Kid/Adult Distance Tracker

Overview

We've all heard horror stories of kids being left in the car on a hot day because the adult has somehow forgotten about them. This device will monitor the distance between the adult and the child so that if there are ever more than 10 feet away, an alarm will be sent via Nova Cellular USB Modem and the Raspberry Pi Zero W to another person to alert them to the situation.

Part 1

The advantage of this device is that it will be much simpler and safer than a GPS style tracker. The distance between the child and the adult can be measure via some kind of Wi-Fi signal, which can be built cheaply, maybe with a pair of ESP8266 (signal strength will be a rough measure of the distance). The alarm will then be sent via Nova Cellular USB Modem and the Raspberry Pi Zero W carried by the adult.

Part 2

The device is also safer than a location tracker because it only measure the distance between the child and the adult, so it can not be used to actually locate the child.

The idea can also be extended to one adult leading a group of children (such as a kindergarten teacher with little kids), with one "master device" carried by the adult keeping track of multiple "slave" devices carried by the children.