g2c
Member
I had not as yet gone thoroughly through this literature and i must admit that i ignored the "code" multiple access scheme. I think i now understand how come on each of the 11 or so WiFi channels there are so many users communicating
To you proposition: I was thinking of a very simple "wire emulation". Assume i have a dozen of windows to protect. If i used wiring i'd request each sensor to send a keep alive signal every ~second. Lack of a keep alive at the controller's would mean that the sensor has been damaged and an event should be generated. Now, assume i'm using radio transmitters, mainly for aesthetic reasons -running wires by every window at the house envelop would not be so nice- i thought using a different frequency for ever rx/ tx pair at every window i'd have a sensor with a radio transmitter and a minimal intelligence to send a keep alive every~ second and to send "intrusion" in case of IR / varying IR detection. At home, at a protected area yet accessible to electromagnetic waves i'd have as many receivers, each tuned to its corresponding transmitter at the window. The receivers would be connected to a 16 i/os I2c chip and would pulse each it corresponding pin every keep alive and would apply a long steady signal in case of intrusion. A controller (say Arduino) connected to the i2c chip would generate events in case of "no keep alive" or in case of "intrusion". Given the low cost of the radio modules on eBay, the whole system should be pretty low cost. As for the consumption, according to https://www.electro-tech-online.com/threads/cheap-ebay-rf-modules-made-easy-and-fast.134224/ when the transmitter is idle it draws 1uA and assume a 1 ms keep alive transmission every second, we'd have a total of 1*10^(-6)+12*10^(-3) * 10^(-3)=13uA/ a cr2032 .25Ah battery should last .25*10^6/13/24/360~2 years if it were for the transmitter only
Now, from your post i understand that you have a radio alarm system you are happy with and i'd appreciate if you wanted to share your solution
