Re: [time-nuts] End-of-Range: Oscilloquartz OCXO 8600-3
PINGING Mike Monett . Thanks for your off-list offer of assistance with startup of this simulation. Unfortunately, your e4ward.com spam filter is a bit too effective. When I tried to respond to your email, it denied knowing anything about you. Please try again - from a reachable address. Ed ___ 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] Spectratime SRO100/SRO75 rubidium question
Versions of these oscillators prior to firmware version 1.96 had a user programmable DDS in them that could generate up to 20 MHz on pin 11 of the DB25 connector. All references to the commands to program this output have been removed from the current documentation. Does anybody have any info on how to set the user DDS frequency? ___ 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] Pendulum clock suspension
List -- we don't normally do wrist watch or pendulum topics here on time-nuts. There are many publications [1] and forums [2] for that Iovane -- but, here's a quick answer: > This puzzled me since yesterday as I discovered how the suspension of > pendulum clocks is made, that is a springy plate. > I thought that: > -the suspension point (i.e. the point the pendulum moves about) cannot be > considered fixed, > -following the above, the lenght of the pendulum varies during a swing, > -the spring contributes to the oscillation (it cumulates and releases > energy), i.e. not only gravity at work.. > Ok that we can neglect the above yet having an extremely good approximation, > but is it conceptually right? > Thanks for the answers. When you get to 0.1% or ppm or ppb levels, there is a huge difference between pendulum motion as described in physics textbooks vs. how real or precision pendulum clocks operate. Correct, it's not all gravity; the spring suspension itself has some effect on the motion of the pendulum. If this is a problem then you make design decisions about spring length, width, thickness, taper, or what metal to use. Or make the bob heavier, or choose a different operating amplitude. Or skip the spring entirely and use agate or diamond pivot suspension. All of this can be worked out with math or with experimentation. Correct, the effective length of a pendulum may vary during the swing. This is due to the geometry of the suspension, flexure in the rod, and changes in buoyancy. And even if the length were constant, the pendulum is still not isochronous, due to "circular error". Hence the preoccupation with amplitude stability as well as length stability. In general you should not neglect anything until you have modeled or measured it. Also don't confuse accuracy with stability. A pendulum could swing in a "figure 8" for all I care, but as long as it does so consistently it can be a good timekeeper. It's possible that some of the effects you describe affect accuracy more than stability. Given your curiosity about pendulum clocks, I strongly suggest you subscribe to HSN and order the digital archive. These topics are covered in extreme detail there. You will be amazed. /tvb [1] Some pendulum clock resources: AH (Antiquarian Horology), www.ahsoc.org HJ (Horological Journal), British Horological Institute, bhi.co.uk/horological-journal NAWCC (National Association of Watch & Clock Collectors), www.nawcc.org HSN (Horological Science Newsletter), NAWCC chapter 161, www.hsn161.com [2] There are also many clock and pendulum web sites, web forums, and mailing lists. Contact me off-list. ___ 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] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference
Citerar Mark Sims : In the standards definitions that include "at sea level", the question these days is "which sea level?". As ocean temperature changes sea level will change (except maybe in Washington DC). Will the standards be amended to include something like "at sea level in 1990" or will the value being defined drift around with the changing sea level? From the current Swedish vertical datum. (http://www.lantmateriet.se/globalassets/kartor-och-geografisk-information/gps-och-matning/geodesi/rapporter_publikationer/rapporter/lmv-rapport_2007_4.pdf) "This realisation was made using the Normaal Amsterdams Peil (NAP) as zero level in the traditional European way. [...] It has for instance been questioned whether NAP is the most suitable way to fix the zero level. Is it not better to wait for a so-called World Height System (WHS), which is fixed using GPS and a global geoid model of cm accuracy?" Has the World Height System been agreed/released? http://www.euref.eu/documentation/Tutorial2015/t-04-02-Ihde.pdf Picture showing reference origin for vertical datums in Europe. https://en.wikipedia.org/wiki/File:Vertical_references_in_Europe.svg -- Björn ___ 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] Pendulum clock suspension
> This puzzled me since yesterday as I discovered how the suspension of > pendulum clocks is made, that is a springy plate. There is less loss in a suspension like that than there would be in a pivot bearing. The spring doesn't change parameters as it gets dirty or the oil dries out. > -following the above, the lenght of the pendulum varies during a swing, > Ok that we can neglect the above yet having an extremely good approximation, > but is it conceptually right? With a constant length pendulum, there is a slight variation in the frequency with the height (width?) of the swing. (I haven't done the math since college physics which was a long time ago.) It would be interesting to see how much the length of a pendulum changes as the suspension spring bends and how much that changes the resonant frequency and how that compares with the length change due to temperature. I suspect it's down in the noise. -- These are my opinions. 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.
[time-nuts] Pendulum clock suspension
This puzzled me since yesterday as I discovered how the suspension of pendulum clocks is made, that is a springy plate. I thought that: -the suspension point (i.e. the point the pendulum moves about) cannot be considered fixed, -following the above, the lenght of the pendulum varies during a swing, -the spring contributes to the oscillation (it cumulates and releases energy), i.e. not only gravity at work.. Ok that we can neglect the above yet having an extremely good approximation, but is it conceptually right? Thanks for the answers. ant ___ 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] General Radio Model 723D Precision Oscillator (Tuning Fork)
Here is the link to some fine pictures and the schematic. Its uasable. http://worldpowersystems.com/J/instruments/GR723/ As a heads up the AC power comes in and is immediately doubled. Loaded something like 164 VDC. Reg tubes 107 V. Osc draws 35 Ma at 135V B+. Fil 1.42V@47 ma. Distortions quite low .219% Tek AA501. IMD 5.59% Tek AA501. I actually used independent supplies when I fired it up the first time. Totally did not trust the power supply. Takes about 20 seconds to start up. You will hear it running quite apparent. I have a theory. Crystals were invented so you would not need to listen to the tuning fork. Regards Paul WB8TSL On Sat, Dec 9, 2017 at 11:37 AM, paul swed wrote: > Well we are kicking butt on 723 oscillators. I have the 1000 hz model and > found it at the MIT flea about June. > Bad rectifier section. Cap was good though I carefully reformed it. Have > to say what attracted me was the case and then the realization of what it > was. It works very well so now I can make sure my cesium is on frequency. > There is a schematic online but its a picture actually in the wood case. I > copied that as I could find no real details. > I do have the genrad article. > The actual internals are hot. Be careful. It uses an output transformer as > the only isolation. > It makes sense actually. It keeps the 60 Hz magnetics out of the > oscillator. > I thought my tube might be bad as it didn't glow. But its a 1.5 V filament > ohm'ed it out and it was fine. > Lastly I have a hacked power cable. I was going to buy the right plug. But > it actually is a bit unclear. It should be the cenetr ground and they are > around $15 each. Its not the cost. The 3 I see are sort of unclear that > they match my socket. > I swear I actually have one. Some place here. > Regards > Paul > WB8TSL > > On Sat, Dec 9, 2017 at 10:30 AM, Eric Scace wrote: > >> Another fascinating tuning-fork standard was used together with a >> Synchronome to govern the timing of pulses of Morse code on undersea >> telegraph cables in the British empire’s globe-girdling telegraph network. >> Timing was derived electromagnetically from incoming Morse code signals (a >> bi-polar signal where one polarity represented a dit and the other a dah, >> but both dit and dah were of equal length) to set the master at each >> downstream relay/switching station on a cable route. >> >> In essence, brass, mahogany and electromagnetics were use to perform all >> the functions done today on fiber optic cables: signal generation, >> multiplexing, regeneration, and timing recovery… not to mention encoding & >> decoding plus printing. >> >> One can see a working example at the Museum of Undersea Telegraphy in >> Porth Curno, Cornwall — a museum well worth the detour to Land’s End. >> >> — Eric >> >> > On 2017 Dec 09, at 10:11 , Don wrote: >> > >> > Thank you, Pete. -Don >> > >> > == >> > >> > >> > >> > >> > On Sat, 2017-12-09 at 05:57 -0800, Pete Lancashire wrote: >> >> Here's a look at a 723-C (1,000 cps) and how its power supply cap was >> >> handled and a good look inside >> >> >> >> https://www.eevblog.com/forum/reviews/vintage-teardown-general-radio- >> >> 723-c-vacuum-tube-tuning-fork/ >> >> >> >> >> >> The GR Experimenter >> >> >> >> http://www.americanradiohistory.com/Archive-General-Radio/GR%20Exp%20 >> >> 1941_10.pdf >> >> >> >> There is another Experimenter that goes into how the tuningfork was >> >> made >> >> but can't find it >> >> >> >> -pete >> >> >> >> On Sat, Dec 9, 2017 at 5:18 AM, Don wrote: >> >> >> >>> >> >> I was fortunate to find a vintage, General Radio (GR) Model 723D >> Precision Oscillator (tuning fork). >> >> The exceptional wooden case is as 'exciting' to look at as is the >> mechanical tuning fork inside (400Hz). >> >> As it is ac powered, I'll need to recap it before I turn it on. >> Then, we can test for accuracy! (sic). >> >> A real class-act, 'time-nut' oscillator from the last century, >> predating crystals. >> >> Don >> >> Don Lewis >> ___ >> time-nuts mailing list -- time-nuts@febo.com >> To unsubscribe, go to https://www.febo.com/cgi-bin/m >> ailman/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] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference
A 30 cm daily vertical offset is pretty typical. I've seen over 45 cm. Horizontal offsets are usually less than +/- 75 mm per day with the longitude displacement typically twice the latitude displacement. Heather uses a standard model (see http://geodesyworld.github.io/SOFTS/solid.htm) to calculate earth tides. I converted the Fortran code to C and use a more accurate routine for calculating sun and moon positions. The gravity calculation code is from TVB's code. Actual tides experienced at a given location depend can depend upon locally unique factors like underground geology and nearby bodies of water. Compensating altitude for an optical clock would be considerably more complex. --- > You're place really moved a foot in 48 hours? Impressive and scary! ___ 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] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference
Checkhttps://en.wikipedia.org/wiki/Earth_tide According to that, a foot of motion is easily plausible. The Wiki article says that displacements around a meter in the solid crust can be seen over the right intervals. This must wreak havoc in VLBI geodesy work, except that for some in the field this would be the "signal" and most everything else the noise. Dana On Sat, Dec 9, 2017 at 7:42 PM, Tom Holmes wrote: > Mark... > You're place really moved a foot in 48 hours? Impressive and scary! > > From Tom Holmes, N8ZM > > > On Dec 9, 2017, at 8:19 PM, Mark Sims wrote: > > > > Which gets real fun with things like solid earth tides getting > involved. Lady Heather can now calculate and plot solid earth tides. > Over the last 48 hours my place moved up/down 315 mm and gravity changed > 186 microgals... and that was a rather stable period. > > > > -- > > > >> A 1 meter change in elevation corresponds to a frequency offset of > about 1e-16. So for 1e-18 levels of performance you "only" need to know g, > or your elevation to 1 cm accuracy. > > > > ___ > > 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] DATUM RubiSource 2000 RUBIDIUM TIMING SIGNAL REFERENCE
I recently purchased a DATUM RubiSource 2000 RUBIDIUM TIMING SIGNAL REFERENCE does any one have a manual or detailed technical information. Please contact me off list. Thank you Bert Kehren ___ 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] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference
Hi Just as there are Time Nuts, there are Tide Nuts (I suppose it’s capitalized …). There is a a lot of data out there on just what sort of solid tides one might see at this or that point. Bob > On Dec 10, 2017, at 7:29 AM, Azelio Boriani wrote: > > Is that a Trimble Thunderbolt? Is there a way to compute the uncertainties? > > On Sun, Dec 10, 2017 at 2:42 AM, Tom Holmes wrote: >> Mark... >> You're place really moved a foot in 48 hours? Impressive and scary! >> >> From Tom Holmes, N8ZM >> >>> On Dec 9, 2017, at 8:19 PM, Mark Sims wrote: >>> >>> Which gets real fun with things like solid earth tides getting involved. >>> Lady Heather can now calculate and plot solid earth tides. Over the last >>> 48 hours my place moved up/down 315 mm and gravity changed 186 >>> microgals... and that was a rather stable period. >>> >>> -- >>> A 1 meter change in elevation corresponds to a frequency offset of about 1e-16. So for 1e-18 levels of performance you "only" need to know g, or your elevation to 1 cm accuracy. >>> >>> ___ >>> 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] IEEE Spectrum - Dec 2017 - article on chip-scale atomic frequency reference
Is that a Trimble Thunderbolt? Is there a way to compute the uncertainties? On Sun, Dec 10, 2017 at 2:42 AM, Tom Holmes wrote: > Mark... > You're place really moved a foot in 48 hours? Impressive and scary! > > From Tom Holmes, N8ZM > >> On Dec 9, 2017, at 8:19 PM, Mark Sims wrote: >> >> Which gets real fun with things like solid earth tides getting involved. >> Lady Heather can now calculate and plot solid earth tides. Over the last >> 48 hours my place moved up/down 315 mm and gravity changed 186 microgals... >> and that was a rather stable period. >> >> -- >> >>> A 1 meter change in elevation corresponds to a frequency offset of about >>> 1e-16. So for 1e-18 levels of performance you "only" need to know g, or >>> your elevation to 1 cm accuracy. >> >> ___ >> 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] Helmholtz Resonator and other Maintained Oscillators
Hi, Recommended reading relating to this is the acoustical and audio engineering material. "Acoustical Engineering" by Harry F. Olson is a really good book. I covers many of the theory work on speakers etc. and uses electrical models and ways to estimtate their effects. This book I have used to again and again debunk "new" speaker concepts, as it turns out it has already been tried before. AES have released 4 collections of articles out of JAES on speakers. In there is the moderload of Thiele-Small articles that extends the work of Olson to more and more refined methods. Estimating the losses and resonant properties is a key aspect, as they have huge impact on the on the audio. Also, there is a good book on acoustics by Beranek, of Bolt-Beranek-Newman if that rings a bell to Internet old-timers, which may be applicable. I could do a more detailed dig in my library if needed, but there is some good material out there. Cheers, Magnus - AES member and used to do professional audio PA system design On 12/10/2017 01:30 AM, Bill Byrom wrote: The Q of Helmholtz resonators is derived here: https://en.wikibooks.org/wiki/Acoustics/Flow-induced_Oscillations_of_a_Helmholtz_Resonator Some Q measurements of bottles are described here: https://math.dartmouth.edu/archive/m5f10/public_html/proj/ArainGolvach.pdf -- Bill Byrom N5BB On Sat, Dec 9, 2017, at 01:39 AM, Hal Murray wrote: k8yumdoo...@gmail.com said: The flex hose demonstration was interesting in that different regimes of swinging speed resulted in oscillation in different modes. I wonder why. It depends on the speed of the air going through the tube. https://www.youtube.com/watch?v=4aJ36-TlPD4 http://www.exo.net/~pauld/activities/AAAS/aaas2001.html http://www.exo.net/~pauld/summer_institute/summer_day13music/Whirly.html -- These are my opinions. 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. ___ 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.
