She and California neighbor/composer George Antheil co-created a frequency-hopping system (using a player-piano roll) so radio-guided torpedoes could avoid interference jamming — an invention for which they received a patent in 1942, though the U.S. military would not employ the technology for two more decades (during the Cuban Missile Crisis).
A pre cursor for spread spectrum.
Lamarr, whose work laid the foundation for spread-spectrum communication technology, began to be truly recognized for her scientific accomplishments in the ’90s, in the last years of her life.