Before she became famous for her beauty on the silver screen, Hedy Lamarr had another side that Hollywood audiences rarely saw.

During the 1930s and 1940s, Lamarr became one of Hollywood’s biggest stars, appearing alongside actors such as Clark Gable and Spencer Tracy. But away from the cameras, she was fascinated by science, engineering and invention.

During World War II, Lamarr became concerned about German forces interfering with radio-controlled torpedoes. She and composer George Antheil developed a system that could rapidly switch a radio signal between different frequencies in a synchronized sequence.

The idea became known as frequency-hopping spread spectrum. In 1942, Lamarr and Antheil received U.S. Patent No. 2,292,387 for their invention.

The U.S. military did not immediately adopt the system for wartime use, and the inventors never became wealthy from the patent.

But decades later, the underlying concept became extremely important in the development of spread-spectrum communications.

Modern technologies including Bluetooth and some wireless communication systems use techniques descended from the same broad principle. Her contribution was the frequency-hopping concept, which became part of the technological ancestry of modern wireless communications.

So while Hollywood remembered Lamarr as a glamorous movie star, the world of technology eventually recognized something else.

She was also an inventor whose wartime idea helped influence the wireless world we live in today.