I'm trying to cobble together a wireless presence detection system between rooms in two buildings 25m apart. Line of sight is good. Cabling or wiring is not an option. Ideally mains powered but not essential. The transmitting end needs to be 360deg sensor. The receiving end ideally should have facilities for both visual (a light?) and audible (a sounder of some kind) alert. I know Steinel make kit that would do the job but it is hideously expensive. Visonic MCR 304 and Disc MCW might do the job, but I don't know if these two are able to speak to each other independant of an alarm system.
Any ideas please. Nick.