Good day folks,
I've been browsing around the good ol' internet, trying to find out if I'm considering something plausible here, and I think I might be. But that's for you all to help me decide, if ya wouldn't mind helping a newbie out!
So I'm looking to replicate something along the lines of this Child Proximity Sensor or one of these Bluetooth Based Devices (of which there are a few, I only linked to one in particular). I want to create a system wherein one device sends an alert to another paired device if/when they become separated by a specific distance (let's say 25 feet). I have seen plenty of posts around here, and elsewhere, which claim these systems to be entirely unreliable, and even made some out to be a scam of sorts. However, most articles and posts I've found are quite dated, and Bluetooth technology (to my novice knowledge) has come a long way in recent years.
Initially I was planning on using ultrasound and/or IR sensors to accomplish this, but due to their directional nature I can't quite do that without loading a bunch of sensors on each device. Also, unfortunately, it will have to work indoors so GPS doesn't seem to be a reliable option. I know the Bluetooth system I linked to earlier involves a smartphone as the brain, and that is not out of the question here - though I'd rather if I could do without it. If need be it would be ideal to have it as a third device, that maps the distance to the two devices I am monitoring and send alerts to both if the conditions are met. But that's why I'm here, I'm not sure if this is worth pursuing on a moderate budget and just basic knowledge of Bluetooth 4.0. It seems plausible, as does the current alternative of a RF-based system...I just don't know what my next steps are/should be.
Thanks in advance everyone!