BLE Transmitter+Receiver child locator?
Essentially the idea is similar to this "lost child locator" product- http://tinyurl.com/pd8goy7 or these t-shirts- http://tinyurl.com/mkm5b8k
What I'm struggling with is how to carry out the concept without involving a smart phone.
I'm looking for a larger range than 15M, multiple devices to respond to one-another, and for the watch to act as both transmitter and receiver. A simple LED indication is sufficient, no sound or vibration are necessary. I think BLE is the proper signal to work with but I don't want to involve smart phones at all. Compactness is a major plus, but ultimately I would settle for a mint tin or puck sized device. Everything would need to run on a small battery as well.
The practical application of this project is for times when you're in a large crowd and you are looking for your group. If you had a watch tuned to your group, you could more easily track each other down if you knew someone was close.