A measurement of 10 MHz down to 10 uHz - Page 1
Forum section: electronics / projects

author: John Heath
author_rank: Frequent Contributor
timestamp: February 08, 2016, 05:50:24 am
content: Hi to everyone in the group.Weather is fine in Canada , a nice 2 C / 36 F warm day. You have to be Canadian to understand why 2 C is a warm day.I would like to publish my no good ideas in a journal however there will be nothing left but the feathers if the empirical evidence is not firmly stabled to the back of this paper. The empirical evidence must establish that a 5 K volt change in the voltage frame of reference of a stable 10 MHz crystal will cause a change in frequency of .000,005 HZ . 5 uHz change in a 10 MHz oscillator per 5 KV, ouch. If there is anyone one that would know the best way to accomplish this task it would be the EEVblog group which brings myself to these door steps. I would welcome any suggestions. I can say what I have built so far to put a finer focus on the VEPS project.A] A 5 KV double Faraday cage with the inner cage changing from 0 volts to 5 K volts every 10 seconds.B] The 5 K volt source is a small 12 volt BW TV with the HV flyback lead going to the inner Faraday cage.C] The test board is powered by a 12 volt dry fit battery , 2 amp hour and the 10 second 5 K volt cycling is accomplished by a 555 timer and relay that switches the power to the small TV.D] Normally the test board is plugged into power to charge the dry fit battery and make adjustments. In test mode for data logging the board is unplugged running only on battery power with one wire from the outer Faraday cage to earth ground.E] The inner Faraday cage , 5 KV on and off , houses a 10 MHz hermetically sealed crystal oscillator, off the self type , with 5 volts in 10 MHz out with no temperature compensation nor capacity trimmer adjustments. A 9 volt rechargeable battery through a 7805 regulator supplies the power.F] High voltage isolation from the inner Faraday cage is provided by a Toslink TTL data to fiber adapter that is also powered by the 9 volt battery for the 10 MHz test oscillator. A 20 foot toslink fiber cable provides the 10 MHz information to the data logging test board as well as the voltage isolation from the inner Faraday cage.This is what I have so far. Everything works with the bugs worked. This brings us to this nasty business of testing for a 5 uHz change in a 10 MHz oscillator per 5 KV, ouch. If anyone one has thoughts on the best way to accomplish this it would be appreciated.John

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 08, 2016, 06:45:58 am
content: ...Huh?Well...Why would you expect that there would be a difference?How do you expect to prove (p < 0.05) that the effect is of the claimed magnitude, or indeed, measurable at all, under any circumstances?How can you prove that it isn't due to other effects, like power supply noise, or noise coupled into the signal cables, or... dust attracted to the enclosure by the high voltage?A parts-per-trillion change is manifestly meaningless for the noise level of the type of oscillator used, so even if you can prove the hypothesis, and disprove possible alternative ones, what use could it possibly have?At this level, the design of your experiment is almost irrelevant, while the design of your methodology is absolutely critical.Tim

author: TheSteve
author_rank: Unknown
timestamp: February 08, 2016, 06:47:05 am
content: Can't help you on the frequency measurement but you must be in the east or something, 2 degrees is a cold day in the west!

author: DimitriP
author_rank: Super Contributor
timestamp: February 08, 2016, 07:08:53 am
content: I'd like to know what 10Mhz oscillator you have that is stable enough so you can measure a 5uH change to its frequency.

author: miguelvp
author_rank: Super Contributor
timestamp: February 08, 2016, 07:46:22 am
content: Quote from: John Heath on February 08, 2016, 05:50:24 amAnything above freezing is a warm day in Chicago, although it has been a warm winter this year, currently 2 C/35 F it's t-shirt time

author: awallin
author_rank: Frequent Contributor
timestamp: February 08, 2016, 09:37:23 am
content: An off the shelf counter like SR620 or Keysight 53230A or similar has a noise floor of around ADEV(tau) = 2e-11/tau(s)measuring a 5uHz change in 10MHz is 5e-14 fractional, so it takes at least 400 seconds for the counter-noise to average down to that level - assuming you have all other noise sources at a level below the counter.If you need to measure a 5e-14 change faster you need a DMTD or other clever schemes.There are both analog  and digital (e.g. symmetricom 5115A, 5120A, 3120A) implementations.Quite recently there are some interesting SDR-based ideas for DMTD implementations which might be more affordable (e.g. Ettus USRP or similar)http://www.wriley.com/A%20Small%20DMTD%20System.pdfThe best BVA-type quartz crystals are at around 8e-14 or so:http://www.oscilloquartz.com/files/1363164953-Br_%20OCXO%208607.pdfSomething more affordable (40euros on ebay) like a Morion MV89A is at maybe 2e-12 between 1s and 10s - but thats 40-fold worse than what you want to measure at 5e-14...It will draw 1A @ 12V at warmup and maybe 0.4 A @ 12 V when warm - will not last real long on a 9V battery.good luck! (not sure how serious OP is about this..)

author: John Heath
author_rank: Frequent Contributor
timestamp: February 08, 2016, 10:11:38 am
content: Why would you expect that there would be a difference?Hi TimBoy is that a long answer that could easily go on for 20 pages. I will sum it up . There was an engineer , Professor Simhony , that designed integrated circuits. His mind was such that he had to understand all there was about crystallization ,doping and electron flow. The end result was a book published describing the precise properties of a vacuum as positronium cubic matrix spacing 5 f meters.http://simhonytribute.webs.com/epolagravity.htmThe VEPS project is my attempt to tap Professor Simhony's work a little to the left by using virtual positronium not real positronium as a building block for a vacuum. From this added flexibility time dilation from a change in a voltage frame of reference should be possible. A GPS satellite has a projected voltage frame of reference of .5 to .7 M volts positive with a known time dilation .5 Hz at 1 GHz. This is where VEPS project 5 uHz change in a 10 MHz oscillator per 5 KV comes from. If a positive test result can be measured then a reasonable argument could be made that Professor Simhony was right. Also that the use of virtual positronium instead of real positronium would bridge Professor Simhony's work with General Relativity. That would be really cool. It is a long shot but you never know what is under a stone until you turn it over.A parts-per-trillion change is manifestly meaningless for the noise level of the type of oscillator used, so even if you can prove the hypothesis, and disprove possible alternative ones, what use could it possibly have?I can say from progress made that this is an understatement. Hydro 60 cycles per second can only be kept at bay by having everything run on batteries. It is possible that the entire experiment will have to be driven away from the city for reasonable error bars. From my jitter meter it seems it is out of range as well. I was thinking of additional 10 MHz crystals as a high Q band pass to sweeten up the jitter numbers. Will not know until it is tried.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 08, 2016, 10:34:23 am
content: Quote from: T3sl4co1l on February 08, 2016, 06:45:58 amThis ^.This reminds me very much of the "Mikhailov experiment" and Mikhailov's conjecture about frequency change in a relaxation oscillator within a charged cage. In fact, except for the type of oscillator it sounds exactly the same. I spent many months on such an experiment around 15 years ago, and even blew out an expensive HP frequency counter doing it. You can take my word for it, the experimental difficulties are huge and the effect size is .... tiny. Yes, everything has to be run on batteries, the oscillator itself and its power supply have to be completely enclosed in the HV enclosure; getting data out under those circumstances involved optical means rather than wired connections; the lab itself was in an isolated location at least half a mile from other structures..... hoo boy. This is "big science" even if the apparatus itself can basically fit on a table-top.

author: Rerouter
author_rank: Super Contributor
timestamp: February 08, 2016, 10:48:21 am
content: Question, If the change is voltage dependent, why stop at 5KV, Its easier to make a higher grid bias than it is to measure such a small change, And i agree optical coupling would be a must, which introduces its own issues,

author: HAL-42b
author_rank: Frequent Contributor
timestamp: February 08, 2016, 11:17:08 am
content: Interferometry and Doppler techniques are the only thing I can think of that can measure with such sensitivity over such a range. Which means the experiment can't be conducted in air because sound waves would affect it.Have a look at these guyshttp://www.thz.physik.uni-muenchen.de/research/lab/index.htmlTHz Time domain spectroscopy.

author: KE5FX
author_rank: Super Contributor
timestamp: February 08, 2016, 11:28:11 am
content: Quote from: T3sl4co1l on February 08, 2016, 06:45:58 amThere are plenty of OCXOs with an Allan deviation under 1E-12 at t=1 second, and it doesn't take anythingthatexotic to measure them.I've never heard of this effect, though... it sounds like it may require a lot of, um, tinfoil.

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 08, 2016, 11:43:43 am
content: Quote from: Rerouter on February 08, 2016, 10:48:21 amI didn't stop at 5 kV... I was going to 60 kV and even more sometimes. The setup was pretty dangerous now that I reflect on it. And I did wind up toasting a HP 5370B, after all.QuoteExactly......

author: uncle_bob
author_rank: Unknown
timestamp: February 08, 2016, 12:41:29 pm
content: HiOk, the first issue is signal to noise. You want to be sure that your measurement is reading frequency and not something else. Oscillators hop and jump around at the same level that you are trying to detect. So, what is normally done?Excite the system with an AC signal at a fairly low frequency. A 60 KV sine wave would do pretty well. You would need to make very sure that the AC signal does not get into your measurement setup. It would have to be at something other than the power line frequency or you would never sort things out. The measurement would need to be done on a fairly high quality OCXO, but nothing crazy.If the "AC" is down around 1/10 Hz or so, there are a variety of things you could use to detect it. People like Symmetricom would be happy to sell you any of a number of boxes that would do the job. There are resources available to help with the operation of some of those boxes. If the frequency is low enough, a programmable power supply could be used to generate it.Bob

author: dom0
author_rank: Super Contributor
timestamp: February 08, 2016, 12:45:48 pm
content: I wonder how this effect works.Is this the effect of the extremely (160? 200? dB) attenuated (by oscillator casing, hermetic metal crystal packaging etc.) E field on the crystal? Or something different entirely?

author: alsetalokin4017
author_rank: Super Contributor
timestamp: February 08, 2016, 01:02:29 pm
content: The real question should be "is there an effect at all". The "Mikhailov" effect that I was looking for was conjectured by Mikhailov to be due to the external E-field changing the mass of the electrons in the oscillator. When I finally got to the point where I was taking consistent data.... I got null results. Then I wound up toasting the counter due to an accident, and shortly thereafter the organization I was working for folded up entirely.

author: Marco
author_rank: Super Contributor
timestamp: February 08, 2016, 03:52:17 pm
content: The completely ad hoc method I would try without any understanding of the underlying processes or even fully understanding the math and it's implications would be to subsample the oscillator, do FFTs of the central X seconds of each half period to find the dominant frequency, take the difference of the frequencies for each cycle, repeat and average Y times.

author: zapta
author_rank: Super Contributor
timestamp: February 08, 2016, 05:06:32 pm
content: AmpHour had recently a guest that specialize in ridiculously accurate measurements. I would contact him and see if he has any advice. Drop the EEVblog and Dave's name, it may help.

author: nctnico
author_rank: Super Contributor
timestamp: February 08, 2016, 05:20:54 pm
content: Quote from: Marco on February 08, 2016, 03:52:17 pmThis could be a good approach. The jitter and/noise should spread across the spectrum but a frequency offset should stand out.

author: uncle_bob
author_rank: Unknown
timestamp: February 08, 2016, 05:46:46 pm
content: Quote from: nctnico on February 08, 2016, 05:20:54 pmHiYou are looking for an effect that is "greeted with skepticism". The best way to prove that it is there is to use well know techniques. There is already a lot of gear out in the market that will make these measurements. Doing something odd opens you up to challenges. Defending the measurement at the same time as the results is *not* where you want to be. Making a measurement error and missing out on that Nobel Prize, also would be a major bummer.Bob

author: Marco
author_rank: Super Contributor
timestamp: February 08, 2016, 06:22:33 pm
content: Quote from: uncle_bob on February 08, 2016, 05:46:46 pmI guess then just use a PLL FM demodulator and digital lockin amplifier, you should be able to get that from big brand name lab devices.

author: Bud
author_rank: Super Contributor
timestamp: February 08, 2016, 06:33:53 pm
content: Quote from: uncle_bob on February 08, 2016, 05:46:46 pmI wonder what they are... There is an area of research and application of crystal resonators frequency shift called Quartz Crystal Microbalance where they measure shift in frequency caused by depositing molecules on the surface of the crystal (change in mass), and it seems it is a challenge to reliably measure the shift with better than 0.01 Hz resolution. BTW, i recommend OP to read about QCM, there may be a few good ideas to pick up from there.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 08, 2016, 07:54:08 pm
content: Ugh. Word soup.This explanation,Quote from: John Heath on February 08, 2016, 10:11:38 amMeans nearly nothing to me, is incoherent in terms of traditional physics, and Simhony's FAQ describing things in better detail (find it herehttp://www.epola.co.uk/faq/FAQframe.html) is similarly self-inconsistent, poorly thought out, and simultaneously utilizing, and against, various parts of known standard physics.I suppose my insistence on methodology will end up being ignored in the end, which would at least be consistent with the types of "experiments" those kinds of people like to do their childs-play with. But whatever. Best of luck whatever you end up doing, I suppose.Tim

author: TimFox
author_rank: Super Contributor
timestamp: February 08, 2016, 09:05:27 pm
content: An extremely sensitive way to measure small fractional deviations of much, much higher frequency is the Mossbauer effect for gamma-ray frequencies. Seehttp://www.mossbauer.info/mossbauer.html.For example, this was used to measure the difference in gamma-ray photon energy (i.e., frequency) due to gravitation over the height of the tower on the Harvard campus. When the emitting and target nuclei are each constrained by a crystalline lattice (e.g., Co-60 in bulk cobalt), the effective width of the resonant interaction is incredibly narrow and frequency shifts can be measured in the audio range.If your effect is real, it should be visible with the source in one Faraday cage at high voltage, and the target in a grounded Faraday cage where you can do the measurement.

author: uncle_bob
author_rank: Unknown
timestamp: February 08, 2016, 09:59:20 pm
content: Quote from: Bud on February 08, 2016, 06:33:53 pmHiWell the one next to me on the bench here is a Symmetricom 3120A. It will do the job quite nicely. They have many other instruments (as do others) that also will measure the expected impact of a 60KV shift.Truth in lending, I don't work for Symmetricom. I did not work on the 3120A at any point in time. I'm just a happy customer. Yes, there is *slightly* more to the story, but it's not relevant.Bob

author: KE5FX
author_rank: Super Contributor
timestamp: February 08, 2016, 10:12:19 pm
content: Quote from: uncle_bob on February 08, 2016, 09:59:20 pmWarranty void above 10 kV...

author: dannyf
author_rank: Super Contributor
timestamp: February 08, 2016, 10:50:25 pm
content: I think you are probing beyond the envelop of the state of the art measurement technology that mankind has to offer now.

author: uncle_bob
author_rank: Unknown
timestamp: February 08, 2016, 11:06:06 pm
content: Quote from: KE5FX on February 08, 2016, 10:12:19 pmHiAwww shucks .....There goes that Nobel Prize.=====Indeed a *very* bit part of running this experiment would be isolating and protecting everything. That's true at 5KV, it is even more true if you bop up to 60KV. You also need to very carefully isolate your measurement gear. That's not just for safety. You also want to keep leakage from messing up your measurement. Things like isolation transformers for your RF signal may be a bit interesting to design.Bob

author: uncle_bob
author_rank: Unknown
timestamp: February 08, 2016, 11:22:15 pm
content: Quote from: dannyf on February 08, 2016, 10:50:25 pmHiThat just isn't true.The initial statement wants to look for a 1x10^-12 frequency change. You can buy OCXO's on eBay that will have ADEV's in the 1x10^-13 vicinity. Those OCXO's were measured with very normal test gear. It is specialized gear, but it is not "un obtainable". The nice thing about the measurement gear is that it generally gets more accurate the longer the measurement. Something that does 1x10^-10 at 1 second (like a HP 53132) will do 1x10^-12 at 100 seconds or 1x10^-13 at 1,000 seconds. If you go with a 5370 or an SRS620, you start at 2x10^-11 and go from there. There are a *lot* of measurement techniques out there. NIST has very little doubt they can measure frequency down to 1x10^-15.If you do as suggested in another post, take the voltage up from 5KV. That's quite do-able with a variety of gear. It is not gear I have siting here in the family room. It is stuff you can buy. 60KV was suggested. 100KV might be equally easy. Gear that went way above that was state of the art in ... errr ...1890. Having worked with one of those big old beasts, no I would *not* do it like they did it "back in the old days".With a voltage of 100KV, you move your delta F up by a factor of 20. Now you are looking for 2x10^-11 and not 1x10^-12. That's frequency counter territory.Do you want to do this as an AC measurement? Sure. Voltage up / voltage down / repeat is the way to do it. Maybe you can sweep in 10 seconds, maybe it will take longer to do a sweep. Monitor the frequency and the voltage. Look for a nice clean correlation. Keep things running for a few thousand cycles. Pile the data together and you have pretty good confidence.The problem with this (looking at it as a sceptic) is *not* running the experiment. By the cost measures of modern physics, the cost to do this isn't even round off error. The problem is doing it in a way that proves what you find beyond any reasonable challenge. The test gear and OCXO's can do itheir part.Bob

author: dannyf
author_rank: Super Contributor
timestamp: February 09, 2016, 12:12:24 pm
content: Assuming the frequency deviation is stable and you can find a reference source equally stable, one way to measure such tiny frequency deviations is to measure changes in phase differenctials

author: John Heath
author_rank: Frequent Contributor
timestamp: February 09, 2016, 12:18:59 pm
content: Great stuff guys. Thanks to all. I will tough on a few.Quantum effects: In this case brute force toslink fiber is being used not single mode , lots and lots of photons to average out quantum effects. Also the fiber cable is 20 feet at 10 MHz so dispersion should not be a concern ,, I hope.Mikhailov effect: A pretentious phrase such as "subquantum kinetics paradigm" is a red flag. They used mechanical wind up clocks , red flag confirmed. To give this balance many fine contributions to science have been made from the grass roots. Oliver Heaviside would be an example.Symmetricom 3120A: Thanks for the tip. I found a video by the gentleman that designed it.TimFox: Yes just bump up the frequency. I hear you. It is already in the works. The fiber data receiver board for 2 10 MHz clocks also has a true fiber Y mixer to heterodyne the solid state laser carrier. This is done to verify that both the crystal clock and the laser carrier are experiencing the same time dilation at 5 K volts. Two different types of clocks , crystal / laser , experiencing the same time dilation is central to the credibility of VEPS project. If that sounds complicated it is not. I should take a picture of it and post it here. One glance and you will see how simple it is . The real devil is in the details.

author: uncle_bob
author_rank: Unknown
timestamp: February 09, 2016, 12:30:41 pm
content: Quote from: dannyf on February 09, 2016, 12:12:24 pmHiOver any practical time interval, the data does show as phase deltas. There is not going to be enough time to count this out as full cycles. If you want to look directly at the phase, a DMTD setup is one way to do that.Stability wise, it's just a matter of having the budget. There is no technical limit in that area.Bob

author: uncle_bob
author_rank: Unknown
timestamp: February 09, 2016, 12:43:55 pm
content: Quote from: John Heath on February 09, 2016, 12:18:59 pmHiThat is a very brief tour of part of what the box will do. There is a *lot* more in there (frequency, phase, ADEV, MDEV, TDEV etc) that are likely more useful than a straight phase noise measurement. I'm sounding like a sales guy ... sorry about that. The main value of the box is that it is at the low end of price range for that sort of box. They all are "ask for a quote sort of things. You can expect prices start around $10K (but who knows ...) and run up well past $150K for various boxes with this or that option.Bob

author: John Heath
author_rank: Frequent Contributor
timestamp: February 12, 2016, 11:53:55 am
content: Quote from: TimFox on February 08, 2016, 09:05:27 pmHi TimGood stuff and cool link. This is similar to the Pound–Rebka experiment. They used a speaker for a hint of doppler effect to detect time dilation. As my experiment will be held to rather high standards I appreciate your constructive criticism. Better to hear it from you now before publishing.https://en.wikipedia.org/wiki/Pound%E2%80%93Rebka_experimentAs to the second clock to compare there is an identical crystal oscillator that is kept at ground to compare with the Faraday clock. I did not feel it was necessary to have it in a Faraday cage but now that you bring it up it would not hurt. Most of the time the ground clock insin the freezer -10 C to shift its frequency up for a heterodyne difference frequency of 50 to 100 Hz. This puts it in range of my frequency counter that will resolve it down to 80.000,000 Hz. The last 2 zeros is the target for 10 uHz measurement. So far I am not even close to this target with stable reading in the 10 mHz range. By changing from a fiber Y mixer to a XOR mixer 20 DB gain in noise was achieved. This is not enough so it is more pacing the floor. power supply Ripple at 60 Hz is eliminated by using 9 volt rechargeable batteries then a 7805.To address your larger concerns with overall concept. Why would a voltage frame of reference cause time to dilate? If Coulombs law is applied to the letter to a system then there as to be a net expansion of that system if there is a charge parity. Charge parity being number of + and - charges in a system. A bag of 10 - charges. It wants to expand. A bag of 10 + charges . It wants to expand. A bag of 5 - and 5 + charges . It wants to contract. A bag of 4 - and 6 + charges. It want to contract but not as much as 5 - and 5 + charges. From this a statement can be made that charge parity will cause expansion. If I expand the size of a clock it will tick slower to conserve momentum. By combining Coulomb's law with momentum conservation laws time should dilate if there is a offset in charge parity. The Faraday cage at 5 K volts is offsetting charge parity therefore the clock should change in frequency. This was theoretically predicted in around 1930 as an alternative to general relativity's metric tensor.They were more concerned with event horizons and stuff like that but the basic idea was use Coulomb's law not the relative inertia of the system. I can did that link if you would like to have a look at it. I see by my clock that it is 1/4 to 7 . Another day starts.

author: dannyf
author_rank: Super Contributor
timestamp: February 12, 2016, 12:18:50 pm
content: QuoteI guess the question is how "identical" is this "identical" crystal oscillator is? is it sufficiently identical that allows reliable measurement of such small shift?QuoteIs momentum really conserved for the kind of study? For example, when an object moves through space/time where momentum is conserved, is its energy conserved too?

author: uncle_bob
author_rank: Unknown
timestamp: February 12, 2016, 12:42:34 pm
content: Quote from: dannyf on February 12, 2016, 12:18:50 pmHiIF you run a nice periodic AC signal as your high voltage, you will modulate the "victim" oscillator. All you really need to do is keep the reference oscillator from being modulated at the same time. Run the signal for a long time. Let any of the measurement gear take data. Once you have the data, very standard techniques can narrow down the bandwidth. The noise goes down as the bandwidth decreases. The signal stays the same.On a practical basis, you likely need a slow sine wave. That equates to a fairly long test period. All of the techniques work the same way. It's done every time you flip on a GPS and get a signal.Can you measure the effect? yes. Is it there in the first place? I'm still skeptical. The Nobel prize for this year appears to have already been won. You might consider putting off until next year.Just for reference, take a look at what sort of resolution they ran for the gravity wave experiment. The target here is massively easier to hit.Bob

author: John Heath
author_rank: Frequent Contributor
timestamp: February 13, 2016, 12:09:16 am
content: Quote from: dannyf on February 12, 2016, 12:18:50 pmHi DannyfHow identical are the two clocks. Not very identical. At room temperature for both crystal oscillators they are off by about 20 CPS. As room temperature changes by 5 C they can be off by as much as 15 to 25 Hz. Their temperature coefficients do not seem to be matching. However electrically they are identical with the same 7805 regulator , 9 volt rechargeable battery and layout on a small prototype board. . I posted a picture of one of the clocks. The other one in the Faraday cage is the same design. However you asked if it will allow for such a small measurement. The answer is I am not sure. The oscillators only have to be stable for 10 seconds as this is the rate that the Faraday cage changes voltage from ground to 5 K volts. Is this enough with jitter noise and thermal drift for a 10 uHz. Not sure but having a lot of fun trying.Is energy and momentum conserved. Good question. Energy conservation is a given as there is no free lunch for energy. Free energy is not possible , a big no no in physics. Is momentum conserved. All tests so far say yes. A spinning top is a good example. Is the top spinning relative to itself or the universe. Mach , the gentleman that Mach speed is named after , says yes it is relative to the entire universe. It seems he is right as strange as that sounds. This again comes from many tests made. Like they say you can not fight the numbers.Thank you for taking an interest in this.

author: nctnico
author_rank: Super Contributor
timestamp: February 13, 2016, 12:44:10 am
content: IMHO it all comes down to filtering the noise from your data and see if the rate at which you change the high voltage pops up above the noise floor. I'd try and use much better crystal oscillators and regulators though to reduce thermal influences and noise.

author: dannyf
author_rank: Super Contributor
timestamp: February 13, 2016, 01:34:49 am
content: QuoteThe question you will need to ask here is that are those regulators "identical" to at least 10uHz / 10Mhz? Otherwise, they are NOT identical for purpose of yours experiment.QuoteYou may not assume to fast: think of red shift (aka photons through a gravitational field). is energy conserved there?When we are talking about extremes (tiny space or huge distance), what we usually take for granted may no longer be true.

author: dom0
author_rank: Super Contributor
timestamp: February 13, 2016, 01:42:50 am
content: Conservation of energy in ART doesn't really makes sense, since it's a purely local phenomenon iirc.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 13, 2016, 01:43:48 am
content: Quote from: uncle_bob on February 12, 2016, 12:42:34 pmHi BobWell done. I know exactly what you mean. This would have a far better signal to noise somewhat like fine tuning a AM radio to one precise frequency.You are skeptical and you should be as nothing has shown up yet. I log the data on a PC that can run all day. so far all I am seeing is big changes as the ambient temperature goes up and down . There is also a change of 1 cycle per second at 10 MHz that is synchronized with 5 K volt change. This is 100,000 times greater than it should be so clearly a mistake has been made. I suspect a small voltage gradient in the inner Faraday cage effecting the 5 volt regulator. The fiber cable leaving the inner Faraday cage has a voltage gradeint for sure so mabe more attention has to be payed to it. It can not be the crystal oscillator as it is in a hermetically sealed in a tiny metal box. That box is ground that is directly connected to the 5 K volt source.You brought up gravity waves. I heard on the news they hit paydirt. Gravity waves detected for the first time in history.

author: uncle_bob
author_rank: Unknown
timestamp: February 13, 2016, 01:44:59 am
content: Quote from: John Heath on February 13, 2016, 12:09:16 amHiIf you intend to simply measure one OCXO against the other, and not do a "delta" measurement, you will need a pair of hydrogen masers rather than OCXO's. You gain a *lot* with a modulated HV setup.Bob

author: TimFox
author_rank: Super Contributor
timestamp: February 13, 2016, 02:45:55 pm
content: One advantage to my suggestion to use the Mossbauer effect is that all Co-60 nuclei are completely identical, as no electronic components could be, and have negligible (if any) tempco.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 15, 2016, 06:54:00 pm
content: Hi BobI hear you. Hydrogen masers are a little out of my league. Afraid I will have to stick to crystals oscillators. I hear GPS disciplined oscillators are hitting the eBay market in the 100 dollar range , maybe?? One poster said he unplugging the antenna of such a devise and it stayed withing 4 mHz for hours compared to an atomic clock Hmmm. Rather impressive. Maybe I should start doing science instead of just talking about it and buy one of these GPS disciplined clocks. In for a penny in for a pound sorta speak. Being a 66 year old fart the time to be real is now not later.

author: uncle_bob
author_rank: Unknown
timestamp: February 15, 2016, 08:00:06 pm
content: Quote from: John Heath on February 15, 2016, 06:54:00 pmHi.... ok time for a mandatory disclosure ... I design GPSDO's for a living ...There is no advantage to doing this with a GPSDO compared to a couple of OCXO's.Bob

author: John Heath
author_rank: Frequent Contributor
timestamp: February 16, 2016, 04:40:04 am
content: You design GPSDOs , cool. I would like to tax you on some of the details of this especially the GPS interface software. For now you are saying a oven controlled crystal oscillator is all I need. I have 2 frequency counters both with oven controlled oscillators. An old Nixie tube Heath Kit model IB 1102 and a spify new Victor VC2000. Both have oven controlled oscillators. With a little fiddling I could bring a buffered sample of these oscillators out the back. The inner Faraday cage will have to be enlarged and 2 amp hour dry fit battery with car 12 volt to 120 AC adapter to keep the VC2000 running. No way with the Heath kit 1102 as that one is in the 40 to 50 watt range. Why did I not think of this before. Use the frequency counter OCOXs. There is a third virtual frequency counter app on my Samsung Android phone. Best frequency counter money can buy , free actually , but it is limited from 30 Hz to 20 KHz. However it makes up for this with by measuring 40 Hz or so down to 40.000,000 and stable provided the phone is not charging. This means that the Heath Kit and Victor OCOXs have to be offset from each other by at least 40 Hz. The crystal trimmers should have that much range on them. I have a good feeling about this. This will take days so please go on about GPSDOs. How did you get into this ? How hard are they to make? How does the GPS interface software translate into 1 pulse per second? Spare no details.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 16, 2016, 05:22:18 am
content: Quote from: John Heath on February 15, 2016, 06:54:00 pm

author: uncle_bob
author_rank: Unknown
timestamp: February 16, 2016, 06:13:48 pm
content: Quote from: John Heath on February 16, 2016, 04:40:04 amHiOk, well, first you will need some good state of the art OCXO's. You will spend some time shopping for them on eBay and sorting out what you get.. You have the option of either buying a few dozen and sorting to get one or buying a couple (at a much higher price) and sorting to get one. Either way it's a time and labor intensive process. You could also go out and buy a couple brand new with all the bells and whistles. That's likely to be an even bigger hassle (and could run you $10K to $20K each, just for the OCXO's).There is no way to make the measurements with sufficient accuracy with the gear you have described. You will need to buy some much better instruments. You need to measure to 1x10^-13 at 1 second. The video you posted earlier shows an instrument that does this. There are others. In terms of cycles that would be 0.000001 Hz in one second. (unless I fat fingered a zero) Think of it as a frequency counter that displays 14 digits and they all read nice and solid.I'd budget something in the $10 to $30K range to get the project going.Bob

author: Vgkid
author_rank: Super Contributor
timestamp: February 16, 2016, 09:53:05 pm
content: This has gotten interesting.Subscribed.

author: DimitriP
author_rank: Super Contributor
timestamp: February 17, 2016, 04:23:17 am
content: QuoteWhen I started being in the market for an OCXO (once in the market, you are always in the market!)the most expensive/stable one I found on Digikey was for around $1800it goes like this:$1783 0.1ppb$1222 0.2ppb$759 0.5ppband then once we get into the economy units it's all downhill from there ....$305 10ppbso what's the stability of a $10K-20K OCXO?

author: Vgkid
author_rank: Super Contributor
timestamp: February 17, 2016, 06:09:16 am
content: Quote from: DimitriP on February 17, 2016, 04:23:17 amOne of these would work, Rakon HSO14. Since the OSA BVA has been discontinued.http://www.rakon.com/products/families/download/file?fid=39.276I see they have a HSO13. * I got sick to my stomach seeing that appear. I will explain later.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 17, 2016, 10:54:37 am
content: Hi GuysTo sum up .1 ppb 1700 bucks 10 ppb 300 bucks . and secondly the equipment I am using is not up the the task of 10 uHz at 10 MHz.I am going to use a heterodyne strategy to reduce the resolution of a 1X10^-13 test down to 1X10^-7 test. Keep in mind I am not sure , only guessing. Any opinions on this , thumbs up thumbs down , would be much appreciated.!] The rate of change from 0 to 5 K volt frame of reference is 10 seconds so stability down to 10^-13 only needs to last for 10 seconds2] The two 10 MHz reference oscillators are off by 40 Hz then heterodyne together for a beat frequency of 40 Hz. What was 10 Mhz to 10 uHz test is now a 40 Hz to 10 uHz test or 10,000,000.000,010 test to 40.000,010 test.The burning question is will this work. Theory one thing but application another. Is this a pipe dream or could it work. The heterodyne mixer is a XOR gate followed by a R/C low pass filter of 20 K resistor and .1 uf condenser to ground. So far test results really suck with with too much noise reducing measurements range to 10 mHz. It has to improve by a factor of 1000 for 10 uHz.Best guess. Is there any point in continuing with the 40 Hz heterodyne strategy?

author: dannyf
author_rank: Super Contributor
timestamp: February 17, 2016, 12:23:02 pm
content: QuoteYou are measuring phase differentials - see my post on this earlier - not frequency differentials. those ppb/ppm figures are for long-term frequency stability, not phase stability.QuoteScientific research is not just trial-and-error. You have to have a theory on why you should expect some differences and then you can design an experiment to show such differences.

author: uncle_bob
author_rank: Unknown
timestamp: February 17, 2016, 05:52:38 pm
content: HiThe proper term for the heterodyne you are attempting is a single mixer time difference system. A somewhat better approach is a dual mixer time difference system. If you dig into the NIST archives, they have a number of papers on all this.The weakness of either approach is the limiter that turns the sine wave out of the mixer into a square wave in the counter (or external to it). Noise in this process quickly overwhelms the measurement accuracy.If you want to go this way, you probably would do better to design, build, and validate a DMTD system.Bob

author: John Heath
author_rank: Frequent Contributor
timestamp: February 20, 2016, 04:29:33 pm
content: Quote from: dannyf on February 17, 2016, 12:23:02 pmHi DannyIn a mood to write so apologies in advance for longer than necessary answers.As to frequency vs phase measurement. I hear you. This brings to mind Edwin H. Armstrong inventor of FM radio. His first commercial FM broad cast station starts as a phase modulated signal. This was to have better control modulation by changing the amplitude of 0 phase vs 90 phase . This would then go through several resonate frequency multiplying stages with the end result being a 47 MHz frequency modulated broadcast . This would later become television IF and FM radio pushed up to 100 MHz. From this we could say that the difference between phase modulation and frequency modulation depends only on the period of time the measurement is made. A measurement of 1 cps made in .1 seconds would be a phase difference. A measurement of 1 cps over 10 seconds would be a frequency measurement. A frequency difference measurement to resolve 10 MHz down to 10 uHz would require a measuring time period of 2 days to qualify as a frequency measurement as you rightfully pointed out.This being said it should be noted that frequency counters have change as technology has advanced. My frequency counter says 400 Hz is 400.000138 Hz with a sample time period of 1 second. How is this possible? Old school frequency counter would say 400 Hz. New frequency counters take advantage of microprocessors to combining both frequency and period measurements and combine these to measurements for best result resolution. The end result is constant resolution regardless of frequency therefore 400 Hz measured over a period of 1 second reads as 400.000138 Hz not 400 Hz. That particular measurement required a 100 second averaging so the real number number is 400.0001 Hz and fluctuating up and down in the 1 mHz range. So close and yet so far.As to theory and why I would expect an oscillator to have a voltage coefficient frame of reference. When developing a theory there comes a time when the theory starts to write itself. At this point you find yourself in the back seat while the theory drives the car. I have come to personify this theory as Mr VEPS and I can say that his driving skills leave room for improvement , somewhat like a bull in a china shop. However after the pieces are glued back together he is within the limits of empirical evidence. In short it is out of my hands as I am in the back seat at the moment. He is insisting that relative size of a system not the relative inertia will cause time to dilate and that the relative size is changed by charge parity. The only way to remove Mr VEPS from the drivers seat is to test for a small change in time caused by a change in voltage framer of reference , 5 K volts. If it has a negative result I can kick him out of the drivers seat and take back control. If the results are positive I will be stuck in the back seat again. The back seat is not as bad as it sounds. Just sit back and enjoy the ride with no responsibilities.In summary new frequency counters appear to be within range for this measurement , just in range. The real problem is jitter , hydro hum , IC noise , 5 volt regulators and probably a few more that I am not aware of. And the theory that makes this prediction , bad driver Mr VEPS , is also in place. All that is left is a solid measurement for a thumbs up or thumbs down.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 20, 2016, 05:57:42 pm
content: Quote from: uncle_bob on February 17, 2016, 05:52:38 pmHi BobI am in a leaning curve for precise frequency measur4ement as you can tell so I appreciate you taking the time to help myself through this. I can confirm you position that a sine wave is better than a square wave. My main frequency counter comes with a biult in oscillospope to eye ball the input. If I over drive a sine wave into a square wave the readings become unstable in the mHz range. If I back off the gain to the origenal sine wave the rerasding are more stable. This seems counter intuitive but test results comfirm your position that sine wave is better than overr driven square wave. This is good to know but I feel a little uncomfortable not knowing why. Not knowing why will always bite you in the end if it is not nipped in the bud. e a sine wave . If you could expand on why a over driven sine to square wave is less stable. From my shoes a clean and decisive high slew rate up and down should be more stable and yet it is less stable as you said?As to DMTD . This one googled up nicely. I found a nice link that included a diagram. Somehow diagrams get the point across in a way that words can fail. A common language understood in all languages.Link to DMTDhttp://www.wriley.com/A%20Small%20DMTD%20System.pdfThe money shot , the diagram.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 20, 2016, 08:38:52 pm
content: Hi Bob againStill getting use to picture attachment that caused a premature posting.As you can see from the diagram it is a isolation transformer with a full bridge rectifier followed by band pass filters for side band analysis. As my coupling is fiber the isolation is already there. A 1n GHz full bridge diode mixer , TUF R3SM , is over kill so I should get by with a 74hc4066 quad FET switch driven by the reference oscillator as a full bridge mixer. Maybe another 6 to 12 DB reduction in noise?? I can hear you banging your fist on the table as I speak these words. I know it is a reference oscillator square wave that spells trouble from your post. Then again is there a difference between this DMTD class D chopping a bridge rectifier mixer and my proposed 74hc4066 bridge mixer? It will only take a day to prototype it and give it a run.Not sure what a dual mixer time difference system is without digging into the NIST archives. Will speak to it later.A plan B which deals with software interface4 with GPS satellites. If a corona bust comes from out sun the earth it will be sprayed with electrons and protons. Our earth's magnetic field will cause electrons to go right and protons to go left. This means GPS satellites on the right will be in a positive voltage framer of reference and left in negative. As a GPS satellites receiver will average out information from all satellites it can receive it will make a best guess from data it has to my position. If I had access to individual GPS satellite gdata as to my distance from that satellite then a very precise assessment can be made of any change to time dilation of that satellite by comparing east to west GPS rendering of my position. Not sure if my meaning survived the translations into words. To state this in another way. If all east satellites say I am 2 feet east off my real position and all west satellites say I am 2 feet west of my true position when a corona bust from the sun hits the earth then there is a second confirmation that voltage frame of reference will change time dilation. It is for this reason that I have a keen interest in software interface with GPS satellites to gain access to this information. Is there a way to receive raw untouched information from GPS satellites and display it on a computer screen??

author: uncle_bob
author_rank: Unknown
timestamp: February 21, 2016, 12:40:40 am
content: Quote from: John Heath on February 20, 2016, 08:38:52 pmHiSure you can. As long as your desk is above the ionosphere you can get things done pretty easily. The same solar burst that gives you the sudden electron flood bumps the ionosphere and you get a delta delay of (maybe) 50 ns. At 1 ns per foot, that is about a 50' jump. Indeed you can take that down to 10 or 20 ns, but doing so involves processes that would take out the GPS jump.Bob

author: uncle_bob
author_rank: Unknown
timestamp: February 21, 2016, 12:52:03 am
content: Quote from: John Heath on February 20, 2016, 05:57:42 pmHiIf you are an IEEE member, there are a few papers behind their pay wall that dig into all the details of turning slow sine waves into square waves. The square wave is indeed more stable into the counter than the sine wave. The details are all in how you turn the sine wave into a square. With a "high gain" down converter, the sine waves will always be slow / low frequency. Limiter design is not simple.Drive into a good mixer (diode ring) does not really matter sine vs square. If both are done correctly they can work equally well. Again the key word is correctly.To get to the levels you are after, JPL can barely do it with all of the right parts. Substituting other "stuff" is likely to degrade things by 10 to 10,000X. There really isn't a shortcut when it comes to the parts you need to use.Looked at like a radio:You are trying to receive a 2 KHz wide sideband signal at 0.05uV and get 20 db s/n. You can indeed do it. Doing it with just any radio and any preamp hooked up any which way.... not going to happen.These are not toss it together measurements. They require either high quality commercial gear or stuff built with a through understanding of all the issues.Bob

author: John Heath
author_rank: Frequent Contributor
timestamp: February 21, 2016, 08:07:26 pm
content: Quote from: uncle_bob on February 21, 2016, 12:40:40 amYes I see your point. From what I google changes in the ionosphere alter the path the RF signal. Putting my lab bench above the ionosphere would exceed my budget , ha. Thanks for the input.I will post a picture of my super frequency counter. It is free to anyone with a android phone. Would like to know what you think of it.

author: DimitriP
author_rank: Super Contributor
timestamp: February 22, 2016, 02:32:09 am
content: I'm partial to the Function Generator ...

author: jpb
author_rank: Super Contributor
timestamp: February 22, 2016, 09:09:23 am
content: Quote from: uncle_bob on February 21, 2016, 12:52:03 amI am trying to improve my Alan Deviation measurements with such an approach and the paper that I've found most useful (because it is simple) isZERO-CROSSING DETECTORWITH SUB-MICROSECONDJITTER AND CROSSTALKhttp://www.dtic.mil/dtic/tr/fulltext/u2/a515384.pdfI've not built anything yet so I can't comment on difficulties, but my direct measurements of the output of a mixer and the DDS output of an Agilent 33522A with the same 10MHz as a reference input are in good agreement with a crude calculation based on slope and typical counter noise of 300-500uV. The sin output is around 130mV peak at 1Hz so the slope is around 0.8V/s so noise of say 500uV gives an uncertainty of 6E-4 seconds and, surprisingly to me, my measurements on my cheap counter are slightly better than this but of the right order of magnitude (noise floor around 1E-11 i.e. 1E-7 gain in going from 10MHz to 1Hz and then 1E-4 measurement noise in measuring the 1 second period).My plan is to follow a similar scheme to the paper and try and improve the slope by a large factor without increasing the noise significantly. I guess that I will discover all the other noise sources in the system on the way but it will be interesting to find out.

author: PointyOintment
author_rank: Frequent Contributor
timestamp: February 22, 2016, 05:13:18 pm
content: Quote from: John Heath on February 12, 2016, 11:53:55 amI would think this would require all components of the oscillator, or at least the crystal element, to be at 5 kV as well as the cage. Not being directly connected to the cage will cause their voltages to not track the cage's voltage well, I think.Quote from: John Heath on February 21, 2016, 08:07:26 pmInfuriatingly skeuomorphic.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 22, 2016, 10:48:38 pm
content: Quote from: DimitriP on February 22, 2016, 02:32:09 amYa his function generator is a step above as well. He seems to raise the bar with everything he touches. His name is Dr Owen Thomas from the UK. The days when PC virtual test equipment is considered to be a cheap substitute could be coming to an end. Much like digital cameras took over film with the purest and their chemicals kicking and screaming all the way.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 22, 2016, 11:20:43 pm
content: Quote from: PointyOintment on February 22, 2016, 05:13:18 pm

author: John Heath
author_rank: Frequent Contributor
timestamp: February 23, 2016, 12:30:35 am
content: Quote from: jpb on February 22, 2016, 09:09:23 amI saw a clever design in a electronic organ. Take the frequency of interest and use it as a clock driver for a bucket brigade delay line , comb filter. This indeed will get us into trouble if the signal to noise is too high breaking down to chaos. On the bright side if the signal to noise is small enough the signal to noise will be much improved. A balancing act on the bubble between chaos and improved signal to noise. Have a diagram of it.

author: uncle_bob
author_rank: Unknown
timestamp: February 24, 2016, 11:56:05 pm
content: Quote from: jpb on February 22, 2016, 09:09:23 amHiWith any reasonable offset frequency you will get to about 1x10^-11 with that circuit.Bob

author: jpb
author_rank: Super Contributor
timestamp: February 25, 2016, 06:43:02 pm
content: Quote from: uncle_bob on February 24, 2016, 11:56:05 pmI am hoping to get below 10^-12 as I'm getting around 1E-11 without the circuit (i.e. directly feeding the mixer output via a LPF to the counter) - but perhaps we're talking at cross-purposes. I'm taking a figure averaged over 48hrs of measurements not a one-shot measurement value. (That is I take measurements every second and then average (f1-f0)^2 as per the ADEV expression).The authors of the original paper were getting below 10^14 (sub microsecond on the 1 second intervals plus 10^8 on mixing down from 100MHz).But as I said, I've not yet built anything so it is very premature to set myself targets other than just a general improvement on what I currently have.

author: uncle_bob
author_rank: Unknown
timestamp: February 26, 2016, 12:15:00 am
content: HiIf you are using OCXO's for this, they will not hold anything close to 1x10^-11 for 48 hours. That's in an absolutely perfect temperature stable environment. The only practical way to do it is with something that gives you resolution in a second and cycle the high voltage at something like a 10 second per cycle rate. If you slow things down cycle and reading wise, you need to get much better standards (Cesium Atomic clocks or Hydrogen Masers). For a 48 hour setup, the 5071's at ~$75K each would be a lower cost approach.Bob

author: jpb
author_rank: Super Contributor
timestamp: February 26, 2016, 07:20:02 pm
content: Quote from: uncle_bob on February 26, 2016, 12:15:00 amWe have perhaps been talking at cross purposes - I realise that I've perhaps gone off topic from the original poster to the general problem of zero crossing and Alan Deviation measurements. I have no budget or plans to try and acquire an oscillator stable to the degree you mention, only to try and get the intrinsic noise of my setup down when measuring a reference against itself. I've been measuring rubidium references against each other.It would be nice to have a Hydrogen Maser though

author: John Heath
author_rank: Frequent Contributor
timestamp: February 28, 2016, 12:22:25 pm
content: Hi jpbThere is an alternative method to jitter , noise and frequency measurements by separating the measurements into three parts to avoid 75K , ouch , for hydrogen masers. In my case frequency is the only measurement of interest. Old school TVs found a way to separate noise from frequency for horizontal sync by using high Q resonance with only a 2 to 5 percent composite video sync injection. By doing it this way a 25/75 noise to video ratio could still sync up horizontal scanning rate. I use the same method by a 5 percent coupling of both oscillater inputs to 10 MHz crystals tuned to a slightly lower frequency. 90 % of jitter and noise information is lost. However signal to noise is much improved for a frequency measurement. In your case jitter and noise measurement could be a higher priority. For this a phase detector between high Q resonant crystal and oscillator source would improve jitter and noise measurements but frequency information would be lost. In summary by sacrificing jitter and noise information frequency measurement is improved or by sacrificing frequency information noise and jitter information is improved.Related to this in an odd way is energy conservation laws. In physics there is a growing seed of information theory that has gained the status of energy conservation laws. Both energy and information follow the same conservation laws. There are examples where you can slip nature a few bucks under the table to look the other way to violate energy conservation laws. The currency of this less than ethical exchange is energy today with an IOU note for energy tomorrow. Neutrino e/m/tau flavor oscillation is an example of it. As information laws are tracking energy conservation laws the same exchange can be made with nature to give her jitter and noise information in exchange for greater fidelity in frequency information or the compliment of that.To date information theory from physics has not ventured into electrical engineering. If you were to apply information conservation laws to improve noise and jitter measurements it would be a first. I smell a paper here that could be a feather in your cap.

author: jpb
author_rank: Super Contributor
timestamp: February 28, 2016, 02:03:55 pm
content: Quote from: John Heath on February 28, 2016, 12:22:25 pmI guess quantum tunneling is another example of this (you could look at it as "borrowing" energy to get up and over the barrier rather than "tunneling" through it).And of course Heisenburg's classic principle. Though much of this comes down to Fourier Transforms and the fact that if you localize something in one domain (e.g. time domain) then it is uniformly spread out in the other domain (such as frequency).At present I'm too ignorant to fully understand exactly what I'm measuring in terms of whether it is changes in frequency (frequency modulation) or better looked at as jitter. I must admit to not fully understanding your post.I remember a few years ago reading that there was some discussion in the physics community regarding black holes and conservation of information as information is apparently lost if light can't escape. I think the conclusion was it all was retained in the event horizon - I know nothing about black holes but this is the gist of what was reported in the popular press.Fascinating stuff but way off topic!Quote from: John Heath on February 28, 2016, 12:22:25 pmI thought information theory started with electronics rather than physics (Shannon)? Though I have a background in academia and research it is no longer my day job so I do this stuff just for fun - the OP sounds more serious though.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 28, 2016, 04:31:48 pm
content: Measuring 10 MHz down to 10 uHz or your efforts to improve noise and jitter measurements is all about information theory. This is not off topic rather on topic. Claude Elwood Shannon. Glad you put him on the table as it leads to great googling that I am still enjoying. I can see from Wikipedia that he is using entropy as his foundation. I would add that just 5 years ago Dr Susskind raised the bar yet again to say information equals energy. From this he calculates the precise diameter of a worm hole between to black holes. A little over my head but he makes his reasoning is clear , energy = information = surface area of an event horizon. This way one does not use information when it falls in as it is still there stuck on the outside surface frozen in time. So historically it starts with thermodynamics , entropy , statistical thermal dynamics , entropy = organized vs chaos , energy = degree of organized and the last kick at the can information = energy. There are different ways to connect the dots as there were so many bright minds that contributed to information theory as it stands today.In your case of over driving a full bridge mixer with a high slew rate you have lost symmetry information. By this I mean was it a pulse or a square wave? That information is lost and the only way to gain it back is to divide by 2 returning to the symmetry of a square wave. However in doing this frequency information is 1/2. However with over driven high slew rate jitter is easier to measure just by syncing it on a scope and eyeball the right side of the scope. In this case information of symmetry was lost but jitter information was gained. Information theory applied as an energy conservation law is starting to show itself in this example. Most of us already know this intuitively but when it is stated as a law then a greater confidence can come from it to try new ideas.In my case I look for ways to lose jitter and noise information with a blind faith that nature will provide more frequency information in exchange for jitter and noise. A practical application of this in my case is to take a 36 Hz beat frequency between test and reference 10 MHz oscillators and frequency multiply 36 Hz by 1024 to 36 KHz with a 74hc4046 PLL and a 74hc4040 ripple counter. Results so far are miserable but faith in information theory says it should work. It is just a matter of fiddling with the pedestrian details of getting a 74hc4046 to do what the spec sheet says it will do.As to your distinction between jitter and frequency. For my 2 cents I do not see a difference between jitter and random frequency modulation. It is more the source of the noise than the technical classification of the noise. I hope my ambiguous response puts a smile on your face knowing I have no idea either.

author: uncle_bob
author_rank: Unknown
timestamp: February 28, 2016, 04:47:02 pm
content: Quote from: John Heath on February 28, 2016, 04:31:48 pmHiPrecise frequency measurement is a heavily studied area. If you dig into the NIST archives, they have at least 50 years of papers there on various approaches. They also have far more papers on the statistics associated with these measurements that you would ever care to read. Their archives are nice simply because they are free to access. They represent < 10% of the studies in this area.When you talk about an oscillator (or frequency source) in a precise way, you use things that have exact definitions. ADEV is one of those terms. It's whole reason for existing is that back in the 60's they needed a number that was precise as opposed to the other odd ways of describing things. The gear to measure ADEV is the same thing you need to use to measure your two oscillators. The techniques you are proposing have been in use since at least the 1940's in various forms. HP produced and sold pre-built setups that did these things starting in the mid 70's.You can indeed re-invent this all from scratch. That's fine and it can be a lot of fun. You can build up this and that to see what happens. If the target is the original experiment, that sounds like a pretty long many years of detour. If the objective is to simply keep busy, it's as good as anything else to do. I'd suggest starting by breadboarding a single mixer setup and seeing what you get. Then try to optimize it for better performance.What isn't quite in the cards is to have others read a few hundred papers for you and summarize each of them to you step by step. That's going to get really old really fast. Also, much gets lost when that sort of thing is done. You never really get the understanding that is critical to getting the whole system to work. It's like a tech who has a repair manual to follow, but has no idea at all how a system actually works. He can fix a broken system. He will have a very hard time building a system from scratch.Bob

author: John Heath
author_rank: Frequent Contributor
timestamp: March 21, 2016, 05:23:26 am
content: First of all to the many who have responded thank you. The advise given leads to a redesign and fine tuning to resolve 10 MHz down to 10 UHz. Resolution is now 10 mHz ,, sort of . Still off by a factor of 1000 but it is the direction that counts. An odd spectrogram observation is made that I find myself taxed to explain. Perhaps someone else has seen this and would know what it is.The test set up:Two 10 MHz oscillators with a hetrodyne beat frequency of 3390 Hz . The focus of the spectrogram is the 3390 Hz beat frequency. The beat frequency is drifting at about 1 Hz per second every 2 seconds or so. The problem is a close side band that hints there is a way to cheat the system. Cheat in the sense of having more information than one deserves. The frequency change in the side bands 3390 Hz is 100 fold greater in delta frequency than the main frequency. Them question is why and what is causing it to be there. It is my hope that someone has seen this in side bands and can explain why it is there.

author: uncle_bob
author_rank: Unknown
timestamp: March 26, 2016, 09:55:43 pm
content: Quote from: John Heath on March 21, 2016, 05:23:26 amHiOne of your OCXO's has a component in it that is oscillating ... It could be a regulator,or the oven controller, or a buffer amp or something entirely different.Bob

author: John Heath
author_rank: Frequent Contributor
timestamp: March 27, 2016, 08:57:44 pm
content: Hi BobI touched one of the crystal oscillators to heat it up a pinch to lower it by a cycle or 2. The side bands tracked the frequency change but 100 times greater than the crystal frequency change. I know this is grabbing at straws but if 2 more zeros of resolution can be made from side band information then so be it. I have a few 74hc390 and a 74hc4046 to multiply the hetrodyne beat frequency. Something in then rattling and niose of these gates is causing it. Higher harmonic of a the main square wave beat frequency maybe? I am starting to appreciate your input on the magnitude of this measurement. From only 10 MHz 10 mHz is jumping around like a jelly bean. That is 1 percent of 1 cycle per second of 10 MHz. Surely there is a way to increase stability beyond 10 mHz. I have separated the 74390s and 4046 multiplier from the mixer board in the hopes of cleaning it up a bit. Also added a graphic EQ to clean up the beat frequency back to a sine wave. Between these two changes possibly a stable 1 mHz reading can be made. The inertia added to the 4046 PLL for the voltage controlled oscillator is 1 M with 500 U.f. condenser. It takes a good few minutes to creeps up to the target frequency. How could that kind of ineria be jumping around like a jelly bean at 10 mHz. That is a rhetorical question. I am just ventilatingThanks for your interest and I took note of your caution on GPSDOs bought on ebay from another thread. Will need one eventually so it is good to know.

author: uncle_bob
author_rank: Unknown
timestamp: March 27, 2016, 09:20:54 pm
content: Quote from: John Heath on March 27, 2016, 08:57:44 pmHiGrab a couple of YIG oscillators and phase lock their 20 GHz outputs to your 10 MHz OCXO's. You will need some microwave dividers with a good noise floor and an equally good phase detector. Run them into a 20 GHz mixer and you will get a beat note out that moves 2,000X as fast as the 10 MHz note. If you want to go to 10,000X, do it with 100 GHz sources.Now, when you do, make very sure that the close in noise of your PLL is good enough to still be dominated by the noise of the 10 MHz OCXO's. Your microwave sources will be 60 to 100 db more noisy than the OCXO close in. It's that noise you have to keep down in order to still have a good measurement. A multiplication that increases the noise faster than the resolution is easy to do, but not of much use.Once you have the beat note that is clean, you still need to do the digital signal processing on it to come up with the data. The OCXO only is stable enough to see what you want to see if the signal is properly processed.Bob

author: zlymex
author_rank: Frequent Contributor
timestamp: March 28, 2016, 03:29:12 am
content: I can test 10MHz down to 1uHz by a commercial frequency counter.

author: ChunkyPastaSauce
author_rank: Unknown
timestamp: March 28, 2016, 03:53:36 am
content: Quote from: zlymex on March 28, 2016, 03:29:12 amTime to upgrade

author: uncle_bob
author_rank: Unknown
timestamp: March 29, 2016, 11:35:22 pm
content: Quote from: ChunkyPastaSauce on March 28, 2016, 03:53:36 amHiAnd you can be sure it's good to 26 digits in a second because pictures *never* lie.Bob

author: John Heath
author_rank: Frequent Contributor
timestamp: March 30, 2016, 12:24:35 am
content: Stanford Research Systems model SR620. This puppy can park itself on my bench any time it wants.Did not know they made a 26 digit model ?? And why would it have not 1 not 2 but 3 mode switches? You can only use one mode at a time so why would there be 3 mode switches almost as if it were 3 frequency counters. This is indeed odd ?

author: uncle_bob
author_rank: Unknown
timestamp: March 30, 2016, 12:43:41 am
content: Quote from: John Heath on March 30, 2016, 12:24:35 amHiSave yourself the trouble. I have a number of them, the only way to get a perfect display like that is to loop back the internal standard. That way the noise on the reference cancels out and you get that display.Yes, there is one other way to get all zeros. It can also be used to expand the display to 26 digits ...Bob

author: KE5FX
author_rank: Super Contributor
timestamp: March 30, 2016, 01:38:34 am
content: Quote from: ChunkyPastaSauce on March 28, 2016, 03:53:36 am

author: danadak
author_rank: Super Contributor
timestamp: March 30, 2016, 11:10:12 am
content: Basic measurement principles, reciprocal counters, etc..https://www.dropbox.com/s/dmnyb69ntfgd3o3/Counters.zip?dl=0Regards, Dana.

author: John Heath
author_rank: Frequent Contributor
timestamp: April 01, 2016, 11:40:23 am
content: I like the PDF on fundamentals of time and frequency standards. Thanks for posting.

author: mrflibble
author_rank: Super Contributor
timestamp: January 31, 2018, 04:16:09 pm
content: Quote from: John Heath on February 28, 2016, 12:22:25 pmInteresting approach. Do you maybe have a rough schematic of how the oscillator and 10 MHz crystals are connected? IthinkI get what you mean, with that description, but not sure...Incidentally, if I understand what you're doing correctly, isn't that more in the realm of clock recovery, and less in the frequency measurement area? What with reducing close in spurs... Also, if I understand the description correctly, aren't you attenuating the lower-than-fundamental-frequency spurs more than you are attenuating the higher-than-fundamental-frequency spurs?

author: John Heath
author_rank: Frequent Contributor
timestamp: February 01, 2018, 01:29:34 am
content: Quote from: mrflibble on January 31, 2018, 04:16:09 pmThank you for taking an interest in this. "more than you are attenuating the higher than fundamental frequency". Well said and I found this out the hard way after building the electronicsMy alternative solution was to use a graphic equalizer on the beat frequency difference between the two 10 MHz OSCs to try and clean it up a bit. It worked sort of down to 100 m Hz , 10 m Hz on a good day but that is a far cry from a 10 u Hz measurement for the difference between the two. The experiment sits on my bench for the last year with my elisions that some day I will fix it . So far no luck.

author: mrflibble
author_rank: Super Contributor
timestamp: February 01, 2018, 06:52:36 am
content: Quote from: John Heath on February 01, 2018, 01:29:34 amI don't know how much this will help you towards your end-goal. But concentrating on the sub-problem"Reduce close in spurs, and reduce them symmetrically", there's a fairly straightforward modification you can try.Get two more crystals that are also detuned, but these two are tuned to a slightly higher frequency. No doubt there will be mismatches in both frequency location and "spur absorbance" (for lack of a better term). But as long as the frequency differences of the fundamental & low detuned frequency is about the same as for the fundamental & high detuned frequency. You can tune out the mismatches to some degree by adjusting the coupling factors and the dissipation factors. Basically adding a few extra Rs & Cs at the relevant locations.If you characterize your 4 detuned crystals in advance, you can even try to make some educated guesses. Then measure and see how well reality matches your predictions, and adjust model accordingly. I have no idea if the amount of extra work is justified because I cannot predict the results, nor can I predict how useful they are for getting you to your end goal. But like I said, if you just want to see if things improve enough if only that darn spur attenuation was symmetrical, this is a low cost way of finding out. Not taking time spent into account for cost, because the idea would be you pay some time, and you gain some insight. Well, at least that's what I always tell myself in those situations.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 01, 2018, 02:17:17 pm
content: I agree. You have to fail to learn. I can control the beat frequency between the two 10 MHz oscillators to around 10 Hz with temperature or 100 Hz if need be by selecting different crystals. The main problem is jitter noise. Both 10 MHz oscillators have 7805 regulated power supplies coming off a 9 volt rechargeable battery to eliminate ground issues. One of the oscillators comes in through a 20 foot toslink fiber cable. This was necessary to burn off 10 K volts dc from the Faraday cage it lives in. I believe most of the noise is coming from the conversion of TTL to fiber then back to TTL. I tried a brute force fiber direct mixer to recover the beat frequency. With toslink fiber this is easy by using a y connector. This has an advantage of 10 MHz beat plus a 500 THz beat of the two fiber red LEDs. The bandwidth is too broad for it to be useful but maybe with match laser type sources it could pan out. Who needs 10 MHz clock reference if there is the possibility of using a 500 THz source , red light . Much better if it can be made to work. It does work for 10 MHz beat but can not find the 500 THz beat frequency. It could be up in the 200 MHz range putting it out of range my scope to see it in FFT mode?

author: mrflibble
author_rank: Super Contributor
timestamp: February 01, 2018, 07:41:33 pm
content: I suspect that going the laser mixer route will open the external cavity can of worms (due to the narrow linewidth requirements). The ever popular project within a project.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 01, 2018, 11:05:31 pm
content: I got it done by pulling one of the fiber connectors out a little from it's normal snap in position. . By fiddling a bit there is a sweet spot where both laser inputs in the Y adapter are making a 50 / 50 contribution. As luck would have it there was enough friction for the fiber plug to stay put ounce the sweet spot was found. A 500 THz mixer , not bad for of the self parts.

author: mrflibble
author_rank: Super Contributor
timestamp: February 02, 2018, 06:25:56 am
content: Oh wait, I think I understand now what your intention is. So you have two separate laser diodes, shine those into separate fibers, have those fibers meet in the middle aka Y adapter. Then one of following two:1) have something happen at "the sweet spot"2) hope that something happens at "the sweet spot"then have photons propagate through some more fiber towards the detector (presumably a photodiode?). Have photons interact with detector. Do clever things with electronics. Watch scope display.Is that a reasonable discription of the signal chain? Because if yes, then I have some bad news. Photons only do cool stuff when the surrounding matter is really convincing. Otherwise they are lazy bastards and will just ignore their fellow photons. Even when those fellow photons are really close at Y-sections. But you should have known that, because hey, boson. Want something more? Hire fermions (electrons).(no photon-photon interaction at the Y-section)

author: John Heath
author_rank: Frequent Contributor
timestamp: February 02, 2018, 02:53:42 pm
content: I understand what you are saying about the boson quantification issue. Photons in itself is quantification in it purest form and there is not much that can be done about it. However in this case it is thousands of photons mixing together so it will average out to our friendly Newtonian world. By using a Y adapter for the fiber acts as an adder to mix the two 10 MHz oscillators. With a little luck it will also mix the two red lasers for the 500 THz frequency difference.My goal is to measure the voltage coefficient of a crystal oscillator. Not the voltage driving the crystal but the voltage frame of reference voltage coefficient. For example when flying in an air plane at 32,000 feet your voltage frame of reference is around +100 K volts. Does a crystal oscillator run at the same speed at 100 K volt frame of reference . This is the question answer. This is the reason for my 10 K volt Faraday cage to change the voltage frame of reference of the crystal every 10 seconds by 10 K volts and test for a small difference. My predicted frequency change is 50 u Hz for a 10 MHz crystal for a 10 K volt change in voltage frame of reference. As you can imagine a 50 u Hz change of 10 MHz is not easy to measure.

author: mrflibble
author_rank: Super Contributor
timestamp: February 02, 2018, 04:28:56 pm
content: I admire your optimism, but that's not what I was getting at.QuoteSnowball's chance in hell. Just no way. But tell you what. If you bought that fiber + splitter at regular consumer prices at the magic emporium, and it does indeed do proper mixing in the fiber, I will buy said fiber by the truckload for double the price. What the hell, make it triple! People have to do actual work with temperature controlled lasers, gratings + control loops just to get lasers that enable that. And after that they have to expend actual effort in getting fiber optics with juuust the right properties. How likely is it that"stick it in at an oblique angle"is a substitute for that?You can even employ logic... What makes the Y-section different from a straight edge of fiber? What makes a photon more likely or less likely to mix in the y-section than a straight fiber stretch? Given these two hints, take the situation of a single laser A, laser B is off. With just laser A in a straight piece of fiber, or the magic y-section for that matter, why would those photons not suddenly selfmix in equivalent circumstances?Because the photons of just laser A passing through the magic Y-section with "properties" have sufficiently different energies that if they were doing what you hope they were doing, then you'd also be able to see that (the selfmixing). And then you would heat/cool the laser, and check if the change in measured signal agrees with expectations for the selfmixing scenario.The 10 MHz beat you are seeing is not photon-photon "mixing" interaction. What you are seeing is the equivalent of this setup:- take photodiode- divide it in left and right part (just for sake of argument, in reality people don't give a shit because same results no matter where you shine)- laser A of some nominal wavelength, use 10 MHz signal to modulate laser A supply current, voltage, whatever really.- laser B of some nominal wavelength, use another 10 MHz signal to modulate laser B supply current, voltage, whatever really.- shine laser A on the left part of the photodiode- shine laser B on the right part of the photodiodeTadaaaaaa, "mixing". For suffiently correct use of the word mixing. In that setup you will indeed be able to see the beat frequency that is the difference between the two 10 MHz signals. But alas, no 500 THz mixer on the cheap.Couple of random links:https://en.wikipedia.org/wiki/Laser_linewidthhttps://en.wikipedia.org/wiki/Tunable_laser#Narrowband_tuninghttps://en.wikipedia.org/wiki/Four-wave_mixing#Applications_of_FWMgoogle this one: "laser diode external cavity wavelength", loads of articles related to one of the required ingredients.or google this: "four-photon mixing fiber". Yes, your hoped for case would be two-photon mixing, but the info density is higher for the 4-photon google.Anyways, Ihopethat makes it clear what you are seeing. If not ...that was my best shot.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 03, 2018, 12:36:11 am
content: Incidentally: for a long time a lot of people believed that independent light sources couldn't produce interference fringes (or coherent RF mixing products -- same thing, temporal rather than spacial). Of course, with no justification for that -- on the contrary, theory clearly predicts such. This is a consequence of belief-based-on-experience versus belief-based-on-proof. Both belief systems have their downsides regarding new information: the experimentalist assumes nothing new will ever happen, except when it does; the theorist assumes that that theory is complete, that nothing new will be added to it.As it turns out, lasers just needed to be cleaned up a little bit. After all, we're talking parts per billion stability here, either to obtain a reasonably clean beat frequency, or to obtain an interference pattern that can be photographed with a high speed camera, if perhaps not observed by eye.Tim

author: John Heath
author_rank: Frequent Contributor
timestamp: February 03, 2018, 12:39:23 am
content: I would call your best shot a double side band in the side pocket. Well done. You put your finger right on the problem. A 500 THz beat frequency is unlikely. It was a quick test so it did not hurt to try. Results were negative in agreement with your thoughts. Why would I even try for the 500 THz beat ? An act of desperation as you never know when god will cut you some slack. Not in this case.It is worse than you think. In order of best to least best fiber cable there is single mode , multi mode and then there is toslink fiber. I am using tosling fiber. It is a standard developed by Toshiba to replace audio cables with fiber. Workable band width is 10 MHz driven by a red LED not solid state laser. On the positive side it is as cheap as dirt. I can buy toslink fiber cables terminated with their plugs at the local dollar store. Toslink TTL to fiber and fiber to TTL adapters are only 30 bucks each. The original reason was to burn off 10 K volts from the Faraday cage. The idea of a 500 THz red beat frequency with Y adapters came to mind later.The 50 u Hz measurement is still out of range. I am only down to 10 m hz range on a good day for a 10 MHz crystal. There is a third option. Increase the voltage frame of reference change from 10 K volts to 200 K volts with a Van de Graph generator. They are on ebay for about 300 bucks. This would change the predicted frequency change from 50 u Hz to 1 m Hz. Still just outside the range of measurement but getting warmer.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 03, 2018, 12:55:01 am
content: Quote from: T3sl4co1l on February 03, 2018, 12:36:11 amA laser interference pattern is what was used to detect a gravity waves. As you say if you clean it up a bit it could be possible for a beat frequency. Air craft navigation laser ring to replace gyros is another example of beat frequency . Interference pattern from a double slit experiment is a third example. As long as there are enough photons for them to average out to a wave.

author: T3sl4co1l
author_rank: Super Contributor
timestamp: February 03, 2018, 02:43:50 am
content: Well, those are all correlated sources (a single laser). You can do that with sunlight, if your experiment has a short enough path length to maintain (spacial) coherence. You can't do it with, say, two separate incandescent bulbs. But you can do it with two independent radio antennas on the same frequency, or two independent lasers tuned to the same frequency.Tim

author: John Heath
author_rank: Frequent Contributor
timestamp: February 03, 2018, 05:18:37 am
content: Quote from: T3sl4co1l on February 03, 2018, 02:43:50 amThe coherence of a red laser pointer is surprisingly high. All photons lined up in phase and polarity 0 degrees. On my red pointer a 90 degree polarizing sheet will blank out the laser to the point that it can not be seen. However if you start to take a closer look at the photon and width it is not as perfect as it seems. The LED photon source that is driving the laser resonate cavity sets the range of photons available. It is the resonate light cavity in front of the LED that is narrowing the band width for the photons. How narrow is that? I googled into the wee hours of the night and found it was narrow but not really narrow like you would expect. The problem is in the cavity walls where the photons resonate. Tiny imperfections in it's flatness causes little side bands on the laser light. With all these little imperfections in the resonate cavity a LED type laser ends up looking like a bell curve with 3 DB points at 200 MHz for 500 THz. That is a high Q for for 500 THz but under a magnifying glass it is a dirty carrier. A Helium laser is better but that is mainly because it has a glass resonate cavity not plastic one like the red LED pointer.I am going to google up some laser band widths so you can see what I am getting at and some nice lectures on the subject.

author: mrflibble
author_rank: Super Contributor
timestamp: February 04, 2018, 02:20:03 pm
content: Quote from: John Heath on February 03, 2018, 05:18:37 amMmmh? The resonant cavity of that red laser diode would be made of semiconductor. The edges (mirrors) are formed by cleaving the crystal.Quick reference, third paragraph here:https://en.wikipedia.org/wiki/Laser_diode#Failure_mechanismsQuoteWhen designing experiments: more precision, less assumptions based on suboptimally-evolved-monkey-brain intuitions. I should know, I have one of those suboptimally evolved things as well. Intuition for avoiding sable tooth tigers? Check! Intuition for avoiding locations strewn with fellow primate bones? Check! Intuition for dealing with 100+ dimensional subspaces? No habla 4+-d senor!But seriously, don't just assume stuff.

author: cdev
author_rank: Super Contributor
timestamp: February 04, 2018, 03:04:56 pm
content: I would recommend looking for a TruePosition surplus GPSDO, they can be found for as little as $40 on ebay.Performance is quite decent.Quote from: John Heath on February 15, 2016, 06:54:00 pm

author: mrflibble
author_rank: Super Contributor
timestamp: February 04, 2018, 03:54:41 pm
content: Also, to tune that new-found laser enthusiasm to a proper linewidth, these may be beneficial:https://www.thorlabs.com/tutorials.cfm?tabID=f7dfa931-5afa-441b-8176-292d8735b143https://www.rp-photonics.com/external_cavity_diode_lasers.htmlEspecially Thorlabs has pretty good overall information IMO.Before you jump down the laser rabbit hole, I've been told that laser rabbit holes can be very deep indeed. Something to keep in mind while working out your hobby time & money budget.If the hypothetical effect you want to verify grows linearly with voltage difference, then instrumentation step 1 is a no-brainer. Get a vandergraafgenerator thatjuuuuustgets through the door. Clear room of furniture & cats. Off you go! As you have found, beyond a certain point the cost & difficulty of precision timing goes up. The incremental cost of upgrading voltage at this point would seem far lower than the timing part. I hesitate to bring it up, but the even lower cost part to upgrade would be theory & thought experiments. Consider working out your idea to the max. If the effect whatever-it-is exists, planet earth is not the only place. What are other places you can look? Can you take previous discoveries and steal ideas there? We live on a planet with pretty cool lightning. Those water molecules in that cloud up there live at a pretty large potential difference compared to the planet below. What would be the effect of that? Same question for planets.Gah, I was going to google a reasonable site/paper with the kind of info I was thinking of.This just in! Our solar system could be destroyed by lightning!http://www.systovi.com/en/faq/can-solar-system-be-destroyed-by-lightning/Yeah well, okay, that's a solar system too I suppose. But not the one I was looking for.Anyways, thinking some more about it, due to proximity lighting on our planet is the most practical. So given the potential difference, is there any difference that would be caused by the hypothetical effect? I dunno, marginal difference in ozone percentage? Difference in nitrogen oxides? Why go to the trouble of building stuff when you have a free lab all around you for the basic sanity checks?Another one that comes up during the"What if?". Suppose that voltage difference isconsistent withtime dilation. (Nope, not going any stronger than consistent with). Then looking for parallels you can take general relativity. Dump a clock down the cliff into the gravity well, tada time dilation. And if I understood your hypothetical situation correctly then the hypothesis would be: put clock in Faraday cage, crank up the voltage, tada time dilation. Right? If so, what happens during the ramping up and down of the voltage? Does the time taken for ramping up/down make any difference? What happens when you putanotherFaraday cage next to it? What happens when you now also ramp up the voltage on the neighboring Faraday cage? Any predictions there? Basically you can take everything you already know from general relativity and work out the parallel case. It would be silly to ignore relativity just because it's inconvenient and forces you to think a little more. Because general relativity gives you some hints that you will now have to be prepared for inconvenient things. If you have a model that actually has an answer for that, and predicts new verifiable behavior, then I say gogogo. It has low probability, but worth a shot. If not, well ...IMO: Biggest wins at this stage are thought experiments + inspired star gazing. After that working out the model beyond the "if voltage, then time dilation" stage. If it survives that, then up the voltage. And only then fiddle with the timing side. Possibly less fun, but more practicable. Or"stick it in at an oblique angle"again, and hope for the best. Oh well, if nothing else you end up with more cool toys to play with, that's always a plus.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 04, 2018, 04:27:17 pm
content: Quote from: mrflibble on February 04, 2018, 02:20:03 pmNice find. It is a little more sophisticated than I thought. Not sure if the cheap dollar store laser pointers are horizontal or edge type as the good stuff in inside the LED case.Avoiding saber tooth tigers. I did a little paper on that one. More like a long post. Fight or flight response. A cave man see a saber tooth tiger and think " did my new and improved club impress the guys at the camp fire last and saber tooth tiger ,, I should leave" . That cave man waited too long multitasking so he became a lunch for the tiger. Another cave man but he is limited as he can not think if rushed or scared. You would think he would be tiger lunch for sure. No as he can not think when scared so all he does is react to what his eyes see " dangerous tiger " so he runs without waiting. He lives to fight another day. We evolved from the one that can not think . The logical one that can multitask did not make it to the benefit of tigers. There is actually a test that can be done in psychology that will lead to incorrect conclusions verifying limited cognitive abilities in the fight or flight response.

author: John Heath
author_rank: Frequent Contributor
timestamp: February 04, 2018, 04:39:00 pm
content: Quote from: cdev on February 04, 2018, 03:04:56 pmI hear you. I have been looking at GPSDO for a while. I could tweak up all my frequency counters and also see how stable they are over with room temperature. Can not bring myself to put a credit card number on the net. I know it is done all the time but with my luck something will go wrong. I wish there was a store where you can go and say I want this from ebay , here is your deposit. Why do we not have internet stores??

author: cdev
author_rank: Super Contributor
timestamp: February 04, 2018, 04:45:27 pm
content: PM user KE0LFXHe might have one he could sell you.If you get one, this thread might be useful.https://www.eevblog.com/forum/projects/gpsdo-loss-of-satellitesfix-troubleshooting/Also, there is a PDF you can find on this web site which is invaluable in getting the hookup right.http://www.packratvhf.com- I think its been moved, my old URL no longer works. If you cant find it PM me and I'll get the relevant info to you. Its very simple.The cards have both RS-232C (12v) and 3.3 volt serial connections.Also here are all the (known) commands in a single page:https://github.com/pigrew/trueposctrl/blob/master/GPSDO_commandset.hYou will need to connect to it via a serial console to tell it to start working (command $PROCEED) when its booted up, and also to get it to do a survey when you first turn it on and whenever you move its location.Quote from: John Heath on February 04, 2018, 04:39:00 pm

author: John Heath
author_rank: Frequent Contributor
timestamp: February 04, 2018, 06:29:48 pm
content: Quote from: mrflibble on February 04, 2018, 03:54:41 pmThank you for a quality response. Can do this justice without breaking it up into 5 or 6 responses. And also thank you for reading the complete thread to understand the reason for doing a voltage frame of reference test for time dilation. As a science nerd you learn to keep your cards close to your chest as people will laugh. In your case I will put the cards on the table. A little teaser , Coulomb is Q * Q / R^2 for distance. This means a positive charge in a vacuum of virtual + an - charges , quasi quark or virtual positronium what ever your cup of poison is , will have a greater effect on negative charges than positive charges of a vacuum. It is written in Coulomb's law Q * Q/R^2. We lost symmetry for the net density of a vacuum. Einstein had something to say about gravity caused by a change in the shape of space. The teaser is just maybe Special and General relativity could sit under the same roof. Who needs the complication of a metric tenser if it turns out to be as easy as Coulomb's law. However without establishing a clear voltage coefficient for time dilation it is just wishful thinking.I will be cutting little bits of your post out to respond to your other points. Hey there is no hurry so why rush.

author: mrflibble
author_rank: Super Contributor
timestamp: February 05, 2018, 10:17:58 am
content: Quote from: John Heath on February 04, 2018, 06:29:48 pmIndeed. If you have some time, you might enjoy these:

author: John Heath
author_rank: Frequent Contributor
timestamp: February 05, 2018, 01:52:39 pm
content: Yes you have to love Feynman. He has the ability to put things in a way that most get it the first time. When I watch a Feynman video I can not help but think of Art Carny , I am sure I misspelled that. The honey mooners series on TV in the 1960s with Jacky Gleason and Art Carny. There is a stand up comedian in Feynman that wants to come out and it is Art Carny in my mind , ha. Is it just me?