Numerous people have written to me regarding the invention of spread-spectrum and I have recently become aware of several more proposals that antedate the Lamarr-Antheil patent.  One is the patent of Willem Broertjes (1932 US; 1929 Germany).  The other is a reference in Johannes Zenneck's book Wireless Telegraphy (US, 1915; Germany 1908) to a method for preserving secrecy of messages. There are others.