I'm not convinced they will be impressed by your scheme for ultra VLF signalling Andy but it'd make a nice Radcom article
On Sun, 7 Feb 2021, 21:44 Andy Talbot, <andy.g4...@gmail.com> wrote: > The UK has a standalone frequency locked grid supply, nominal 50Hz, which > typically wanders +/- about 0.15Hz RMS over several minutes , with > occasional short-lived excursions out to 0.2 or 0.3Hz. Average number of > cycles per period generally is normalised to 50Hz after a few days. > The typical loading for the country ranges over ~25GW to 45GW > > Now, I wonder: > I can probably measure the grid frequency to a few micro Hz over a period > of tens of seconds. So I make a continuous recording of this, averaged over > say 10 second periods. > Now take a 7kW load (the maximum reasonably possible on a domestic circuit) > and switch it on and off at intervals of perhaps 10 minutes, precisely > timed so it can be correlated with the frequency log. That 7kW load will > be about 0.2ppm of the average for that for the whole of the UK. By post > processing, and some deep correlation covering days worth of cycles of load > on-off with the frequency, I wonder if it would be possible to see the > loading, the mean frequency changing by a few uHz. > Not sure what the time constant of the grid control is, but for* small > signals* I doubt it can be faster than a few minutes. > > There was a serious outage on 9 August 2019 that caused frequency to drop > below 49.5Hz and initiate automatic load shedding; that happened over a > period of a couple of minutes but was a large scale problem. > > https://www.ofgem.gov.uk/publications-and-updates/investigation-9-august-2019-power-outage > > Andy > www.g4jnt.com > _______________________________________________ > 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.