Re: [time-nuts] labview, gpib, gps , logging data and lost data points!!
Norman, > Does EZ-GPIB support visa? Yes, it is not a complete implementation but it should be enough for tasks like that. > The idea was to save the data in text files and post-process > with excel. Sure possible, but if the decoding can be done in realtime why not do it. > Based on my observations, the gpib routine takes 300ms to > complete. For my HP counters the rule applies: Once they are configured and you can be sure that they have terminated a measurement (either because they triggred the bus SRQ line or by knowing that they received a signal on the stop input) you can ask for the result and you get it with high speed, merely microseconds then milliseconds. > There are two reasons for Labview. One is it's used quite a bit. The > other is that the learing curve isn't quite as steep as C++ or VB. As I did already say: There is a readey to go example that performs the complete decoding. The only prerequisite is a positive going pps on either of the RS232 status input lines. 73s and my best regards Ulrich, DF6JB P.S. I just received an feedback that the version of 2008-10-29 may contain a bug. Please wait with a test of EZGPIB until a later version is available. > -Ursprungliche Nachricht- > Von: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Im Auftrag von Norman J McSweyn > Gesendet: Mittwoch, 29. Oktober 2008 17:40 > An: Discussion of precise time and frequency measurement > Betreff: Re: [time-nuts] labview, gpib, gps ,logging data and > lost data points!! > > > Ulrich, > Does EZ-GPIB support visa? I know there was a thread a few > months back > kicking around the idea. > > The way the code is written now, I'm getting a response to @@Hn and > parsing that. > > The idea was to save the data in text files and post-process > with excel. > > Using the SRQ (and your idea as from the counter to generate a timing > mark (to start the serial vi). This makes a lot of sense because I'll > know that the data in the message will be for the next second > (timestamped with this second) > > Based on my observations, the gpib routine takes 300ms to > complete. It's > just setup, trigger and read. I'll have to change this. > > There are two reasons for Labview. One is it's used quite a bit. The > other is that the learing curve isn't quite as steep as C++ or VB. > > Either way, you've given much to think about! > Thanks, > Norm n3ykf > > ___ > 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] Z3805 and Fluke.I
Hi All, I think this is a great idea to replace my legacy Z3816A!... I also hope they'll offer as a gift the software to drive it, and they should gratify Bill K8CU to modify his software GPSCON to support the Z3805 if it's not done yet!... ;-)) 35 bucs sems to be reasonable to me, these difficult financial days... Considering also that these receivers are also legacies, certainly pulled off from legacy networks... Best 73's to all of you. pf, F5BQP - Original Message - From: "Rich and Marcia Putz" <[EMAIL PROTECTED]> To: Sent: Thursday, October 30, 2008 12:46 AM Subject: [time-nuts] Z3805 and Fluke.I > > Hi ALL; > > Since Fluke.I is now advertising on our forum, perhaps he should make > special deal for all us for real time-nuts, like a Z3805 for $35 or so! > What do the rest of you think? > Rich > ___ > 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. > > > __ Information NOD32 3568 (20081030) __ > > Ce message a ete verifie par NOD32 Antivirus System. > http://www.nod32.com > > ___ 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] Z3805 and Fluke.I
- Original Message - From: "Steve Rooke" <[EMAIL PROTECTED]> To: "Discussion of precise time and frequency measurement" Sent: Thursday, October 30, 2008 3:43 AM Subject: Re: [time-nuts] Z3805 and Fluke.I > > 2008/10/30 Rich and Marcia Putz <[EMAIL PROTECTED]>: >> Since Fluke.I is now advertising on our forum, perhaps he should make >> special deal for all us for real time-nuts, like a Z3805 for $35 or so! >> What do the rest of you think? > > Does that include shipping? > I don't think so... I would pay extra for that... ;-)) But from China it would overshoot the price... Best 73's pf, F5BQP > 73, Steve > -- > Steve Rooke - ZL3TUV & G8KVD > Omnium finis imminet > > ___ > 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. > > > __ Information NOD32 3568 (20081030) __ > > Ce message a ete verifie par NOD32 Antivirus System. > http://www.nod32.com > > ___ 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] Z3805 and Fluke.I
Pierre-François (f5bqp_pfm) wrote: > Hi All, > > I think this is a great idea to replace my legacy Z3816A!... > I also hope they'll offer as a gift the software to drive it, and they > should gratify Bill K8CU to modify his software GPSCON to support the Z3805 > if it's not done yet!... ;-)) > 35 bucs sems to be reasonable to me, these difficult financial days... > Considering also that these receivers are also legacies, certainly pulled > off from legacy networks... > > Best 73's to all of you. > > pf, F5BQP > > > $35 would be great, but I suspect it may be a good bit less than the current owner has invested. But I can't, myself, see paying a bit more than double what I invested in my Z3816A. Might be ok for some, but seems way pricey vs the current available Thunderbolts unless there is some major advantage that I don't know about. Lost the link, was it rs422 control port? I don't see that as an advantage. The 3816 talks to standard serial without modification. I think what you have is pretty good. Not all that much legacy vs most of my favorite stuff. Can't see why it would wear out soon. No Cs or Rb. His listing does short the Z3816A by a few ports in the comparison. There are 4 1 PPS ports, not two and there are also 4 19.6608 MHz ports. If you don't have use for the 19.6 ports, I did find a way to convert mine to make them 10 MHz square wave outputs. See: http://www.xertech.net/Projects/Z3816/3816_mod.html This gives the 3816 these outputs: standard 2 10 MHz sine, 4 1 PPS pulse and then 4 10 MHz square wave. For those who can afford, happy shopping. For any who have Z3816A's and want more 10 MHz, I hope my mod works for you. ___ 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] Measuring ADEV with a PM6681 or CNT-81
Thanks to all who replied, and sorry for the delay. I was away and unfortunately unable to follow the discussion until today. >From Tom's comments and others I extract that the PM6681 can only be used for >measuring the ADEV when employing the picket fence technique. A direct >measurement is prevented by the counter's dead-time. Apart from a suitable >divider, I'd probably need to write my own piece of software for massaging the >data so that it can be used for an ADEV plot. Unless of course there is some >software readily available that includes handling of the picket fence >technique. My other idea of using two counters in lockstep, so that they measure alternate periods of the signal, hasn't been commented on. Is it a silly idea, apart from the fact that it needs two counters? Has anyone tried anything like it? Thanks and Cheers Stefan -Ursprüngliche Nachricht- Von: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] Im Auftrag von Tom Duckworth Gesendet: Samstag, 25. Oktober 2008 03:11 An: 'Discussion of precise time and frequency measurement' Betreff: Re: [time-nuts] Measuring ADEV with a PM6681 or CNT-81 Stefan, Well, I have been sort of staying out of the recent discussions regarding oscillator stability measurements, ADEV, etc., but here goes my two cents worth. I hope it doesn't muddy the waters too much and is somewhat helpful. There is a fundamental problem with trying to do ADEV (Allan Deviation) with a counter that has a gated measurement engine (all standard counters). The problem is that when the count engine gate closes (so the counter can compute the number of events, report the result as a frequency, and clear its registers), the counter is blind (dead time) to any signal at the input. Allan deviation REQUIRES than a minimum number of measurements be made back-to-back (no dead time between measurements) in order to capture nondeterministic fluctuations of the signal you're trying to measure. This requires a measuring device (counter) that continuously records ALL events. It does this by time-stamping a fixed period in a separate register in the counter along with the input register (the signal being measured), and a time-base register that records the frequency the signal is to be compared with. There is no 'gate' as such in a time-stamping counter. Most stability measurements, longer than say 100 seconds, are made in the frequency domain because energy changes, as a result of heat, are by far the predominate cause of stability (aging) issues (see below). Stability issues within shorter time periods, say <100 sec., are often nondeterministic, and cannot be accurately quantified in the frequency domain, but must be measured in the time domain, using statistical weighting. In other words, unpredictable, and often little understood, events (Shot and thermal noise in the active devices, random variations in the frequency-determining elements, cosmic rays, etc.) often predominate short term stability measurements and must be described statistically, as their occurrence and duration are random. Allan deviation is a widely accepted time-domain statistical measurement whose calculated results compare well with the more common frequency domain measurement of longer time periods. Allan deviation measurements are based on the sample variance of the fractional-frequency fluctuations. Without specifying the number of samples N, and the repetition interval T, for measurements of duration t, the measure of frequency stability is dimensionless and would converge to a meaningless limit. Secondly, some actual noise processes contain substantial fractions of the total noise power in the instantaneous fractional-frequency range below one cycle per year. In order to improve compatibility of data, it is important to specify a particular N and T. The Allan variance chooses N=2 and T=t (i.e. no dead time between measurements). A good estimate can be obtained by a limited number, m, of measurements (m=*100). Root Allen variance is expressed as a quantity divided by the square of the measurements of duration t, (i.e., 3 x 10-11/*t). . Classical variance diverges for commonly observed noise processes, such as random walk (i.e., the variance increases with an increasing number of data points). The advantage with the Allan variance is that it: * converges for all noise processes observed in precision oscillators; * has straightforward relationship to power law spectral density (spectral density of the frequency fluctuations); * is easy to compute, and; * is faster and more accurate in estimating noise processes than the Fast Fourier Transform. Aging in quartz crystal oscillators is caused by changes in either the quartz crystal itself or the associated components found in the oscillator assembly. Aging is the result of a combination of several factors having complex, and only partially understood, components that effect the aging specificatio
[time-nuts] Time-zones and World time..
Hi, I've been under the radar for a while so have not been able to keep up with the threads I was contributing to but that has been done to death and I will drop them. I've been very interested in reading peoplels thoughts on time-zones. Has there been any moves to adopt a common time for all countries in the world so as to alleviate the difficulties in dealing with time-zones?" I know there was the idea of Internet-time going around some time ago but I think that seems to have died a death. Thinking about it, what's the problem of adapting to daily life which is shifted by some number of hours off the clock. If we all used UTC everyone around the world would know when a certain time was in their own day. In my case for New Zealand, +12 hours would probably be adopted for the country, so AM becomes PM and I'd get up at 7PM (still that's not much different from now :) instead of AM. I guess the question is, what's the likely-hood of a world standard time being adopted (sort of like Star Trek)? 73 Steve - ZL3TUV -- Steve Rooke - ZL3TUV & G8KVD Omnium finis imminet ___ 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] Measuring ADEV with a PM6681 or CNT-81
Stefan, > Apart from a suitable divider, I'd If you a dedicated follower of PIC microcontrollers you find something suitable here on Tom's pages http://www.leapsecond.com/pages/ppsdiv/ Otherwise if you like AVRs then you can find something on my pages http://www.ulrich-bangert.de/html/downloads.html Suitable sine to ttl circuits designed by Bruce Griffiths are to be found at http://www.ko4bb.com/~bruce/CLKSHPR.html Best regards Ulrich > -Ursprüngliche Nachricht- > Von: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Im Auftrag von Heinzmann, > Stefan (ALC NetworX GmbH) > Gesendet: Donnerstag, 30. Oktober 2008 12:42 > An: Discussion of precise time and frequency measurement > Betreff: [!! SPAM] Re: [time-nuts] Measuring ADEV with a > PM6681 or CNT-81 > > > Thanks to all who replied, and sorry for the delay. I was > away and unfortunately unable to follow the discussion until today. > > From Tom's comments and others I extract that the PM6681 can > only be used for measuring the ADEV when employing the picket > fence technique. A direct measurement is prevented by the > counter's dead-time. Apart from a suitable divider, I'd > probably need to write my own piece of software for massaging > the data so that it can be used for an ADEV plot. Unless of > course there is some software readily available that includes > handling of the picket fence technique. > > My other idea of using two counters in lockstep, so that they > measure alternate periods of the signal, hasn't been > commented on. Is it a silly idea, apart from the fact that it > needs two counters? Has anyone tried anything like it? > > Thanks and Cheers > Stefan > > > -Ursprüngliche Nachricht- > Von: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] Im Auftrag von Tom Duckworth > Gesendet: Samstag, 25. Oktober 2008 03:11 > An: 'Discussion of precise time and frequency measurement' > Betreff: Re: [time-nuts] Measuring ADEV with a PM6681 or CNT-81 > > Stefan, > > > > Well, I have been sort of staying out of the recent > discussions regarding oscillator stability measurements, > ADEV, etc., but here goes my two cents worth. I hope it > doesn't muddy the waters too much and is somewhat helpful. > > > > There is a fundamental problem with trying to do ADEV (Allan > Deviation) with a counter that has a gated measurement engine > (all standard counters). The problem is that when the count > engine gate closes (so the counter can compute the number of > events, report the result as a frequency, and clear its > registers), the counter is blind (dead time) to any signal at > the input. Allan deviation REQUIRES than a minimum number of > measurements be made back-to-back (no dead time between > measurements) in order to capture nondeterministic > fluctuations of the signal you're trying to measure. This > requires a measuring device (counter) that continuously > records ALL events. It does this by time-stamping a fixed > period in a separate register in the counter along with the > input register (the signal being measured), and a time-base > register that records the frequency the signal is to be > compared with. There is no 'gate' as such in a time-stamping counter. > > > > Most stability measurements, longer than say 100 seconds, are > made in the frequency domain because energy changes, as a > result of heat, are by far the predominate cause of stability > (aging) issues (see below). Stability issues within shorter > time periods, say <100 sec., are often nondeterministic, and > cannot be accurately quantified in the frequency domain, but > must be measured in the time domain, using statistical > weighting. In other words, unpredictable, and often little > understood, events (Shot and thermal noise in the active > devices, random variations in the frequency-determining > elements, cosmic rays, etc.) often predominate short term > stability measurements and must be described statistically, > as their occurrence and duration are random. Allan deviation > is a widely accepted time-domain statistical measurement > whose calculated results compare well with the more common > frequency domain measurement of longer time periods. > > > > Allan deviation measurements are based on the sample variance > of the fractional-frequency fluctuations. Without specifying > the number of samples N, and the repetition interval T, for > measurements of duration t, the measure of frequency > stability is dimensionless and would converge to a > meaningless limit. Secondly, some actual noise processes > contain substantial fractions of the total noise power in the > instantaneous fractional-frequency range below one cycle per > year. In order to improve compatibility of data, it is > important to specify a particular N and T. The Allan variance > chooses N=2 and T=t (i.e. no dead time between measurements). > A good estimate can be obtained by a limited number, m, of > measureme
Re: [time-nuts] Time-zones and World time..
Steve Rooke wrote: > I guess the question is, what's the likely-hood of a world standard > time being adopted (sort of like Star Trek)? I would say it's very unlikely to happen. People tend to prefer the time in their area to match up with the day. So, having the sun come up at 7pm wouldn't suit a lot of people. Recently the islanders on Jersey rejected a proposal to move to Central European Time (CET) see http://www.timeanddate.com/news/time/jersey-time-zone-referendum.html Dave ___ 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] What's the time Mr Wolf...
Hi, This may have already been covered in this group so please excuse me for not combing the archives. I could Google for this but I'll get a quicker answer here and I know it will be the correct one. !) Who decides on what is the correct time? 2) Is the time standard stored on one master grandfather clock? 3) As (2) is unlikely, if a number of clocks are involved, are they in different countries? 4) As (3) is likely, how are they synchronised? 5) If this involves communicating with each other, what medium is used and how are delays handled (a la NTP pings)? 6) If all the clocks are synchronised in one place and then transported all over the World, how is the Einstein affect of time dilation handled due to the clocks changing in flight? Now the interesting ones (for me anyway). 7) Where are the clock(s) located which provide the time for the GPS satellites? 8) If they are actually in the satellites, how are they all kept synchronised with each other and the "master grandfather clock" on the ground? 9) Are the satellites in geostationary orbit? 10) If they are geostationary, or move in relation to the ground, how are the affects of the Einstein time dilation handled as they may be travelling at a different speed than a point on the surface of the Earth? 11) Extrapolating this, a point on the Equator would be moving faster that a point at the poles or even Greenwich, for that matter. So would a clock at each location move out of synchronisation with each other? Aren't you glad I'm back :) BTW, where is /tvb these days, I haven't seen any postings by him while I have catching up? 73 Steve - ZL3TUV -- Steve Rooke - ZL3TUV & G8KVD Omnium finis imminet ___ 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] Time-zones and World time..
2008/10/31 David Ackrill <[EMAIL PROTECTED]>: > I would say it's very unlikely to happen. People tend to prefer the > time in their area to match up with the day. So, having the sun come up > at 7pm wouldn't suit a lot of people. But people would get used to it after a while, maybe a generation, and whose to say that the sun should come up at 7am, it's really just an arbitrary concept. > Recently the islanders on Jersey rejected a proposal to move to Central > European Time (CET) see > http://www.timeanddate.com/news/time/jersey-time-zone-referendum.html I guess that is because we put the important decisions in the hands of voters :) 73 Steve - ZL3TUV -- Steve Rooke - ZL3TUV & G8KVD Omnium finis imminet ___ 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] What's the time Mr Wolf...
At 01:46 +1300 31-10-2008, Steve Rooke wrote: > I could Google for this but I'll get a >quicker answer here To me that reads as "My time is more valuable than yours". Not to pick on you in particular, but I see this attitude a lot lately in fora, support groups and mailing lists. From your list it does look like most questions could indeed be answered by a few minutes of Googling, though. JDB. [apologies if you feel I snipped too much context, but this phrase in particular hit a nerve] -- LART. 250 MIPS under one Watt. Free hardware design files. http://www.lartmaker.nl/ ___ 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] What's the time Mr Wolf...
At 02:09 +1300 31-10-2008, Steve Rooke wrote: > it's not always easy to formulate a >phrase to trigger the answer required out of Google and which sources >should I go to or believe. Fair enough. For your first six questions, I'd use keywords including "nist" and "time", and start following links from there. For the GPS stuff handy keywords include "navstar", "usno" and "gpsworld". Good luck, JDB. [from a somewhat different (sub)culture, but this may be useful too: http://www.catb.org/~esr/faqs/smart-questions.html ] -- LART. 250 MIPS under one Watt. Free hardware design files. http://www.lartmaker.nl/ ___ 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] What's the time Mr Wolf...
My apologies to the list, it was unthoughtful of me. This was not my intent, what I really meant was it's not always easy to formulate a phrase to trigger the answer required out of Google and which sources should I go to or believe. Really this was more meant to be a compliment to the contributors of this list. 73 Steve - ZL3TUV 2008/10/31 J.D. Bakker <[EMAIL PROTECTED]>: > At 01:46 +1300 31-10-2008, Steve Rooke wrote: >> I could Google for this but I'll get a >>quicker answer here > > To me that reads as "My time is more valuable than yours". > > Not to pick on you in particular, but I see this attitude a lot > lately in fora, support groups and mailing lists. From your list it > does look like most questions could indeed be answered by a few > minutes of Googling, though. > > JDB. > [apologies if you feel I snipped too much context, but this phrase in > particular hit a nerve] > -- > LART. 250 MIPS under one Watt. Free hardware design files. > http://www.lartmaker.nl/ > > ___ > 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. > -- Steve Rooke - ZL3TUV & G8KVD Omnium finis imminet ___ 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] Time-zones and World time..
With the great ease of computers to make the transformations, there really isn't any point in removing local timezones. It is just a table after all... it is nothing like the old days when every major town used Local Sidereal Time (eg. 12:00 is when the sun is at its highest). That caused major problems for the railroads. The biggest problem with local timezones is all of the continuously changing variations on Daylight Savings Time. That accounts for the majority of the changes in the unix tz functions. It was recently reported that the onset of DST coincides with an increase in heart attacks, and the return to standard time coincides with a decrease in heart attacks. Yet another reason to ditch Daylight Savings Time. -Chuck Harris Steve Rooke wrote: > Hi, > > I've been under the radar for a while so have not been able to keep up > with the threads I was contributing to but that has been done to death > and I will drop them. I've been very interested in reading peoplels > thoughts on time-zones. Has there been any moves to adopt a common > time for all countries in the world so as to alleviate the > difficulties in dealing with time-zones?" I know there was the idea of > Internet-time going around some time ago but I think that seems to > have died a death. Thinking about it, what's the problem of adapting > to daily life which is shifted by some number of hours off the clock. > If we all used UTC everyone around the world would know when a certain > time was in their own day. In my case for New Zealand, +12 hours would > probably be adopted for the country, so AM becomes PM and I'd get up > at 7PM (still that's not much different from now :) instead of AM. > > I guess the question is, what's the likely-hood of a world standard > time being adopted (sort of like Star Trek)? > > 73 > Steve - ZL3TUV ___ 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] Time-zones and World time..
Chuck Harris wrote: > With the great ease of computers to make the transformations, > there really isn't any point in removing local timezones. It > is just a table after all... it is nothing like the old days when > every major town used Local Sidereal Time (eg. 12:00 is when the > sun is at its highest). That caused major problems for the > railroads. > > The biggest problem with local timezones is all of the continuously > changing variations on Daylight Savings Time. That accounts for > the majority of the changes in the unix tz functions. > > It was recently reported that the onset of DST coincides with an > increase in heart attacks, and the return to standard time coincides > with a decrease in heart attacks. Yet another reason to ditch > Daylight Savings Time. > > -Chuck Harris > > Such "effects" are somewhat suspect as there is unlikely to have been any comparable control group not subject to DST. Also disentangling seasonal effects from possible DST related effects is somewhat problematic. Bruce ___ 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] What's the time Mr Wolf...
> Hi, > > This may have already been covered in this group so please excuse me > for not combing the archives. I could Google for this but I'll get a > quicker answer here and I know it will be the correct one. > > !) Who decides on what is the correct time? BIPM, the same guys that keeps the meter and the kilogram, etc. > 2) Is the time standard stored on one master grandfather clock? No. > 3) As (2) is unlikely, if a number of clocks are involved, are they in > different countries? About 350 clocks in 50 countries, last I heard. > 4) As (3) is likely, how are they synchronised? They aren't synchronized in the traditional sense. But they are slowly steered toward the mean. Each country has their own official time but all follow the same mean time scale (UTC). > 5) If this involves communicating with each other, what medium is used > and how are delays handled (a la NTP pings)? NTP is not used. Instead the clocks are compared using special GPS receivers, or dedicated round-trip satellite links. Relativistic and Sagnac corrections are applied as necessary. > 6) If all the clocks are synchronised in one place and then > transported all over the World, how is the Einstein affect of time > dilation handled due to the clocks changing in flight? The clocks typically aren't moved; they stay in their laboratories. But when clocks are transported, yes, relativistic effects are calculated and corrections applied. > > Now the interesting ones (for me anyway). > > 7) Where are the clock(s) located which provide the time for the GPS > satellites? USNO, in Washington DC. > 8) If they are actually in the satellites, how are they all kept > synchronised with each other and the "master grandfather clock" on the > ground? Yes, there are clocks in the satellites too. Their phase and rate can be updated by ground control. > 9) Are the satellites in geostationary orbit? No. > 10) If they are geostationary, or move in relation to the ground, how > are the affects of the Einstein time dilation handled as they may be > travelling at a different speed than a point on the surface of the > Earth? Geostationary or not, there are satellite relativistic effects which are taken into account. > 11) Extrapolating this, a point on the Equator would be moving faster > that a point at the poles or even Greenwich, for that matter. So would > a clock at each location move out of synchronisation with each other? Yes, and this also is taken into account. When you get down to measuring absolute frequency at 1e-14 and 1e-15 levels one always takes the local gravitational field into account, which is mostly a function of altitude, but also latitude. > Aren't you glad I'm back :) BTW, where is /tvb these days, I haven't > seen any postings by him while I have catching up? > > 73 > Steve - ZL3TUV > -- > Steve Rooke - ZL3TUV & G8KVD > Omnium finis imminet /tvb ___ 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] Time-zones and World time..
Bruce Griffiths wrote: > Chuck Harris wrote: ... >> >> It was recently reported that the onset of DST coincides with an >> increase in heart attacks, and the return to standard time coincides >> with a decrease in heart attacks. Yet another reason to ditch >> Daylight Savings Time. >> >> -Chuck Harris >> >> > Such "effects" are somewhat suspect as there is unlikely to have been > any comparable control group not subject to DST. > Also disentangling seasonal effects from possible DST related effects is > somewhat problematic. Correlation not being equal to causation always causes some lay folk problems. Though no one said that the DST shift caused the increase; it would be interesting to know if when the US changed its DST dates, the effect followed the change. -Chuck Harris ___ 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] labview, gpib, gps , logging data and lost data points!!
Ulrich, I'll give ezgpib a try! Unfortunately it won't be until Feb. My vacation is coming to an end. Have about 15 or 20 more hours budgeted to play with my toys. Have fixed the dropped data points, however. Used a timed sequence structure inside a for loop. The sequence structure has two frames. The first is the gpib routine. When that completes, Moto gps routine runs. Does it all in less than a second!!! How's that for precise timing? :-) The way the gps routine is set up, I'm polling the board, rather than setting it up to output every second. The m12+t user's guide says the buffer on the gps board is read every second. How is that true if I poll the board and get a response in 200ms? I'm presently polling the @@Hn. Think I'll add @@Gb and parse that. It'll give me the time stamp from the moto board. That along with the time stamp from the pc ought to get me more troubleshooting data at least. BTW: I'm flushing the serial buffer prior to reading it, so the data is in response to my query, rather than being data that is in response to the previous poll. tnx es 73 de Norm n3ykf ___ 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] Time-zones and World time..
Hi Chuck: Not all of the U.S. uses DST, so there's a control group. Have Fun, Brooke Clarke http://www.prc68.com/P/Prod.html Products I make and sell http://www.prc68.com/Alpha.shtml All my web pages listed based on html name http://www.PRC68.com http://www.precisionclock.com http://www.prc68.com/I/WebCam2.shtml 24/7 Sky-Weather-Astronomy Web Cam Chuck Harris wrote: > Bruce Griffiths wrote: >> Chuck Harris wrote: > > ... > >>> It was recently reported that the onset of DST coincides with an >>> increase in heart attacks, and the return to standard time coincides >>> with a decrease in heart attacks. Yet another reason to ditch >>> Daylight Savings Time. >>> >>> -Chuck Harris >>> >>> >> Such "effects" are somewhat suspect as there is unlikely to have been >> any comparable control group not subject to DST. >> Also disentangling seasonal effects from possible DST related effects is >> somewhat problematic. > > Correlation not being equal to causation always causes some lay folk > problems. Though no one said that the DST shift caused the increase; > it would be interesting to know if when the US changed its DST dates, > the effect followed the change. > > -Chuck Harris > > ___ > 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] What's the time Mr Wolf...
On Thu, Oct 30, 2008 at 8:46 AM, Steve Rooke <[EMAIL PROTECTED]> wrote: > Hi, > > This may have already been covered in this group so please excuse me > for not combing the archives. I could Google for this but I'll get a > quicker answer here and I know it will be the correct one. I think it was approximately a year ago in the archives that there was a good thread of suggested (mostly online) readings. As well, an affordable and highly readable book is _Splitting the Second : The Story of Atomic Time_ by Tony Jones, ISBN-13: 978-0750306409. Highly recommended, and I think it covers nearly all of your questions. -Michael ___ 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] Time-zones and World time..
Brooke Clarke wrote: > Hi Chuck: > > Not all of the U.S. uses DST, so there's a control group. That's true, but it cannot be said that the areas that don't use DST are equivalent to those that do in all respects that might cause heart problems. It is thought the change in sleep/wake patterns is what causes the stress to the heart, so I would be most interested in what happened to identical populations when the DST date changed. Unfortunately, he study period was from 1987 through 2006, so I believe it missed the shift in DST dates. The Swedish researchers that did the study said the number of heart attacks drops 5% for the 7 days after the US changes from DST to standard time, and spikes on the Monday we go back to DST. I expect that the daily risk will be found to shift with the change in the DST date. -Chuck Harris ___ 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] Time-zones and World time..
Never mind it happens right before the holidays. I'm stressed either way. On Thu, Oct 30, 2008 at 9:36 AM, Chuck Harris <[EMAIL PROTECTED]> wrote: > Brooke Clarke wrote: > > Hi Chuck: > > > > Not all of the U.S. uses DST, so there's a control group. > > That's true, but it cannot be said that the areas that don't > use DST are equivalent to those that do in all respects that > might cause heart problems. > > It is thought the change in sleep/wake patterns is what causes > the stress to the heart, so I would be most interested in what > happened to identical populations when the DST date changed. > > Unfortunately, he study period was from 1987 through 2006, so > I believe it missed the shift in DST dates. > > The Swedish researchers that did the study said the number of > heart attacks drops 5% for the 7 days after the US changes from > DST to standard time, and spikes on the Monday we go back to DST. > > I expect that the daily risk will be found to shift with the > change in the DST date. > > -Chuck Harris > > ___ > 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] 53310A help
Does anybody know how to use the signal source that comes with the HP 53310A Modulation Domain Analyser? The MDA is fine, but I don't have a manual for the signal source, and there seems to be nothing coming out of it - and yes, I checked the battery. There's no mention of how to use the signal source in the 53310A manual. regards Grant Hodgson ___ 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] Time-zones and World time..
At 9:42 AM -0400 10/30/08, Chuck Harris wrote: >With the great ease of computers to make the transformations, >there really isn't any point in removing local timezones. It >is just a table after all... it is nothing like the old days when >every major town used Local Sidereal Time (eg. 12:00 is when the >sun is at its highest). That caused major problems for the >railroads. > >-Chuck Harris Chuck, I don't think you meant to say sidereal time, which is based the stars, not the sun. There are 366.25 or so days in a sidereal year! -- --David Forbes, Tucson, AZ http://www.cathodecorner.com/ ___ 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] Measuring ADEV with a PM6681 or CNT-81
> Apart from a suitable divider And I have one PCB left for my divider if that's of interest ... Price as before GBP20 plus shipping (GBP12 outside UK) plus 5% Paypal tax! PS has anyone had a chance to measure the phase noise from my divider yet - I just don't have the tools to do it, and I know that a few of you suggested you'd look at that after building it. Cheers Dave -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Heinzmann, Stefan (ALC NetworX GmbH) Sent: 30 October 2008 11:42 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Measuring ADEV with a PM6681 or CNT-81 ___ 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] What's the time Mr Wolf...
Tom, Have you received any of my recent PMs? 2008/10/31 Tom Van Baak <[EMAIL PROTECTED]>: ... > > /tvb > 73 Steve -- Steve Rooke - ZL3TUV & G8KVD Omnium finis imminet ___ 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] What's the time Mr Wolf...
2008/10/31 michael taylor <[EMAIL PROTECTED]>: > > I think it was approximately a year ago in the archives that there was > a good thread of suggested (mostly online) readings. > > As well, an affordable and highly readable book is _Splitting the > Second : The Story of Atomic Time_ by Tony Jones, ISBN-13: > 978-0750306409. Highly recommended, and I think it covers nearly all > of your questions. Thanks for the pointers Michael, I'll see if I can get hold of a copy of the book via an inter-library loan. 73, Steve -- Steve Rooke - ZL3TUV & G8KVD Omnium finis imminet ___ 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] What's the time Mr Wolf...
Thanks for the very informative reply Tom. 2008/10/31 Tom Van Baak <[EMAIL PROTECTED]>: > >> 11) Extrapolating this, a point on the Equator would be moving faster >> that a point at the poles or even Greenwich, for that matter. So would >> a clock at each location move out of synchronisation with each other? > > Yes, and this also is taken into account. When you get down > to measuring absolute frequency at 1e-14 and 1e-15 levels one > always takes the local gravitational field into account, which is > mostly a function of altitude, but also latitude. Guess I've been dumb here but this must mean that not only is time affected by relativistic effects but also oscillators as well then. If gravity affects frequency, can this effect be seen as a daily change in the EFC voltage of a GPS locked standard as caused by the Moon? Does this also affect the frequency of the atomic standards used to measure time? All this must make the measuring of absolute frequency to the high orders of accuracy quite complex. 73, Steve -- Steve Rooke - ZL3TUV & G8KVD Omnium finis imminet ___ 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] What's the time Mr Wolf...
2008/10/31 J.D. Bakker <[EMAIL PROTECTED]>: > At 02:09 +1300 31-10-2008, Steve Rooke wrote: >> it's not always easy to formulate a >>phrase to trigger the answer required out of Google and which sources >>should I go to or believe. > > Fair enough. For your first six questions, I'd use keywords including > "nist" and "time", and start following links from there. For the GPS > stuff handy keywords include "navstar", "usno" and "gpsworld". Thanks for your understanding and useful pointers, this is exactly what I was referring to. If you don't know where to start, it's not always easy to get to the goal. > Good luck, I'll need it.. 73, Steve -- Steve Rooke - ZL3TUV & G8KVD Omnium finis imminet ___ 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] Time-zones and World time..
David Forbes wrote: > At 9:42 AM -0400 10/30/08, Chuck Harris wrote: >> With the great ease of computers to make the transformations, >> there really isn't any point in removing local timezones. It >> is just a table after all... it is nothing like the old days when >> every major town used Local Sidereal Time (eg. 12:00 is when the >> sun is at its highest). That caused major problems for the >> railroads. >> >> -Chuck Harris > > Chuck, > > I don't think you meant to say sidereal time, which is based the > stars, not the sun. There are 366.25 or so days in a sidereal year! > Yes, you are right. The term stuck in my head from an astronomy course I took in the distant past. About the only point in my life where I studied all of the major time systems and how they inter-related... Apparently without any great retention... sigh! Local Solar Time is the LST I was thinking of... only, I guess 00:00:00 is high noon in LST Maybe Local Sundial Time? -Chuck Harris ___ 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] What's the time Mr Wolf...
Hi Steve; I think God decides the time the fun parts is watching humans try to sort it out. Currently the World has accept a specific number of vibrations (9,192,631,770) of a Cesium-133 atom to define one second. For the USA the master clock F1 is in Colorado and although the GPS sat's are monitored in Colorado their onboard clocks are Checked and corrected from Texas. Best Wishes; Thomas Knox Quoting "Steve Rooke" <[EMAIL PROTECTED]>: > Hi, > > This may have already been covered in this group so please excuse me > for not combing the archives. I could Google for this but I'll get a > quicker answer here and I know it will be the correct one. > > !) Who decides on what is the correct time? > 2) Is the time standard stored on one master grandfather clock? > 3) As (2) is unlikely, if a number of clocks are involved, are they in > different countries? > 4) As (3) is likely, how are they synchronised? > 5) If this involves communicating with each other, what medium is used > and how are delays handled (a la NTP pings)? > 6) If all the clocks are synchronised in one place and then > transported all over the World, how is the Einstein affect of time > dilation handled due to the clocks changing in flight? > > Now the interesting ones (for me anyway). > > 7) Where are the clock(s) located which provide the time for the GPS > satellites? > 8) If they are actually in the satellites, how are they all kept > synchronised with each other and the "master grandfather clock" on the > ground? > 9) Are the satellites in geostationary orbit? > 10) If they are geostationary, or move in relation to the ground, how > are the affects of the Einstein time dilation handled as they may be > travelling at a different speed than a point on the surface of the > Earth? > 11) Extrapolating this, a point on the Equator would be moving faster > that a point at the poles or even Greenwich, for that matter. So would > a clock at each location move out of synchronisation with each other? > > Aren't you glad I'm back :) BTW, where is /tvb these days, I haven't > seen any postings by him while I have catching up? > > 73 > Steve - ZL3TUV > -- > Steve Rooke - ZL3TUV & G8KVD > Omnium finis imminet > > ___ > 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] Time-zones and World time..
Local Solar Time noon would still be 12:00:00. If I remember correctly, the one that has noon as 00:00:00 is Astronomical time (e.g. GMAT). Cheers Dave -Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Chuck Harris Sent: 30 October 2008 18:49 To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Time-zones and World time.. Local Solar Time is the LST I was thinking of... only, I guess 00:00:00 is high noon in LST Maybe Local Sundial Time? -Chuck Harris ___ 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] What's the time Mr Wolf...
> If gravity affects frequency, can this effect be seen as a daily > change in the EFC voltage of a GPS locked standard as caused by the > Moon? Does this also affect the frequency of the atomic standards used > to measure time? All this must make the measuring of absolute > frequency to the high orders of accuracy quite complex. Yes, very complex. No, you won't see it in something like a GPSDO. The effect you're talking about here is thousands to millions of times less than what you can measure. 12 hour or diurnal effects in a GPSDO are very common, but they are due to local temperature, GPS orbits, multipath, etc. /tvb ___ 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] Time-zones and World time..
2008/10/31 Chuck Harris <[EMAIL PROTECTED]>: > With the great ease of computers to make the transformations, > there really isn't any point in removing local timezones. It > is just a table after all... it is nothing like the old days when > every major town used Local Sidereal Time (eg. 12:00 is when the > sun is at its highest). That caused major problems for the > railroads. This assumes we are talking about electronic systems and means of communications, what I was really thinking about was how this affects people's ability to easily understand communication between countries. This is not only affected by the plethora of local time-zones but with ever changing daylight savings times. I communicate with the UK daily and we have just gone through a period from being 11 hours ahead, then 12 and now 13 hours ahead as the DST changes are different in each country. When I communicate with the US, I have to work out which time-zone the place I'm talking to is in and correct for that. It's probably not so much of a problem for someone in America as you get used to the time-zone differences but this adds complexity for an outsider. I just wondered if it would add global communications and buisiness to have a single World standard. > The biggest problem with local timezones is all of the continuously > changing variations on Daylight Savings Time. That accounts for > the majority of the changes in the unix tz functions. Not so hard under Unix as the tz updates are easy to pick up but Windows can be a problem if updates are not turned on, IE. some service packs can break an application but you still need things like the tz updates. > It was recently reported that the onset of DST coincides with an > increase in heart attacks, and the return to standard time coincides > with a decrease in heart attacks. Yet another reason to ditch > Daylight Savings Time. Hmmm... death by DST, how would that go down in an inquest. So is the Government responsible for these deaths or the population for voting for it... 73, Steve -- Steve Rooke - ZL3TUV & G8KVD Omnium finis imminet ___ 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] Time-zones and World time..
As I recall, Local Solar Time is also known as Apparent Solar Time, and is defined as when the sun reaches its highest point over some local meridian of interest (town hall?). That point in time is called 00:00:00... Which sort of makes sense because you can directly observe high-noon, but midnight can only be estimated. -Chuck Harris David C. Partridge wrote: > Local Solar Time noon would still be 12:00:00. > > If I remember correctly, the one that has noon as 00:00:00 is Astronomical > time (e.g. GMAT). > > Cheers > Dave > -Original Message- > From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On > Behalf Of Chuck Harris > Sent: 30 October 2008 18:49 > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Time-zones and World time.. > > Local Solar Time is the LST I was thinking of... only, I guess 00:00:00 is > high noon in LST Maybe Local Sundial Time? > > -Chuck Harris ___ 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] Time-zones and World time..
> -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Chuck Harris > Sent: Thursday, October 30, 2008 12:09 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Time-zones and World time.. > > As I recall, Local Solar Time is also known as Apparent Solar > Time, and is defined as when the sun reaches its highest > point over some local meridian of interest (town hall?). > > That point in time is called 00:00:00... Which sort of makes > sense because you can directly observe high-noon, but > midnight can only be estimated. > > -Chuck Harris > One can, of course, observe meridian passage for a variety of stars at night, and from that determine the time (given a calendar and the appropriate almanac data), so you could directly observe midnight. Don't forget too, that solar noon varies quite a bit (minutes) from "mean solar time" over the year. If you're navigating your ship with noon sun sights, this is pretty important. ___ 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] What's the time Mr Wolf...
In message: <[EMAIL PROTECTED]> "Steve Rooke" <[EMAIL PROTECTED]> writes: : 2008/10/31 Tom Van Baak <[EMAIL PROTECTED]>: : > : >> 11) Extrapolating this, a point on the Equator would be moving faster : >> that a point at the poles or even Greenwich, for that matter. So would : >> a clock at each location move out of synchronisation with each other? : > : > Yes, and this also is taken into account. When you get down : > to measuring absolute frequency at 1e-14 and 1e-15 levels one : > always takes the local gravitational field into account, which is : > mostly a function of altitude, but also latitude. : : Guess I've been dumb here but this must mean that not only is time : affected by relativistic effects but also oscillators as well then. Yes. Oscillators will still resonate in their frame of reference at their normal rate. If that frame of reference is slightly different than the defined standard frame of reference, then you need to take that into account when you are comparing frequency data with others in a two-way time exchange. The objective is to tick at the same rate as the standard frame, when the standard frame is measured from your frame of reference... : If gravity affects frequency, can this effect be seen as a daily : change in the EFC voltage of a GPS locked standard as caused by the : Moon? Does this also affect the frequency of the atomic standards used : to measure time? All this must make the measuring of absolute : frequency to the high orders of accuracy quite complex. Gravity affects time. The problem devolves into the classic case of trying to keep things in sync between different frames of reference. The tidal effects are much smaller than those from position. I don't think that these effects are visible at the 10-14 or 10-15 level, but since I don't know what level they are visible at, I can't be sure. I'm sure that someone on this list, maybe as part of their PhD thesis, has measured this and can report it :-) Warner ___ 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] What's the time Mr Wolf...
> The tidal effects are much smaller than those from position. I don't > think that these effects are visible at the 10-14 or 10-15 level, but > since I don't know what level they are visible at, I can't be sure. > I'm sure that someone on this list, maybe as part of their PhD thesis, > has measured this and can report it :-) > > Warner Gravitational effects on frequency near the earth are on the order of 1e-16 per meter of elevation. This level is too small to measure directly, but if you separate clocks by say, 1 km, the frequency shift is now 1e-13, which is very measurable. Since no national timing labs are actually at mean sea level they all take altitude into account in their primary standards. Tidal effects (so-called earth tides) are a couple of ten cm over 6 hours and thus down in the 1e-17 range. No one has seen these effects on atomic clocks yet. First, it's just too small to be measured, even with the best optical clocks, but second, the nearby reference clock that you use would also experience the same pull (!) and thus a relative comparison would reveal nothing. /tvb ___ 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] What's the time Mr Wolf...
As I recall, the lunar gravity force is on the order of a few ppm of "g" (and I assume solar force is comparable). So, the period of a pendulum does vary according to the time of day and phase of moon. (about a ppm or so) I seem to recall that acceleration sensitivity of a crystals is on the order of a ppb/g, so the effect on a XO of the moon is down in the 1E-15 range.. Jim > -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of M. Warner Losh > Sent: Thursday, October 30, 2008 12:28 PM > To: time-nuts@febo.com; [EMAIL PROTECTED] > Subject: Re: [time-nuts] What's the time Mr Wolf... > > In message: > <[EMAIL PROTECTED]> > "Steve Rooke" <[EMAIL PROTECTED]> writes: > : 2008/10/31 Tom Van Baak <[EMAIL PROTECTED]>: > : > > : >> 11) Extrapolating this, a point on the Equator would be > moving faster > : >> that a point at the poles or even Greenwich, for that > matter. So would > : >> a clock at each location move out of synchronisation > with each other? > : > > The tidal effects are much smaller than those from position. > I don't think that these effects are visible at the 10-14 or > 10-15 level, but since I don't know what level they are > visible at, I can't be sure. > I'm sure that someone on this list, maybe as part of their > PhD thesis, has measured this and can report it :-) > > Warner > > ___ > 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] 53310A help
Hi, 1. connect as shown on the Quick Start Signal Source. 2. Signal source ON, 3. select Frequency Modulation, 4. press Autoscale. This should give a sine on the display. Does this work? If yes I will make a scan of the manual. My Quick Start Signal Source is still alive. How about your eprom? regards, Henk On Oct 30, 2008, at 18:41, Grant Hodgson wrote: > Does anybody know how to use the signal source that comes with the > HP 53310A > Modulation Domain Analyser? The MDA is fine, but I don't have a > manual for > the signal source, and there seems to be nothing coming out of it - > and yes, I > checked the battery. There's no mention of how to use the signal > source in > the 53310A manual. > > regards > > Grant Hodgson > > > > ___ > 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] What's the time Mr Wolf...
> Thanks for your understanding and useful pointers, this is exactly > what I was referring to. If you don't know where to start, it's not > always easy to get to the goal. This may not directly answer any of your questions, but it sure is a fun read. * Time Too Good to Be True, Daniel Kleppner Physics Today, March 2006, page 10 HTML version (needs cookies): http://scitation.aip.org/error/cookies.jsp?url=http%3a//scitation.aip.org/jour nals/doc/PHTOAD-ft/vol_59/iss_3/10_1.shtml PDF version, needs new pdf reader: http://www.physicstoday.org/vol-59/iss-3/pdf/vol59no3p10_11.pdf -- These are my opinions, not necessarily my employer's. I hate spam. ___ 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] What's the time Mr Wolf...
> -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Hal Murray > Sent: Thursday, October 30, 2008 4:35 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] What's the time Mr Wolf... > > > > Thanks for your understanding and useful pointers, this is exactly > > what I was referring to. If you don't know where to start, it's not > > always easy to get to the goal. > > This may not directly answer any of your questions, but it > sure is a fun read. > > * Time Too Good to Be True, Daniel Kleppner > Physics Today, March 2006, page 10 > In the third column.. Not many years ago the possibility of merely detecting the minute effect of gravity on time was enough to inspire experimentalists. Over the years the accuracy of atomic clocks has become so high that the corrections for general relativity are not merely visible, they are so large that overlooking them in comparing the rates of atomic clocks in different laboratories2 or in the timing algorithms for the Global Positioning System3 (PHYSICS TODAY, May 2002, page 41) would cause catastrophes. Hah... It's at the point where it's a viable science experiment for children in middle school (thank you Tom for doing this.. Now my daughters ask why we only have a GPSDO in the garage, and we don't have an atomic clock. ) ___ 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] Time-zones and World time..
Steve Rooke wrote: > Hi, > > I've been under the radar for a while so have not been able to keep up > with the threads I was contributing to but that has been done to death > and I will drop them. I've been very interested in reading peoplels > thoughts on time-zones. Has there been any moves to adopt a common > time for all countries in the world so as to alleviate the > difficulties in dealing with time-zones?" I know there was the idea of > Internet-time going around some time ago but I think that seems to > have died a death. Thinking about it, what's the problem of adapting > to daily life which is shifted by some number of hours off the clock. > If we all used UTC everyone around the world would know when a certain > time was in their own day. In my case for New Zealand, +12 hours would > probably be adopted for the country, so AM becomes PM and I'd get up > at 7PM (still that's not much different from now :) instead of AM. What's this AM and PM stuff got to do with it. You mean you would go up at 19 rather than 7? > I guess the question is, what's the likely-hood of a world standard > time being adopted (sort of like Star Trek)? About zilch. 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] OFC (McCoy?)(Isotemp?) OCXO
Just received this OCXO from mr. fluke in China. Took exactly 14 days from time of order to get here to W. Washington. Hooked it up like the Isotemp 134 diagram. He said it would work, and it works perfectly. The Isotemp spec EFC voltage range (positive slope) is 0 to the ref. voltage, in my set-up, +8.0V. On this OFC unit, I found no change in frequency until the EFC gets to about 1.28V. It reached 10 MHz, to within 1E-9, at about 3.33V, with a total frequency span (1.28V to 7.9V) of 10.6E-7, or very roughly 1.6E-7/V. Unlike the Isotemp 134, this one has no trimming adjustment, so the only freq. control is via the EFC line, whose slope seems quite non-linear. Output is a very clean sine wave, about 2.8Vp-p unloaded and 1.8Vp-p into 50 ohms. This thing reaches temp fast and seems to be quite stable, but I won't have any reliable data until it is used in a more permanent way with stable supply voltages. Seems like a very nice unit. Dick Moore ___ 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] Time-zones and World time..
Chuck Harris wrote: > With the great ease of computers to make the transformations, > there really isn't any point in removing local timezones. It > is just a table after all... it is nothing like the old days when > every major town used Local Sidereal Time (eg. 12:00 is when the > sun is at its highest). That caused major problems for the > railroads. Which is the reason to coordinate it. Slightly off, but not too much for it to be a major obsticle. > The biggest problem with local timezones is all of the continuously > changing variations on Daylight Savings Time. That accounts for > the majority of the changes in the unix tz functions. Having Daylight Saving Time as such is not as big issue as not having it coordinated between countries. > It was recently reported that the onset of DST coincides with an > increase in heart attacks, and the return to standard time coincides > with a decrease in heart attacks. Yet another reason to ditch > Daylight Savings Time. Interestingly enought, the decrease does not fully compensate the increase... so the net effect is an increase in heart attacks. 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] What's the time Mr Wolf...
> This may not directly answer any of your questions, but it sure is a fun read. > >* Time Too Good to Be True, Daniel Kleppner > Physics Today, March 2006, page 10 > > HTML version (needs cookies): > http://scitation.aip.org/error/cookies.jsp?url=http%3a//scitation.aip.org/jour > nals/doc/PHTOAD-ft/vol_59/iss_3/10_1.shtml > > PDF version, needs new pdf reader: > http://www.physicstoday.org/vol-59/iss-3/pdf/vol59no3p10_11.pdf Hal, and James, see my follow-up to Kleppner's article... http://ptonline.aip.org/journals/doc/PHTOAD-ft/vol_60/iss_3/16_1.shtml http://link.aip.org/link/PHTOAD/v60/i3/p16/s1/pdf /tvb ___ 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] What's the time Mr Wolf...
2008/10/31 Hal Murray <[EMAIL PROTECTED]>: > > This may not directly answer any of your questions, but it sure is a fun read. > >* Time Too Good to Be True, Daniel Kleppner > Physics Today, March 2006, page 10 > > HTML version (needs cookies): > http://scitation.aip.org/error/cookies.jsp?url=http%3a//scitation.aip.org/jour > nals/doc/PHTOAD-ft/vol_59/iss_3/10_1.shtml > > PDF version, needs new pdf reader: > http://www.physicstoday.org/vol-59/iss-3/pdf/vol59no3p10_11.pdf > This makes an excellent and very entertaining read, thank you Hal. The whole subject of time is very fascinating and far more interesting than I ever thought before. Many thanks to all of you who have enlightened me so much. 73, Steve -- Steve Rooke - ZL3TUV & G8KVD Omnium finis imminet ___ 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] What's the time Mr Wolf...
2008/10/31 Tom Van Baak <[EMAIL PROTECTED]>: > http://www.physicstoday.org/vol-59/iss-3/pdf/vol59no3p10_11.pdf > > Hal, and James, see my follow-up to Kleppner's article... > > > http://ptonline.aip.org/journals/doc/PHTOAD-ft/vol_60/iss_3/16_1.shtml > http://link.aip.org/link/PHTOAD/v60/i3/p16/s1/pdf > Beautiful, just beautiful! 73, Steve -- Steve Rooke - ZL3TUV & G8KVD Omnium finis imminet ___ 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] Time-zones and World time..
2008/10/31 Magnus Danielson <[EMAIL PROTECTED]>: > > What's this AM and PM stuff got to do with it. You mean you would go up > at 19 rather than 7? Indeed it does mean that, and the 12 hour shift in time works for NZ as compared to UTC because we are pretty close to 180 deg longitude away from Greenwich. Sorry, if it was a clumsy piece of writing. >> I guess the question is, what's the likely-hood of a world standard >> time being adopted (sort of like Star Trek)? > > About zilch. In the foreseeable future. 73, Steve -- Steve Rooke - ZL3TUV & G8KVD Omnium finis imminet ___ 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] beautiful jump
Hi guys, there is a very nice Crystal jump visible online today: _http://resco.ucol.mx/Fury/gpsstat.htm_ (http://resco.ucol.mx/Fury/gpsstat.htm) Has anyone else seen a similar effect today? This jump will be visible online for a couple more hours today. While it looks very nice, these jumps are not what we want to see of course. bye, Said ___ 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] What's the time Mr Wolf...
> -Original Message- > From: [EMAIL PROTECTED] > [mailto:[EMAIL PROTECTED] On Behalf Of Tom Van Baak > Sent: Thursday, October 30, 2008 5:06 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] What's the time Mr Wolf... > > > This may not directly answer any of your questions, but it > sure is a fun read. > > > >* Time Too Good to Be True, Daniel Kleppner > > Physics Today, March 2006, page 10 > > > > HTML version (needs cookies): > > > http://scitation.aip.org/error/cookies.jsp?url=http%3a//scitation.aip. > > org/jour nals/doc/PHTOAD-ft/vol_59/iss_3/10_1.shtml > > > > PDF version, needs new pdf reader: > > http://www.physicstoday.org/vol-59/iss-3/pdf/vol59no3p10_11.pdf > > Hal, and James, see my follow-up to Kleppner's article... > > > http://ptonline.aip.org/journals/doc/PHTOAD-ft/vol_60/iss_3/16_1.shtml > http://link.aip.org/link/PHTOAD/v60/i3/p16/s1/pdf > Oh, you bet.. My daughters saw that (or more properly, your webpage about it), and that's when they started asking why WE couldn't do that. ___ 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] beautiful jump
> This jump will be visible online for a couple more hours today. > > While it looks very nice, these jumps are not what we want to see of course. Said, What environment is this GPSDO in? Is there any chance that it is on a table or bench or rack shelf that got moved or even slightly bumped at the time in question? /tvb ___ 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] beautiful jump
Hi Tom, that's possible, this particular unit has been jumping all along, even at night when no one is in the office. Usually it's not just one jump, but a series of jumps. A mechanical bump would usually result in a disturbance, but not a permanent change in the EFC voltage. The unit is located in a remote sensing station in Mexico at the University of Colima. bye, Said In a message dated 10/30/2008 19:26:46 Pacific Daylight Time, [EMAIL PROTECTED] writes: Said, What environment is this GPSDO in? Is there any chance that it is on a table or bench or rack shelf that got moved or even slightly bumped at the time in question? /tvb ___ 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] beautiful jump
OK, if no one was around that lessens the chance of vibration. Still, I didn't want to rule that possibility out. Some of my oscillators are very sensitive to any sort of shock. Even to the point of becoming crude seismometers. I found with shock, they don't always return back to normal; i.e., it's a permanent change (a frequency jump) not a temporary glitch (like a phase jump). But I haven't studied this enough to know for sure. Has anyone else looked into the effects of vibration and shock on XO or OCXO? Is yours an MTI 250-series OCXO? /tvb - Original Message - From: [EMAIL PROTECTED] To: [EMAIL PROTECTED] ; time-nuts@febo.com Sent: Thursday, October 30, 2008 7:37 PM Subject: Re: [time-nuts] beautiful jump Hi Tom, that's possible, this particular unit has been jumping all along, even at night when no one is in the office. Usually it's not just one jump, but a series of jumps. A mechanical bump would usually result in a disturbance, but not a permanent change in the EFC voltage. The unit is located in a remote sensing station in Mexico at the University of Colima. bye, Said In a message dated 10/30/2008 19:26:46 Pacific Daylight Time, [EMAIL PROTECTED] writes: Said, What environment is this GPSDO in? Is there any chance that it is on a table or bench or rack shelf that got moved or even slightly bumped at the time in question? /tvb ___ 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] beautiful jump
Hi Tom, that particular unit is a 270 MTI. The jump was about 29ns before the loop pulled it back, this is a bit more than what I would expect on this OCXO with vibration induced noise. The user has tried before to see if vibration is an issue, it was not some time ago. bye, Said In a message dated 10/30/2008 19:55:42 Pacific Daylight Time, [EMAIL PROTECTED] writes: Is yours an MTI 250-series OCXO? /tvb ___ 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] wavecrest available
Hi guys, fyi: a Wavecrest DTS-2077 is available from someone for $5 on Ebay. That's the high-end unit with 1.3GHz range. item: 120326604028 Seems they have a matching arm generator. bye, Said ___ 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] Time-zones and World time..
-Original Message- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Steve Rooke > When I communicate with the US, I have to work out which time-zone the place I'm talking to > is in and correct for that. It's probably not so much of a problem for someone in America > as you get used to the time-zone differences but this adds complexity for an outsider. > I just wondered if it would add global communications and buisiness to have a single World standard. When most people communicate with other time zones it's via telephone or email, and when they calculate the destination local time, it's to answer the question "Are they likely to be awake?" or "Are they more likely to be at work or at home?". Having a global time won't solve this problem, you will still have to do the conversion to find out the local time to answer these questions. If you're scheduling radio comms then the Military probably have the correct approach - Zulu time for everything. Sam. Disclaimer : The contents of this e-mail including any attachments are intended only for the person or entity to which this e-mail is addressed. If you are not, or believe you may not be, the intended recipient, please advise the sender immediately by return e-mail, delete this e-mail and destroy any copies. The Company does not warrant nor guarantee that this email communication is free from errors, virus, interception or interference. ___ 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.
