 signal frequencies and if the swing due to the noise is large compared to the swing due to the signal [v(t)], deciphering is impossible." Curiously enough, as a result of the use of an exponential form of modu- lation, Hansen's design is constructed as a TR-FM-SS communication sys- tem at radio frequency (RF), but equivalently at demodulated baseband, it is simply a "typical noise masking" add/subtract TR system. (This latter appraisal of [65] is from the case file-open to the public as for any issued patent-in Crystal City on an SR-SS invention [49] of major importance to a later period in this history.) Moreover, except for its TR vulnerabilities, Hansen's system is good AJ design, and as he points out, a large amount of additional noise can be injected at the RF output of the transmitter's intel- ligence channel for further masking without seriously degrading system per- formance. Surprisingly, without the spectral spreading and chronometer-controlled reference signal filters, Hansen's system would bear a strong resemblance to a TR-FM system described in 1922 by Chaffee and Purington [66]. Hence, the concept of transmitting a reference signal to aid in the demodulation of a disguised information transmission is over sixty years old! E. M. Deloraine's history [67] of the early years at ITT contains segments recounting the efforts and risks undergone in France during World War II to protect valuable information, and to eventually transport it to the United States. In a daring move, Louis Chereau, then Director of Patents and Information under Deloraine at ITT's Paris Laboratories, indicates [2] that he visited the French Patent Office in Vichy just before the Germans crossed the demarcation line, for the purpose of removing Henri Busignies' MTI patent application on "Elimination of fixed echoes," filed in Lyon on May 27, 1942, and also Ferdinand Bac's LORAN application. The MTI applica- tion was based on a busignies memorandum, dated October 24, 1940, and the memorandum in turn was motivated by a "brainstorming