I've switched off my t'bolt. If I can't be closer than 21ns to the correct time, it just isn't worth it.
:) On 29 March 2010 01:36, Bob Camp <[email protected]> wrote: > Hi > > If you get arrested for keeping your bar open 21 ns after official closing > time, it's the USNO version you need to be "right with". The BIPM isn't going > to help you with the judge. > > Bob > > On Mar 28, 2010, at 7:58 AM, Arnold Tibus wrote: > >> The answer looks to me a bit difficult reading the USNO definition : >> >> INTERNATIONAL TIME SCALES AND THE B.I.P.M. >> http://tycho.usno.navy.mil/bipm.html >> >> citing: >> "...the U.S. Naval Observatory timescale, UTC(USNO), >> and its real-time implementation, Master Clock #2 (MC #2), >> are kept within a close but unspecified tolerance of the >> international atomic timescale published >> by the Bureau International des Poids et Mesures >> (International Bureau of Weights and Measures [BIPM]) >> in Sevres, France." >> >> "...Hence, all these atomic timescales are called >> Coordinated Universal Time (UTC), of which USNO's >> version is UTC(USNO)." >> >> "...The difference between UTC (computed by BIPM) and any other >> timing center's UTC only becomes known after computation and >> dissemination of UTC, which occurs about two weeks after the fact. >> This difference is presently limited mainly by the long-term frequency >> instability of UTC. >> UTC(USNO) has been kept within 26 nanoseconds of UTC during >> the past year through frequency steering of our Master Clocks to our >> extrapolation of UTC." >> >> So I do understand that BIPM is the world's time keeper, but there >> may be a difference between the UTCs of up to 26ns? >> >> "...Since synchronization is never perfect, we provide the latest data >> below on the differences between UTC and the UTC of other timing >> centers, including USNO,..." >> and >> "...All of our reference clocks are real-time approximations of UTC(USNO), >> and as such are denoted UTC(USNO,MC). Master Clock #2 (MC #2) is >> our official reference clock..." >> >> So I understand this as, that the USA do refer to the time reference >> of USNO - and the rest of the world to BIPM directly? >> >> Since dec. 2009 the PTB in Braunschweig, Germany (with the new >> CSF2) and the BIPM in Sevre are the only countries running 4 of the >> most precise primary Cs fountain clocks, if I am informed correctly. >> Together they should run quite close to the time defined by BIPM I think, >> and according our law our official time is transmitted by the PTB. >> >> Now, How do I have to interprete the readout of GPSDOs like >> Trimble's Thunderbolt and others PPS difference in ns to UTC? >> >> To which UTC? I suppose to the time transmitted by the US GPS SATs. >> Is there another difference in UTC to BIPM included? >> What is with Glonass (and will be later perhaps with Galileo)? >> >> In fact the use of GPS is already spreaded all over the world and >> in use in many technical applications, meaning that the world does >> refer to UTC given by US GPS !? >> >> Does it make sense under this circumstance as Time Nut to go >> below the Xns (26ns ?) frontier as absolute measure? >> Will this ever be possible? (Everything is relative...) >> >> But excuse me in case I do miss and misunderstand something >> fully... >> >> Arnold, DK2WT >> >> >> On Sun, 28 Mar 2010 22:29:22 +1300, Steve Rooke wrote: >> >>> What puzzles me is who is the keeper of "legal time" for the other >>> 93.4% of land mass and 95.5% of population of the World other than the >>> US. >> >>> On 28 March 2010 04:49, David Forbes <[email protected]> wrote: >>>> At 11:11 AM -0400 3/27/10, Bob Camp wrote: >>>>> >>>>> I would bet that if you went deep enough into the details, that the Army >>>>> at some point was less than enthusiastic about having to ask the Navy when >>>>> ever they wanted to know what time it was. >>>> >>>> My guess is that the Army just asked Western Union, who asked the Navy. >>>> >>>> -- >>>> >>>> --David Forbes, Tucson, AZ >>>> http://www.cathodecorner.com/ >>>> >> >> >> >> >> >> >> >> _______________________________________________ >> 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. > -- Steve Rooke - ZL3TUV & G8KVD A man with one clock knows what time it is; A man with two clocks is never quite sure. _______________________________________________ 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.
