If you know the name Hedy Lamarr , you probably know her as an actress whose overt display of nudity and sexuality in the 1933 film ECSTASY helped to solidify the connection between art-films and forbidden subjects for American audiences. Upon immigrating to America, she became a major Hollywood star, and remained so for years.
She was also a hobbyist inventor who, in 1941, with avant-garde composer George Antheil, came up with an ingenious way to guide Allied naval torpedoes. Radio control had already been used to guide the trajectory of torpedoes fired from ships and submarines, but Axis scientists easily found a way to jam the signal and misdirect the fire.
Lamarr and Antheil had the idea that a code might be created that is similar to the markings on a player piano roll, a code of such complexity that it could not be decoded without access to a very specific algorithm. The two patented the idea and, though it was not used by Allied forces during the war, it attracted considerable interest later. The technology (called Spread Spectrum) evolved into the mechanism we now use for encoded wi-fi and Bluetooth transmission.
Here is the patent for Spread Spectrum, also known as Secret Communication technology, in case you ever want to build an encoded guidance system of your own. FYI: Hedy's real name, Hedy Kiesler Markey is the name that appears on the patent.