I tried using mine with the sensor just 5' from the driveway and 75' from the receiver. There was a clear, unobstructed view between the two. It never worked well. I knew it was cheap and may need some "tweaking", so I tried to be patient. I tried everything, followed the instructions, taped over the lens... first a little, then more, then alot. Nothing worked. Gave frequent false alarms, often failed to warn when there WAS a visitor. Then quit working altogether within a few weeks.