What type of tracking technology is practical for young children?

Question

We've all had the fear of having our children kidnapped. What type of technology can I use to locate my child if they get lost or kidnapped? I'm not necessarily looking for a specific product, but rather a summary and comparison of the types of tracking products that can be used.

The factors that I would consider important are safety, cost, practicality for children ranging from infant age until 6-7 years old, and ease of use for the parent.

Update: I took out 'GPS' from the title to make the question more generic.

Update 2: Another factor that is important is concealability. How easy can the device be hidden on the child without others knowing about it (perhaps including the child themselves).

Answer 1

Such devices already exist, though mainly to locate and recover stolen cars. They're about the size of a cell phone and work by a combination of GPS and cell triangulation.

Look for "carfinder." In Austria, the local automobile club offer these ad rentals if you're driving to Eastern countries:
http://www.oeamtc.at/carfinder/?id=2500%2C1142696%2C%2C
http://www.oeamtc.at/carfinder/?id=2500%2C1114220%2C%2C
(German)

Also, here's an English link to the manufacturer:
http://www.dolphin-technologies.com/&sprache=en

Answer 2

If I were to get such a device, it would have the following characteristics:

1. It should be useful for something else.
2. It should look like another device, maybe a watch, stopwatch, jewelry, etc.

Answer 3

• Someone with malicious intent will remove/destroy/jam the device.
• Someone with good intent will make sure it is working properly.

Thus, doing something like that gives bad guys the ability to track your child's movements when they are safe, meanwhile you aren't likely to have recourse if they are taken.

It seems like a net loss in security to me.

That said, if you must get such a device, make it a cell phone. GPS tracking, triangulation by tower reception in the absence of a satellite fix, connection (from which to transmit location) anywhere there is a cell tower, and the ability to call out in an emergency.