Hollywood called her the most beautiful woman in the world and never asked what else she could do. In 1942 Hedy Lamarr co-patented FREQUENCY HOPPING: a radio that leaps between channels on a secret schedule, so an enemy can’t jam it — you can’t block a signal that won’t hold still. It’s the ancestor of Wi-Fi and Bluetooth. Slide the jammer and watch it miss.
Frequency hopping spread spectrum: both radios share a pseudo-random sequence of channels and jump together many times a second. A jammer parked on ONE channel only corrupts the small fraction of hops that happen to land there — with N channels, about 1/N — and error-correction cleans the rest. The instrument runs a real seeded hop sequence. A fail-loud self-check throws unless a single-channel jammer catches only ~1/8 of hops across 8 channels while the sequence still visits every channel.
A toy fixed-N model with a single-channel jammer; real spread-spectrum adds error-correcting codes, wider bands, and adaptive hopping. The 1/N jammed-fraction and full-band coverage are exact for the seeded sequence.