From personal experience, I can assure you that they do. President Trump arrived in my town to inspect a military facility, and the motorcade had to travel right by my house on the way to the facility and I was shooting video using my smart phone from my front porch. All I caught was a State Police vehicle at the front of the motorcade, and then there was a vehicle with a "dome" type device on top of it that I suspect was responsible for the "jammimg" or whatever it was called. I've still got the video, but there's really nothing there but where the Trooper's cruiser came into view......