Tuesday, October 14, 2014

Frequency-Hopping Inventor, Hedy Lamarr

In honor of International Ada Lovelace Day, I am writing about the actress and inventor, Hedy Lamarr. I like this photo of Lamarr because I like to think she's reacting to the Internet idiots who post comments claiming women don't belong in technology. 

"Really," she would say, in her smoky, low voice. "You should have been there when I invented frequency-hopping, a technology still used today on wireless networks. I invented it to prevent Hitler from jamming the Allies' radio-controlled torpedoes. How about you, dude? What have you invented lately?" 

Lamarr was a Hollywood film star in the 1930s and 1940s. She was born Hedwig Eva Maria Kiesler in 1913 in Vienna, Austria. She married young and was unhappy in her marriage. She wrote in her autobiography that her husband, Fritz Mandl, a munitions manufacturer, was extremely controlling. 

In the 1930s, Lamarr accompanied her husband to dinners and meetings with arms developers and learned about control systems for aircraft. The marriage broke up in 1937, and Lamarr, an anti-Nazi of Jewish descent, escaped to Paris, then London, then Hollywood. She took her knowledge of control systems with her.  

Lamarr met her co-inventor, the avant-garde musician George Antheil, at a party in 1940. At the party, Lamarr proposed the idea of frequency-hopping as a method for radio remote control of torpedoes. Frequency-hopping could reduce the danger of detection or jamming of radio-controlled torpedoes. 

Although the idea of radio control for torpedoes was not new, the concept of frequency-hopping was. Broadcasting over a seemingly random series of radio frequencies, switching from frequency to frequency at split-second intervals, prevents radio signals from being jammed. The receiver can be synchronized to the transmitter to allow the two to jump frequencies together. If both the sender and receiver hop in sync, they understand the message, but anyone trying to eavesdrop hears random noise. 

Lamarr and Antheil obtained a patent for their "Secret Communication System" on August 11, 1942. The US Navy was unfortunately not interested in this early version of frequency-hopping. However, the idea was finally implemented in 1962, when it was used by US military ships during a blockade of Cuba, after the patent had expired. 

Subsequent patents in frequency-changing have referred to the Lamarr-Antheil patent as the basis of the field, and the concept lies behind anti-jamming devices used today. In modified form, frequency-hopping is used to send secure wireless transmissions in many modern communications systems.

The Electronic Frontier Foundation honored Lamarr with a belated award in 1997. Lamarr died in Casselberry, Florida on 19 January 2000. She was 85. 

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