Similar idea, but using RFID, was in CH. That idea is more implementable now, although yours is not too far.

Parents might buy this, although younger kids sometimes arent allowed out of sight without adult supervision, and older ones might ditch the watch. If the kid didn't know where the transponder was, there might be a big loss of trust someday.

I see the logig davidwei. I just want to change the perspective a bit.

This shouldn't be hidden from the kids. The basis of family life should always be trust and being in possesion of your childrens trust.

Your kids should know about it and understand the reason for it. Yes the current teen generation will maybe rebel against the idea, but in a few year - if correctly implemented - the new generations would see it as wearing underwear.

I had a friend whos' brother ran into some loan shark trouble. His parent didn't wanna provide the money because they thought he was lying. He got bruised a bit by the guys.

I told them the following: rather believe him, give the money and see him live - or - dont give him the moeny and see him dead. When it comes to children, certain levels of trust should be negotiable.

We pray we never have to loose that trust, but if it is broken in the event of saving a life - I am willing to take that chance and still kiss them goodnight when they aren't looking

Similar to my own idea (ChildSafe RFID), but with different and more expensive technology, though greater range - yes, a good thing for the future when GPRS and GPS hardware is cheap and more plentiful...

Good Luck!

for VIP's children's shoes etc. ..

..and can be improved (espionage and other practical purpose)

such as tracking missing person of international interest (missionaries/peacecorps).

This has been done over and over. Nothing new here.
It takes about 5 min to connect a gps to a gsm phone module.
Try googling "gps trackers" and see here http://en.medicalint...e=P-Columba-Solution

There are at least 2 dozen similar products in the US alone, not to mention their clones sold in qty by the Chinese. You can get bracelets, watches, shoes etc with gps and a cell phone module. Disney even has a special purpose phone for this, as well, most of the American cell carriers are offering this service for tracking kids and alzheimers patients already.
By the way, it's "necklace"... if you can't even spell it, maybe you should not try building it!

I have seen the child thing before. but u could always try to make your thing different then others.