O grupo do cão

UNITED STATES PATENT OFFICE
2,292,387
SECRET COMMUNICATION SYSTEM
Hedy Kiesler Markey, Los Angeles, and George
Antheil, Manhattan Beach, Cakif.
Application June 10, 1941, Serial No. 397,412
6 Claims. (Cl. 250-2)

This invention relates broadly to secret communication systems involving the use of carrier waves of different frequencies, and is especially useful in the remote control of dirigible craft, such as torpedoes.
An object of the invention is to provide a method of secret communication which is relatively simple and reliable in operation, but at the same time is difficult to discover or decipher.

http://www.hedylamarr.at/f_erfindunge.html