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04.12

From Film Star to Frequency-Hopping Inventor

By Donald Christiansen

I’m guessing that some younger readers may not know who Hedy Lamarr was. Old-timers remember her as a popular Hollywood star of the mid-20th century. Characterized by MGM studio mogul Louis B. Mayer as “the most beautiful girl in the world,” a title said to originally have been bestowed by stage director Max Reinhardt, she appeared in some 25 Hollywood films between 1938 and 1958.

Unknown to her fans and many of her Hollywood colleagues was her creative side. They were unaware that when the cameras were not rolling, Ms. Lamarr might be at home at her drawing board, diligently working at some concept that might lead to a commercial product or a patentable invention.


Film star Hedy Lamarr in Ziegfeld Girl (1941)

Although an admirer of Hedy Lamarr the movie star (I particularly remember her in “Ziegfeld Girl,” costarring James Stewart, Judy Garland, Lana Turner, and Tony Martin, and “H. M. Pulham, Esq.,” with Robert Young and Van Heflen, I too was unaware of her innovative proclivities until 1984, when historian of cryptology David Kahn authored an article in IEEE Spectrum. It revealed to the uninitiated the existence of a 1941 patent issued to Lamarr and her co-inventor, George Antheil, based on frequency-hopping and titled “Secret Communication System.” World War II had been raging in Europe, and Hedy, a native Austrian, left her munitions magnate husband Friedrich Mandl and relocated to the United States in 1937. As Hitler moved relentlessly in his attempt to conquer most of northern Europe, she was appalled by the German U-boat sinking of the SS City of Benarus. The Benarus was carrying 456 passengers and crew, among them 90 children being evacuated to Canada (only 13 children survived, and a total of 245 lives were lost). She considered quitting the movie business and offering her services to the newly organized National Inventors Council (NIC), chartered to evaluate technology that could be useful in wartime, and chaired by inventor Charles Kettering. She did neither, however.

In Hollywood, Hedy had met George Antheil, not an engineer but a composer with “a fair grasp of electronics,” as historian Kahn expressed it. Antheil joined her in her attempt to devise a jam-proof guidance system for Allied torpedoes. A year before Pearl Harbor, she told Antheil she knew “a good deal about new munitions and various secret weapons,” presumably knowledge acquired while she was privy to discussions between Mandl and his munitions agents.

While not on the movie set, Lamarr would work with Antheil in her apartment to move her idea from concept to a practical system. In her early working documents a reference is made to the 116RX, the 1939 Philco radio console that featured the first wireless remote control (termed the Mystery Control and offering the listener options to select up to eight stations, a volume control, and an off switch). This could have been just one among several inputs that inspired her to come up with the idea she called “hopping of frequencies” and which led to the anti-jamming proposal. In the patent claim, frequency hopping is described as follows: "In a radio communication system comprising a radio transmitter tunable to any one of a plurality of frequencies and a radio receiver tunable to any one of said plurality of frequencies, the method of effecting secret communications between said stations which comprises changing the tuning of the transmitter and receiver according to an arbitrary, nonrecurring pattern."

In an initial proposal to the NIC in 1940, the frequency hopping was not automatic but was produced manually and at rather long intervals. The NIC expressed interest, and the inventors went forward to complete a patent application, which, by the time it was filed in 1941, included a punched-tape mechanism as an example of how the frequency hopping could be automated. The punched tape would select different capacitors to generate the various frequencies.


Figures from U.S. Patent No. 2,292,387, Secret Communications
System, an anti-jam torpedo guidance invention

The Philco remote-control principle was brought into the patent description as a device to convert the torpedo’s received signals to instructions that would move the torpedo rudders as needed to track a target. Solenoids that would be simultaneously activated in both transmitter and receiver were connected to clock motors that drove the punched tapes in synchrony. The patent was issued in August, 1942, to H. K. Markey (Hedy’s new married name) and George Antheil.

The Put-downs

Despite the issuance of the patent and its endorsement by the NIC, the Navy did not take it seriously. Some attribute this to the possibility that men in the military at that time might assume that the most beautiful woman in the world could not have intelligence and imagination, and certainly not technical savvy.  Also, the United States had by then been drawn into the war and the Navy was confronted with the fact that its torpedoes were not that reliable in hitting and sinking enemy ships—for a variety of reasons, not all of which were fully understood. Perhaps they did not want to chance what seemed to them a very sophisticated and unproven solution. But a more likely probability existed. Part of the proposal read as follows: “. . . we contemplate employing records of the type used . . . in player pianos and which consist of long rolls of paper having perforations variously positioned in a plurality of longitudinal rolls along the records. In a conventional player piano there may be up to 88 rows of perforations . . . .” This may have led the Navy reviewers to envision having to enlarge torpedoes to accommodate portions of a player piano. Indeed, after the Navy rejection, Antheil wrote that he and Lamarr were told the invention was “too bulky [to fit] the average torpedo.”

In September 1941, the New York Times ran a story “Actress Devises ‘Red-Hot’ Apparatus for Use in Defense,” evidently leaked to it by someone at the NIC. The story said only that “so vital is her discovery to national defense that government officials will not allow publication of its details,” and did not mention Antheil at all. The latter omission plus a dispute between the co-inventors the previous year may have prompted Antheil to write in correspondence that Hedy was “an incredible combination of childish ignorance and stupidity—and definite flashes of genius.” Even so, he always credited the creative idea of frequency hopping to Hedy.

Post-war Endorsements

The war ended and the “secret” invention went dormant, but the technique surfaced in later years under its new descriptor, spread spectrum. Its subsequent uses are well covered in Robert Dixon’s Spread Spectrum Systems (1984), and in Pulitzer-Prize-winning author Richard Rhodes’ 2011 book, Hedy’s Folly.

In 1997, Carmelo Amarena, an electrical engineer and digital wireless communication specialist, discussed the invention with Ms. Lamarr. She told him she thought first of a torpedo that was remote controlled, and by radio. Amarena never felt, he said, that he was talking to a movie star, but rather to a fellow inventor.

Robert Price, chief scientist at M/A-COM Linkabit, for a 1983 paper had interviewed Hedy and concluded that the invention was probably more than a score of years ahead of its time. In a 1984 IEEE Spectrum article, Price is quoted as saying he found the invention to be “complete in its potent anti-jamming concept even before Pearl Harbor.”

In 1997, Hedy Lamarr received the Pioneer Award of the Electronic Frontier Foundation, an honor for which she was nominated by David Hughes, a previous winner of the award, himself a retired Army colonel and digital wireless expert. At the same ceremony George Antheil was also honored, posthumously. When Hedy, then 82, learned of the award she said to her son Anthony “it’s about time.”

Oh, yes. Ms. Lamarr, the inventor, has a star on the Hollywood Walk of Fame.

Resources

Markey, H.K., et al., Secret Communication System, U.S. Patent 2,292,387, Aug. 11, 1942.

Antheil, G., Bad Boy of Music, Doubleday, 1945.

Lamarr, H., Ecstasy and Me—My Life as a Woman, Bartholomew House, 1966.

Price, R., “Further Notes and Anecdotes on Spread-Spectrum Origins,” IEEE Trans. on Communications, Vol. 31, No. 1, 1983.

Dixon, R.C., Spread Spectrum Systems, Wiley, 1984.

Kahn, D., “Cryptology and the origins of spread spectrum,” IEEE Spectrum, Sept. 1984.

Viterbi, A.J., “Spread Spectrum Communications: Myths and Realities,” IEEE Communications, 50th anniversary issue, May, 2002.

Walters, R., “Spread Spectrum: Hedy Lamarr and the Mobile Phone, www.booksurge.com,  2005.

Rhodes, R., Hedy’s Folly, Doubleday, 2011.

 

Comments may be emailed directly to the author at donchristiansen@ieee.org or submitted through our online form.

 

Donald Christiansen is the former editor and publisher of IEEE Spectrum and an independent publishing consultant. He is a Fellow of the IEEE. He can be reached at donchristiansen@ieee.org.

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