As noted above the propagation can make quite a mess of things. When wwvb launched way back there was a HP journal showing that in NY city you could establish something like 1 X 10-7th as I recall. I have seen all the propagation twists and turns. I suppose if you were 300-400 miles from the transmitter and could receive groundwave signals you might do 10 X better or more. Regards Paul.
On Mon, Jun 4, 2012 at 3:35 AM, mike cook <[email protected]> wrote: > > Le 4 juin 2012 à 05:43, David I. Emery a écrit : > > > On Sun, Jun 03, 2012 at 09:20:59AM -0700, J. Forster wrote: > >> Is there any indication the carriers of WWVB and MSF are locked > together? > >> > >> -John > >> > >> ================= > > > > Given it's only 60 KHz and certainly somewhere north of parts in > > 10^13 and probably down to 10^14 or 10^15 the distinction kinda escapes > > one. > > > > They may not be locked to each other, but are so close in > > frequency that relative drift would be AWFULLY slow... especially if its > > more like 10^15 from primary maser standards... > > > > There are only 5.184 * 10^9 cycles of 60 KHz in a day after > > all... and it takes a while for a error of a few parts in 10^15 to > > pile up to one whole cycle... > > > > From the doc on NIST and NPL sites, we are not in maser country here. The > transmitters frequencies are disciplined by cesium standards. For WWVB the > frequency is kept to a few parts in 10^13 ( NIST Special Publication 423) > and for MSF at 2 parts in 10^12 and are both sync'd to UTC(k). As tvb > points out, the the received signal will be phase shifted according to TOD > and atmospheric conditions. The guys at NPL monitor(ed) the MSF signal to > provide(ed) data for anyone wanting to use it for calibration in monthly > bulletins of performance. I expect NIST do the same for WWVB but have been > able to find a ref. Check out < > http://npl.co.uk/upload/pdf/user_guide_bullitins.pdf> and the last > bulletin that the site links point to , for april 2011, < > http://resource.npl.co.uk/time/bulletins/msf/msfbul_04_2011.pdf>. What is > interesting from the MSF data is that the phase offsets are quite > significant where they are received in what I expect are optimal conditions > at midday when ionospheric effects are minimal. I don't know what happened > to latter issues if any. Did they abandon them? > > > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
