@Mark Ollig
Hollywood actress Hedy Lamarr and American composer George Antheil filed a US patent application June 10, 1941, Serial No. 397,412, titled “Secret Communication System.”
Issued as US Patent No. 2,292,387 Aug. 11, 1942, during the height of World War II, their invention described a system designed to make radio communications difficult to discover or decipher.
On the patent, Lamarr was listed as Hedy Kiesler Markey, her legal name at the time, which blended her maiden surname with her married name.
They proposed a frequency-hopping system in which the transmitter and receiver switched in sync among as many as 88 preset frequencies.
This rapid, synchronized hopping, with both ends changing in the same order at the same time, kept their link in step and, in principle, would make the intended torpedo control signals much harder to jam or intercept.
The patent states, “This invention relates broadly to secret communication systems involving the use of carrier waves of different frequencies, and is especially useful in the remote control of dirigible craft, such as torpedoes.”
It continues, “An object of the invention is to provide a method of secret communication which is relatively simple and reliable in operation, but at the same time is difficult to discover or decipher.”
As a child in Vienna, Lamarr’s father taught her about machines, such as streetcars and printing presses, which sparked her technical interest in inventing and solving problems.
While still in her teens, Lamarr studied acting in Vienna and caught the attention of pioneering theater director Max Reinhardt, who helped launch her professional stage and film career.
In 1933, Lamarr married industrialist Fritz Mandl, attending his meetings with scientists and defense experts, where she gained knowledge about weapons and radio technology, including how jamming could disrupt radio connections.
In 1937, just before World War II erupted in Europe, she met Louis B. Mayer in London.
He was the head of Metro-Goldwyn-Mayer (MGM), a Hollywood studio based in Culver City, CA, known for its high-quality films and roster of major stars.
She accepted an MGM contract during the ocean voyage to the United States and then moved to Hollywood to begin her new career under the stage name Hedy Lamarr.
Hedy Lamarr starred in films like “Algiers” (1938), “Ziegfeld Girl” (1941), and “Samson and Delilah” (1949).
During her movie career, she became interested in a specific wartime issue: how to keep enemy forces from jamming the radio signals used to guide Allied radio-controlled torpedoes.
In 1940, while war raged in Europe and the United States had not yet entered the conflict, Lamarr met composer George Antheil at a Hollywood dinner party.
She was quoted as having discussed her discomfort with making money while Europe was in crisis.
Lamarr and Antheil’s later conversations turned to the use of radio control and jamming techniques, which led to a design for protecting radio-guided torpedoes from interference.
As World War II unfolded in Europe, they worked together on a frequency-hopping control method to counter Axis jamming of Allied radio-guided torpedoes.
Antheil, a pioneering composer, explored the idea of syncing several player pianos playing simultaneously via perforated paper rolls during his live performances.
His most famous work, Ballet Mécanique, was originally scored for 16 synchronized player pianos.
That work gave him a practical sense of timing, coordination, and expertise to control multiple machines simultaneously.
He drew on that experience when he helped Lamarr design the patent’s synchronization mechanism for the frequency-hopping system, using as many as 88 preset frequencies, matching the 88 keys on a piano keyboard.
Lamarr and Antheil developed a method to rapidly switch between preset radio frequencies, with only the sender and receiver aware of the pattern.
Their idea used matching perforated paper rolls in both the transmitter and receiver, each programmed with the same hopping sequence, a preset pattern of frequency changes, ensuring both sides remained in step as the radio frequency changed.
As the rolls moved forward together, the connection stayed in sync even as the carrier frequency changed.
This coordinated hopping pattern is often cited as an early analog example of what is now known as spread-spectrum signaling, a concept that later engineers adapted into electronic and digital forms.
The Navy rejected it in 1942 because the paper-roll synchronization mechanism was too cumbersome for a torpedo.
It is also clear to me that the vacuum-tube electronics of that era would have added unnecessary size and complexity to any practical version of their device meant for use inside a torpedo.
Lamarr and Antheil’s patent was granted during World War II, but it wasn’t until transistor technology emerged in the 1950s that their idea became practical for use in compact electronic devices.
In 1957, during the Cold War, as solid-state electronics progressed, engineers at Sylvania explored developing a version of Lamarr and Antheil’s patented system using solid-state transistors.
In the following years, as new technologies matured, the military began implementing spread-spectrum and frequency-hopping techniques.
The development of spread-spectrum and frequency-hopping technologies paved the way for Bluetooth, invented in 1994, which uses frequency-hopping spread spectrum (FHSS) in the 2.4 gigahertz band to reduce interference.
The Global Positioning System (GPS), which became fully operational in the mid-1990s, also uses direct-sequence spread spectrum (DSSS) for improved signal reception.
The first Wi-Fi standard, the Institute of Electrical and Electronics Engineers (IEEE) 802.11 specification, released in 1997, employed methods such as frequency hopping and DSSS.
In 1999, IEEE 802.11a introduced orthogonal frequency-division multiplexing (OFDM) in the 5 gigahertz band for faster data rates.
This evolution of wireless standards continues to this day.
As of this year, Wi-Fi 6 (using the 2.4 and 5 GHz bands) and Wi-Fi 6E (which adds the 6 GHz band) are commonly found in new routers, offering maximum theoretical speeds of approximately 9.6 Gbps.
Also, Wi-Fi 7 (IEEE 802.11be) is now available in high-end devices, offering multi-gigabit speeds with peak data rates of around 40 Gbps under optimal conditions.
Lamarr and Antheil’s collaboration played a key role in shaping the “truly ahead of its time” wireless technologies we rely on today.
George Johann Carl Antheil was born July 8, 1900, in Trenton, NJ, and died Feb. 12, 1959, in New York City, NY, at age 58.
Hedy Lamarr, born Hedwig Eva Maria Kiesler Nov. 9, 1914, in Vienna, Austria, died Jan. 19, 2000, in Casselberry, FL, at age 85.
