A solution that uses three off-the-shelf Arduino units. if speed is not a requirement this could be set up cheaply and not be on crowded radio freqs. an FM radio link requires no license and could be broadcast all over town, but anyone with an FM radio hears you. I need to talk to units all over my 2 acres. id and discourage pigs, rats, and other desert pests. there seems to be no such system. many here in Tucson would pay big bucks to protect expensive cars from rats. much more hate to pick up the trash the pigs spread. still, more would like a system to light and run different sequences on their driveways. on top of that people want a security system they can know how it works and expand it themselves. then new radio system work by magic and you must buy expansions from them. an Arduino system is more a hobby than anything else.