I got the same problem with my neighbor, he is always throwing garbage at my car. I surfed the internet and find a solution which suits me, maybe my advise will also help you. I bought a simple usb camera and instaled it on my window, than I just downloaded the program, which is called Xeoma and run it in a trial version. When I found out that everyrhing is ok, just bought 1 camera license.
Here is the link to this soft: http://felenasoft.com/xeoma/en/features/ Hope this will help you with you problem.
