That is the record. It requires no additional drama to be worth knowing.
## The Paper Strip and the Frequency Hop: A Summary for the Reader
The patent proposes this: a transmitter and a receiver, one on a surface ship and one in a torpedo, each carrying an identical perforated paper strip. Both strips are driven by spring clock motors calibrated to run at exactly the same constant speed. At the moment of firing, both strips begin moving simultaneously, triggered by the break in the torpedo’s connection to the ship.
As the strips advance, perforations in the paper activate or deactivate tuning condensers in the respective oscillators, changing the frequency at which the transmitter broadcasts and the frequency to which the receiver is tuned. Because both strips are identical and both advance at the same constant rate, both devices change frequency at the same moment, to the same frequency. The steering commands — left-turn tones, right-turn tones — ride on these hopping carrier frequencies, and the torpedo’s rudder responds.
An adversary monitoring the channel hears fragments of signal on any single frequency, none of them long enough to interpret. An adversary trying to jam the signal would need to broadcast simultaneously across all possible frequencies at sufficient power to overwhelm the signal on each one — an energy requirement that was impractical with 1942 technology.
The mechanism was never built into a deployed weapon. The concept it described was later implemented using solid-state electronics that made frequency hopping reliable, small, and fast enough for military and eventually commercial use. The patent is public. The names on it are Hedy Kiesler Markey and George Antheil. The date is 1942.
That is the story. It was always the story. It took the rest of the century to become widely known, and it is still, in its full form, less widely known than the simplified version that replaced it.
The full form is worth knowing.