies and trying out their products, I learned that there are many less icky, entirely defensible uses for such devices. For example, some parents use trackers to make sure their children get to school and back safely each day. Others build them into their teenage drivers' cars so they can be alerted if the kids drive recklessly. There's also the elder-care market - GPS trackers embedded into medical-alert devices can help locate and provide emergency help for parents with Alzheimer's.
And don't forget the dog: a tracker attached to its collar can let you know if it wanders out of your yard, and help you find it if it doesn't come back. The more I heard about these devices' applications, the less unseemly they began to feel; indeed, for many people, GPS tracking could soon become a regular part of life.
Among the companies pushing for this future is Amber Alert GPS, a Utah-based firm that was founded in 2007 after Russell Thornton, a businessman, lost his 3-year-old son at an amusement park. After a frantic 45-minute search, Mr. Thornton found the boy hiding in a play structure, but he was traumatized by the incident, and it spurred him to build a device that would help other parents avoid that fate.
Amber Alert's tracker is about the size of a child's palm, and it looks a bit like an old-school pager. It can be slipped into a pocket or backpack, or placed in a carrying case attached to a child's belt loop. According to Carol Colombo, the chief executive of Amber Alert GPS, most customers buy the device for children between the ages of 2 and 10 - children old enough to be mobile, but too young to carry a cellphone. Still, the Amber Alert can act as a quasi-phone; with a press of a button on the device, your children can send a text or initiate a voice call with you, and you can also dial in to the tracker and listen to their surroundings.
I found the Amber Alert extremely simple to set up and use. The company's Web site, which allows you to configure and monitor the tracker, is well designed and intuitive, and its iPhone and Android apps also work quite well. Amber Alert offers more customizable alert settings than any other child-tracking system I tested: among them, there's an option to receive an alert each time your child comes within 500 feet of an address listed on a sex-offender database.
The only downside to the Amber Alert is its price. The device sells for $200, and it requires a service plan, which goes for $14.99 a month for basic tracking features, and $24.99 a month if you would like extras, including voice-calling and sex-offender alerts.
Another child-tracking device I tested, the Securus eZoom, is slightly larger than the Amber Alert and doesn't have some of that device's advanced features (like voice calling), but it is also significantly cheaper. The eZoom sells for $99.99, and its monthly plan is $19.99. If you pay for two years at once, you can bring the price down to $12.99 a month.
Securus also makes a couple of GPS devices for other uses. The eCare is meant for seniors who need medical help. In addition to tracking, it has an SOS button that initiates a voice call to an emergency call center. The eCare sells for $99.99, with a $29.99-a-month service plan. Finally, there's Securus's dog tracker, called SpotLite, a water-resistant, two-ounce module that hooks on your pet's collar. (The company says the device is best for dogs weighing more than 10 pounds; it's not recommended for cats because of its size.)
Then there is a GPS device designed for keeping track of your most important possession: yourself. The SPOT Satellite GPS Messenger, which sells for $119.99 and requires a $99-a-year contract, is meant for adventurous types who routinely wander far off the grid.
If you find yourself in an emergency in a place without any cellphone connectivity, you can hit a button on the SPOT to alert rescuers to your location; the device works almost anywhere in the world as long as you have a clear view of the sky. If you're not in trouble, you can use the SPOT to send a message letting your friends know you're fine. They can also track your progress across the Outback on a map. The SPOT has led to dozens of rescues, including of two people whose plane crashed into the Gulf of Mexico early in October.
This article has been revised to reflect the following correction:
Correction: October 22, 2012
An earlier version of this article incorrectly stated the name of the chief executive of Securus. His name is Chris Newton, not Newtown.