On 06/07/17 20:58, Joe Taylor wrote: > Richard -- > > On 7/6/2017 3:48 PM, Richard Lamont wrote: >> Is it a good idea to use AM broadcast transmitters as a frequency >> standard when the regulatory tolerance (ITU and many countries) for such >> transmitters is +/- 10 Hz? Is that good enough for the purpose? >> >> 73, >> Richard G4DYA > > As described here > http://www.physics.princeton.edu/pulsar/K1JT/FMT_User.pdf > my experience has been that (at least in NA) the carriers of big-city AM > broadcast stations are "on frequency" to within better than 1 Hz. > > It's always best to over-determine your fitted calibration line by using > more independent calibrators than the minimum necessary. Then you can > reliably identify outliers, and remove them from your analysis.
Well the experiment I've just done certainly bears that out. Using a K3S + GPSDO + audio spectrum analyser, I've just measured about several stations near me and most were within 1 Hz. The others, except one, were all within 3 Hz. The booby prize goes to BBC Radio Stoke on 1503 kHz, which was 9 Hz low. Still in spec though. 73, Richard G4DYA ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot _______________________________________________ wsjt-devel mailing list wsjt-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/wsjt-devel
