Re: [time-nuts] Phase noise and geomagnetism
>Da: t...@leapsecond.com >Data: 01/05/2014 8.07 > >Hi Antonio, > >At some level, frequency standards are all affected by every environmental factor Tom, thanks for your comments. There is some geomagnetic activity today May 8, see http://www.swpc.noaa. gov/rt_plots/satenv.html (GOES Hp and estimated Kp). Did anybody notice anything? (with reference to noises in measurements). Antonio I8IOV ___ 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] Phase noise and geomagnetism
Hi, Antonio, I regularly note the geomagnetic Kp value when I take part in an FMT but most of the discussion of this takes place on K5CM's FMT-nuts mail list (as far as I know). Fortunately, most FMTs have not coincided with a major storm but there have been a few where some really weird effects were noted, probably due to "minor" disturbed geomagnetic conditions. 73, ... Martin VE3OAT Antonio I8IOV wrote : > > Hi all,thanks for your replies.Geomagnetic storms are known > to produce easily detectable effects at earth, sometimes dramatic > ( http://en.wikipedia.org/wiki/Solar_storm_of_1859 , > http://www.youtube.com/watch?v=7ukQhycKOFw ), sometimes serious > (compasses get crazy), sometimes minor (only aurorae boreales and > other minor effects). I think that time-nuts should be aware > whether these fenomena might affect their measurements or not. > Geomagnetic activity data are easily available at the NOAA website > http://www.swpc.noaa.gov/ , so checks would be easy. I hope to > see some reports here sooner or later.Antonio I8IOV > ___ 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] Phase noise and geomagnetism
Hi Antonio, At some level, frequency standards are all affected by every environmental factor. Typically the manufacturer shields or controls or compensates for each factor, in order to create a product that meets spec. But it is always fun to measure this yourself. Here are a couple of ways to make the measurements: 1) One is to create a large artificial change in the environment. We do this when we measure the tempco of oscillators. Try it at 0 C, 25C, and 50C. It's also how we measure the effect of voltage or load or humidity or gravity. It would be very easy to check AC or DC magnetic susceptibility using the same technique. 2) The other method is to remove the existing shielding or compensation that a frequency standard has. So turning off the oven is a great way to see how strongly temperature affects a crystal. Removing the mu-metal shield from a Rubidium would also make a nice experiment (the military uses unshielded Rb clocks as magnetometers to track submarines). 3) The final method is to add an additional level of shielding or control. A good example here is creating an second oven to control the ambient temperature seen by a frequency standard. Or placing a frequency standard in a soft foam block to reduce seismic effects. One can learn about environmental sensitivity by comparing the performance with and without this additional homebrew layer of environmental shielding. Regardless of which methods are used, what you end up with is a "calibration" value, or sensitivity coefficient. That is, what level of change in environmental parameter X causes how much change in oscillator frequency, or stability. The most common ones are numbers like 1ppm/C (temperature) or 1e-8/volt (voltage) or 1e-9/2g (acceleration). A classic example of these coefficients is: http://leapsecond.com/museum/10811a/10811a-spec.jpg The fun of having frequency standards at home is that you can validate these specification with little effort and sometimes improve the performance of the oscillator, either by additional shielding, or by active compensation. Of course, the big labs do this from time to time. Here are some papers to read: Environmental Sensitivities of Cavity Tuned Hydrogen Masers Environmental Factors and Hydrogen Maser Frequency Stability Influence of Environmental Factors on Hydrogen Maser Frequency Stability http://tf.boulder.nist.gov/general/pdf/1201.pdf http://tf.boulder.nist.gov/general/pdf/1252.pdf http://tf.boulder.nist.gov/general/pdf/2592.pdf Environmental Effects on the Medium and Long Term Frequency Stability of Quartz Oscillators Environmental Sensitivities of Quartz Crystal Oscillators Environmental Sensitivities of Quartz Oscillators http://tf.boulder.nist.gov/general/pdf/819.pdf http://tf.boulder.nist.gov/general/pdf/906.pdf http://tf.boulder.nist.gov/general/pdf/957.pdf Not only will you find numbers and graphs, including magnetic effects, but you will also see how to perform these experiments and how to properly interpret and report the results. Remember also that in the timing industry we use quartz for stability and so we shield from the environment. But there's an entire other industry out there that uses quartz as extremely sensitive sensors; for temperature, for acceleration, for pressure, for air quality, etc. If you have any questions, let me know. Finding external effects is really fun. Creating the calibration charts takes time but is well worth it. We tend to focus a lot on temperature, but other factors can be measured as well. My favorite surprise was when I realized that my Sulzer quartz oscillator was so stable and yet so sensitive that it could detect when the kids used the bathroom (in the room next to my lab). So everything affects everything; the only question is by how much. If it's 10 dB below the ADEV(tau) of the oscillator, then no worries. If it's more than that, then you get to decide if you want to make your oscillator a better timekeeper or a better sensor. /tvb - Original Message - From: To: "Discussion of precise time and frequency measurement" Sent: Wednesday, April 30, 2014 3:28 PM Subject: Re: [time-nuts] Phase noise and geomagnetism > > Hi all,thanks for your replies.Geomagnetic storms are known to produce easily > detectable effects at earth, sometimes dramatic ( > http://en.wikipedia.org/wiki/Solar_storm_of_1859 , > http://www.youtube.com/watch?v=7ukQhycKOFw ), sometimes serious (compasses > get crazy), sometimes minor (only aurorae boreales and other minor effects). > I think that time-nuts should be aware whether these fenomena might affect > their measurements or not. Geomagnetic activity data are easily available at > the NOAA website http://www.swpc.noaa.gov/ , so checks would be easy. I hope > to see some reports here sooner or later.Antonio I8IOV ___ ti
Re: [time-nuts] Phase noise and geomagnetism
Hi all,thanks for your replies.Geomagnetic storms are known to produce easily detectable effects at earth, sometimes dramatic ( http://en.wikipedia.org/wiki/Solar_storm_of_1859 , http://www.youtube.com/watch?v=7ukQhycKOFw ), sometimes serious (compasses get crazy), sometimes minor (only aurorae boreales and other minor effects). I think that time-nuts should be aware whether these fenomena might affect their measurements or not. Geomagnetic activity data are easily available at the NOAA website http://www.swpc.noaa.gov/ , so checks would be easy. I hope to see some reports here sooner or later.Antonio I8IOV ___ 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] Phase noise and geomagnetism
It's not exactly a time-nut quality oscillator, but the Earth's Schumann Resonances (circa 7.83 Hz) are perturbed slightly as solar activity changes the effective size of the ionosphere: http://en.wikipedia.org/wiki/Schumann_resonances On Mon, Apr 28, 2014 at 5:18 PM, iov...@inwind.it wrote: > As our geomagnetic field gets quite noisy during geomagnetic storms (which > are connected to solar activity), I was wondering if this could affect > phase noise of oscillators. I see that theoretically it could. Has anybody > ever measured phase noise increments which could be explained this > way?Antonio I8IOV > ___ > 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] Phase noise and geomagnetism
Hi Antonio: There's a sheet metal bender up the road from me and one of their customers was HP. The metal had special magnetic properties and was used to shield an HP oscillator, don't remember which one, but maybe one of the Cs units. So for that unit a change in the very small Earth's magnetic filed would not make much difference. http://www.prc68.com/I/Sensors.shtml#Magnetic Have Fun, Brooke Clarke http://www.PRC68.com http://www.end2partygovernment.com/2012Issues.html iov...@inwind.it wrote: As our geomagnetic field gets quite noisy during geomagnetic storms (which are connected to solar activity), I was wondering if this could affect phase noise of oscillators. I see that theoretically it could. Has anybody ever measured phase noise increments which could be explained this way?Antonio I8IOV ___ 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] Phase noise and geomagnetism
Antonio, That is a great question. I am not 100% sure of the answer myself, but I am sure others will chime in. I used to be responsible for an RF lab in which we did a lot of low-noise measurements; had shielded racks, chamber, etc. - I can tell you from experience that anything that can raise or effect the noise floor can affect the measurement(s). So, in this case, I would think that is true; so I would postulate that it is possible. But, there may be some on the list that have made these measurements and will share their experience and expert knowledge. 73's, John AJ6BC On Mon, Apr 28, 2014 at 2:18 PM, iov...@inwind.it wrote: > As our geomagnetic field gets quite noisy during geomagnetic storms (which > are connected to solar activity), I was wondering if this could affect > phase noise of oscillators. I see that theoretically it could. Has anybody > ever measured phase noise increments which could be explained this > way?Antonio I8IOV > ___ > 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] Phase noise and geomagnetism
Hi Antonio you must remember the "static" geomagnetic field is around 50,000nT and the biggest Solar induced events are around 500nT so the effect might be difficut to detect as events of this size are not very common. More common events are in the 100 to 200nT range. Alan G3NYK - Original Message - From: To: Sent: Monday, April 28, 2014 10:18 PM Subject: [time-nuts] Phase noise and geomagnetism As our geomagnetic field gets quite noisy during geomagnetic storms (which are connected to solar activity), I was wondering if this could affect phase noise of oscillators. I see that theoretically it could. Has anybody ever measured phase noise increments which could be explained this way?Antonio I8IOV ___ 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] Phase noise and geomagnetism
As our geomagnetic field gets quite noisy during geomagnetic storms (which are connected to solar activity), I was wondering if this could affect phase noise of oscillators. I see that theoretically it could. Has anybody ever measured phase noise increments which could be explained this way?Antonio I8IOV ___ 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.
