I'm looking for a way to build a multipart system where a central receiver circuit could indentify if one or more transmitter circuits are within roughly 3 feet of the transmitter. There would need to be up to 10 transmitters, with at least 4 different "codes" that the receiver could differentiate between.
(Similar to RFID tech, but I need more range, the transmitter can be active rather than passive if needed, and only reasonable accuracy is required.)
The application is an automatic feeder for my hobby farm, where my miniature cattle and my horses can get food, without the other animals stealing it from them. (If you just leave food out, the big horse will steal all the miniature cattle's food) The animals would have the transmitters hanging off of their collars/halters. The feeder needs to identify that an animal is checking the feeder, then a micro-controller will decide if the animal needs food (or has eaten enough for the day), which kind, etc. and dispense as needed.
The detection circuit is the part I'm struggling with.
(Similar to RFID tech, but I need more range, the transmitter can be active rather than passive if needed, and only reasonable accuracy is required.)
The application is an automatic feeder for my hobby farm, where my miniature cattle and my horses can get food, without the other animals stealing it from them. (If you just leave food out, the big horse will steal all the miniature cattle's food) The animals would have the transmitters hanging off of their collars/halters. The feeder needs to identify that an animal is checking the feeder, then a micro-controller will decide if the animal needs food (or has eaten enough for the day), which kind, etc. and dispense as needed.
The detection circuit is the part I'm struggling with.