Secret high tech employed to prevent presidential assassination

Barack Obama has received more assassination threats than any president-elect in U.S. history. While Obama's Secret Service protection has obviously been flawless thus far, according to some speculative reports, any would-be assailants might be in for some major pain or instant discovery, thanks to some outlandish technology. This must mean that new tank-like presidential limo is just the beginning of the presidential shield of protection.
The methods and gadgets used by the Secret Service are highly classified, but writers and researchers are speculating that one of the secret devices could be a rifle-sized weapon using the military's "active denial system" that beams sound waves directly into an assassin's skull. That's gotta hurt, at least disabling the killer long enough for agents to quickly move the president out of harm's way.
Other reports have the Secret Service using special terahertz scanners that can see through clothing, spotting a concealed weapon from a distance. There's also talk of sophisticated radio jammers that could disable any remote-controlled bombs. Let's hope all this stuff, if it exists, works flawlessly. If not, maybe they could just use a body double for Obama's non-speaking public appearances.