Hedy Lamarr was not “the” inventor. Many developed this concept — going all the way back to 1908. But she DID submit & co-own a top-secret workable patent.
From Wikipedia: “The most celebrated invention of frequency hopping was that of actress Hedy Lamarr and composer George Antheil, who in 1942 receivedU.S. Patent 2,292,387 for their “Secret Communications System”. This early version of frequency hopping used a piano-roll to change among 88 frequencies, and was intended to make radio-guided torpedoes harder for enemies to detect or to jam. The patent was rediscovered in the 1950s during patent searches when private companies independently developed Code Division Multiple Access, a civilian form of spread-spectrum.”