Documentary sheds light on Hollywood star, inventor

With George Antheil, Hedy Lamarr invented spread-sprectrum communications in 1942.

What do a 1930’s Hollywood star and the inventor of spread-spectrum communications have in common? They are one and the same.

The new documentary Bombshell highlights not just the acting career of Hedy Lamarr, but her contributions as an inventor. With George Antheil, Lamarr invented spread-sprectrum communications in 1942 and, specifically, the frequency-hopping version.

Explains Innovation editor Richard Langley, “When a signal’s frequency is quickly shifted in a seemingly random way among a large number of frequencies, the signal can become buried in the background noise and difficult to detect.

“However, when received, the signal can be recovered by changing the tuned frequency in exactly the same manner as was used for the transmission, thereby lifting the signal out of the noise, allowing it to be heard. Enemy eavesdroppers might not even know a signal was present and wouldn’t be able to decode it anyway unless they knew the frequency-shift sequence.

“Another way to create a spread-spectrum signal is to spread it using a direct pseudorandom code sequence, and this is what GPS and the other GNSS do.”

Lamarr and Antheil’s radio system answered a different need — to guide torpedoes to their targets during World War II. The team was granted U.S. Patent No. 2,292,387 for a “Secret Communication System.”

Their system “employs a pair of synchronous records…which change the tuning of the transmitting and receiving apparatus from time to time, so that without knowledge of the records an enemy would be unable to determine at what frequency a controlling impulse would be sent.”

Bombshell, a Zeitgeist Films release, opened in theaters Nov. 24.