I keep on hearing how 1940s Hollywood actress Hedy Lamarr was a talented inventor, and how during the war years, she and a player piano technician collaborated on a frequency-hopping radio communications system for guiding torpedoes to their targets without the enemy being able to eavesdrop on the signals and jam them. She and her collaborator received a US patent for this invention, although it was rejected by the Navy as being “impractical”. Many years later, this concept of “frequency hopping” was incorporated into many other communications technologies, and is a common technology in today’s RF environment.

Somehow, this just doesn’t ring true. Torpedoes travel under water and cannot be reached by radio waves. Guiding them by radio seems impossible, at least using 1940s tech. Does anyone here know anything about this? I’ve tried looking this up but all I find is feminist propaganda instead of any actual radio engineering.