Oh indeed I agree John. LORAN has spoiled me also at least till nov I hear. The Canadians are a drop better then us at saving the system. I am definitely figuring out the old ways and can't say that I like it all that much. Always have gps for the moment.
On Fri, Jul 30, 2010 at 10:08 AM, J. Forster <j...@quik.com> wrote: > Partly. > > There are hourly jogs in the WWVB signal and also diurnal shifts of the > order of a cycle at 60 KHz. > > The Fluke receivers havs a counter for microseconds, but it's difficult to > intrerpret w/o the stripchart too. > > Frankly, 60 KHz is a PITA IMO. Oh for LORAN! > > -John > > ========== > > > > > > So on a 60 khz signal the long strip chart recorder is simply a super > long > > low pass filter averaging out the doppler somewhat. It really doesn't do > > that well. The mark-1 eyeball does a better job. Right? > > > > On Tue, Jul 27, 2010 at 4:53 AM, Geoff <vk2...@ozemail.com.au> wrote: > > > >> On Tue, 27 Jul 2010 09:08:49 am Chuck Harris wrote: > >> > I suppose that you could always cheat? Since you know where the > >> > transmitter is going to be, if you could get a timenut near to the > >> > transmitter to give you a beacon to measure 24hrs prior to the event, > >> > you could use the diurnal variations that you observed (observe?) on > >> > the beacon to predict the skywave offset due to Doppler at the time > >> > of the event. > >> > > >> > -Chuck Harris > >> > > >> > Murray Greenman wrote: > >> > > You guys are trying to crack a nut with a sledgehammer! > >> > > > >> > > For a start, as Didier says, you can't possibly read the frequency > >> of a > >> > > sky-wave signal to 0.01Hz in any short time frame since the Doppler > >> on > >> > > the signal can be as much as 1ppm (i.e. 10Hz at 10MHz). You can only > >> > > infer it closer than that by studying the frequency in the very long > >> > > term. > >> > > > >> > > In addition, you'll never know how much of the daily variation is > >> > > ionospheric, and how much is due to thermal changes at the source. > >> snipped > >> > >> There is one possible way of getting an accurate reading from a sky wave > >> signal over a short(ish) period. Plot a doppler shift curve with as fine > >> a > >> resolution as you can manage. Then look for a point of inflexion in the > >> curve, that is a point where the second derivative of the curve function > >> is > >> zero. The frequency at that time will be that transmitted as at that > >> instant > >> the path length is not changing. You may have to examine your data set > >> visually and mathematically examine a much smaller section. Of course if > >> you > >> don't get a point of inflexion you'll need much more data :-). > >> > >> Cheers, Geoff vk2tfg. > >> > >> > >> _______________________________________________ > >> time-nuts mailing list -- time-nuts@febo.com > >> To unsubscribe, go to > >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > >> and follow the instructions there. > >> > > _______________________________________________ > > time-nuts mailing list -- time-nuts@febo.com > > To unsubscribe, go to > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > and follow the instructions there. > > > > > > > > _______________________________________________ > time-nuts mailing list -- time-nuts@febo.com > To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.