 had a duplicate rotating genera- tor, properly synchronized SO that its locally produced noise replica could be used to uncover the voice signal. The U.S. version of this patent was issued in 1940, and was considered prior art in a later patent [49] on DS- SS communication systems. Certainly, the Kotowski-Dannehl patent exam- plifies the transition from the use of key-stream generators for discrete data encryption [50] to pseudorandom signal storage for voice or continuous sig- nal encryption. Several elements of the SS concept are present in this patent, the obvious missing notion being that of purposeful bandwidth expansion. The Germans used Kotowski's concept as the starting point for devlop- ing a more sophisticated capability that was urgently needed in the early years of World War II. Gottfried Vogt, a Telefunken engineer under Kotowski, remembers testing a system for analog speech encryption in 1939. This employed a pair of irregularly slotted or sawtoothed disks turn- ing at different speeds, for generating a noise-like signal at the transmitter, to be modulated/multiplied by the voice signal. The receiver's matching disks were synchronized by means of two transmitted tones, one above and one below the encrypted voice band. This system was used on a wire link from The Historical Origins of Spread-Spectrum Communications Germany, through Yugoslavia and Greece, to a very- and/or ultra-high fre- quency (VHF/UHF) link across the Mediterranean to General Erwin Rommel's forces in Derna, Libya. In January 1943, British troops captured, from General Rommel's forces in North Africa, a communication transceiver called the "Optiphone" (or "Photophone"). Developed in Germany in the mid-1930s (and covered by U.S. Patent No. 2010313 to the Zeiss works), this system could provide voice communications over a light-path up to four miles long under reasonably clear atmospheric conditions [51]. While it would be far-fetched to view such (prelaser) incoherent optical communications as SS in nature, the interest- ing aspect 