[adrian_b]

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]

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.