A few years ago I did some measurements of WWV Doppler shift, measured by a 0.1 Hz resolution you get in an HP 3586C selective voltmeter. It's not quite a phase record but does show the significant shifts that occur.
See https://www.febo.com/pages/hf_stability/ John ---- On Nov 20, 2018, 6:44 PM, at 6:44 PM, Bob kb8tq <[email protected]> wrote: >Hi > >Having looked at WWV with a Carrier -> BFO -> audio card approach (and >a radio >locked to an Rb standard …) you have dig a bit to find a situation that >is >beyond a tenth of a ppm. If you average over minutes or tens of >minutes (which >is exactly what you do with WWVB) the only time you get past 0.1 ppm is >the >same sort of day/night propagation mode shift that drives WWVB nuts …. > >Bob > >> On Nov 20, 2018, at 5:35 PM, Donald E. Pauly <[email protected]> >wrote: >> >> That was the first time that I had seen an xy plot of WWV versus a >> stable crystal oscillator. It is even worse than I thought. I had >to >> look up FRK to see that it is a rubidium standard. I talked to Jim >> Maxton the chief engineer of WWVB many times around 1995. At the >time >> I was in Gila Bend 80 miles southwest of Phoenix. He had a Hewlett >> Packard cesium standard at Ft Collins. They were using a dual view >> GEOS Geostationary satellite to set the cesium to match the master >> clock in Boulder. If the cesium was good to 10^-13, that is 8.6 μs >> per day. I can't remember how close he tried to keep it or how often >> he adjusted it. It looked like that I could determine the start of >> the second to the individual transmitter cycle. Time transfer >> accuracy was therefore limited to the height changes of the >ionosphere >> at sunrise and sunset. >> >> The main disturbance was wind blowing the antenna. Ordinarily the >> phase would jitter a few degrees per second. I could tell the wind >> speed by the phase jitter without checking the Ft Collins weather. >If >> memory serves, the loaded Q at 60 kc was about 200. A half percent >> tuning error caused a 45° phase error. I have seen a 45° excursions >> on several occasions over a minute more than once. My receiver had a >> slow lock mode that could spot them. It also had a 45° phase switch >> on the 100 kc local oscillator to eliminate the station ID from 10 to >> 15 minutes after the hour. There was therefore no disturbance in >lock >> during it. I was never able to measure any error in the 45° phase >> advance. One degree would have been obvious. >> >> When I first got my receiver going, the phase would advance nearly >40° >> at the start of the second when the power was reduced by 10 db. It >> had been doing so for years and nobody noticed it. Maxton took an >> unneeded condenser out of his time code generator which fixed most of >> it. The new transmitter fixed the rest. >> >> Ft Collins is at 5,003 ft and clocks there run fast by 1.663·10^-13. >> (g/c^2)/meter) compared to sea level. How did you correct for >> altitude on yours? I presume that frequency is defined at sea level >> but I don't know that. Sea level clocks at the North or South Poles >> run fast relative to those at equator sea level by 1.192·10^-12. >> >> WB0KVV >> πθ°μΩω±√·÷Γλφ|Δ >> >> On Tue, Nov 20, 2018 at 9:06 AM jimlux <[email protected]> wrote: >>> >>> On 11/20/18 1:54 AM, ew via time-nuts wrote: >>>> Starting 1970 I used a modified Tracor 599H on WWVB with excellent >results. It had a mechanical counter with 100 nsec, resolution. Noisy >but perfect. Yes you have to take Ionosphere sunrise and sunset in to >consideration and the hourly shift, but being a very early riser 4AM >because of Europe no problem. Better than 2 E-11 per day and 4 E-14 per >month. >>>> >>>> In the 90 ties with my FRK having temperature and aging control >frequency was better than 1 E-12 all the time. >>>> >>>> Bert Kehren >>>> In a message dated 11/19/2018 9:58:39 PM Eastern Standard Time, >[email protected] writes: >>>> >>>> HF propagation of WWV or WWVH is horrible compared to VLF >propagationof WWVB at 60 kc. In this video the 5 mc WWV signal from Ft >Collins,Colorado is being received in New Jersey. It was compared >against astable 5mc crystal source. You can see a shift of a few >cycles persecond over a few seconds. This is due to the movement up or >down ofthe ionosphere at a substantial fraction of the speed of sound. >>> >>> In general terms, the coherence time of the ionosphere is single >digit >>> seconds - that is, there's essentially no correlation between >>> propagation path at one time and the propagation path 10 seconds >later. >>> >>> The "general length" of the path will be the same, but the details >>> different. >>> >>> The actual ionization in the ionosphere can best be described as >moving >>> "clouds" there's a fair amount of spatial inhomogeneity. In the >same >>> sense that milk reflects light from a multitude of little fat >globules. >> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > >_______________________________________________ >time-nuts mailing list -- [email protected] >To unsubscribe, go to >http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
