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 <[email protected]> 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 -- [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. > > _______________________________________________ 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.
