Hedy Lamarr and modern wireless: beyond Hollywood prejudices

Innovator, scientist, inventor : Hedy Lamarr was not only a Hollywood diva, but also and above all the mastermind behind modern wireless technology . A nobel intelligence accompanied by a goddess beauty, which obscured the merits of one of the most important inventions in history. Clever, brilliant, rebellious, she did everything possible not to give in totally to the will of those who saw her only as a collector's item: she continued to cultivate her passion for mathematics despite the schemes in which she was locked up. Her obstinacy led her to develop a communication system that is the basis of modern broadcasting.

Hedy Lamarr: a life of success and conflict

Hedwig Eva Maria Kiesler was born in Vienna on November 9, 1914. From an early age she became passionate about the world of entertainment and acting, and in 1931 she decided to devote herself entirely to an acting career. To do so he abandoned his engineering studies, in which he excelled, but his passion for the sciences never left her. The woman's career began to take off but so did the rumors about her : the film Ecstasy in particular created an ambiguous aura around Lamarr, who lent itself to the first full nude scene and the first cinematic orgasm. Because of this, relations with the family became more difficult: the parents did not approve of those controversial scenes that gave rise to indiscretions, accusations and censorship.

Hedy Lamarr in one of his films. Source: Physics World
Hedy Lamarr in one of his films. Source: Physics World

In 1937 she moved to Los Angeles to follow her acting career and in the same year she met Louis B. Mayer, founder of Metro-Goldwyn Mayer, who made her become the same as Hollywood and renamed it with the name we all know it by: Hedy Lamarr. The woman had several loves in her life, but none of them treated her as more than an object. Her unrivaled beauty was the only thing worth mentioning in the Hollywood world, and she never managed to break free from the prejudices and limitations imposed. But that did n't stop Hedy Lamarr from developing the technology behind modern wireless communication .

The birth of the technology behind modern wireless: the Frequency-Hopping Spread Spectrum

In 1940, during one of the many Hollywood parties, Lamarr met the composer George Antheil and a deep friendship was established between the two. With the war that raged often their speeches centered on weapons, in particular radio-controlled torpedoes, and it was from these reflections that Lamarr's idea was born: to interfere with the radio signals of the torpedo controls by modifying the transmission frequencies . This could provide a big advantage against enemies, making it more difficult for them to spot torpedoes.

George Antheil and Hedy Lamarr. Source: Houston Piano Company
George Antheil and Hedy Lamarr. Source: Houston Piano Company

The system was built using Antheil's multi-instrumental apparatus, consisting of pianolas, pianos, xylophones, copper timpani, electric bells, flutes and a harmonica. The initial system involved the use of a piano-roll , a real perforated roll normally used to make the piano play. The apparatus used 88 frequencies, the same number as those of a piano. By continuously changing the transmission of frequencies, the American torpedoes would have been invisible to the Germans. The two called their invention SCS – Secret Communication System and filed the patent in 1942 . However, SCS was only used in 1962: the system was considered too cumbersome and, moreover, it was frowned upon because it was invented by a woman .

An image of Lamarr's patent for the SCS. Source: H.K. Markey et Al - Secret Communication System (patent)
An image of Lamarr's patent for the SCS. Source: HK Markey et Al – Secret Communication System (patent)

The invention aimed to provide a simple and secure communication system but at the same time difficult to decipher. The transmission frequencies between emitter and receiver were not stable , but were changed regularly preventing the enemy from picking up the communication and predicting the direction of the radio-controlled torpedo. In the idea of ​​Lamarr and Antheil the “rolls” of the pianos could have been used, so the frequency changed following the perforations of the sheets. The two communication stations had to be calibrated and synchronized in order to follow the same frequency jumps, at the same moments.

The frequency hopping in wireless communications

But what does wireless technology have to do with Hedy Lamarr's invention? SCS is at the origin of the frequency-hopping spread spectrum (FHSS) , the radio transmission technique used to increase the bandwidth of a signal. Also in this case the transmission frequency is varied at intervals of time that can be provided in a pseudorandom manner. The system has become the basis of modern GSM telephone technology because it is able to guarantee the privacy of communications between users.

The FHSS allowed the use of code-division multiple access (CDMA) communications, the most widely used communication protocol in wireless networks. Initially it was intended for 2G networks, but with the W-CDMA (wideband CDMA) version it became part of 3G technology and in the transmissions of GPS satellites. In addition to the secrecy of the communication, the FHSS, by periodically varying the transmission frequency, guarantees good resistance to disturbances and interference.

In the FHSS the signal changes frequency continuously. Source: MathWorks
In the FHSS the signal changes frequency continuously. Source: MathWorks

Technology is also the basis of Bluetooth . In this case they use 79 different frequencies in the band between 2400 and 2584.3 MHz, "jumping" (hopping) continuously from one. Bluetooth rapidly varies frequency: we are talking about 1600 hops per second. The two devices share the frequency pattern and it is rare that there is interference from a third device. The hopping patterns are generated in a pseudo-random way , so as to make it difficult to use the same pattern by a device external to the communication.

Hedy Lamarr and wireless: a little recognized merit

The success of Lamarr's idea did not come at the right time: the refusal of the Navy, also motivated by the sex and origin of the inventor, threw the SCS into oblivion for almost 20 years. It was only during the 1950s, in fact, that the military began to understand its real value, and in 1962 it was used for the first time under the name of CDMA . The patent had expired for 3 years.

The system was subsequently improved and declassified for civilian use: in the 1980s Lamarr's invention achieved global success . The awards, however, came only in the 90s, such as the Electronic Frontier Foundation Pioneer Award, or the recognition of the Inventors Club of America and the Kaplan Medal, an Austrian honor of great importance. World Inventor Day falls on November 9, Lamarr's birthday. Unfortunately, the woman was unable to enjoy these merits: by now old she communicated with the world only through a telephone and no longer made public appearances. He died on January 19, 2000.

Gal Gadot will play Hedy Lamarr in an Apple TV miniseries. Source: Vanity Fair
Gal Gadot will play Hedy Lamarr in an Apple TV miniseries. Source: Vanity Fair

The story of Hedy Lamarr leaves a lot of bitterness in the mouth. Past prejudices and the unhealthy Hollywood environment that has taken advantage of her have prevented the world from knowing in due course the brilliant mind behind one of the most important and used technologies in the world. The mathematician and actress never abandoned her passion for engineering but had to cultivate it almost in secret, even apologizing to those who did not accept this side of her.

According to the world, his path had to be only one. Lamarr never mentioned his research and studies during interviews because he knew no one would be interested. If we know its history, it is mostly thanks to posthumous articles and documentaries . The past cannot be changed, but we can make sure that nothing like this happens again. We continue to talk about women like her and we begin to recognize the merit without any more gender bias. The mind is not and cannot be incompatible with the physical aspect .

The article Hedy Lamarr and modern wireless: Beyond Hollywood prejudices comes from Tech CuE | Close-up Engineering .