Re: [time-nuts] nubie querie
It's all very well to talk about zero-crossing detection in an hour glass, but you haven't got an oscillator until you have some uniform means to flip it. Then you can talk about measuring the period (two flips) over some useful interval. Seems like the flip should take a second or so. Too fast and the glass breaks, too slow and you get sliding effects on the pile as it rotates. Tom says the deltas are around ten seconds, so whatever happens in one second doesn't much matter, as long as it is repeatable. Same thing with the crossing detector. You don't want much sand left in the upper glass, but you want it to be repeatable. Across the throat is probably OK, but you could put a led in the center of each end, and detect light scatter from the top on the bottom pile when enough sand runs out. Hmmm . . . This might be more interesting than the pendulum experiment that I never got to. Won't need expensive counters, either. Bill Hawkins ___ 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] nubie querie
Not to kick sand in your face, but it seems that in order for your automated turn-over device to work, as well as to accurately measure the time intervals, you would need a means to determine when the sand quits flowing. Correct. It's not unlike a zero crossing detector. The period of the sand flowing cycle is only 0.000278 Hz (1/hour). Possibly an accelerometer or microphone, with the added benefit of being able to hear the close-in phase noise. I wasn't planning on it but an optical detector sampled by a sound card might also give a pleasant audio signal as well as a data source from which the end-of-sand point can be determined with greater accuracy. I admire your dedication to monitoring the hour long periods of the sand timer so diligently. Truly a time-nut! You now all see why the hourglass is on top of the H-maser. Issues of installation, environment, reliability, instrumentation, gravity, data analysis, noise, stability and long-term frequency drift are very similar for both clocks. And given the sand inside, it's also a ... quartz crystal oscillator. /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] nubie querie
On Sat, 06 Mar 2010 08:03:01 +1030, Matthew Smith wrote: >So, if the mass is closer to the centre of the planet, it weighs more? >Never really considered this before, but fascinating nonetheless. No! The gravitational attraction will decrease once penetrating the surface. At the center of gravity there should be no attraction anymore - the attraction will be the same to all directions summing to 0. What does the pendulum and the hour glass? Interesting, are there already some measurement results done in deep mines? Arnold ___ 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] nubie querie
As one who has measured vague things like hourglass time to great accuracy, I would suggest finding a robust definition of "end of flow". This would inevitably involve watching the flow past the "end of flow" to determine retrospectively when the flow had effectively ceased. To be fair to the hourglass you should at least use a caesium standard to keep time while this process occurs, you can then confidently correct the reversals of the hourglass for the turn-over dead time. It should make for a simple timer, cheers, Neville Michie ___ 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] nubie querie
Matthew Smith wrote: Quoth Bruce Griffiths at 2010-03-06 07:58... Yes it does due to the variation of gravitational attraction between the object and the Earth with height above the ground. However this classical effect is very small and probably virtually impossible to measure. So, if the mass is closer to the centre of the planet, it weighs more? Never really considered this before, but fascinating nonetheless. Wonder if this would affect the moment of a pendulum. For a spherical Earth with a spherically symmetric mass distribution the vertical gradient is around -0.3ppm/m. For the real Earth with the situation is somewhat more complex: http://gge.unb.ca/Personnel/Vanicek/MeanVerticalGradient.pdf The period of a pendulum will vary with its height above the terrain. 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] nubie querie
Quoth Bruce Griffiths at 2010-03-06 07:58... > Yes it does due to the variation of gravitational attraction between the > object and the Earth with height above the ground. > However this classical effect is very small and probably virtually > impossible to measure. So, if the mass is closer to the centre of the planet, it weighs more? Never really considered this before, but fascinating nonetheless. Wonder if this would affect the moment of a pendulum. -- Matthew Smith Smiffytech - Technology Consulting & Web Application Development Business: http://www.smiffytech.com/ Blog/personal: http://www.smiffysplace.com/ LinkedIn: http://www.linkedin.com/in/smiffy Skype: msmiffy Twitter: @smiffy ___ 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] nubie querie
Yes it does due to the variation of gravitational attraction between the object and the Earth with height above the ground. However this classical effect is very small and probably virtually impossible to measure. Bruce Gerard PG5G wrote: Eh, does the weight change if the sand runs from top to bottom? Some quantum mechanic effect I am missing? Or maybe a change in gravity as the sand drops from high to low? phil wrote: Even defining when the sand timer is "done" is not a real simple thing. Waiting for that very last particle to drop may not be the best approach. Bob You could measure of the weight of the hourglass. Phil ___ 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] nubie querie
Eh, does the weight change if the sand runs from top to bottom? Some quantum mechanic effect I am missing? Or maybe a change in gravity as the sand drops from high to low? phil wrote: Even defining when the sand timer is "done" is not a real simple thing. Waiting for that very last particle to drop may not be the best approach. Bob You could measure of the weight of the hourglass. Phil ___ 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] nubie querie
Even defining when the sand timer is "done" is not a real simple thing. Waiting for that very last particle to drop may not be the best approach. Bob You could measure of the weight of the hourglass. Phil ___ 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] nubie querie
Plus the effect of a star quake when the crystalline crust rearranges itself. Somewhat analogous to a crystal jump. Bruce Bob Camp wrote: Hi Then there's the phase noise of the pulsar "oscillator" - For a simple crystal oscillator the two word answer might be "Leeson's model". That of course is a cop out since it clearly defines multiple things that contribute to phase noise. Bob On Mar 5, 2010, at 9:39 AM, Richard (Rick) Karlquist wrote: Don Collie jnr wrote: I`m not sure that questions like these is welcome on this list, but here goes anyway : 1/ What are the the 10 sources of the most constant [invariant] frequencies known to man, in order of decreacing constancy? Four immediately come to mind. I vaguely remember reading that pulsars have some fantastic stability like 1E-20. I don't remember how they established this. 2/ What is the mechanism in an oscillator, that is responsible for phase noise? [In only one sentence please] Thermal (Johnson) noise in the resonator and thermal and shot noise in the active device. If this is known, then it becomes easier to design low phase noise oscillators. Perhaps, but just knowing the mechanism doesn't tell you that the phase noise is inversely proportional to loaded Q, which you would also need to know to optimize phase noise. I hope you enjoy these questions,.Don. ___ 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 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] nubie querie
Hi A clock and a hazmat site all rolled into one. Bob On Mar 5, 2010, at 2:41 PM, paul swed wrote: > OK then if you ground up cesium azide and put it in the hour glass wouldn't > you have a cesium clock at much lower cost (And accuracy) then an HP?? > Might last quite a while also. > > On Fri, Mar 5, 2010 at 1:53 PM, Tom Van Baak wrote: > >> Even defining when the sand timer is "done" is not a real >>> simple thing. Waiting for that very last particle to drop may >>> not be the best approach. >>> Bob >>> >> >> Correct. Marking time with an hour glass is not that different >> from marking time with a 1PPS. Each signal has a rise time; >> one picks the appropriate live trigger level or sampled slope >> waveform model to minimize jitter. >> >> Waiting for the last grain is like waiting for the last millivolt of >> a TTL 1PPS pulse; no one does that. >> >> Note that [this] hourglass interval has a standard deviation on >> the order of 10 seconds. So my initial goal is 1 second timing >> resolution, which turns out to be pretty easy to do optically. >> >> Whether sand or cesium, phase comparators have a minimum >> resolution. While lower resolution is better, if the ADEV of the >> DUT is too far above the ADEV of the comparator then that >> resolution is wasted. So detection to a granularity of 1 second >> is sufficient for this application. >> >> >> /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 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] nubie querie
OK then if you ground up cesium azide and put it in the hour glass wouldn't you have a cesium clock at much lower cost (And accuracy) then an HP?? Might last quite a while also. On Fri, Mar 5, 2010 at 1:53 PM, Tom Van Baak wrote: > Even defining when the sand timer is "done" is not a real >> simple thing. Waiting for that very last particle to drop may >> not be the best approach. >> Bob >> > > Correct. Marking time with an hour glass is not that different > from marking time with a 1PPS. Each signal has a rise time; > one picks the appropriate live trigger level or sampled slope > waveform model to minimize jitter. > > Waiting for the last grain is like waiting for the last millivolt of > a TTL 1PPS pulse; no one does that. > > Note that [this] hourglass interval has a standard deviation on > the order of 10 seconds. So my initial goal is 1 second timing > resolution, which turns out to be pretty easy to do optically. > > Whether sand or cesium, phase comparators have a minimum > resolution. While lower resolution is better, if the ADEV of the > DUT is too far above the ADEV of the comparator then that > resolution is wasted. So detection to a granularity of 1 second > is sufficient for this application. > > > /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 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] nubie querie
Even defining when the sand timer is "done" is not a real simple thing. Waiting for that very last particle to drop may not be the best approach. Bob Correct. Marking time with an hour glass is not that different from marking time with a 1PPS. Each signal has a rise time; one picks the appropriate live trigger level or sampled slope waveform model to minimize jitter. Waiting for the last grain is like waiting for the last millivolt of a TTL 1PPS pulse; no one does that. Note that [this] hourglass interval has a standard deviation on the order of 10 seconds. So my initial goal is 1 second timing resolution, which turns out to be pretty easy to do optically. Whether sand or cesium, phase comparators have a minimum resolution. While lower resolution is better, if the ADEV of the DUT is too far above the ADEV of the comparator then that resolution is wasted. So detection to a granularity of 1 second is sufficient for this application. /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] nubie querie
I vaguely remember reading that pulsars have some fantastic stability like 1E-20. I don't remember how they established this. Rick, See: http://www.leapsecond.com/museum/pulsar for some pulsar ADEV stability plots and links to many research papers with all the details. /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] nubie querie
Hal Murray wrote: rich...@karlquist.com said: I vaguely remember reading that pulsars have some fantastic stability like 1E-20. I don't remember how they established this. Do you remember how long ago you read that? It might have been some handwaving back before they had good data. For a while, the astronomers were seriously trying to take back the official clock from the physicists. They didn't make it. I think a lot of the interest started when somebody discovered a pulsar ticking at close to 1 KHz. That was in 1982. They have collected enough data to see things like star-quakes which are glitches in the rotation rate due to geologic type shifts similar to the recent discussion of 1.26 microseconds per day from the Chile quake. They decay by gravitational radiation and speed up when accretion adds more momentum and energy. That's what I remember from reading the literature on pulsars as well. They act a lot like quartz crystals, in fact, with frequency drift and frequency jumps. In short, there is no macro-scale clock that will ever work as well as an atomic clock, since an atomic clock depends on the behavior of subatomic particles with a handful of state variables, whereas a macro-scale clock depends on the behavior of large and changing lumps of disparate matter with gazillions of state variables. I realized as a teenager that the difficulty of predicting the future is geometrically (or so) proportional to the number of state variables. So the cesium clock is one of the few gadgets whose future behavior can be predicted to any reasonable extent. --David Forbes ___ 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] nubie querie
rich...@karlquist.com said: > I vaguely remember reading that pulsars have some fantastic stability > like 1E-20. I don't remember how they established this. Do you remember how long ago you read that? It might have been some handwaving back before they had good data. For a while, the astronomers were seriously trying to take back the official clock from the physicists. They didn't make it. I think a lot of the interest started when somebody discovered a pulsar ticking at close to 1 KHz. That was in 1982. They have collected enough data to see things like star-quakes which are glitches in the rotation rate due to geologic type shifts similar to the recent discussion of 1.26 microseconds per day from the Chile quake. They decay by gravitational radiation and speed up when accretion adds more momentum and energy. Scientists predict pulsar starquakes June 5, 2006 http://www.lanl.gov/news/index.php/fuseaction/home.story/story_id/8528 Middleditch and his team have discovered that for one particular pulsar, named PSR J0537-6910, the time until the next quake is proportional to the size of the last quake. Using this simple formula, the scientists have been able to aim NASA's Rossi X-ray Timing Explorer at the pulsar a few days before a quake to watch the event unfold. [A fun read.] -- 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] For Bruce Lane...
FWIW I have seen a lot of failures of these units in both Trak and Odetics units. Item is being sold "as is". Not sure how much I'd want to offer. Rob K -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark Sims Sent: 05 March 2010 1:37 AM To: time-nuts@febo.com Subject: [time-nuts] For Bruce Lane... Hello Bruce, I tried to send you an email directly, but your spam filtering seems to be getting in the way again. Ebay item 150418469678 has a Magellan 5000 GPS board on it... might be handy to have a spare for your unit. It is from an Odetics unit. Mark _ Hotmail: Trusted email with powerful SPAM protection. http://clk.atdmt.com/GBL/go/201469227/direct/01/ ___ 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] nubie querie
For a simple crystal oscillator the two word answer might be "Leeson's model". That of course is a cop out since it clearly defines multiple things that contribute to phase noise. Bob And Leeson's model is basically the same as Edson's model, circa 1950 (Edson: Vacuum Tube Oscillators) with 1/f noise added. However, crystals have "excess noise" above and beyond simple thermal noise. There is no model, you just have to characterize the crystal. Rick Karlquist N6RK ___ 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] Nubie querie...
Thought from an interloper: It would seem to me that the best reference point would be the instant a piece of sand leaves a specific point from the "restricted center", the "spout". In pondering over the methodology it would appear that the first piece of sand would hit the bottom of the vessel while the last piece would land somewhat higher on the pile, thus the transit time is shorter. What about the size,shape and weight of each grain? What about dispersion of the angle leaving the spout due to more than one grain at a time leaving? Gotta love this group! Burt, K6OQK At 08:12 AM 3/5/2010, time-nuts-requ...@febo.com wrote From: "Stan, W1LE" Subject: Re: [time-nuts] nubie querie If the time duration of the sand timer is defined as when the first grain of sand lands on the bottom, until the last grain of sand lands on the pile of sand on the bottom, maybe an optical circuit may sense the passing and interruption with a light beam. Possibly the optical sensor mounted in the restricted center could sense the first grain starting to pass and when the last grain has passed. That my change the definition, but it should be repeatable. The acoustic approach has merit. I could then apply some DSP and more test equipment. Much easier than listening to the grass grow. I personally like definitive starts and stops, to stay within my attention span. Stan, W1LE Burt I. Weiner Associates Broadcast Technical Services Glendale, California U.S.A. b...@att.net K6OQK ___ 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] nubie querie
Like it very well On Fri, Mar 5, 2010 at 11:12 AM, Mark Sims wrote: > > Google "USB Hourglass" or visit http://home.comcast.net/~hourglass/ and > you will see that it has already been done. His application was as a > random number generator. Should be available as a kit soon... > _ > Hotmail: Free, trusted and rich email service. > http://clk.atdmt.com/GBL/go/201469228/direct/01/ > ___ > 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] nubie querie
You've not seen me on a bad day - I've been known to flip quite often! :-) Dave -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of David Forbes Sent: 05 March 2010 16:20 To: Discussion of precise time and frequency measurement; Tom Van Baak Subject: Re: [time-nuts] nubie querie At 10:25 AM -0800 3/4/10, Brooke Clarke wrote: >Hi Tom: > >In the last slide you show a sand timer. Do you have accuracy data for it? > Wouldn't that depend on the consistency with which the human flips the hour glass? They don't flip themselves, you know. -- --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. ___ 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] nubie querie
At 10:25 AM -0800 3/4/10, Brooke Clarke wrote: Hi Tom: In the last slide you show a sand timer. Do you have accuracy data for it? Wouldn't that depend on the consistency with which the human flips the hour glass? They don't flip themselves, you know. -- --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] nubie querie
All of this reminds me of a cartoon I saw ages ago, I think was called "BC". Characters were from the cave-man era. Regardless, in one cartoon there is a guy sitting in the middle of a desert. His friend comes up and asks him what he is doing. The guy replies that he is going to count all of the sand in the desert. His friend says - you are crazy, that will take forever. The guys says, what you think, I am that stupid? I just count every other one, when I am done I will just double it. Regards - Mike Mike B. Feher, N4FS 89 Arnold Blvd. Howell, NJ, 07731 732-886-5960 -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Friday, March 05, 2010 11:02 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] nubie querie Hi So can you / do you actually *see* the last grain in the hourglass in question? If we are looking at something that is not observed in "normal operation" we have re-defined the function of the device. Bob On Mar 5, 2010, at 10:50 AM, Raj wrote: > The variability will depend on friction between particles and the last particle's physical slide down the glass! > > At 05-03-10, you wrote: >> Hi >> >> Even defining when the sand timer is "done" is not a real simple thing. Waiting for that very last particle to drop may not be the best approach. >> >> Bob >> >> >> On Mar 5, 2010, at 9:20 AM, Tom Holmes, N8ZM wrote: >> >>> tvb... >>> >>> Not to kick sand in your face, but it seems that in order for your automated >>> turn-over device to work, as well as to accurately measure the time >>> intervals, you would need a means to determine when the sand quits flowing. >>> Possibly an accelerometer or microphone, with the added benefit of being >>> able to hear the close-in phase noise. >>> >>> I admire your dedication to monitoring the hour long periods of the sand >>> timer so diligently. Truly a time-nut! >>> >>> Regards, >>> >>> Tom Holmes, N8ZM >>> Tipp City, OH >>> EM79xx >>> > > > ___ > 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 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] nubie querie
Google "USB Hourglass" or visit http://home.comcast.net/~hourglass/ and you will see that it has already been done. His application was as a random number generator. Should be available as a kit soon... _ Hotmail: Free, trusted and rich email service. http://clk.atdmt.com/GBL/go/201469228/direct/01/ ___ 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] nubie querie
Hi So can you / do you actually *see* the last grain in the hourglass in question? If we are looking at something that is not observed in "normal operation" we have re-defined the function of the device. Bob On Mar 5, 2010, at 10:50 AM, Raj wrote: > The variability will depend on friction between particles and the last > particle's physical slide down the glass! > > At 05-03-10, you wrote: >> Hi >> >> Even defining when the sand timer is "done" is not a real simple thing. >> Waiting for that very last particle to drop may not be the best approach. >> >> Bob >> >> >> On Mar 5, 2010, at 9:20 AM, Tom Holmes, N8ZM wrote: >> >>> tvb... >>> >>> Not to kick sand in your face, but it seems that in order for your automated >>> turn-over device to work, as well as to accurately measure the time >>> intervals, you would need a means to determine when the sand quits flowing. >>> Possibly an accelerometer or microphone, with the added benefit of being >>> able to hear the close-in phase noise. >>> >>> I admire your dedication to monitoring the hour long periods of the sand >>> timer so diligently. Truly a time-nut! >>> >>> Regards, >>> >>> Tom Holmes, N8ZM >>> Tipp City, OH >>> EM79xx >>> > > > ___ > 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] nubie querie
The variability will depend on friction between particles and the last particle's physical slide down the glass! At 05-03-10, you wrote: >Hi > >Even defining when the sand timer is "done" is not a real simple thing. >Waiting for that very last particle to drop may not be the best approach. > >Bob > > >On Mar 5, 2010, at 9:20 AM, Tom Holmes, N8ZM wrote: > >> tvb... >> >> Not to kick sand in your face, but it seems that in order for your automated >> turn-over device to work, as well as to accurately measure the time >> intervals, you would need a means to determine when the sand quits flowing. >> Possibly an accelerometer or microphone, with the added benefit of being >> able to hear the close-in phase noise. >> >> I admire your dedication to monitoring the hour long periods of the sand >> timer so diligently. Truly a time-nut! >> >> Regards, >> >> Tom Holmes, N8ZM >> Tipp City, OH >> EM79xx >> ___ 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] nubie querie
If the time duration of the sand timer is defined as when the first grain of sand lands on the bottom, until the last grain of sand lands on the pile of sand on the bottom, maybe an optical circuit may sense the passing and interruption with a light beam. Possibly the optical sensor mounted in the restricted center could sense the first grain starting to pass and when the last grain has passed. That my change the definition, but it should be repeatable. The acoustic approach has merit. I could then apply some DSP and more test equipment. Much easier than listening to the grass grow. I personally like definitive starts and stops, to stay within my attention span. Stan, W1LE Bob Camp wrote: Hi Even defining when the sand timer is "done" is not a real simple thing. Waiting for that very last particle to drop may not be the best approach. Bob On Mar 5, 2010, at 9:20 AM, Tom Holmes, N8ZM wrote: tvb... Not to kick sand in your face, but it seems that in order for your automated turn-over device to work, as well as to accurately measure the time intervals, you would need a means to determine when the sand quits flowing. Possibly an accelerometer or microphone, with the added benefit of being able to hear the close-in phase noise. I admire your dedication to monitoring the hour long periods of the sand timer so diligently. Truly a time-nut! Regards, Tom Holmes, N8ZM Tipp City, OH EM79xx -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Van Baak Sent: Friday, March 05, 2010 1:44 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] nubie querie In the last slide you show a sand timer. Do you have accuracy data for it? Hi Brooke, The past 3 hours the "one hour" timer measures 56:24, 56:19, and 56:30. That's at 67 F room temp. Somewhere I have enough clean data to compute the ADEV; it's more stable than accurate. It also has a tempco (one day when my wife wasn't looking I collected data inside the kitchen refrigerator, and oven). I would guess it has very little dependence on barometric pressure or humidity since all the sand is sealed inside the blown glass bulb. Eventually I will mechanically automate the hourly turn-over and get 24x7 long-term data. If I also model the tempco it may be possible to temperature compensate the rate error. I don't know where the flicker floor will be. My prediction is this hour-glass will gradually speed up as the glass or the sand slowly wear over time. /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 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 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] nubie querie
Hi Then there's the phase noise of the pulsar "oscillator" - For a simple crystal oscillator the two word answer might be "Leeson's model". That of course is a cop out since it clearly defines multiple things that contribute to phase noise. Bob On Mar 5, 2010, at 9:39 AM, Richard (Rick) Karlquist wrote: > Don Collie jnr wrote: >> I`m not sure that questions like these is welcome on this list, but here >> goes anyway : 1/ What are the the 10 sources of the most constant >> [invariant] frequencies known to man, in order of decreacing constancy? Four >> immediately come to mind. > > I vaguely remember reading that pulsars have some fantastic > stability like 1E-20. I don't remember how they established > this. > >> 2/ What is the mechanism in an oscillator, that is responsible for phase >> noise? [In only one sentence please] > > Thermal (Johnson) noise in the resonator and thermal and shot noise in the > active device. > >> If this is known, then it becomes easier to design low phase noise >> oscillators. > > Perhaps, but just knowing the mechanism doesn't tell you that the > phase noise is inversely proportional to loaded Q, which you would > also need to know to optimize phase noise. > > >> I hope you enjoy these questions,.Don. >> ___ >> 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 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] nubie querie
Don Collie jnr wrote: I`m not sure that questions like these is welcome on this list, but here goes anyway : 1/ What are the the 10 sources of the most constant [invariant] frequencies known to man, in order of decreacing constancy? Four immediately come to mind. I vaguely remember reading that pulsars have some fantastic stability like 1E-20. I don't remember how they established this. 2/ What is the mechanism in an oscillator, that is responsible for phase noise? [In only one sentence please] Thermal (Johnson) noise in the resonator and thermal and shot noise in the active device. If this is known, then it becomes easier to design low phase noise oscillators. Perhaps, but just knowing the mechanism doesn't tell you that the phase noise is inversely proportional to loaded Q, which you would also need to know to optimize phase noise. I hope you enjoy these questions,.Don. ___ 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] nubie querie
Hi Even defining when the sand timer is "done" is not a real simple thing. Waiting for that very last particle to drop may not be the best approach. Bob On Mar 5, 2010, at 9:20 AM, Tom Holmes, N8ZM wrote: > tvb... > > Not to kick sand in your face, but it seems that in order for your automated > turn-over device to work, as well as to accurately measure the time > intervals, you would need a means to determine when the sand quits flowing. > Possibly an accelerometer or microphone, with the added benefit of being > able to hear the close-in phase noise. > > I admire your dedication to monitoring the hour long periods of the sand > timer so diligently. Truly a time-nut! > > Regards, > > Tom Holmes, N8ZM > Tipp City, OH > EM79xx > > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of Tom Van Baak > Sent: Friday, March 05, 2010 1:44 AM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] nubie querie > >> In the last slide you show a sand timer. Do you have accuracy data for > it? > > Hi Brooke, > > The past 3 hours the "one hour" timer measures 56:24, > 56:19, and 56:30. That's at 67 F room temp. Somewhere > I have enough clean data to compute the ADEV; it's more > stable than accurate. > > It also has a tempco (one day when my wife wasn't looking > I collected data inside the kitchen refrigerator, and oven). > > I would guess it has very little dependence on barometric > pressure or humidity since all the sand is sealed inside the > blown glass bulb. > > Eventually I will mechanically automate the hourly turn-over > and get 24x7 long-term data. If I also model the tempco it > may be possible to temperature compensate the rate error. > > I don't know where the flicker floor will be. My prediction is > this hour-glass will gradually speed up as the glass or the > sand slowly wear over time. > > /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 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] nubie querie
tvb... Not to kick sand in your face, but it seems that in order for your automated turn-over device to work, as well as to accurately measure the time intervals, you would need a means to determine when the sand quits flowing. Possibly an accelerometer or microphone, with the added benefit of being able to hear the close-in phase noise. I admire your dedication to monitoring the hour long periods of the sand timer so diligently. Truly a time-nut! Regards, Tom Holmes, N8ZM Tipp City, OH EM79xx -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom Van Baak Sent: Friday, March 05, 2010 1:44 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] nubie querie > In the last slide you show a sand timer. Do you have accuracy data for it? Hi Brooke, The past 3 hours the "one hour" timer measures 56:24, 56:19, and 56:30. That's at 67 F room temp. Somewhere I have enough clean data to compute the ADEV; it's more stable than accurate. It also has a tempco (one day when my wife wasn't looking I collected data inside the kitchen refrigerator, and oven). I would guess it has very little dependence on barometric pressure or humidity since all the sand is sealed inside the blown glass bulb. Eventually I will mechanically automate the hourly turn-over and get 24x7 long-term data. If I also model the tempco it may be possible to temperature compensate the rate error. I don't know where the flicker floor will be. My prediction is this hour-glass will gradually speed up as the glass or the sand slowly wear over time. /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 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.
