Typically cable company is responsible. When you find a ground loop. If you have a monster power with coax around try it put the cable signal in then another from the out to your cable box or T.V. Since cable isolators are somewhat harder to find these days I find that to be the easiest work around.
If you search Ground loop isolators it should give you, I think it's called Jansen transformers. Really well regarded company specializes in lots of different isolators.
Hopefully you can find the source easily
