Do You Have Lamarr in Your Car?

It has been suggested that the short-range wireless protocol known as Bluetooth should instead have been called Lamarr, in honor of the actress/inventor Hedy Lamar.

Hedy (maiden name Kiesler) was born in Vienna in 1914. From her early childhood she was fascinated by acting–and she was also very interested in how things worked, an interest which was encouraged by her bank-director father.  She began acting professionally in the late 1920s, and gained fame and notoriety when she appeared–briefly nude–in the film Ecstasy.  It was followed by the more respectable Sissy, in which she played the Empress Elisabeth of Austria.

In 1933, Hedy married the arms manufacturer Friedrich Mandl, finding him charming and fascinating and also probably influenced by his vast wealth.  She was soon turned off by his Fascist connections and his extremely controlling nature–rather ridiculously, he even tried to buy up all copies and negatives of Ecstasy.  He did not allow her to pursue her acting career, but did require her to participate, mainly as eye-candy, in high level meetings with German and Italian political leaders and with people involved in military technology.  What she heard at these sessions both interested and alarmed her.

Finding her marriage intolerable and the political situation in her country disturbing, Hedy left and first came to London. There she met MGM head Louis B Mayer, who offered her an acting job at $125/week.  She turned down the offer, but booked herself onto the same transatlantic liner as Mayer, bound for the USA.  On shipboard, she impressed him enough to receive a $500/week contract.  He told her that a name change would be desirable, and she settled on “Lamarr”…the sea.

With the outbreak of war in Europe, Hedy followed the news closely.  For reasons that are not totally clear, she began thinking about the problems of torpedo guidance:  the ability to correct the weapon’s course on its way to the target would clearly improve the odds of a hit.  She had heard the possibility of a wire-guided torpedo discussed over dinner at Mandl’s…but this approach had limitations.  Radio was an obvious alternative, but how to prevent jamming?

As an anti-jamming technique, she hit on the idea of having the transmitter and the receiver change frequencies simultaneously and continuously…she may have been inspired partly by the remote-control radio receiver which was available at the time, possibly either she owned one or had seen one at somebody else’s home.  With synchronized frequency changes at both ends of the radio link, jamming would be impossible unless an enemy knew and could emulate the exact pattern of the changes.  But how to synchronize the transmitter and the receiver?

Enter Hedy’s friend George Antheil, who called himself “the bad boy of American music.”  Antheil was fascinated by player pianos and had created and performed compositions which depended on simultaneous operation of several of these players.  Maybe the punched paper strips used by player pianos could provide a solution to the frequency-hopping problem?

US Patent 2282387, issued to Hedy Kiesler Markey (the name reflecting a brief unsuccessful marriage) and George Antheil, implemented this approach.  The feeding of the paper strip on the launching ship and that inside the torpedo would be started simultaneously, and the holes in the strips would select the frequencies to be used at any given time…88 rows are mentioned, offering 88 frequency choices, but obviously this number could be smaller or larger.  Commands to the rudder of the torpedo would be sent via modulation of a carrier wave on the always-changing frequency selected.  (The two inventors had retained an electrical engineer to assist with specification of some of the details.)


The invention was presented to the government-funded National Inventors Council…before or after the issue date of the patent is not clear…and the idea was classed in the “red hot” category.  Although the Council included such luminaries as the legendary executive and inventor Charles Kettering, the Navy decided not to pursue the idea.

Hedy threw herself into war work, selling savings bonds and helping at the Hollywood Canteen.  She made numerous movies, including Tortilla Flat (1942),  Dishonored Lady (1947), and Samson and Delilah (1949).  The frequency-hopping secret communication system, as it was titled in the patent filing, was forgotten.

Why did the Navy reject the idea?…and what, if any, is the link between the Lamarr/Antheil invention and today’s extensive use of frequency-hopping and spread-specturm technology?

It has frequently been asserted that the idea was rejected because the Navy couldn’t believe that a movie star and a musician could create a major advance in weapons technology.  I don’t think this is a very likely explanation…after all, the secret communication system had been endorsed by highly credible individuals on the National Inventors Council.  More likely is George Antheil’s own explanation:  the way the system was presented, with mention of the player piano, led the reviewing officers to believe that it would be too bulky to fit in a torpedo.  One other factor that was surely important was that the Navy was already having serious problems with an existing improvement to conventional torpedos: the magnetic fuses that were supposed to detonate the warhead on a proximity basis were turning out to be extremely unreliable. Making torpedos explode reliably probably seemed much higher-priority than improving their guidance.

How well would the idea have worked in practice?  An antenna on the torpedo extending above the water would seem necessary for any reasonable frequency choice.  I believe WWII torpedos ran at least 6-10 feet below the surface, deeper if they were intended to explode beneath the target vessel’s keel:  getting the antenna above the surface would have required a tube extending for that distance, probably with stability as well as drag implications. And the launching vessel or aircraft would have had to remain in the area throughout the time of the torpedo’s travel, at risk to itself.  (I’m not sure if aircraft use…for launching glide bombs or powered missiles…was considered, but this might have been a more immediately practical application of the idea.)

The Lamarr/Antheil invention of the early 1940s came to nothing, yet frequency-hopping technology and the closely related spread spectrum technology play a very important role in today’s word.  In his book Spread Spectrum, Rob Walters–who seems quite knowledgeable in the relevant electronics–attempts to put the secret communications system in the context of the development of modern related technologies.

The closest direct connection he found was an antisubmarine buoy system dating from about 1954.  The sonobuoy was intended to listen for submarines and transmit appropriate signals to an airplane somewhere in the area.  There could be multiple sonobuoys and multiple aircraft operating in the same general area. The technical project manager for the effort was a man named Romuald Ireneus Scibor-Marchocki, who remembers the following:

When we received the contract to develop the Sonobuoy, we were provided with a copy of the H Kiesler Markey patent.  Since it was dated a decade previously, we assumed that it was an existing secret technology designed by some clever electrical engineer, working under a Navy contract and thus obligated to assign the patent to the Navy.

But the assumption was incorrect:  no such assignment had ever been made, and, legally, the Navy and the contractor probably should have obtained a license to use the patent.  As it happened, the sonobuoy project never made it past the prototype stage:  instead, the scheme was abandoned in favor of a shore-linked sonobuoy which didn’t need a radio link.  Working at a different company in the 1960s, Romuald developed another frequency-hopping system: this one for remote control of drones.  Whereas the frequency-hopping in the Lamarr/Antheil system had been controlled by punched paper tape, and in the sonobuoy system by engraved protusions on a metal cylinder, the drone-control system used a fully electronic approach.

Frequency-hopping and spread-spectrum systems were increasingly adopted for the military use in the late 1950s and the 1960s:  Sylvania’s Blades system for the Navy, and GE’s Phantom for the Air Force.  Consumer use would have to wait until the 1990s and beyond, first in cordless telephone systems and then cell phones and Bluetooth.

Bluetooth uses 79 radio channels in the 2.4 Ghz range, with a devices hopping among these frequencies at the rate of 1600 hops per second.  All devices in an area will be using these same 79 frequencies, but with differing individual hop sequences, so that the data streams can be kept separate (the occasional collisions which occur when two devices choose the same frequency at the same time will result in retransmission.)  Bluetooth is used for a wide range of applications, including wireless control of and communication between a mobile phone and a car stereo system, wireless streaming of data collected by a fitness device to phone or PC, and to replace wired communication previously used in bar code scanners, GPS systems, and medical equipment.

The protocol was named for the tenth-century king Harald Bluetooth, who united dissonant Danish tribes into a single kingdom–the idea being that Bluetooth unites communication protocols.  In the book that I linked above, Rob Walters suggested that Lamarr would have been an appropriate alternative name, recognizing Hedy Lamarr’s pioneering work in this field.

Hedy acted in dozens of moves, of varying quality–I see that our blogfriend Robert Avrech has rated the 1941 film H M Pulham, Esq (which I just watched) as her very best.  In financial terms, her greatest success was probably Samson and Delilah, the highest-grossing film of 1949.    She attempted to produce her own film, Loves of Three Queens (1954),  but was unsuccessful at arranging distribution.  Her career declined in the 1950s, and her personal life does not seem to have been a very happy one.

In 1997, Hedy Lamarr and George Antheil were honored with a Pioneer award from the Electronic Frontier Foundation.  She lived until the year 2000.

An article in IEEE Explore, from the Institute of Electrical and Electronics Engineers, reviews another book about Hedy Lamarr and her invention:  Hedy’s Folly:  The Life and Breakthrough Inventions of Hedy Lamarr, Richard Rhodes.  (Compare the rather tacky cover art for this book with the appealingly creative artwork used for the Wlaters book)

Sheila O’Malley, a good source on everything movie-related, has several posts that mention Hedy Lamarr and her films.  Also, Robert Avrech has a Hedy Lamarr image board on Pinterest.





18 thoughts on “Do You Have Lamarr in Your Car?”

  1. Making torpedos explode reliably probably seemed much higher-priority than improving their guidance.

    That and depth control. A good book about the problems and the reason why they were not fixed before 1943 is “Iron Men and Tin Fish.

    As usual, a government bureaucracy is involved.

  2. The problems of communicating with torpedoes wouldn’t have applied to aircraft that would have benefited enormously from secure communications. I doubt that this was lost on anyone at the time. The problem with other implementations was establishing and maintaining synchronization between the receiver and transmitter. The problem has since been solved with a clever application of math that I don’t pretend to understand.

    There have been a lot of brilliant ideas like this that can only be realized after years of progress in seemingly unrelated fields. Airplanes weren’t really practical with the engines available at the turn of the century. Unfortunately for the inventors, the patents are usually long expired when their idea finally becomes useful.

  3. Unfortunately for the inventors, the patents are usually long expired when their idea finally becomes useful.

    The Wright Brothers spent years defending patents.

  4. It is a little ambiguous whether the patent would have been found to have applied to the Sonobuoy project, which used engraved protusions on a metal cylinder to control the frequency-hopping. The Lamarr/Antheil patent says “our system applies a pair of synchronous records, one at the transmitting station and one at the receiving station, which change the tuning of the transmitting and receiving apparatus from time to time”…pretty general…but then goes on to say “we contemplate employing records of the type used for many years in player pianos”, and then goes on to describe the paper tape system. The patent would have been stronger if they had followed the paper tape description with a statement about “other approaches to the synchronization will be apparent to those knowledgeable in the electrical arts,” or something of the sort, which I have seen in several other patents.

  5. I read “Hedy’s Folly” some years ago and, despite the cheesecakey cover, it’s a good book. Very entertaining and it explains in some detail how Hedy got involved in inventing. It’s been a while, but as I recall, she was very smart and inquisitive and ran a kind of salon in California that exposed her to a lot of diverse ideas. She started pursuing inventions as an intellectual counterweight to the vapidity of Hollywood.

  6. “The patent would have been stronger if they had followed the paper tape description with a statement about …”

    Nowadays patents are worded in order to claim they just invented anything and everything under the sun. I think the patent troll movement has driven some of that. If you’re going to end up in court or arbitration anyway, you might as well arm yourself as much as possible in advance.

  7. “It has been suggested that the short-range wireless protocol known as Bluetooth should instead have been called Lamarr, in honor of the actress/inventor Hedy Lamar.”

    By who?

  8. There was/is a fascination program on Netflix on Hedy – after seeing that I think she should be remembered as an inventor and not an actress. Considered an “enemy alien” she didn’t receive a penny from the Govt on what evolved to cell phone technology – worth an estimated $30 Billion – yet the govt asked her to tour the country to sell war bonds.

    She used to work on her inventions in a movie set trailer between takes.

    Amazing woman.


  9. Bill…googling, I see it asserted with various degrees of vehemence that her patent was ignored (or even “seized”) because of her enemy alien status. Neither of the two books I linked, both of which appear to be very well-researched, suggests that her technical “enemy alien” status was the cause of the non-use of the invention.

    I suspect that if Lamarr & Antheil had assigned someone to market the technology to the Defense Department and its contractors, they might have gotten some hits. But the value of frequency-hopping/spread spectrum for general use increased greatly as complex electronics became orders of magnitude cheaper, which was mostly after the patent expired.

  10. You make a good point David. Although I’m going to watch that documentary called Bombshell again tonight

    That was their claim; that the government seized it because of her background in Austria

    But I can see the other side too. A groundbreaking invention from a movie star?

  11. I recall reading an article some years back that noted that Lamarr’s accomplishments tend to get oversold by the “Women in Science Have Been Ignored” crowd. She WAS talented, but much of her work was far more derivative than is usually acked… the notion of spread spectrum was not, according to the article, all that unknown at the time, having been suggested more than once by others, just not ACCOMPLISHED effectively. And I gather Lamarr’s technique did not solve the essential synchronization problem, which made the idea sit on the shelf for decades until the electronics basis for it came of age.

  12. OBH re synchronization…seems to me that the paper tape approach to synchronization, when the mechanisms were driven by clockwork or constant-speed motor, would have worked fine for a limited period of time, maybe a few minutes. For longer periods of time, the patent mentions that synchronization methods involving periodic transmission of synchronizing pulses were well-known in automatic telegraphy and could be adopted.

    The main limitations seem to be link (a) cost, (b) size, (3) speed/hop rate, and (4) sequence distribution. I think the Lamarr/Antheil approach would have been suitable for certain military systems, but probably not for much in the way of commercial use until the electronics advanced.

  13. Bill…”I think she should be remembered as an inventor and not an actress.”

    Why not both? There are lots of actresses, and lots of inventors, but relatively few people who excel in both areas.

    I always enjoy learning about people who excel at multiple & very different fields. Here’s a woman who combines the skills of metallurgists and concert pianist:

  14. David-

    I saw the biography again on Hedy Lemarr called Bombshell. If you can get ahold of that I really recommend it. They interview her son and daughter and play these long lost interview tapes of her

    A number of things from that program stood out for me; one of which was she always considered her beautiful face to be an impediment for acknowledgment for what she really loved.


    Judging from that program I believe she would’ve rather had acknowledgment as an inventor but of course being an actress who made every man want her and every woman want to imitate her isn’t a bad way to leave the world either.

  15. Bill, I remember that comment about “her beautiful face” in the Bombshell video…I have also seen the assertion made on social media that her beauty made it impossible for her to succeed as an inventor.

    I think this is highly questionable. Remember, as a child she was very very interested in acting, and being good-looking certainly helped in pursuing that career…and the money she had at that work and the contacts she developed certainly helped in her inventing work.

  16. > I think the Lamarr/Antheil approach would have been suitable for certain military systems

    Offhand, it sounds fragile and unreliable to me. Doable, yes, suitable for a weapon that needs to be reliable and quickly set up, no. As mentioned above, there were other problems with American torpedoes that were more far more pressing, such as maintaining depth and exploding on impact.

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