I have the same setup about 300 feet distance and its about 90 percent successful. It also tends to give false positives with passing school busses and some farm equipment. It can miss small and fast moving vehicles in my driveway.I have a Mighty Mule detector that is buried beside the driveway and transmits to the receiver in the house. It detects moving metal and ignores everything else. If someone drives past it real slow it won't be set off, but it's been dependable for many years now. I also have 2 receivers on the same channel (one detector) since we spend a fair amount of time in both buildings. Not sure of the range but I think it's in the neighborhood of 150' but it can reach farther.