Just a quick search as I got curious myself after posting in here.
Here is a little video to give you an idea.
However I did come across a Polish article claiming that the Blue Raider unit is unless from a distance as well and when not stationary as in the video. You can read it for yourself but you're going to have to know Polish or have your browser translate it. Not sure how extensive their testing was, although it makes perfect sense that you would need a much more sizable unit to give off more power to be able to completely block the signal.