Hedy Lamarr played a key role in the invention of spread-spectrum technology. She conceptualizing the idea of frequency hopping, which is sending radio signals from different frequency channels.
Lamarr and her co-inventor, George Antheil, developed the technology to help the Navy remotely control torpedoes. The randomized channel switching made of frequency hopping made it difficult for outside agents to understand what was being communicated.
Her work on spread-spectrum has played a part in many modern wireless technologies, such as Bluetooth and Wi-Fi, and led to her being inducted into the National Inventors Hall of Fame in 2014.