Get an alarm system that enables you from inside to sound a large and obnoxious horn and turns out outside lights.
It may or may not call the cops automatically as you set it up.
1. Tells a BG that you are aware. Thus, they may go away.
2. It can call the cops. Some folks say - Blah, blah - the cops are 1/2 hour away. So start them rolling and it establishes you felt under threat. Give them a head start on saving you if needed.