I remember when studying covert channel communication (as part of computer security) that during the cold war one of the ways you could transmit very low bit rate data (1 bit per minute or slower) was by modulating the power consumption of an industrial plant, something that a spy would be easily able to do simply with a chronograph. Presumably you would be able to do the same thing by modulating the frequency of a generating power plant, for instance 49.99 Hz = 0, 50.01 Hz = 1, or some frequency low enough that no equipment would ever notice, unless you are actually looking out for this.
-- Fio Cattaneo Universal AC, can Entropy be reversed? -- "THERE IS AS YET INSUFFICIENT DATA FOR A MEANINGFUL ANSWER." -----Original Message----- From: time-nuts <time-nuts-boun...@lists.febo.com> On Behalf Of John Moran, Scawby Design Sent: Monday, 8 February, 2021 09:37 To: time-nuts@lists.febo.com Subject: Re: [time-nuts] Daft idea with the National Grid On Sun, 7 Feb 2021 20:45:57 -0800 Jim Lux said - "If you happen to own something like a steel mill running electric furnaces or an aluminum refinery, so you can manipulate the load..." Sometime in the late '80s, my first decent sized computer system came on line at a telecom factory in England. It ran fine for a few days then crashed. Rebooting made it run fine for another 7 days then it crashed again, and then every 7 days at almost the same time - like a very poor clock. Monitoring the mains voltage with an expensive hired monitor showed a huge drop in voltage lasting about ten seconds at the relevant time. It turned out that the biggest steel rolling mill in Europe was only 5 miles away and they were testing new motors on the rolls. We had some interesting visits and talks with them and persuaded them to turn the motors on one by one instead of in batches and, in conjunction with some hefty mains filtering, the problem went away. That sort of load step must have been noticed by the electricity suppliers, and half the computers in the city! John _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.