Thread HiJack, on a somewhat related note
("Excuse me while I whip this out...")
I also heard several years ago that the Chinese have a method of detecting stealth aircraft, by reading television and radio transmission signals as the aircraft passes through its airspace. As the signal is interrupted, they can determine the speed and size of the aircraft.
Please, don't ask where I read this from, although I believe it was Reuters, sometime in the early 90's, after Desert Shield.