Hi With the Loran boxes, you were doing well to get down to the 100 ns level. When you did, it always was a questionable sort of reading. More or less - is this real??? I spent a *lot* of time watching that data ….
Estimating what WWVB is doing over long baselines as the weather changes is not at all easy. To keep things in sync you need solid data all the time. Guessing at your time source and then trying to discipline against it does not make for a rational disciplining system. Again … I spent a lot of years looking at those phase plots. Could you do pretty well for a few days with either one? Sure you could. For a system time source you are looking at 24 hours a day / 365 days a year sort of performance. We are going round and round talking about the sort of solar flares that haven’t happened in many decades (if ever …). The sort of stuff that disrupts WWVB or Loran (at the 10’s or 100’s of nanoseconds level) happens many times a year, even in a good year. Ramp up the sun spots and it can get really interesting. Is it better if I can toss rocks and hit the transmit antenna? Sure it is. Not everybody was / is within a hundred miles of a master for Loran-C or of Ft. Colins for WWVB. If you are going to use WWVB, it’s got to work in Miami, Florida and in Bangor, Maine. Working out carrier phase on WWVB as MSF comes in at equal strength in New England … yikes …. There are good sound reasons why the WWVB disciplined systems gear got dumped a long time ago and replaced with GPS. The GPS based gear performs better and is more reliable. Bob > On Aug 30, 2018, at 12:46 PM, Scott McGrath <scmcgr...@gmail.com> wrote: > > One does not get the same instantaneous accuracy that one gets from GPS but > with a long baseline the offsets to your site can be determined. With > eLoran you can get similar levels of accuracy as the old Austron monitors > used to prove > > Content by Scott > Typos by Siri > > On Aug 30, 2018, at 12:27 PM, Bob kb8tq <kb...@n1k.org> wrote: > > Hi > > WWVB as transmitted ( = right at the input to the antenna) is a wonderfully > stable signal. As soon as > that signal hits the real world things start to degrade. Propagation between > transmit and receive sites > is a big deal, even at 60 KHz. On top of that, there is a *lot* of manmade > noise at 60 KHz. The receive > signal to noise will never be as good as you might like it to be …. > > 60 KHz has a period of 16.667 us. GPS gives you ~10 ns sort of time quite > quickly. Resolving the WWVB > carrier to that level is a major challenge. Identifying a single “cycle edge” > as the magic timing ID with either > the old or new modulation formats …. yet another significant challenge. Net > result is that you just can’t > get the same sort of timing out of WWVB. > > Bob > >> On Aug 30, 2018, at 11:15 AM, Mike Bafaro <m.baf...@comcast.net> wrote: >> >> According to what I have heard the 60KHz WWVB carrier is guaranteed accurate >> to the atomic standard and is considered traceable. I remember when I was >> in the Navy years ago I remember taking our unit's HP5245L for calibration >> and they used a VLF tracking receiver at 60KHz to do the calibration. If >> WWVB goes off the air what is the replacement for the 60KHz standard? >> >> Mike >> >> -----Original Message----- >> From: time-nuts [mailto:time-nuts-boun...@lists.febo.com] On Behalf Of Perry >> Sandeen via time-nuts >> Sent: Wednesday, August 29, 2018 6:34 PM >> To: time-nuts@lists.febo.com >> Cc: Perry Sandeen >> Subject: [time-nuts] WWV and legal issues >> >> Yo Dudes!� >> WWV and all its variations distribute what in the USA is the legal standard >> of time (from USNO) and frequency (NIST). >> �If one is running a freq cal service IIRC it is a legal requirement to be >> able to have traceability to WWV. >> >> If one was to rely on other sources, one has no guarantee that it 1. It is >> as accurate as claimed and 2. It can't be *diddled* with accidentally or >> deliberately. >> Although GPSDO's are very good and popular, they come from satellites that >> are vulnerable to damage from earth based resources. >> When your time and frequency standard(s) is under control on your own >> physical territory then they stand or fail on their own.� >> After the atom bombing of Hiroshima and Nagasaki, one of the major inventors >> of the bomb (I don't remember who) went to see US president Harry Truman and >> essentially told him that the scientists who developed the bomb should have >> a say of how or when it should be used. >> Truman is reported to have said for him to leave his office and told an aid >> that was responsible for his schedule to "never in hell let that (or any >> other) scientist� come to his office to influence American defense policy." >> Considering its status from both a scientific and political perspective, >> IMNSHO it will go on as before. >> To explain the political. No government official wants to see China or the >> Russian federation tell the world quote: See, the USA can't be trusted for >> something as important and simple as frequency and time.� However we are >> your friends who you can trust. Unquote. >> Regards, >> >> >> >> >> >> This is a case of practical use of WWV albeit over 50 years a go the >> fundamentals are still valid today. >> At Karamursel Air station TUSLOG 234 I was assigned to the base receiver >> site.� Our base had to purposes.� to� � >> >> >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> >> >> _______________________________________________ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
