I'm working on a home automation setup and I'm trying to find the best way for the system to know when I'm home. A motion sensor won't work because my wife or my dogs may be home when I'm not. The two things I almost always carry with me are my keys and my cell phone and I liked this solution which pings the phone to see if it has joined the home wifi network. The only problem is that my phone goes to sleep very quickly when not used. This would make it good at detecting when I get home (if I just wake the phone for a few seconds on entering), but not when I leave. My other thought would be a bluetooth tag on my keys with a reader near the door, but how could it tell arriving from leaving? Anyone have any suggestions?
A keyfob(-sized) device, based on an RF transceiver (Zigbee, perhaps) that spends 99% of its time asleep, periodically waking up and listening for "query" messages from one or more corresponding base stations located around your home. On receipt of a "query" the keyfob responds with an "acknowledge" message. If there is an extended period (say, 5 minutes) during which no base station receives an "acknowledge" message then you can assume that your keyfob is not at home.
A useful extension to the concept is to have the keyfob report its battery status in the "acknowledge" messages, and have the base stations tell you when to replace the battery.
How about an RFID tag or smallest RFID object embedded in your FLESH! :)
JK,You could use an RFID based system, more like a tag. But the problem to differentiate between leaving and coming back will be there. Maybe 2 of those,so if one is activated, and the other is activated as well after a small time, then the order could help the system figure out if you are leaving or are back.
Another expensive option would be to use an Image detection system.
I think, using your phone would be the best option, dont they have the option to still check if the phone goes to the sleep mode?
Another stupid way would be to have a system says Hi, when someone steps in, and as you reply, it does voice pitch detection to figure out who it is.