Bluetooth technology is common today, even becoming a part of current hearing aid development to eliminate wired communications. While there are many events that led to its development, one story stands out because of its seemingly oddity to inventive technology. It had to do with the invention of frequency hopping, or what is now often called spread spectrum technology. Spread spectrum transmission helped galvanize the digital communications boom, forming the technical backbone that makes cellular phones, fax machines, Bluetooth, and other wireless operations possible.
That oddity relates to a lady named Hedy Lamarr. The reason for this oddity is that Hedy Lamarr was a 1940s-1950s Hollywood beauty (called the most beautiful women in the world) and leading lady in many films, but is also considered as having co-invented the concept of wireless frequency hopping, which is used today in Bluetooth, GPS, Wi-Fi, and cell phone technology. Without frequency hopping (also called spread spectrum transmission), Bluetooth and some of the other current transmission technologies would not exist. So, Lamarr may as easily be considered, along with her colleague George Antheil, as a co-inventor of Bluetooth technology. Although there have been a couple of other claims to the invention, none rise to the exotic interest level or international circumstances surrounding Lamarr’s participation.
But, what does this have to do with munitions and WWII, as the title suggests? As Paul Harvey (deceased American commentator) would say “…and now, the rest of the story.”
A Little History of Hedy Lamarr
As stated, Hedy Lamarr was a 1940s –1950s Hollywood beauty and leading lady. But, unknown to many star struck movie goers who couldn’t see past her beauty and acting skills, she was also a mathematician and creative inventor.
Born Hedwig Kiesler, she came from an unremarkable Jewish family in Vienna, Austria. Her father was a banker, and she accompanied him on long walks, absorbing his detailed explanations of how things worked – printing presses, streetcars, and other modern marvels at the time. Even though intelligent and accomplished on the piano, she declined a technical career to become an actress, becoming a star in her teens. Her sudden stardom included a marriage to plutocrat Fritz Mandl, an Austrian industrialist and arms manufacturer, doing business with the Nazi and Italian military.
Her husband was so controlling that he barred her from acting and she was forced to accompany him on many of his business trips. She devised an escape plan that involved gathering classified military intelligence while on these trips. She was adept at speaking and writing at length on inventions, especially munitions with plans related to remote-controlled torpedoes (which were never produced because the guidance system was too susceptible to disruption). As Mrs. Fritz Mandl, she had closely observed the planning and discussions that attempted to design remote-controlled torpedoes. Her beauty and manner allowed her to obtain information from Mandl and his cronies, and she had an ability to understand and retain what she learned. She eventually used this classified information as blackmail against her husband to allow her to flee to the United States where she signed a movie deal with MGM based on her notoriety, changed her name, and settled in California. This was in 1937, before WWII broke out.
In a book written about her by Richard Rhodes (2012), he writes that Lamarr didn’t drink or socialize much, but enjoyed inventing things to kill time between shoots. Her home included a drafting table and tools for her inventive skills. Inventing became her hobby, and while qualifying somewhat as an inventive genius, it was only during WWII that her inventions moved beyond practical ideas, when in 1940 she partnered with a misfit pianist and composer named George Antheil. Antheil had lost a brother in Finland as one of America’s first casualties in the war. And, the sinking of a cruise ship in 1940 by Nazi U-boats, resulting in the drowning of seventy-seven British school children being evacuated to Canada, compelled 26-year-old Lamarr, a passionate opponent of the Nazis, to do something to assist the Allied cause.
Lamarr envisioned airplanes controlling torpedoes remotely from above, and adjusting their direction using radio pulses. The problem was that torpedoes could receive radio instructions on only one predetermined radio frequency. So, if the enemy figured out that frequency, they could jam transmission by flooding the signal with noise and sending the torpedo off course.
As a result, at a cocktail party, and after listening to Antheil play the piano and its constantly changing notes, she had an idea: instead of sending radio control signals to a torpedo using one frequency, which could be jammed or intercepted easily, why not send the signal over constantly changing frequencies in a pre-arranged pattern, like notes in a song. With this, she and Antheil zeroed in on improving difficult-to-control torpedoes to assist in the Allied war effort.
Frequency Hopping (Spread Spectrum Transmission)
Lamarr’s solution to overcoming frequency jamming was to have the plane and torpedo jump in tandem to different frequencies over and over (frequency hopping), much like turning a radio dial every few seconds. So, it didn’t matter if the enemy jammed one frequency, both the sender and receiver would soon switch to another frequency.
Resolving how the plane and torpedo could hop in perfect synchrony was the know-how that Antheil provided. He had experimented with generation and automated control of musical instruments and sounds for some of his musical compositions, which required synchronization.
They tested out the theory using the 88 frequency keys of the piano to control the frequency hops. While George played a note on the piano, Hedy repeated it at the same time on another scale in a pattern known to both of them. They further tested this using a player piano mechanism using perforated paper rolls between two pianos that would turn in synchronization with each other. Her frequency hopping concept was elegant and original.
Translating this to torpedoes, the encrypted identical sequencing code for frequencies that would be held by both the controlling ship/airplane and the torpedo, avoiding enemy frequency jamming because it would be impractical for them to scan and jam all 88 frequencies. And, if they did hit the frequency on one of its hops, it would be there for only a fraction of a second. Thus, Lamarr’s concept of “spread-spectrum radio” was born.
Concept Leads to Patent
In 1940, their “frequency hopping” device was submitted to the National Inventors Council, a semi-military inventors’ association. They then filed a patent application for the “Secret Communication System” in 1941, and the patent was granted by the United States Patent Office in 1942.
Unknown to the public, Lamarr and Antheil immediately placed their patent at the disposal of the U.S. military for the express purpose to assist in the defeat of Hitler. For whatever the reason, the U.S. military did not deploy the “secret communication system” during WWII, most believing that a Hollywood beauty had nothing to contribute, and even if it worked, that it would be too bulky. Still, in the 1950s the Navy commissioned a project for airplanes to acoustically detect submarines using sonar buoys remotely controlled from airplanes. That concept is still in place.
Aside from this use, Lamarr and Antheil’s secret communication system languished in obscurity, not being used, until twenty years later (1962) when it was employed between ships of the U.S. Navy during the Cuban Missile Blockade, not for torpedo use, but to provide secure communications. But from then on, their invention of frequency hopping has taken center stage in wireless communications. No one made any money from Lamarr and Antheil’s invention or from their patent, which eventually expired. Then, in the 1950s, Sylvania introduced a similar concept and coined the term “spread spectrum.”
And Today
In the 1990s, when Hedy Lamarr was in her early 80s, one of the pioneers of wireless communications for computers was exposed to her patent. The patent and the concept behind it were so ingenious that she was belatedly honored for her invention.
It turns out that the technology was good for more than just secrecy. In today’s communications systems, it allows many devices to operate in the same radio spectrum without interfering with each others’ signals. So that while different peoples’ cell phones operate in the same spectrum, they don’t interfere with each other because they are all working off different patters of microsecond frequency changes. The signals never “bump” into each other.
Based upon the Lamarr/Antheil invention, Microsoft, Ericsson, IBM, Intel, Agere, Motorola, Nokia, and Toshiba, plus thousands of associate and adopter member companies began a special interest group (SIG) in 1998 to develop wireless technology utilizing the radio frequency- hopping concept to replace RS 232 (wired) connection cables. Engineers came to realized that the Lamarr/Antheil frequency-hopping invention could solve some sticky problems arising when multiple electronic devices had to communicate, without interference, when in close proximity to each other. Today, a more general version of frequency hopping forms the foundation for GPS, Wi-Fi, cell phones, Bluetooth, and other wireless communications.
Lamarr’s work led to her being inducted into the National Inventors Hall of Fame in 2014.
And who said that beauty and brains don’t mix?
Dr Wayne Stabb
http://hearinghealthmatters.org/waynesworld/
References
- Rhodes, Richard. Hedy’s Folly: The Life and Breakthrough Inventions of Hedy Lamarr, the Most Beautiful Woman in the World, First Vintage Books, August, 2012.