Re: [time-nuts] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
Hi > On May 10, 2015, at 3:58 AM, Magnus Danielson > wrote: > > Hi, > > On 05/07/2015 11:48 PM, Bob Camp wrote: >> Hi >> >> >>> On May 7, 2015, at 8:02 AM, Pete Stephenson wrote: >>> >>> On 5/7/2015 1:22 PM, Bob Camp wrote: Hi I guess on a general level: 1) How do they generate the Swiss version of UTC (fleet of hydrogen masers run into to a .. :) >>> >>> According to their website they use an ensemble of commercial cesium >>> clocks (they show some photos of HP 5071As) and a hydrogen maser. I'll >>> be sure to ask them for details. >>> 2) How do they link that version of UTC with the rest of the world? (BIH etc) >> >> BIH = Bureau International de l’Heure >> They are the people who (by treaty) decide what time it *really* is. In >> order to do this they need to >> be able to evaluate the various time scales around the world. That >> evaluation process requires some >> method of direct inter comparison of time scales over very long distances. >> Typical approaches range >> from “clock trips” to TWSTT ( or TWSTFT) to GPS based techniques. > > As I recall it, they do no longer check the time-scales alone, but report the > time difference of all their clocks in relation to their time-scales, such > that TAI gets calculated out of all available clocks. > Actually, they first produce another time-scale from all clocks for optimum > stability and then frequency correct it into TAI and from that uses the > leap-second to produce UTC. Typically each lab run their own ensemble > algorithm and then use one of their clocks to feed a microstepper that then > produces the UTC(lab) of that lab. Some also produces a TAI equivalent in the > form of TA(lab). The algorithm steering the microstepper also get's fed > corrections from the UTC calculations in order to steer the labs UTC to be > inline. This is also used to steer slave-clocks such as the GPS clock to be > inline with USNO (if they haven't changed anything in the details). > > Knowing this overall process helps in understanding what you see and ask the > questions. I believe they still issue a monthly circular that looks at a weighted “vote” of all the time scales in the world. The numbers in that circular are what (by treaty) tell the various authorities around the world how far ahead or behind the official “right time” they are. To do that they need some form of inter comparison data. Bob > >> In addition to the comparison process it’s self, there is also a lot of >> internal cross checking and analysis >> that goes into a typical time scale. Often the associated equipment base is >> pretty substantial. It’s also a >> good thing to look at to pick up ideas for (lower cost) implementation in a >> basement lab. > > Indeed. > > Cheers, > Magnus > ___ > 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.
Re: [time-nuts] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
Hi, On 05/07/2015 11:48 PM, Bob Camp wrote: Hi On May 7, 2015, at 8:02 AM, Pete Stephenson wrote: On 5/7/2015 1:22 PM, Bob Camp wrote: Hi I guess on a general level: 1) How do they generate the Swiss version of UTC (fleet of hydrogen masers run into to a .. :) According to their website they use an ensemble of commercial cesium clocks (they show some photos of HP 5071As) and a hydrogen maser. I'll be sure to ask them for details. 2) How do they link that version of UTC with the rest of the world? (BIH etc) BIH = Bureau International de l’Heure They are the people who (by treaty) decide what time it *really* is. In order to do this they need to be able to evaluate the various time scales around the world. That evaluation process requires some method of direct inter comparison of time scales over very long distances. Typical approaches range from “clock trips” to TWSTT ( or TWSTFT) to GPS based techniques. As I recall it, they do no longer check the time-scales alone, but report the time difference of all their clocks in relation to their time-scales, such that TAI gets calculated out of all available clocks. Actually, they first produce another time-scale from all clocks for optimum stability and then frequency correct it into TAI and from that uses the leap-second to produce UTC. Typically each lab run their own ensemble algorithm and then use one of their clocks to feed a microstepper that then produces the UTC(lab) of that lab. Some also produces a TAI equivalent in the form of TA(lab). The algorithm steering the microstepper also get's fed corrections from the UTC calculations in order to steer the labs UTC to be inline. This is also used to steer slave-clocks such as the GPS clock to be inline with USNO (if they haven't changed anything in the details). Knowing this overall process helps in understanding what you see and ask the questions. In addition to the comparison process it’s self, there is also a lot of internal cross checking and analysis that goes into a typical time scale. Often the associated equipment base is pretty substantial. It’s also a good thing to look at to pick up ideas for (lower cost) implementation in a basement lab. Indeed. Cheers, Magnus ___ 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.
Re: [time-nuts] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
In message <554b6547.5070...@burnicki.net>, Martin Burnicki writes: >Poul-Henning Kamp wrote: >> Ask them how/why the HBG transmitter screwed up the 2006 leapsecond ? > >If I remember correctly then the transmitter would have needed to be >overhauled, which would have been very expensive. That's why they shut it down. I'm asking why the sent the leap-second one second early in 2006 ? See: http://phk.freebsd.dk/Leap/20051231_HBG/ -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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.
Re: [time-nuts] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
Hi > On May 7, 2015, at 8:02 AM, Pete Stephenson wrote: > > On 5/7/2015 1:22 PM, Bob Camp wrote: >> Hi >> >> I guess on a general level: >> >> 1) How do they generate the Swiss version of UTC (fleet of hydrogen masers >> run into to a .. :) > > According to their website they use an ensemble of commercial cesium > clocks (they show some photos of HP 5071As) and a hydrogen maser. I'll > be sure to ask them for details. > >> 2) How do they link that version of UTC with the rest of the world? (BIH etc) BIH = Bureau International de l’Heure They are the people who (by treaty) decide what time it *really* is. In order to do this they need to be able to evaluate the various time scales around the world. That evaluation process requires some method of direct inter comparison of time scales over very long distances. Typical approaches range from “clock trips” to TWSTT ( or TWSTFT) to GPS based techniques. In addition to the comparison process it’s self, there is also a lot of internal cross checking and analysis that goes into a typical time scale. Often the associated equipment base is pretty substantial. It’s also a good thing to look at to pick up ideas for (lower cost) implementation in a basement lab. Bob > I'm not familiar with that particular acronym (BIH), but I am curious > how they link their version of UTC. > >> Not so much a picture of this or that. More a tour of an entire process. > > Right. > > Cheers! > -Pete > ___ > 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.
Re: [time-nuts] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
On 5/7/2015 1:22 PM, Bob Camp wrote: > Hi > > I guess on a general level: > > 1) How do they generate the Swiss version of UTC (fleet of hydrogen masers > run into to a .. :) According to their website they use an ensemble of commercial cesium clocks (they show some photos of HP 5071As) and a hydrogen maser. I'll be sure to ask them for details. > 2) How do they link that version of UTC with the rest of the world? (BIH etc) I'm not familiar with that particular acronym (BIH), but I am curious how they link their version of UTC. > Not so much a picture of this or that. More a tour of an entire process. Right. Cheers! -Pete ___ 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.
Re: [time-nuts] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
Poul-Henning Kamp wrote: Ask them how/why the HBG transmitter screwed up the 2006 leapsecond ? If I remember correctly then the transmitter would have needed to be overhauled, which would have been very expensive. Since the German DCF77 transmitter can also be received in Switzerland and DCF77 receivers were much more common than HBG receivers the decision was taken to finish HBG transmission. Martin ___ 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.
Re: [time-nuts] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
In message <7fa86d93-1c83-4fe8-84a0-ddb7a542a...@n1k.org>, Bob Camp writes: Ask them how/why the HBG transmitter screwed up the 2006 leapsecond ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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.
Re: [time-nuts] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
Hi I guess on a general level: 1) How do they generate the Swiss version of UTC (fleet of hydrogen masers run into to a .. :) 2) How do they link that version of UTC with the rest of the world? (BIH etc) Not so much a picture of this or that. More a tour of an entire process. Bob > On May 7, 2015, at 5:38 AM, Pete Stephenson wrote: > > Hi all, > > I recently inquired about taking a tour of the METAS time lab[1] and > they said they'd be willing to show me around. > > Is there anything in particular that fellow time-nuts would be > interested in me asking them about or (if possible) photographing? > > Cheers! > -Pete > > [1] http://www.metas.ch/metas/en/home/fabe/zeit-und-frequenz.html > > -- > Pete Stephenson > ___ > 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] Tour of METAS (Swiss Federal Institute of Metrology) time lab: any questions or requests?
Hi all, I recently inquired about taking a tour of the METAS time lab[1] and they said they'd be willing to show me around. Is there anything in particular that fellow time-nuts would be interested in me asking them about or (if possible) photographing? Cheers! -Pete [1] http://www.metas.ch/metas/en/home/fabe/zeit-und-frequenz.html -- Pete Stephenson ___ 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.
