Re: [time-nuts] Clock accuracy
On Fri, July 19, 2019 5:20 pm, donald collie wrote: > Assuming the "accuracy" of the GPSDO is 1 part in 10^12 > then the inaccuracy after 100 years will be up to That would assume that your oscillator maintained accuracy of 1 part in 1^12 without correction, and the GPS system stopped providing corrections for 100 years. Does not seem likely unless your GPSDO has a cesium beam tube. More likely is that without correction your oscillator is more like a few parts in 10^9, in which case the drift would be magnitudes larger, or there is some equivalent to GPS for the entire time, so your clock is only off in the medium term by parts in 10^12 but gets constantly corrected by GPS, so there is essentially 0 long term error, and maybe parts in 10^9 short term error, depending on the time constants in the correction loop which compares the local clock output to GPS time. > : 60x60x24x365.25x100x1x10^-12= 3ms [approximately] > - which is probably good enough for an old fella. I have > I wanted to know what sort of long term > accuracy I could expect from the GPS constellation - looks as if 1 part in > 10 to the 12th is about right. That is not cumulative though. Think of it more like the average error from "true" GPS time when averaged over an hour, and GPS time should be within some small number of nanoseconds of "true" UTC essentially always. -- Chris Caudle ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Clock accuracy
Hi Depending on what you do or don’t consider GPS is somewhere in the 3 to 30 ns range without corrections and better than that with corrections. Your GPSDO has some internal “stuff” that also gets into the act. Indeed if you went to a dual band receiver and used any of the many free correction services, you could get well below 3 ns. Over your 100 year span, 30 ns comes out to about 1x10^-17. Bob > On Jul 19, 2019, at 6:20 PM, donald collie wrote: > > Thanks to all who replied! It looks like the antioxidants will win and the > clock will fail before the 100 years are up. Assuming the "accuracy" of the > GPSDO is 1 part in 10^12 then the inaccuracy after 100 years will be up to > : 60x60x24x365.25x100x1x10^-12= 3ms [approximately] - which is probably > good enough for an old fella. I have to admit that I have an ulterior > motive for asking this question : I wanted to know what sort of long term > accuracy I could expect from the GPS constellation - looks as if 1 part in > 10 to the 12th is about right. > Cheers!...Donald > C. > > On Sat, Jul 20, 2019 at 7:01 AM Bob kb8tq wrote: > >> Hi >> >> The simple answer is that your clock is locked directly to a set of time >> sources built >> into the GPS satellites. Those sources are corrected by ground stations >> via comparison >> to NRL and NIST (and indirectly other sources as well). The various ground >> reference >> time systems get measured and evaluated to form what we call the right >> time. This >> is done by BIH in Paris. That process also keeps NRL and NIST “in sync” >> with the correct time. >> >> Since everything is locked together, there really isn’t any long term >> drift. As long as >> everything is functioning (and the PPS is from GPS not some random >> divider) you >> should be “on time” to within 100 ns pretty much forever. The time >> involved could >> be GPS time or UTC depending on how you associate time stamps with your >> PPS edges. >> >> If indeed something goes wrong with GPS ( as unfortunately happened to >> Galileo >> very recently), your time could be just about anything if the error is >> undetected. If >> it is detected, your will go into holdover. The drift then depends very >> much on just >> what “Trimble” you have inside your setup. 10 us a day for the first day >> is not an >> uncommon number to see. Since it’s really frequency drift rather than time >> drift, >> the second day will be worse and it just goes downhill from there. >> >> If your PPS *is* from some random divider off of (say) 10 MHz, then every >> time power >> goes out, it will come back up at a random point in the second. If you >> punch >> a button to “sync” it, you will only be able to move it in 100 ns steps ( >> the period >> of 10 MHz). If the 10 MHz edge is “right on” with GPS that’s fine. If it’s >> off by some >> random amount ….. not so fine. >> >> This gets into a vary basic gotcha: A typical GPSDO *does* get the output >> PPS from >> the 10 MHz. The PPS output direct from a GPS module probably is closer to >> “on time” >> that the GPS PPS. It will bounce around a lot more, but it likely is >> closer to being correct. >> >> Lots of twists and turns …... >> >> Bob >> >>> On Jul 19, 2019, at 1:17 AM, donald collie >> wrote: >>> >>> Without wanting to show my ignorance by confusing accuracy, and >> precision, >>> etc, would some kind person please answer the following : Let me explain >> - >>> I have my prototype GPS diciplined [ Trimble inside] standard frequency >>> source connected to both a divide by 5,2,5 and 2 producing all the >>> reference frequencies necessary for the various bits of equipment in my >>> workshop, AND the 1pps >>> output connected to a 7474 "T" flipflop and thence via a 100uF capacitor >> to >>> a modified $10 analogue wall clock. Can anybody tell me this : If I live >>> another 100 years [Let`s say I take antioxidants ;-) ] what sort of >> error >>> should I expect in this clock? [I know that it`s better than 1 second per >>> day] >>> ___ >>> time-nuts mailing list -- time-nuts@lists.febo.com >>> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >> >> >> ___ >> time-nuts mailing list -- time-nuts@lists.febo.com >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. >> > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow
Re: [time-nuts] Clock accuracy
Thanks to all who replied! It looks like the antioxidants will win and the clock will fail before the 100 years are up. Assuming the "accuracy" of the GPSDO is 1 part in 10^12 then the inaccuracy after 100 years will be up to : 60x60x24x365.25x100x1x10^-12= 3ms [approximately] - which is probably good enough for an old fella. I have to admit that I have an ulterior motive for asking this question : I wanted to know what sort of long term accuracy I could expect from the GPS constellation - looks as if 1 part in 10 to the 12th is about right. Cheers!...Donald C. On Sat, Jul 20, 2019 at 7:01 AM Bob kb8tq wrote: > Hi > > The simple answer is that your clock is locked directly to a set of time > sources built > into the GPS satellites. Those sources are corrected by ground stations > via comparison > to NRL and NIST (and indirectly other sources as well). The various ground > reference > time systems get measured and evaluated to form what we call the right > time. This > is done by BIH in Paris. That process also keeps NRL and NIST “in sync” > with the correct time. > > Since everything is locked together, there really isn’t any long term > drift. As long as > everything is functioning (and the PPS is from GPS not some random > divider) you > should be “on time” to within 100 ns pretty much forever. The time > involved could > be GPS time or UTC depending on how you associate time stamps with your > PPS edges. > > If indeed something goes wrong with GPS ( as unfortunately happened to > Galileo > very recently), your time could be just about anything if the error is > undetected. If > it is detected, your will go into holdover. The drift then depends very > much on just > what “Trimble” you have inside your setup. 10 us a day for the first day > is not an > uncommon number to see. Since it’s really frequency drift rather than time > drift, > the second day will be worse and it just goes downhill from there. > > If your PPS *is* from some random divider off of (say) 10 MHz, then every > time power > goes out, it will come back up at a random point in the second. If you > punch > a button to “sync” it, you will only be able to move it in 100 ns steps ( > the period > of 10 MHz). If the 10 MHz edge is “right on” with GPS that’s fine. If it’s > off by some > random amount ….. not so fine. > > This gets into a vary basic gotcha: A typical GPSDO *does* get the output > PPS from > the 10 MHz. The PPS output direct from a GPS module probably is closer to > “on time” > that the GPS PPS. It will bounce around a lot more, but it likely is > closer to being correct. > > Lots of twists and turns …... > > Bob > > > On Jul 19, 2019, at 1:17 AM, donald collie > wrote: > > > > Without wanting to show my ignorance by confusing accuracy, and > precision, > > etc, would some kind person please answer the following : Let me explain > - > > I have my prototype GPS diciplined [ Trimble inside] standard frequency > > source connected to both a divide by 5,2,5 and 2 producing all the > > reference frequencies necessary for the various bits of equipment in my > > workshop, AND the 1pps > > output connected to a 7474 "T" flipflop and thence via a 100uF capacitor > to > > a modified $10 analogue wall clock. Can anybody tell me this : If I live > > another 100 years [Let`s say I take antioxidants ;-) ] what sort of > error > > should I expect in this clock? [I know that it`s better than 1 second per > > day] > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Efratom MFS system Questions
Hi It’s been more than a while since I last tore into one of those beasts. My recollection is that the output modules have a set of buffer amps on them. Each buffer has filtering appropriate to the designated output frequency. One *could* convert a 5 MHz module to 10 MHz by swapping out a bunch of coils and caps. Then you need to work out the mystery of how to feed it. If the main box just has a 5 MHz OCXO and 5 MHz Rb …. not so easy. If it’s a 10 MHz main box and the 5 is divided, then indeed pretty easy. Bob > On Jul 19, 2019, at 4:21 PM, Walter Shawlee 2 wrote: > > I got a nice system a while back (Modular System *808-400-14*) with both > rubidium and crystal oscillators. > I am getting some faults showing up, and need some insight into system > operation and how to fix it. > > I got all the docs on the FEBO site which were very helpful, but they do have > have answers to my most pressing questions. These are issues I am trying to > solve: > > *MBF front and rear modules:* The front unit (no jacks, only a fault light) > seems to be what sets the division for rear buffers (yes/no?) however, I > cannot see any relationship to the alphanumeric part numbers in the FEBO > docs, and the all numeric parts numbers on the actual units. Is there > anything explaining what module number is what type? Can the rear buffers be > of different types, for say 5Mhz, 10Mhz, etc. all in one frame, or does the > front MBF module set the *only* frequency available? I am getting a fault > light on the front unit, and back ones are outputting a varying (wrong) > frequency. the rear buffers are nominally 5Mhz, can I make them 10Mhz > through any mods? seems like it should be possible if I had the manual for > this module type. > * > **MXO Crystal Oscillator module:* How is this adjusted? I can see no access, > and it is off frequency. I can't imagine a way to set it out of the frame, so > it feels like a way must be possible to do it while installed, but what is > it? I found the info for adjusting the Rubidium, so I feel it must be out > there somewhere. > > *Is there any hope of manuals for any modules?* *How about connector maps or > frame drawings?* Efratom became Symmetricom, then Microsemi, and now > everything MFS related seems to be lost. Two days of web searching did not > turn up anything useful, so I am hoping someone has info on the list they are > wiling to share. *Any chance of module extender cables?** > * > any help appreciated, as this is a wonderful unit that cries out to be fully > operational in my lab. I am happy to send parts from two *Efratom 1PPS > Drawers* I have (with *MDP/MPS/BFM/ACI* Modules-black in color, probably not > compatible with the MFS units) to anybody that has useful info or parts to > share. > > all the best, > walter > > -- > Walter Shawlee 2 > Sphere Research Corp. 3394 Sunnyside Rd. > West Kelowna, BC, V1Z 2V4 CANADA > Phone: +1 (250-769-1834 -:- http://www.sphere.bc.ca > +We're all in one boat, no matter how it looks to you. (WS2) > +All you need is love. (John Lennon) > +But, that doesn't mean other things don't come in handy. (WS2) > +Nature is trying very hard to make us succeed, but nature does not depend on > us. > We are not the only experiment. (R. Buckminster Fuller) > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP5370A vs B version
The "B" version uses custom hybrid modules for the inputs... and the CH1 and CH2 hybrids are not the same... so you can't swap a CH1 hybrid with a CH2 hybrid. I think the A and B model counters are fairly equivalent in their sensitivity to input damage. It seems to be a lot harder to find replacement parts for the "B". ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] HP5370A vs B version
Hi They both run hot and have “interesting” calibration procedures. Count on spending some time running through this and that to get the best performance out of them. The B does seem to run a bit better, but both meet the same basic specs. The SR610 is a very similar device (with some similar calibration procedures). I would go for one of them rather than the 5370. The 610 seems to be just a little bit easier to keep running. If cost is no object ( … as if …) there are indeed a number of devices out there that now do a much better job than the 610 or the 5370. Finding (say) a TImePod on the used market seems to be a bit rare …. Bob > On Jul 19, 2019, at 2:00 PM, Taka Kamiya via time-nuts > wrote: > > What are the differences between HP5370A and 5370B version? > I have been told A's input ports are rather delicate and it has been better > protected on B version. I found notes on A and B and looked a them side by > side but honestly, they are difficult to compare. Anyone on list who had > both and can tell from experience? > > --- > (Mr.) Taka Kamiya > KB4EMF / ex JF2DKG > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Efratom MFS system Questions
I got a nice system a while back (Modular System *808-400-14*) with both rubidium and crystal oscillators. I am getting some faults showing up, and need some insight into system operation and how to fix it. I got all the docs on the FEBO site which were very helpful, but they do have have answers to my most pressing questions. These are issues I am trying to solve: *MBF front and rear modules:* The front unit (no jacks, only a fault light) seems to be what sets the division for rear buffers (yes/no?) however, I cannot see any relationship to the alphanumeric part numbers in the FEBO docs, and the all numeric parts numbers on the actual units. Is there anything explaining what module number is what type? Can the rear buffers be of different types, for say 5Mhz, 10Mhz, etc. all in one frame, or does the front MBF module set the *only* frequency available? I am getting a fault light on the front unit, and back ones are outputting a varying (wrong) frequency. the rear buffers are nominally 5Mhz, can I make them 10Mhz through any mods? seems like it should be possible if I had the manual for this module type. * **MXO Crystal Oscillator module:* How is this adjusted? I can see no access, and it is off frequency. I can't imagine a way to set it out of the frame, so it feels like a way must be possible to do it while installed, but what is it? I found the info for adjusting the Rubidium, so I feel it must be out there somewhere. *Is there any hope of manuals for any modules?* *How about connector maps or frame drawings?* Efratom became Symmetricom, then Microsemi, and now everything MFS related seems to be lost. Two days of web searching did not turn up anything useful, so I am hoping someone has info on the list they are wiling to share. *Any chance of module extender cables?** * any help appreciated, as this is a wonderful unit that cries out to be fully operational in my lab. I am happy to send parts from two *Efratom 1PPS Drawers* I have (with *MDP/MPS/BFM/ACI* Modules-black in color, probably not compatible with the MFS units) to anybody that has useful info or parts to share. all the best, walter -- Walter Shawlee 2 Sphere Research Corp. 3394 Sunnyside Rd. West Kelowna, BC, V1Z 2V4 CANADA Phone: +1 (250-769-1834 -:- http://www.sphere.bc.ca +We're all in one boat, no matter how it looks to you. (WS2) +All you need is love. (John Lennon) +But, that doesn't mean other things don't come in handy. (WS2) +Nature is trying very hard to make us succeed, but nature does not depend on us. We are not the only experiment. (R. Buckminster Fuller) ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] HP5370A vs B version
What are the differences between HP5370A and 5370B version? I have been told A's input ports are rather delicate and it has been better protected on B version. I found notes on A and B and looked a them side by side but honestly, they are difficult to compare. Anyone on list who had both and can tell from experience? --- (Mr.) Taka Kamiya KB4EMF / ex JF2DKG ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Clock accuracy
Hi The simple answer is that your clock is locked directly to a set of time sources built into the GPS satellites. Those sources are corrected by ground stations via comparison to NRL and NIST (and indirectly other sources as well). The various ground reference time systems get measured and evaluated to form what we call the right time. This is done by BIH in Paris. That process also keeps NRL and NIST “in sync” with the correct time. Since everything is locked together, there really isn’t any long term drift. As long as everything is functioning (and the PPS is from GPS not some random divider) you should be “on time” to within 100 ns pretty much forever. The time involved could be GPS time or UTC depending on how you associate time stamps with your PPS edges. If indeed something goes wrong with GPS ( as unfortunately happened to Galileo very recently), your time could be just about anything if the error is undetected. If it is detected, your will go into holdover. The drift then depends very much on just what “Trimble” you have inside your setup. 10 us a day for the first day is not an uncommon number to see. Since it’s really frequency drift rather than time drift, the second day will be worse and it just goes downhill from there. If your PPS *is* from some random divider off of (say) 10 MHz, then every time power goes out, it will come back up at a random point in the second. If you punch a button to “sync” it, you will only be able to move it in 100 ns steps ( the period of 10 MHz). If the 10 MHz edge is “right on” with GPS that’s fine. If it’s off by some random amount ….. not so fine. This gets into a vary basic gotcha: A typical GPSDO *does* get the output PPS from the 10 MHz. The PPS output direct from a GPS module probably is closer to “on time” that the GPS PPS. It will bounce around a lot more, but it likely is closer to being correct. Lots of twists and turns …... Bob > On Jul 19, 2019, at 1:17 AM, donald collie wrote: > > Without wanting to show my ignorance by confusing accuracy, and precision, > etc, would some kind person please answer the following : Let me explain - > I have my prototype GPS diciplined [ Trimble inside] standard frequency > source connected to both a divide by 5,2,5 and 2 producing all the > reference frequencies necessary for the various bits of equipment in my > workshop, AND the 1pps > output connected to a 7474 "T" flipflop and thence via a 100uF capacitor to > a modified $10 analogue wall clock. Can anybody tell me this : If I live > another 100 years [Let`s say I take antioxidants ;-) ] what sort of error > should I expect in this clock? [I know that it`s better than 1 second per > day] > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Clock accuracy
There are some ideas for long-lived clock mechanisms here : http://longnow.org/clock/ On Fri, Jul 19, 2019 at 5:00 PM Robert LaJeunesse wrote: > You might want to consider an LED digital wall clock. I have a homebrew > LED clock that's going strong after some 46 years of continuous 24/7/365 > operation. The MM5314 is even a packaging reject unit I grabbed when it was > a brand new design and I was a mere co-op engineering student working at > the factory. > > > Sent: Friday, July 19, 2019 at 1:17 AM > > From: "donald collie" > > To: "Discussion of precise time and frequency measurement" < > time-nuts@lists.febo.com> > > Subject: [time-nuts] Clock accuracy > > > > ... a modified $10 analogue wall clock. Can anybody tell me this : If I > live > > another 100 years [Let`s say I take antioxidants ;-) ] what sort of > error > > should I expect in this clock? [I know that it`s better than 1 second per > > day] > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Clock accuracy
For curiosity sake, this sounds like it is a Master Clock > Slave Clock system. Are the slave clocks DC Impulse driven or do they have AC synchronous gearbox motors which then correct on/near the hour every 12 hours? For instance at 6 O'clock twice a day on let's say the 58th minute? You want something more accurate than a TCXO module which might plug into a slot on the backplane of the master clock? Donald Resor N6KAW -Original Message- From: time-nuts On Behalf Of paul swed Sent: Friday, July 19, 2019 6:34 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Clock accuracy Jim Boy did you actually hit the issues. I have run into all of them. The bearings are a real issue. I have one clock I need to pull down and lube. Pain in the butt. Regards Paul On Fri, Jul 19, 2019 at 9:20 AM Jim Harman wrote: > Somewhat tongue in cheek, from another relative beginner: > > There are also several seconday effects you will need to consider over > the next 100 years: > > -- Do you have a way of changing the battery in the clock without it > stopping? > -- Will the $10 clock's bearings last 100 years? > -- If the 1 pps output from your GPSDO comes directly from the GPS, > and not by dividing down the oscillator, how will you handle holdover > events, when it may skip some pulses? > -- Is the adjustment range of your oscillator sufficient to compensate > for > 100 years of drift? > -- Will the other components in your GPSDO (esp. electrolytic > capacitors) last 100 years? > -- Will the GPS system still be operating 100 years from now, or will > it go the way of LORAN? You might need a provision for seamlessly > switching to a different 1-pps source if the technology changes. > > > On Fri, Jul 19, 2019 at 5:10 AM Hal Murray > wrote: > > > > > > If I live another 100 years [Let`s say I take antioxidants ;-) ] > > > what > > sort > > > of error should I expect in this clock? [I know that it`s better > > > than 1 second per day] > > > > You didn't say anything about skipping leap seconds. > > > > Ignoring that part, and assuming you have a good antenna, and > > assuming > the > > GPS > > operators don't screwup and/or that your GPSDO has good enough > > holdover, it will be right on. > > > > Your system is tracking GPS. So the next question is what do you > > expect your clock to be tracking? If you want to track UTC, then > > you need to > research > > the > > offset between GPS and UTC. (Hint: It's not very big.) > > > > > > -- > > These are my opinions. I hate spam. > > > > > > > > > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, > > go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > > > -- > > --Jim Harman > ___ > time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go > to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Clock accuracy
You might want to consider an LED digital wall clock. I have a homebrew LED clock that's going strong after some 46 years of continuous 24/7/365 operation. The MM5314 is even a packaging reject unit I grabbed when it was a brand new design and I was a mere co-op engineering student working at the factory. > Sent: Friday, July 19, 2019 at 1:17 AM > From: "donald collie" > To: "Discussion of precise time and frequency measurement" > > Subject: [time-nuts] Clock accuracy > > ... a modified $10 analogue wall clock. Can anybody tell me this : If I live > another 100 years [Let`s say I take antioxidants ;-) ] what sort of error > should I expect in this clock? [I know that it`s better than 1 second per > day] ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Junior Time Nuts looking for HP5370B
I absolutely loved mine. Until that input chip went. :-( On Sat, 20 Jul 2019 at 00:01, Taka Kamiya via time-nuts < time-nuts@lists.febo.com> wrote: > Does anyone have HP5370B that is working well for sale? I am in Central > Florida USA. Please respond to me off list with your offer. > > --- > (Mr.) Taka Kamiya > KB4EMF / ex JF2DKG > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Clock accuracy
Jim Boy did you actually hit the issues. I have run into all of them. The bearings are a real issue. I have one clock I need to pull down and lube. Pain in the butt. Regards Paul On Fri, Jul 19, 2019 at 9:20 AM Jim Harman wrote: > Somewhat tongue in cheek, from another relative beginner: > > There are also several seconday effects you will need to consider over the > next 100 years: > > -- Do you have a way of changing the battery in the clock without it > stopping? > -- Will the $10 clock's bearings last 100 years? > -- If the 1 pps output from your GPSDO comes directly from the GPS, and not > by dividing down the oscillator, how will you handle holdover events, when > it may skip some pulses? > -- Is the adjustment range of your oscillator sufficient to compensate for > 100 years of drift? > -- Will the other components in your GPSDO (esp. electrolytic capacitors) > last 100 years? > -- Will the GPS system still be operating 100 years from now, or will it go > the way of LORAN? You might need a provision for seamlessly switching to a > different 1-pps source if the technology changes. > > > On Fri, Jul 19, 2019 at 5:10 AM Hal Murray > wrote: > > > > > > If I live another 100 years [Let`s say I take antioxidants ;-) ] what > > sort > > > of error should I expect in this clock? [I know that it`s better than 1 > > > second per day] > > > > You didn't say anything about skipping leap seconds. > > > > Ignoring that part, and assuming you have a good antenna, and assuming > the > > GPS > > operators don't screwup and/or that your GPSDO has good enough holdover, > > it > > will be right on. > > > > Your system is tracking GPS. So the next question is what do you expect > > your > > clock to be tracking? If you want to track UTC, then you need to > research > > the > > offset between GPS and UTC. (Hint: It's not very big.) > > > > > > -- > > These are my opinions. I hate spam. > > > > > > > > > > ___ > > time-nuts mailing list -- time-nuts@lists.febo.com > > To unsubscribe, go to > > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > > and follow the instructions there. > > > > > -- > > --Jim Harman > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Junior Time Nuts looking for HP5370B
Does anyone have HP5370B that is working well for sale? I am in Central Florida USA. Please respond to me off list with your offer. --- (Mr.) Taka Kamiya KB4EMF / ex JF2DKG ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Clock accuracy
Hello to the group drift won't be the issue. Power outages will. That type of disruptive issue. >From the analog clock guy. Use 4 on the wall for different time zones. All synced... Also battery backup. But every now and then we get big outages and lightning storms. Thats what gets the clocks. Regards Paul On Fri, Jul 19, 2019 at 5:10 AM Hal Murray wrote: > > > If I live another 100 years [Let`s say I take antioxidants ;-) ] what > sort > > of error should I expect in this clock? [I know that it`s better than 1 > > second per day] > > You didn't say anything about skipping leap seconds. > > Ignoring that part, and assuming you have a good antenna, and assuming the > GPS > operators don't screwup and/or that your GPSDO has good enough holdover, > it > will be right on. > > Your system is tracking GPS. So the next question is what do you expect > your > clock to be tracking? If you want to track UTC, then you need to research > the > offset between GPS and UTC. (Hint: It's not very big.) > > > -- > These are my opinions. I hate spam. > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Clock accuracy
Somewhat tongue in cheek, from another relative beginner: There are also several seconday effects you will need to consider over the next 100 years: -- Do you have a way of changing the battery in the clock without it stopping? -- Will the $10 clock's bearings last 100 years? -- If the 1 pps output from your GPSDO comes directly from the GPS, and not by dividing down the oscillator, how will you handle holdover events, when it may skip some pulses? -- Is the adjustment range of your oscillator sufficient to compensate for 100 years of drift? -- Will the other components in your GPSDO (esp. electrolytic capacitors) last 100 years? -- Will the GPS system still be operating 100 years from now, or will it go the way of LORAN? You might need a provision for seamlessly switching to a different 1-pps source if the technology changes. On Fri, Jul 19, 2019 at 5:10 AM Hal Murray wrote: > > > If I live another 100 years [Let`s say I take antioxidants ;-) ] what > sort > > of error should I expect in this clock? [I know that it`s better than 1 > > second per day] > > You didn't say anything about skipping leap seconds. > > Ignoring that part, and assuming you have a good antenna, and assuming the > GPS > operators don't screwup and/or that your GPSDO has good enough holdover, > it > will be right on. > > Your system is tracking GPS. So the next question is what do you expect > your > clock to be tracking? If you want to track UTC, then you need to research > the > offset between GPS and UTC. (Hint: It's not very big.) > > > -- > These are my opinions. I hate spam. > > > > > ___ > time-nuts mailing list -- time-nuts@lists.febo.com > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > -- --Jim Harman ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Clock accuracy
> If I live another 100 years [Let`s say I take antioxidants ;-) ] what sort > of error should I expect in this clock? [I know that it`s better than 1 > second per day] You didn't say anything about skipping leap seconds. Ignoring that part, and assuming you have a good antenna, and assuming the GPS operators don't screwup and/or that your GPSDO has good enough holdover, it will be right on. Your system is tracking GPS. So the next question is what do you expect your clock to be tracking? If you want to track UTC, then you need to research the offset between GPS and UTC. (Hint: It's not very big.) -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] Clock accuracy
I am in some ways a beginner also. But here is one way to calculate error. Figure the number of seconds in 100 years. You just compute the number in a minute (60) times the minutes in an hour (60) times the hours in a day (24) and so on. When you get to 100 years after all the multiplications you will have calculated the number of seconds in 100 years. Myultiply that by the error in your time base. If the error is one part in 10 to the 12th, then you multiply by the number of seconds in 100 years and it will give you the error, in seconds, after 100 years. Bob On Thursday, July 18, 2019, 11:05:08 PM PDT, donald collie wrote: Without wanting to show my ignorance by confusing accuracy, and precision, etc, would some kind person please answer the following : Let me explain - I have my prototype GPS diciplined [ Trimble inside] standard frequency source connected to both a divide by 5,2,5 and 2 producing all the reference frequencies necessary for the various bits of equipment in my workshop, AND the 1pps output connected to a 7474 "T" flipflop and thence via a 100uF capacitor to a modified $10 analogue wall clock. Can anybody tell me this : If I live another 100 years [Let`s say I take antioxidants ;-) ] what sort of error should I expect in this clock? [I know that it`s better than 1 second per day] ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there. ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
Re: [time-nuts] AN/URQ-10A - on frequency doublers
good info Rick ROY - I have spiced up in LTSPICE a doubler and 4 harmonics which you can vary the amplitudes of the harmonics in the current sources I1, I2, I3, I4. There is a basic tank circuit on the output which you can connect/ disconnect etc. www.cortexrf.com.au/5_meg_doubler.asc Rick , you are right the harmonics on the source really do mess with it... you could also do a digital frequency doubler. that's easy, dependson ur jitter spec.. . or a PLL using a DBM as a phase detector with a regenerative divider if you really want to knock yourself out. many cats and skins cheers On 18/07/2019 11:54 PM, Richard (Rick) Karlquist wrote: The 5071A has a chain of doublers from 10 to 320 MHz. One thing I learned in designing this is that it is important to drive the doublers with pure sine waves. It might seem like if I double from 10 to ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
[time-nuts] Clock accuracy
Without wanting to show my ignorance by confusing accuracy, and precision, etc, would some kind person please answer the following : Let me explain - I have my prototype GPS diciplined [ Trimble inside] standard frequency source connected to both a divide by 5,2,5 and 2 producing all the reference frequencies necessary for the various bits of equipment in my workshop, AND the 1pps output connected to a 7474 "T" flipflop and thence via a 100uF capacitor to a modified $10 analogue wall clock. Can anybody tell me this : If I live another 100 years [Let`s say I take antioxidants ;-) ] what sort of error should I expect in this clock? [I know that it`s better than 1 second per day] ___ time-nuts mailing list -- time-nuts@lists.febo.com To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
