Actually, the Van Eck phenomenon was written up by Van Eck based on information that was eventually released by the US government. I know for a fact it was being studied a number of years earlier based on a sweep i did while with AFOSI. While doing a sweep of a secure facility I noted a "waterfall" effect on the display of specially modified Tek 491 being used to analyze signals received by a Mason A-3B. Not willing to leave something so interesting alone, I worked on the display and was able to determine that it was being generated as a comm center specialist was typing messages. When he came to the end of the page and hit send (or whatever the key was back then) the message was sent to the teleprinter and the signal was "dumped" from the screen and from my display. It was neat to watch it being built up, but very puzzling for about an hour or so. To the best of my knowledge, that was one of the first write-up on the principle (that was back in the mid or late 70's if my failing memory serves me). Van Eck merely put together the equipment necessary to demonstrate it and do the civilian "technical" paper. (Just think, it could just as easily have been the Tim Johnson Principle. Did I ever tell you about coming up with the theory on how to decipher the signals generated by the ball on an IBM Selectric typewriter. I ran across that one in a sensitive area and using a Mason A-3B CM receiver (again) was able to determine there were variations on the location of the pulses in the frequency spread of the signal generated by the typewriter. I think that was one of the things that helped generate the TEMPEST program. The Tech Agents with OSI ran up against a lot of neat signals and came up with fixes and generated a whole bunch of concerns within the intelligence community. tim Johnson -- Tim Johnson Technical Security Consultants Inc. PO Box 1295 Carrollton, GA 30112 770-836-4898 770-712-2164 Cell What you say in private is your business. Keeping it private is ours. Georgia License # PDC 002074 Technical Security Consultants Inc. Member INTELNET Espionage Research Institute Association of Former Office of Special Investigations Special Agents-Technical Agent http://www.dbugman.com