I’ve thought about that beam directed thing and it scares the heck out of me. Just a speaker, really, but highly directional so no one can hear it except the person it’s pointed at. Only trouble with it would be the line of sight requirement, so I imagine there are other methods they use.
I found that sound “beam” thing to be interesting as well.
It instantly made me think of the noise, or whatever it was, in Cuba that injured diplomatic personnel. I know nothing about sound technology but intuitively the dots seemed to have some sort of relationship.
Cel towers. This is why all the apps ask if they can use your location. We target ourselves.