New-Tech Europe Magazine | November 2018

Grace Hopper

Hedy Lamarr

then Hollywood. During World War II she heard the enemy had quickly found a way to jam the steering commands sent to the radio-controlled torpedoes the US Navy had introduced. She worked out that the best way to deal with the jamming signal was to make the original signal much less predictable. George Antheil, a composer friend helped Lamarr develop a device that would let the signal hop across different frequencies, using a player-piano mechanism to provide the coding. Each mark on the piano roll moved to a new frequency, making it possible to encode the hopping in a way that would be very difficult for the enemy to predict and, as a result, jam. The invention gained a patent in 1942 but the US Navy refused to work with it. The organisation cited technical difficulties but was known for preferring to use only inventions from its own engineers. Half a century later, Lamarr’s idea of frequency hopping finally found a mainstream application as part of the Bluetooth standard. The protocol for personal area networks uses the concept of frequency hopping to avoid being inadvertently jammed by other competing signals in the heavily used unlicensed spectrum around 2.4GHz. Her work also influenced the direct-sequenced form of spread spectrum that is used in WiFi as well as the signals sent by Global Positioning Systems satellites – which need to avoid being jammed, like the torpedo commands, by hostile forces. So many years had passed since the original patent appeared that it took some time for Lamarr’s contribution to be recognised widely. But her reputation as a pioneering inventor is now secure. In contrast to Lamarr, Grace Murray Hopper had formal training in mathematics and the advantage of working for the US Navy when she developed a way to make computing much more efficient. But she worked in a part of the computing industry that its architects

had deemed unimportant: software. British computer scientist and developer of the EDSAC Maurice Wilkes, later recalled how he had been surprised when trying to develop for the machine he had built in 1949: “It had not occurred to me that there was going to be any difficulty about getting programs working.” A century earlier, Ada Lovelace, another outsider with a keen interest in engineering, had seen the potential in programming a machine such as Charles Babbage’s Difference Engine. But it would take a revolution of ideas much later for her ideas to be recognised. To the first computing hardware engineers, a computer was human: someone who computed the answers to a difficult problem but who could turn to an automated system as one would today to a pocket calculator. So, the first programmers of electronic calculating machines were primarily women who were skilled mathematicians who could analyse each intermediate result and work on the next step. The idea of a stored-program computer formed quite slowly and it was the wife of computer architect John von Neumann, Klára Dán who developed the first software for it. But one of her fellow programmers, Betty Holberton, had to work hard

History Makers

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