Here's another question that's not related to ponds but that I figure someone on here has probably had some experience with.

I'm shopping around for some kind of alarm system for the entrance to our property. We have no gate, just an open driveway with fence posts on either side. Our house is around 600' from the driveway entrance. I'm thinking of some kind of system that's powered by a battery or possibly a solar panel. When a car drives through the entrance it would transmit a radio signal to one or more receiver units in the house that would beep to alert us that someone was entering the property. I'd like to have multiple receiver units in the house so that we can hear the alert from different rooms. Hopefully it could be adjusted to only trigger on cars or trucks and not give us false alarms when an animal walks through.

Has anyone seen anything like this? Any recommendations on where to start looking for it?