Many readers have written in regarding the origins of spread spectrum technology, which is used today in wireless LANs and wireless local loop systems, so I thought I'd share a bit of historical trivia.
According to a number of reports, Austrian-born silver-screen actress Hedy Lamarr invented spread spectrum well before the digital communications age. Before fleeing Nazi-occupied Austria and leaving then-husband, Fritz Mandl (who sold weapons to Adolf Hitler), Lamarr came up with the idea of a radio-controlled torpedo but discovered the signal could be too easily jammed.
Later, while working with composer George Antheil in London, Lamarr broached the radio-controlled torpedo idea. She and Antheil decided that if they could change the frequency randomly, the system would work. The two received a patent (Patent No. 2,292,387) for their device in August of 1942.
The system used radio frequencies that changed at irregular periods and were synchronized between the transmitter and receiver using a special code. At each end of the transmission were identical slotted paper rolls, similar to those used on player pianos (Antheil's contribution, as a musician). These dictated the code according to their pattern of slots. Signals could be transmitted without being detected, deciphered or jammed.
Lamarr and Antheil reportedly attempted to give the technology away to the U.S. government after they relocated to Hollywood, with the altruistic intent to defeat the Nazis. But the U.S. was skeptical about the paper components. Later, in the1950s, Sylvania Electronic Systems Division developed an electronic spread-spectrum system based on Lamarr and Antheil's idea using digital components in place of the paper rolls.
Spread spectrum played a role in the Cuban Missile Crisis in 1962, allowing the military to use carrier waves that resembled random noise, making it difficult for an eavesdropper to know that a communication was taking place. In the mid-1980s, the US military declassified spread-spectrum technology, and the commercial sector began to develop it for consumer electronics.
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Joanie Wexler is an independent networking technology writer/editor in Campbell, Calif., who has spent most of her career analyzing trends and news in the computer networking industry. She welcomes your comments on the articles published in this newsletter, as well as your ideas for future article topics. Reach her at joanie@jwexler.com.
Network World Wireless archive
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A report from the field
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AT&T Wireless leaves the nest
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