[ame=http://www.amazon.com/PetSafe-Wireless-Containment-System-PIF-300/dp/B0001ZWZ8O]Amazon.com: PetSafe Wireless Pet Containment System, PIF-300: Pet Supplies[/ame]
this is an example...an in house transmitter sends a signal..there is a new product that can be configured not in a circle but in a rectangle to fit your property. Looks like nobody is using this from what I am reading.
the dog learns to hear a beep from the collar when nearing the boundary and hopefully needs one time getting the current to learn...I'm told it is not a "shock" like an electric fence, but more like static energy.
http://www.havahartwireless.com/stor...og-fence/5144g