An enemy listening on any single frequency would hear fragments of signal. An enemy trying to jam a single frequency would interfere with only that fraction of a second before the system moved on. The communication would be, in effect, secret not because it was encrypted in the conventional sense but because it was distributed across frequencies faster than any monitoring or jamming system could follow.
Lamarr called this concept an idea she’d had. Antheil called it a technical realization of a principle he’d been using in composition. Both descriptions are accurate.
## The Patent and Its Mechanism
The application they submitted on June 10, 1941, described the system in careful technical language that is worth taking seriously rather than paraphrasing into simplicity.
The transmitter they proposed incorporated a variable-frequency oscillator connected to seven tuning condensers — capacitors, in modern terminology — arranged so that activating any one of them altered the frequency at which the transmitter broadcast. The selection of which condenser was active at any moment was controlled by a perforated paper strip passing over a suction-based pneumatic control head. The principle was exactly that of a player piano: where the paper was solid, suction held a small piston up, leaving a switch open. Where the paper had a perforation, air entered the pneumatic chamber, a spring pushed the piston down, and the switch closed, activating the corresponding tuning condenser. The strip moved forward continuously, and the transmitter’s operating frequency changed wherever the perforation pattern changed.
The receiver in the torpedo contained four condensers corresponding to four possible receivable frequencies, activated by the same mechanism reading an identical paper strip. The patent also specified three additional rows — labeled A, B, and C — that were “false” or decoy channels that the receiver could not tune to, creating additional complexity in the paper roll pattern that would frustrate anyone trying to decode the frequency sequence without knowing the strip’s design.