They are probably responsible for most of the ground loop system hums out there

I've seen at least 3 guys fix an issue like this in the last few months by discovering that the cable/sat installer set a seperate ground rod for the cable during install which can create the noise. If the noise occurs with this method, - The cable should be grounded to the main ground rod for the house which is usually nearby. A fourth just found that his clamp was loose and the cable was not tight to the rod, snugging got rid of it. It's one of the quickest fixes to eleminate.