Sorry, misread your post. I'm glad that your frequency-skipping device will use more than two frequencies. And it was June 10, 1941 when frequency-switching patent was issued.

"In the United States Hedy Lamarr and George Antheil, shunned by the Navy, no longer pursued their invention. But in 1957, the concept was taken up by engineers at the Sylvania Electronic Systems Division, in Buffalo, New York. Their arrangement, using, of course, electronics rather than piano rolls, ultimately became a basic tool for secure military communications. It was installed on ships sent to blockade Cuba in 1962, about three years after the Lamarr-Antheil patent had expired. Subsequent patents in frequency changing, which are generally unrelated to torpedo control, have referred to the Lamarr-Antheil patent as the basis of the field, and the concept lies behind the principal anti-jamming device used today, for example, in the U.S. government's Milstar defense communication satellite system."

But I'm glad you're keeping busy.