Analysis of Hedy Lamarr's Contribution to Spread-Spectrum Communication

The stories of Hedy Lamarr and the computer women at NASA get repeated endlessly as if they're the only contributions women have ever made to CS, which must be absolutely discouraging to the young girls who are interested enough to dig deeper and find out that Hedy's contribution was essentially negligible.

It'd be much better to talk about Liskov, Goldberg, the women at Bluetooth SIG, or the countless other examples available.

readthenotes1• 9 months ago

It will be even more discouraging now that the well actually guys will say that it wasn't true...

relaxing3• 9 months ago

What’s discouraging is seeing that any contribution by a woman is going to be picked over and minimized.

AlotOfReading3• 9 months ago

The intention behind these stories is to tell learners "people like you made great contributions, so can you". If your main example is a woman whose contribution is a patent that didn't inspire any of the things popularly attributed to it, the actual subtext you're communicating is that there are no better examples.

"You'll be minimized too!" isn't exactly a great subtext to encourage interest in the field, compared to other positive examples like the people I've already mentioned.

thomassmith652• 9 months ago

The hyperbole that 'Hedy Lamarr invented Bluetooth' seems innocuous to me - it's a pop culture thing, like the claim that 'Steve Jobs invented the personal computer'.

I wouldn't lose sleep over hypothetical crestfallen child engineers. If they read a biography of Hedy Lamarr, they'll finish it more impressed, not less. She was an exceptional person.

kragen4• 9 months ago

That sounds like "Cocaine seems innocuous to me—it's a party drug, like strychnine."

It's hard to imagine a historical myth about personal computing more harmful than the myth that it was invented by a man who spent his life trying to take the power of personal computing away from the people!

N1ckFG• 9 months ago

Afaik the basis of the Bluetooth thing is that out of all the different kinds of spread-spectrum radio we use now, Bluetooth happens to be the closest to her original design. So it's a drastic simplification, but not wrong.

kragen4• 9 months ago

Diana Merry, Lorinda Cherry, Fran Allen, Lynn Conway, Grace Hopper. There were numerous smaller contributors as well; my friend Ann Hardy, for example, had to rewrite the OS for her cloud computing startup from the ground up to get it to be usable, but got denied stock options because she was a woman and eventually got pushed into management.

leephillips• 9 months ago

George Antheil’s autobiography, Bad Boy of Music, is quite entertaining. In it he recounts his adventures related to this patent. If I recall correctly (I read it decades ago but I think I’m right here), he describes a close and co-equal collaboration with his friend Hedy Lamarr on this invention. Therefore I think these remarks by the author:

‘Since the actual invention is a player-piano-like mechanism, and since experimental musician George Antheil had expertise in the inner workings of player pianos, and further since Hedy Lamarr evidently had no such expertise, it may be more appropriate to call the Lamarr-Antheil patent “Antheil’s patent.”’

are inappropriate and unjustified.

adrian_b2• 9 months ago

True.

Moreover, Hedy Lamarr was the one who had the idea of using FHSS, not being aware about the unknown patents where the same idea had been proposed earlier.

The contribution of Antheil has been in the practical implementation of her idea, so it would be ridiculous to call it "Antheil's patent".

There are plenty of inventions like this, where one inventor has the idea on which the invention is based, without having enough practical experience in that domain to complete the invention, so a second inventor with appropriate experience is brought in, who may be the author of the bulk of the practical implementation, but who is not the author of the original idea.

In such cases, both are rightly called inventors, as none of them could have completed the invention without the other.

researcher-one4• 8 months ago

What Antheil says and what actually happened may, in reality, diverge considerably. Antheil evidently knew exactly nothing about what was going on, except for his knowledge of player-piano mechanisms. The invention is what it is -- nothing more and nothing less -- than a cumbersome mechanical mechanism that had no further influence on anyone. His autobiographical account of events is highly dubious.

The key to inventorship, as defined by a patent, is whether or not someone contributes something to the intellectual conception of at least one of the claims. Unless the "practical implementation" makes its way to the claims, the "practical implementer" is not an inventor. Note the drawings that accompany the Lamarr patent -- anything of substance was contributed by their helper (a tenured professor of RF engineering at CalTech), who is NOT listed as an inventor.

So I ask again: given that Hedy Lamarr made no pretense of knowledge of the player-piano mechanism, and that each claim is tightly interwoven with player-piano mechanisms, what, exactly, did Hedy contribute? This is, of course, a rhetorical question; we shall never know the answer.

Animats• 9 months ago

Look at the prior art. The key prior patent cited is BAESECKE, (2,134,850). This has a "wobbler" to change the transmitting frequency, which is fine, but that patent is vague as to how the receiving end stays in sync. Markey gets that syncing up transmitter and receiver is the real problem, and talks of it as a solved problem from television. (This is 1941, experimental TV exists.) Some mechanisms are discussed, borrowed from multiple player piano synchronization, which is where this technology came from.

Voice cryptosystems of the pre-WWII period included the Western Electric A-3 scrambler [1] There's one on eBay! [2] That split audio into a number of frequency bands, which were shifted and reassembled. At the receiving end, the process was reversed. The shift pattern changed periodically, on the order of tens of seconds. That was slow enough that keeping the thing in sync was possible with clockwork of the period. Note that this is working on the audio, not the RF; it's a scrambler, not a frequency hopper. This is what AT&T used for transatlantic commercial voice. Worked OK, mediocre security. Only 6 different frequency shift patterns were in use at a time. The Germans cracked it.

This is not the better known SIGSALY. That's a similar concept, but with a lot more audio channels, much more frequent changes, a one-time key for the changes, and more hardware than some mainframe computers. The A-3 was a desk-side wooden box. Neither system does frequency-hopping of the RF signal.

Hedy Lamarr's first husband was an arms manufacturer, and she apparently paid attention when visiting the factories. Hence the radio-controlled torpedo, which is close to Tesla's radio-controlled boat.

MARKEY (2,292,387) describes a cross between a radio-controlled boat and a set of synchronized player pianos. There's some handwaving around the sync problem. The trouble with syncing a frequency hopper is that you have trouble even finding the signal to get started. But if you're launching a torpedo or a bomb from a larger craft, both ends of the connection can be started in sync and will probably stay in sync long enough for the bombing run. Doing this with a player piano roll reader, vacuum pump and all, is probably not the right approach.

Trying to get things to sync up reliably has a long history. Edison's first useful invention was a way to get stock tickers to sync. There's a long history of clunky mechanisms, early ones involving flywheels or big tuning forks, and later electronic ones with too many screwdriver adjustments. Not until the invention of phase locked loops did it really Just Work. (I'm into restoring early Teletype machines, and I'm way too aware of the early days of sync problems.)

Markey was just too early. Reasonable idea, but not practical at the time due to lack of supporting technology.

[1] https://chris-intel-corner.blogspot.com/2012/02/intercepted-...

[2] https://www.ebay.com/itm/205373065319

marshray2• 9 months ago

Ouch.

From the article: "A letter on 3 October 1941 from the Lyon and Lyon attorney to Lamarr and Antheil says '...we rather doubted at the time that method claim 7 would be considered patentable, since the invention appears to reside more in a new apparatus than in a new method.' Thus, the attorney representing the applicants agreed with the patent examiner that the evidence was against Lamarr-Antheil’s definitive method claim to FHSS, which was claim 7."

This analysis makes it pretty clear that EFF's 1997 assertion that she and Antheil "developed and [...] patented the concept of 'frequency-hopping' that is now the basis for the spread spectrum radio systems" is flatly untrue.

This isn't to say that she wasn't an inventor or innovator, or didn't put together existing known techniques in a new way to address a relevant and interesting problem.

nine_k2• 9 months ago

But frequency hopping without the ability to (re-)synchronize is hardly practical. It's like inventing the principle of the machine gun, firing many bullets in quick succession, without inventing the mechanism of automatic removal of the spent shell and pushing in a new round. Such prior art would not dethrone Hiram Maxim.

Same here: if it's the Lamar's invention that makes frequency hopping practical, then she is still the (co-)inventor of most of modern radio communication.

marshray2• 9 months ago

The thing approved by the patent office is 100% specific to a mechanism using two "moving" "elongated strips" to encode a sequence of frequency changes. It doesn't explain how they are kept synchronized, or provide a way to recover from loss of sync. Perhaps torpedoes were a case where an initial synchronization would work long enough.

As said before, the idea of coordinated frequency hopping was already known at the time.

kragen4• 9 months ago

I think you mean it would not dethrone Dr. Gatling, whose contraption did indeed automatically remove spent shells, which illustrates just how fuzzy these questions of attribution are.

marze2• 9 months ago

I find the article unconvincing, although I'm open to being convinced. With historical hindsight, it should be easy to see if the Lamarr et al patent seems novel. Just because an examiner doesn't allow a claim, I don't see that as strong evidence it wasn't novel at the time. They always are rejecting claims, sometime for good reason, sometimes not.

A more convincing article would focus on purported prior art patents, and let the reader judge if really anticipated frequency hopping.

researcher-one4• 8 months ago

One of the key requirements for getting a patent is that the invention must be novel. So indeed, their work is novel; it's just not of any importance at all. It is a Rub Goldberg mechanical mechanism. To understand this, you need to focus on the invention as defined by the granted claims, not on whatever prior art may be disclosed in the patent's specification (the wordy bulk of most patents).

marze2• 8 months ago

To me, the interesting question is, were they the first to come up with the concept of communicating while jumping around on a random-like sequence of frequencies. What was the prior art?

adrian_b2• 9 months ago

TLDR: Hedy Lamarr and her co-inventor did not invent the principle of frequency-hopping spread spectrum (FHSS) communication, but just a practical device implementing this technique, because the principle of FHSS had already been stated in prior work.

Nevertheless, while there have been a handful of earlier patents where the inventors had the same idea of using FHSS, those patents have remained unknown among the vast amount of useless patents so it is pretty certain that Hedy Lamarr has rediscovered FHSS independently.

After WWII, the evolution of FHSS in military communications has started from the patent of Hedy Lamarr, while the prior work has remained as obscure as before.

Gibbon1• 9 months ago

I read a book by Marvin Simon on Spread Spectrum. The book is very helpful in that each chapter starts with a problem. History of how people tried to solve it. Before moving on to the canonical solution.

Technically and conceptually these problems are not simple nor were well known or understood at the time Lamarr was working on them. It took from the mid 40's to the mid 60's for all the parts to come together.

YeGoblynQueenne• 9 months ago

The HN hivemind on Hedy Lamar: she was not the first to think of the technique, only the first one to make it work.

The HN hivemind on Jurgen Schmidhuber: he was only the first to think of the technique, not the first one to make it work.

Yes, I'm a big ol' meanie.

researcher-one4• 8 months ago

The following comes from CHATgpt's search on the German Army's use of FHSS during the first world war:

Here is the closest verbatim passage I found from Jonathan Zenneck’s *Wireless Telegraphy (1915), in the chapter “Methods for Preserving Secrecy of Messages.” The wording is slightly abridged due to the scan quality: “Furthermore, the apparatus can be so arranged that the wave-length is easily and rapidly changed, and then the wave-length varied in accordance with a pre-arranged programme, perhaps automatically. This method was adopted by the Telefunken Co. at one time.”

Note that the book was published in 1915, when Hedy Lamarr was less than one year old.

Anyone interested in the topic might also look at the work of Dr. Tony Rothman on the same question of Hedy's supposed invention. Tony was the scientific advisor to the filming of the PBS special called "Bombshell." He is a man of considerable standing, accomplishments, and qualifications.

Regarding Hedy's patent -- as I said in my paper, note bene: the application of a known technique (FHSS) for its intended purpose (security) does not constitute an invention. Hedy'a attorney tried to convey this message to her in his correspondence, but the message never sunk in.

researcher-one4• 8 months ago

Another interesting myth is that Hedy Lamarr was a competent mathematician. I would like to see any evidence supporting this. She quit school at age 16 (IIRC). Perhaps this is another instance where people who have no knowledge of mathematics perpetrate an urban legend, in the same way that people who have no knowledge of invention or communication engineering perpetrate the myth that the world is in Hedy's debt because "she invented FHSS."

Analysis of Hedy Lamarr's Contribution to Spread-Spectrum Communication

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