Hedy Lamarr – an engineering pioneer
Hedy Lamarr is recognised around the world as one of the most
beautiful women to have graced the silver screen. Yet despite this
celebrity few people are aware that she was also responsible for one
of the key communications technologies of the 21st Century –
spread spectrum. Born in Vienna in 1914, the daughter of a
successful banker, Hedwig Eva Maria Keisler, first found fame when
she appeared in Ecstasy, an Austrian-Czech film with a story line
considered highly daring for its time. Containing what was reputedly
the first instance of nudity in cinematic history, her appearance in
the film brought her considerable notoriety in a society that was
becoming increasing repressed. As the Nazi movement within Germany
and Austria became ever more powerful, so her husband Fritz Mandl,
an armament manufacturer became more ever more closely involved with
the regime. Fearing for the future, and against her husband’s
wishes, she packed her bags, reputedly drugged her maid, and escaped
through an upstairs window, fleeing firstly to London and thence to
Hollywood.
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“Any girl can be
glamorous. All you have to do is stand still and look stupid.”
Hedy
Lamarr |
Hedwig, now Hedy, pursued her two great passions in life, acting
and mathematics. A stream of highly acclaimed films followed, with
Hedy Lamarr becoming one of the great pin-ups of the thirties and
forties. However, Hollywood proved less than intellectually
challenging so Hedy kept her mind active by considering a problem
that she had heard her first husband discuss, namely the ease with
which a signal sent to a radio controlled torpedo could be blocked.
She realised that if the signal jumped quickly from frequency to
frequency and if both sender and receiver changed in the same order,
then the signal could never be blocked by a third party without
knowledge of how the frequency was changing.
Her celebrity brought invitations to many and varied ‘Tinsel
Town’ parties. It was at one such party that she met George
Antheil, an avant-garde musician, scrawling her phone number in
lipstick on the windscreen of his car as she left. As the Second
World War hung in the balance, the pair worked together to develop a
‘secret communication system’ intended for use as a radio
guidance device for US torpedoes. While Lamarr contributed the
theory, Antheil provided a possible means of implementation using
paper rolls such as those included in Pianolas. By 1942 a patent had
been granted to Hedy Kiesler Markey and George Antheil. The patent
details the concept of ‘frequency hopping’ to quickly shift the
radio signals of control devices, making them less vulnerable to
radio interference or jamming. Today the technique is better known
as spread spectrum.
Lamarr-Antheil patent
The Lamarr-Antheil patent expired after 17 years and was not
renewed, but all later patents for spread spectrum technology
acknowledge the original. The technology was classified by the US
government and used during Cuban Missile Crisis. In 1985 it entered
the public domain when the FCC made it available for limited use.
Today, with the widespread availability of cheap and ultrafast
microprocessors, spread spectrum offers an effective and inexpensive
way to communicate over long distances, privately and efficiently.
It provides the basic principle that enables the simultaneous
multi-channel operation of modern digital cellular telephony.
Furthermore, the efficiency of transmission is such that low-power
transmitters can be used over considerable distances, with many
transmitters and receivers occupying the same frequency band —
thereby enabling inexpensive wireless access to public networks.
George Antheil died in 1959. Hedy Lamarr, the inventor of a
technology that underpins some of the most valuable and profitable
areas of the modern radio communications industry died in 2000.
Neither received any payment for their work.
contributed by Helena Leeson
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