Does anyone have any experience using a cellular phone to detect presence?
Background
I have made a Raspberry Pi based surveillance system that uses a PIR sensor to detect the presence of intruders. Intruder detection triggers the pi camera module to take pictures and send me them via email. This works great - except that i keep forgetting to arm and disarm the system. Eventually the idea occurred to me that i always have my cell phone in my pocket where ever i go - wouldn't it be great if i could somehow use this to automate the process of arming and disarming the system. That would be a perfect solution!
I figured that i could find a way to get the system to detect the mac address of my cellular among the IP addresses that are active in my LAN. As long as it is among them the system should be disarmed. If it is not present, then the system should be armed. I implemented the idea only to find out that i occasional get sent pictures of myself while at home with my cell phone on me. I then wrote some test code to investigate further what was happening by continually printing a list of all the devices registered with IP addresses in my LAN, and sure enough my cell phone kept dropping out. I presume that it (my cell phone) turns off wifi capability whenever it is not in use to save power because when i pick it up to check out the status the wifi is active and suddenly it is visible in my network again. Similar attempts using bluetooth gave the same results. I tried googling to find out how to stop my phone from turning off the wifi to save power. I soon found that i was not alone with this problem - many others with Samsung Galaxy A5 2017 cell phones were struggling to keep their wifi on and trying unsuccessfully to find out how to do so.
So, i hope that someone here has been experimenting with this kind of problem and are willing to share any knowledge which may assist me to find a suitable solution to this problem.
By the way, i apologize if i have chosen the wrong group to post this in. My reason for choosing the members group is that i really do not know which is the correct forum for this kind of post.
-raymond