Re: [time-nuts] Improving ocxo temp control
My experience with industrial temperature control says there is always a time lag between applying power to the heater and raising the temperature at the thermistor. Because there is a lag, there is a gain beyond which the system oscillates. But I haven't read the non-referenced papers, so I could be wrong. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob kb8tq Sent: Friday, May 18, 2018 9:46 PM Hi There are a number of papers out and about about the limits on OCXO performance. The bottom line is that coming up with a high resolution control circuit is the easy part of the task. Simple answer to the question: Set up a thermistor bridge and feed the difference into an op amp. Crank up the gain on the op amp to whatever you feel comfortable running. Some simple numbers: Thermistor changes 3% / C Single thermistor bridge changes 1.5% / C Output of the circuit will change the oven by 150C from power off to full on Neglecting the scale factors for simplicity Put in a gain of 100 on the op amp So, the bridge moves 1% and the controller goes from full off to full on. Crank in more gain "as required". The op amp isn't bothered until you get into the millions. With the simplified numbers above, the circuit has a thermal gain of 150. Getting much past 300 with a single oven is unusual. Bob > On May 18, 2018, at 2:03 PM, Gilles Clement <clemg...@club-internet.fr> wrote: > > Hi, > I am trying to improve performance of an OCXO. > Could you point me at a good design of a high resolution oven temperature controler please ? Preferably analog. > Thx much, > Gilles. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anybody have suggestions for time related science fairprojects?
Well, how about the frequency drift between a pendulum, a tuning fork, and a crystal. Atomic standards could be added depending on availability. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal Murray Sent: Thursday, May 10, 2018 11:56 PM To: time-nuts@febo.com Cc: Hal Murray Subject: [time-nuts] Anybody have suggestions for time related science fairprojects? A few months ago, I was a judge for the county level middle school science fair. (I'm not very good at what they wanted, but that's a different problem.) What sort of interesting time related experiments can a middle school geek do? Borrowing serious gear may not be off scale as long as a youngster can run it. - An alternat meaning to the "nut" part of time-nuts: ") https://www.snopes.com/fact-check/schools-removing-analog-clocks/ -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Anybody have suggestions for time related science fairprojects?
Um, time dilation by altitude if you have access to a mile high change. Or subjective time dilation when a person is prevented from doing a task on time. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal Murray Sent: Thursday, May 10, 2018 11:56 PM To: time-nuts@febo.com Cc: Hal Murray Subject: [time-nuts] Anybody have suggestions for time related science fairprojects? A few months ago, I was a judge for the county level middle school science fair. (I'm not very good at what they wanted, but that's a different problem.) What sort of interesting time related experiments can a middle school geek do? Borrowing serious gear may not be off scale as long as a youngster can run it. - An alternat meaning to the "nut" part of time-nuts: ") https://www.snopes.com/fact-check/schools-removing-analog-clocks/ -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Better quartz crystals with single isotope ?
Good questions. The one that bothers me is the magnetic levitation required to compare the standard to anything. You can't put other materials inside the vacuum bell with the standard. I looked up the paper, but it's behind a $40 pay-wall. Electromagnets will levitate permanent magnets, but the effect is not stable, with the free magnet sliding out of the field. Diamagnetic materials will be stable, but the effect is so weak it would require superconducting electromagnets. Quartz, as it happens, is diamagnetic. Now the problem is to apply identical levitation to dissimilar materials. This would seem to require identical superconducting magnets and identical levitated platforms. Identical currents can flow in the levitating magnets simply by connecting them in series. In order for the platforms to be identically levitated, they have to be an identical distance from the levitating magnet. Measuring that to the required precision could be a challenge. Machining physical parts can be done to 10 E-6. That's not enough, so the mechanism will require calibration. I suppose they could compare it to the present platinum standard. Then there's the question of calibration interval, and what to use as the standard. Counting oscillations of atoms would be so much easier. I think Rick's three points make this a non-starter. It's a case of experts in metrology not having enough expertise in quarts resonators. In answer to why they can't use 10 grams, the comparison has to be 100 times more accurate than that for 1000 grams. Hope I haven't strayed too far off topic, and wasted my time. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard (Rick) Karlquist Sent: Sunday, April 22, 2018 4:11 PM To: Discussion of precise time and frequency measurement; Bob kb8tq Subject: Re: [time-nuts] Better quartz crystals with single isotope ? On 4/22/2018 10:20 AM, Bob kb8tq wrote: >> Do we know anybody in the quartz business who needs a really cool >> research project ? > > You could put it on the list with the 1 Kg quartz resonator proposal ... > > https://tf.nist.gov/general/pdf/2638.pdf > <https://tf.nist.gov/general/pdf/2638.pdf> > > Also an offshoot of people thinking about the implications of all this as it relates to resonators. > > > Bob > The cited article "must be true" because of its authors, I guess, but it makes no sense to me. They seem to be assuming that the resonant frequency is inversely proportional to mass? We all know three things: 1. Frequency is inversely proportional to thickness. Not mass. 2. Frequency aging is affected by stress relaxation in well built resonators. The old idea that mass is gradually evaporating from the resonator to the enclosure (glass enclosures) or mass is gradually evaporating from the enclosure (metal enclosures) to depositing on the resonator is simply obsolete in terms of current technology. Thus again frequency is not a proxy for mass. 3. Resonators can "jump" in frequency without jumping in mass. Given these facts, I am lost as how this is supposed to work. Surely, the authors are well aware of the 3 items above. Also, why does the resonator have to be a whole kilogram anyway. If it weighed exactly 10 grams, couldn't you still compare it to a kilogram using 100:1 leverage? Can anyone straighten me out? Rick ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Pulsars, clocks, and time nuts (Jim Palfreyman)
It seems that pulsars are rotating stellar objects that have no reason to change their rotation, except to decay. Ruling out causes from the stellar object, one is left with things that might be orbiting the object and their ability to absorb the pulse that is aimed at us. One could move further out to the extremely low probability that some interstellar object absorbed the pulse. This doesn't explain the sawtooth, unless one of those orbiting bodies is affecting the rotation rate of the pulsar, such as a binary star. Disclaimer: I know very little about radio astronomy, but I've read a lot of hard science fiction. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dana Whitlow Sent: Friday, April 13, 2018 8:39 AM To: Tom Van Baak; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Pulsars, clocks, and time nuts (Jim Palfreyman) Tom's discussion about pulsars brought back some memories... Many pulsars exhibit skipped pulses. And one curiosity that I didn't see mentioned in Tom's discussion is that some pulsars even exhibit behavior reminiscent of the "sawtooth jitter" so evident in the PPS outputs of most GPS receivers. See figures 12-11 & 12-12 in "An Introduction to Radio Astronomy" (2nd edition) by Burke and Graham-Smith. The first ed also contains the basic plot (as figure 12-8 in this case), but whose explanation is not as up-to-date). For a deeper treatment of pulsars, also see https://www.cv.nrao.edu/course/astr534/PDFnew.shtml by Condon and Ransom (both of NRAO). The above two references are the best Radio Astronomy tomes I've yet seen.. Pulsar timing has been (and still is) a very big deal in radio astronomy, as it is key to verification of certain points of Einstein's General Theory of Relativity. Here are two web sites in which audio recordings of various pulsar sounds (made with larger radio telescopes) are presented. https://www.youtube.com/watch?v=uHEVo-LkDrQ (You may ignore the video part, even though it's "cute", but the audio portion is a fine example of the pulse to pulse variations exhibited by many pulsars, all wrapped up in one pulsar) http://www.jb.man.ac.uk/pulsar/Education/Sounds/0329_stack.mp4 (I think this is the best overall site, giving quality recordings of a fair number of different pulsars) Dana On Fri, Apr 13, 2018 at 2:54 AM, Tom Van Baak <t...@leapsecond.com> wrote: > Amazing news... 1.2.3. > > 1) Many of you know that pulsars are weird astronomical sources of > periodic signals. Some are so accurate that they rival atomic clocks > for stability! True, but I don't have a 100 foot antenna at home so > I'll take their word for it. Plus, you have to account for a myriad of > PhD-level > corrections: from earth's rotation to general relativity. And, like > quartz or rubidium clocks, pulsars drift (as they gradually slow > down). Precision timing is not easy. If you poke around the web you > can find numerous articles describing their detection and measurement > and exploring their use as reference clocks, both here and potentially for deep-space timekeeping. > > 2) If you do a lot of clock measurement at home then you know the dark > side of working with precision clocks. There are signal quality > issues, measurement resolution issues, reference stability > limitations, offset, drift, phase jumps, frequency jumps, missed or extra cycles, glitches, etc. > For example, quartz oscillators (depending on make / model / luck) can > exhibit frequency jumps; i.e., without warning they just change > frequency without your permission. Ok, maybe not by a lot, but enough > to notice; perhaps enough to cause trouble to any naive GPSDO PID > algorithm that assumes steady state from the oscillator you thought was stable. > > 3) Now the exciting part! Fellow time-nut Jim Palfreyman studies pulsars. > You've seen postings from him now and then over the years. It turns > out Jim is the first person to catch a pulsar in the act of a > frequency jump. After > 3 years of continuous searching! This is really cool. Just amazing. > You can't get more time nutty than this. And it just got published in Nature. > It's a perfect never-give-up, i-eat-nanoseconds-for-breakfast, time > nut thing to do. I am so impressed. > > To quote Jim: > > On December 12, 2016, at approximately 9:36pm at night, my phone > goes off with a text message telling me that Vela had glitched. The > automated process I had set up wasn't completely reliable - radio > frequency interference (RFI) had been known to set it off in error. > > So sceptically I logged in, and ran the test again. It was genuine! > The excitement was incredible and I stayed up all night analysing > the data. > > What surfaced w
Re: [time-nuts] Quieting the HP-113AR Clock/Frequency Divider
Here's another experience with a 103 crystal standard with the requisite 100 KC output and a 113 clock. I craved the clock because I'd seen it in the Smithsonian precision time exhibit. The 103 was certainly quiet, but the 113 was not, in spite of its heavy cast aluminum case. The 1 KC stepping motor sings at a frequency that is most sensitive to the ear. What were they thinking at HP? So I built an enclosure in an existing set of shelves. Quarter inch paneling defined the enclosure, which was lined with thick fiberglass insulation on all sides. The door was an insulated plywood panel that had magnetic latches, so you could pull it loose to read the clock. You could hardly hear it with the door closed. Both the 103 and 113 were in the enclosure, reducing the temperature changes typical of Minnesota. An external 28 volt power supply trickle charged two 12V 7AH batteries with diodes to provide battery power when the line went out. At the time, the power company was upgrading underground service, so there were many opportunities to observe switchover. I'm sorry to say that I didn't keep detailed records of accuracy. IIRC, the clock was within a few seconds of WWV at he New Year. All in all, another fine learning experience. Sold the 103 and 113 after a few years, and got into telephone GPS with a pair of HP Z3801A and a 16 foot plastic pipe mast for two HP conical antennas. Ended with the Lucent stuff. Inquiries for recycling Lucent stuff welcome. Bill Hawkins bill.i...@pobox.com -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Jeremy Nichols Sent: Saturday, March 17, 2018 9:39 PM To: time-nuts@febo.com Subject: [time-nuts] Quieting the HP-113AR Clock/Frequency Divider Those of us with the 1960-vintage HP-113AR/BR Clock/Frequency Divider know how noisy they are. The mechanical clock movement of my 113AR is loud enough that I really don't want to be in the same room with it. I don't know if the clocks are noisy from brand-new or if the mechanism gets noisier as the various parts wear with age. Here's how I quieted mine: . Wrap the outer cabinet of the 113AR in stick-on automotive sound deadener. . Put the 113AR in a fully enclosed 4U rack cabinet. . Stuff insulation into the cabinet so the 113AR is completely surrounded except for the front panel. Should anyone be interested, I can provide detailed notes, a shopping list, and pictures. Total cost was about US$150 and would have been a lot less if I could have found a used cabinet at the surplus store. Jeremy ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Recommendations for Mains Power Monitor / Logger
Well, this synchronization follows the laws of physics. If the energy generated doesn't equal the energy consumed, then the frequency may raise or lower. This is for steam turbines. If the energy come front an inverter from a DC tie line, as it does from the four regions in the US, the frequency is anything it wants to be. Well not quite. Raising the inverter frequency a hair causes the tie line to be the major source of energy. One could track the use of energy by frequency to make investment decisions in manufacturer's stocks. The problem with zero crossing triggers is the amount of noise caused by solid state power supplies and by tap changing by the power companies to match loads to minimize transmission losses. I've considered using a mechanical synchronous motor and slotted wheel to eliminate noise near the zero crossing, but now that I am 80, I don't give a darn, you see. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Albert via time-nuts Sent: Saturday, March 10, 2018 5:58 PM There isn't a whole lot of justification for measuring power line frequency. We are all synchronized (in the first world at least) and while there are phase instabilities, it's seldom the frequency varies enough to overcome the noise. As for voltage, it's much more steady than several years ago. Most people have 122 Volts, give or take a couple. Again, not a whole lot of purpose in recording it. The distortion is another story. It's never quite sinusoidal but there is also some random noise picked up between the generators and the load. Looking at the 'scope it's seldom it looks like the textbook picture of a sine wave. Chances are most distortion is odd harmonic. Distortion probably mostly comes from loads which are not resistive, such as switching power supplies, rectifiers, fluorescent lamps, and such. These loads draw currents that are not sinusoids and so cause voltage drops that are also of that character. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Frequency deviations in Europe affect clocks
Well, if you don't pay your bills, the power company can't afford the fuel required to keep up with demand. Stability of the system frequency requires a balance between supply and demand. If the demand exceeds supply then the generators must slow down. In a synchronous network, all generators must slow down to reduce strain on the network. If strain is exceeded, circuit breakers pop until the demand equals supply. So if a part of the network has to slow down from lack of fuel, then the entire network has to slow down to prevent popping circuit breakers until demand power equals supply. Hope that helps, Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of David G. McGaw Sent: Thursday, March 08, 2018 11:01 PM Subject: Re: [time-nuts] Frequency deviations in Europe affect clocks Can someone please explain why not paying your bills causes the grid and therefore the clocks to slow down? None of the reports, either for the technical or lay person, give a reason. David N1HAC ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Replacement A9 boards for the HP 5065A
Group, After 40 years of doing PID control for industrial processes, I'm used to an error tolerance of 10E-3. So I couldn't understand an integrator with a 10 K resistor and a 5 mfd capacitor. But this is time nuts, and the tolerance is more like 10E-13. An integrator as a controller takes any deviation from zero error voltage and moves the output in a direction that will return the error to zero. In this case, 10 K is the practical lower limit to the input resistor for the desired time constant, with 5 mfd as a practical upper limit. Any current flowing in that resistor changes the value of zero error, which causes the output to move when the actual error is zero. This makes the frequency wander. The current can come from the opamp bias or capacitor leakage when the output is not zero. Similarly, a change in the opamp zero offset causes a false error which makes the output move when it shouldn't. So I withdraw my comment about aluminum electrolytics, which was made without a timenuts perspective. Determining maximum error currents and offsets is simply a matter of mathematics, which is left as an exercise for the student. Regards, Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Replacement A9 boards for the HP 5065A
Corby A time constant is calculated from R and C. If 50 milliseconds is the correct number, R for 5 mfd is 10,000 ohms. You could use an aluminum electrolytic for the capacitor. Can you tell us where the 50 ms number came from? Regards, Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of cdel...@juno.com Sent: Saturday, February 24, 2018 5:45 PM To: time-nuts@febo.com Subject: [time-nuts] Replacement A9 boards for the HP 5065A Hi, I'm working to make some replacement A9 boards for the HP 5065A to the new style schematic. Will share the Gerber file when done. The integrator capacitor is a 1986 vintage TRW 5.0ufd 50V 10% .42"DX1.0"L axial. Of course it has an HP part number and no manufactures #. Any guess as to what type it is? Polycarbonate, polypropylene, ??? Just wanting to find a good modern replacement for its use. (Integrator with a 50ms time constant.) Thanks, Corby ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] eBay GPS antenna test.
Learned tonight that J. P. Morgan got his start by buying 25 K defective rifles for %3.50 each and selling them to the Army for $25 each. You have no reason to trust a listing. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob kb8tq Sent: Tuesday, February 13, 2018 12:04 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] eBay GPS antenna test. Hi > On Feb 13, 2018, at 12:06 PM, Clint Jay <cjaysh...@gmail.com> wrote: > > Agreed but stock numbers on boxes and packets are usually Arabic > numerals or a barcode. It's also possible the seller used a stock > image which can be copied and pasted into Google web search to track > down the maker or at least a distributor who has data. The seller did post a number of images for the part that was listed. The gotcha is that the part that arrived is not labeled the same way as the part that was listed. Since the device also has issues, the big question is if it has any connection to the part in the listing at all. The seller seems to have been doing GPS stuff for a while. He also has a very good approval rating. My guess is: this isn't the first time he's seen a bump in the road. I'd bet he's got the ability to check this and that out to see what is what. The seller *does* matter when you buy this stuff. That's true no matter what you are getting. No matter how good they are, problems do come up. The question is always how well they address them. We tend to dump pretty hard on these guys. I'm not sure that's always warrantied. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] AM vs PM noise of signal sources
Thank you, Charles. What a clever way to minimize the power dissipation in Q4 with the components of the day. A switching regulator without the steep (and noisy) transients of today's switchers. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Charles Steinmetz Sent: Monday, January 08, 2018 10:21 PM To: time-nuts@febo.com Subject: Re: [time-nuts] AM vs PM noise of signal sources Bill wrote: > What does the unijunction 2N2646 do in the oven controller? For the following discussion, you need to refer to the *corrected* schematic I mentioned in my last post. If you are looking at the HP schematic, you will wonder how the hell it works (and it wouldn't, if HP actually built them as they drew it). The 10544 oven control circuit uses pulse-width modulation to control the heater in a "bang-bang" manner rather than a smooth proportional manner. UJT A3Q3 forms a relaxation oscillator (along with A3C1 and A3R10), with a period of ~250uS (frequency ~4kHz) and a voltage span from ~0v to ~8v. This positive-going ramp is applied to the base of Darlington A3Q2 (MPSA12), which is 1/2 of a differential pair current switch along with A3Q1 (2N3904). The thermistor and associated op-amp circuitry set a threshold voltage between ground and about 7v at the base of Q1. After the relaxation oscillator resets to ~0v, current flows through A3Q1 and A3R8, pulling the base of Darlington A3Q4 negative and turning it on to saturation. The collector of A3Q4 therefore applies essentially the full oven heater supply voltage from Pin 14 (nominally 24v) to the high side of the heater. The oscillator voltage ramps positive toward its ~8v maximum (the trigger point of UJT A3Q3). When the emitter of A3Q2, which is two diode drops below the ramp voltage, exceeds the voltage at the emitter of Q1 (as set by the thermistor and A3U1), Q2 steals the current that has been flowing in A3Q1 and turns Darlington switch A3Q4 off, which interrupts the current flowing through the heater. Some time later (about 250uS after the previous reset), the oscillator voltage reaches the trigger point of the UJT and it resets the voltage on A3C1 to ~0v and the cycle begins again. Thus, every ~250uS the heater is on for a time (set by the thermistor circuitry) and off for the remainder of the ~250uS. This switching action can be seen at the "Oven Monitor", Pin 11 (but note that the instrument may have a capacitor to ground on the mother card side of the oven monitor, to integrate the switching waveform for use by the instrument's health monitor). Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] AM vs PM noise of signal sources
Charles, What does the unijunction 2N2646 do in the oven controller? Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Charles Steinmetz Sent: Monday, January 08, 2018 7:50 AM Also, note that the HP schematics of the 10544 have some errors that were (as far as I can tell) never corrected by HP. I posted a corrected and annotated schematic to Didier's site (ko4bb.com). Here's a link: <http://www.ko4bb.com/getsimple/index.php?id=download=HP_Agilent/HP _10544_Crystal_Oven_Oscillator/HP_10544A_schematic_further_corrected_and _annotated.pdf> Best regards, Charles ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Skilled Math Editor(s) Needed
Friends in time, Perry has apparently reached a major change in his life, perhaps because of a doctor's diagnosis - but there are zillions of other reasons. It seems to me that he is looking for someone to pick up his project and run with it. Advising him on the ways he could continue is probably not useful. He needs someone to take the baton and take it further. I say this as one who has downsized by 75% in order to move into a life care community after my wife and I had cancer scares and no long term care insurance. A cousin was the copy editor for Gone With the Wind and other Doubleday books. I seem to have inherited some of those genes. But I can't tell a bad equation from a good one, and my French ended in High School. Happy new year to the best list on the Internet. Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Test WWV timecube against Cesium, Rubidium, MASER or other precision time (UT-1) metrology
One way to compare any WWV receiver to a local standard is to use the PPS output of a standard against the PPS tick modulated on WWV. The tick is five cycles of a one KHz signal derived from the master frequency. See https://www.nist.gov/pml/time-and-frequency-division/time-services/wwv-a nd-wwvh-digital-time-code-and-broadcast-format It will be a bit tricky to determine the onset of the first cycle amid the noise on shortwave radio. A computation that determined that there were just 5 cycles and worked backwards to determine the timestamp of the beginning or middle of the tick could then allow calculation of the offset between the standard PPS and the tick. Limit of accuracy might be 100 microseconds. Years ago, I had a standard calibrator made by Lavoie that had a vacuum tube WWV receiver. IIRC, the WWV carrier caused a circular sweep on a 2 inch CRT. The sine wave from a standard modulated the intensity of the circular trace, so that a bright half moon appeared on the CRT and rotated at the error rate between the two frequencies. On several evenings the dominant signal varied between WWV and WWVH (identified by the voice broadcasts). Here in Minneapolis the phase difference between the two stations was about 180 degrees, causing the bright arc on the CRT to change sides. So yes, this could be interesting for a hobbyist, but it won't add anything to Science. A MASER is overkill. Heck, so are Rubidium and Caesium. A naked crystal will be rock solid compared to received WWV. OTOH, NTP has marvelous mathematical tricks to reduce Internet propagation delay. A scheme to reduce varying atmospheric delay would be useful, if there weren't much better ways to get a standard frequency. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Patrick Barthelow Sent: Thursday, December 07, 2017 7:48 AM Hello Friends, I am picking up locally a couple of vintage analog Radio Shack SW time cube radios, 70s vintage, 3 switchable SW frequencies. Two types, the one pictured and a Radio Shack model also that has WWV and Weather channel VHF frequencies. I am interested in an accurate bench test to compare the analog shortwave radios time reporting hopefully UT-1 against other available references. For accuracy, and repeatability. Could eventually add an SDR to the mix, too. The 5,10,15 mhz radios obviously are subject to the WWV Ft Collins site, propagation distance delays, somewhat calculable, and the vagaries of Ionospheric propagation, and, propagation delays between the antenna and the measured tap point to the seconds ticks of WWV. I have some friends, microwave professionals, who are also hams here in Auburn who may enjoy doing a bench test, with published results, etc. But wonder if anyone else would be interested in borrowing a RS Timecube radio (and/or use an SDR) and designing an accurate bench test against available modern standards? We are talking probably HUGE UT-1 errors compared to what this group plays with, and that is OK but I think still a worthwhile test, especially if the errors using available and cheap equipment are predictable, and repeatable. https://forums.qrz.com/index.php?attachments/dscn1187-jpg.400844/ - %< - [snip of microwave stuff] Best, 73, Pat Barthelow AA6EG apol <apollo...@gmail.com>lo...@gmail.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent RFTG-u REF0-REF1 cable
It's been a few years since I looked at this, but it seems to me that the message from the receiver to the time processors included an estimate of the reliability of the satellite data. That estimate depends on satellites being in the predicted positions. If there is an error, the time data is marked as invalid. The old messages had 6 satellites, and the newer messages had 8. The messages were identical, except that the newer message reported 2 more satellites. An older time processor would not have been able to handle the new 8 sat message. So, no, you can't mix old and new RFTG modules. If this sounds like I know what I'm saying, you may be disappointed. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Tim Shoppa Sent: Tuesday, November 14, 2017 9:53 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Lucent RFTG-u REF0-REF1 cable Isn't info about what satellites are where, just eye candy and irrelevant to a real GPSDO? Tweaks to the elevation mask ought to be measurable in the PPS quality (if they aren't then they're irrelevant). Tim ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Better GPS coming to phones
Sadly, it is not the phone users who will benefit. It is the advertisers who use your location to send targeted ads. Time marches on. Bill Hawkins -Original Message- From: Mark Sims Sent: Wednesday, September 27, 2017 6:54 AM Broadcom has released a phone chip that supports L5 signals... claims 30 cm accuracy.Maybe you will soon be able to use your phone to set your GPSDO location better... Also the new iphones now support Galileo in addition to GPS and Glonass. http://www.theregister.co.uk/2017/09/27/centimetre_accurate_gnss_chipset _tested/ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Z3801A and Z38XX Issues
Shouldn't that be 8 data bits? Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Richard Solomon Sent: Saturday, September 09, 2017 4:24 PM I downloaded and installed Z38XX, configured both the Port and Device to the recommended parameters: Data Rate: 19,200 Parity: Odd Data Bits: 7 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS Antenna Feed Line Decision
My HP conical antennas had N connectors, so I used 50 feet of RG-8. Z3801 receivers never had a problem. RG-8 is a sturdy cable, which may be the primary consideration for a 38 foot drop unsupported through the mast. Don't have any comparison to lighter cable, though. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Clay Autery Sent: Saturday, September 02, 2017 1:57 PM To: Time Nuts Subject: [time-nuts] GPS Antenna Feed Line Decision Having decision-making problems for the materials for my GPS main feedline. Going to use a TM LMR stock, just can't decide how big to go with it... 26 dB 5vdc antenna on top of a 38 foot mast. Feed will come down the inside/center of mast and exit near the bottom, thence routed through a window and to the GPS distro amp. Antenna will feed GPSDO, NTP Server, Blitzortung System Blue station, and one other device TBD. Just cannot decide how big to go with the antenna to distro amp feed... Assuming 50 feet total (38' mast + 12 feet to amp in shack) @ 1800 MHz (closest to 1725 MHz), here are the losses from just this piece (ignoring the amp to device jumpers): -240 = 5.45 dB XXX - too much loss? -400 = 2.85 dB -500 = 2.30 dB XXX - too hard to find -600 = 1.85 dB -900 = 1.25 dB Money not necessarily a consideration as this is a short run for a permanent installation. Don't anticipate ever moving the GPS antenna to the tower. For 900 and likely 600, likely would not be able to do it in one piece as routing it out of the mast and into the shack would get complicated. Would likely bring it out of the mast at the bottom with a right angle connector, and then use a smaller diameter jumper for the last 12 feet. 500 is pretty uncommon stock wise and it and connectors are harder to find. I already have the tooling for both 240 and 400... but I definitely don't want to challenge ANY of the devices for signal gain. So it mostly boils down to easy vs. more effort ($$ aside) Is it worth the additional trouble to move from -400 to -600 or -900? To NOT lose the 1-1.6 dB additional? I'd appreciate your recommendation and reasoning. Thanks in advance! 73, -- __ Clay Autery, KY5G MONTAC Enterprises (318) 518-1389 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] interesting HP divider and clock on ebay
You don't have to use the long link. Just search eBay for item #232426132876. It's pricey because it is from one of those resellers of surplus laboratory equipment. Who was that outfit in Texas? The front picture reveals that the desiccant is saturated (indicator is pink). Rear view shows blackened silver BNC connectors. These suggest that the instrument hasn't been reconditioned to merit that price. OTOH it could be R@@RE. Owned a 113B a few years ago. The 1 KC stepping motor does scream. Doubt that there's a motor in the 115. Would be interested in a repairable unit to measure my declining years - not for resale. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Jeremy Nichols Sent: Wednesday, August 09, 2017 8:12 PM Definitely spendy. Is the 115 as noisy as the 113 (similar but w/analog clock)? Wonder what *les douanes* would charge to get that back into USA? Could you claim an exemption because it was Made in USA? Jeremy On Wed, Aug 9, 2017 at 5:32 PM Tom Van Baak <t...@leapsecond.com> wrote: > > Boy I have to say the front looks great. Good pixs to look at. > > Price not exciting at all. But maybe someone has a spare kilo-buck. > > Paul, > > More info on the hp 115: > > http://hpmemoryproject.org/wb_pages/wall_b_page_01.htm > > /tvb > ___ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] SOPHOS discussion of GPS jamming and eLoran
SOPHOS is a European anti-malware company that publishes a daily newsletter of oddities in the security world. This article on jamming of S Korean GPS by N Korea may be of some interest. https://nakedsecurity.sophos.com/2017/08/07/cyberattacks-on-gps-leave-sh ips-sailing-in-dangerous-waters/?utm_source=Naked+Security+-+Sophos+List _campaign=f2c7691392-naked%252Bsecurity_medium=email_term=0_ 31623bb782-f2c7691392-455148921 My apologies for the long link. You could try Googling the subject if the link is broken up by your mailer. Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] A milestone approaches
Got this from a friend whose MN license plate is UNIX.
Begin copy of note
I'm curious if your friends on the time wizards mailing list have
noticed that an important moment in computer history approaches.
On Thursday night, 21:40 PM CST, it will be exactly 1.5 billion seconds
since Jan 1, 1970 UT, the Unix EPOCH. At that instant, billions of
Linux and Unix computers and devices, everywhere on the planet, will all
return time() == 15. It will not be until 2033 when that number
reaches 2 Billion. The Thursday date is computed as follows:
% cat >epoch.c
#include
#include
#include
int main(int argc, char **argv) {
const time_t gsec = 1.5e9;
struct tm thursday = *localtime();
char buf[100];
strftime(buf, sizeof(buf), "%m/%d/%y %H:%M:%S", );
printf("Epoch + 1.5B seconds = %s\n", buf);
return 0;
}
% gcc -Wall epoch.c
% ./a.out
Epoch + 1.5B seconds = 07/13/17 21:40:00
%
And if they haven't noticed, it might be a good time to point it out.
End copy of note
Some of us are impressed by long strings of zeros, so here I am,
pointing it out.
Bill Hawkins
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[time-nuts] The clocks at Windsor Castle, UK
Happened to watch a PBS/BBC program called "Queen's Castle" episode 102 - Four Seasons, that was filmed in 2005 at Windsor, not Buckingham. One of the segments was about the castle timekeeper, Steve Davison. He's responsible for 450 clocks, some 300 years old. His biggest challenge is the end of British Summer Time, when each clock must be advanced 11 hours, stopping until striking finishes. Old clocks were not designed for Fall Back. Takes him 16 hours. There was a brief shot of his workshop, with a clock repair in progress. No sign of a time standard. No discussion of leap seconds, either. Tried to find him, but only found a 2013 ad for a time keeper to maintain 1000 clocks in various castles. Hope that wasn't too far off topic. Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Powering up a long inactive 5061A
The first thing you should do is to check the condition of the power fuse. If it is blown or missing, you have some work to do looking for the cause of the fuse trouble. If you are concerned about old electrolytics in the power supply, and you can't check them for capacitance when off, there is an alternative to using a Variac. Cut one wire of an extension cord in order to put a lamp socket in series with the load. If line power is 120 volts, put a 100 watt bulb in the socket. Turn on the unit and be ready to turn it off again if the bulb lights at near or full brilliance. If it does, you have the same work to do as if the fuse had blown. If it starts bright and dims, you may be forming electrolytics. If the bulb maintains the same brightness, try a bigger bulb - or disconnect the ovens. You definitely need to read the part about running the ion pump. Bill Hawkins Disclaimer: I haven't tried this on an HP5061. You could still damage the switchers. You can't detect open capacitors this way. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Hugh Blemings Sent: Thursday, June 15, 2017 1:02 AM My intuition is to set it to one side until I can become familiar with the operating manual and potentially bring power up to it slowly with a Variac or similar. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lady Heather and Lucent RFTGm-II-XO / RFTGm-II-Rb
Been there and done that. Used a PicoScope in serial decoding mode to get the bytes by clipping a probe to one of the serial lines. Got the manual for the Motorola receiver from a web search, found the messages detailed therein. Did this several years ago and those memories have been overwritten. Still have the files, though. Only found Motorola messages, nothing generated by Lucent code. Lucent uses the Motorola messages to control the state of the units. Still have the RFTG assembly with power supply, if there's any interest. Seemed to me the group didn't think it was a fine instrument, but it is well built. Have moved to an old folks home and found other projects to keep me occupied. Make me an offer that might motivate me to pack and ship it, with the data I collected. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark Sims Sent: Thursday, May 25, 2017 5:53 PM I have my RFTG connected and have the Lucent software talking to it. I also have a (crappy) serial port monitor program (Microsoft portmon) running and sniffing the traffic. It appears that the control requests and responses are in what amounts to TSIP format. No idea yet what the contents of those messages are... or how much of it can be figured out... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NOOB Q re LH
Many years ago, an acquaintance tried to sell me his Ercoupe airplane. We went up for a test drive. He gave me the yoke and began pointing out the meaning of all the gauges. I looked up from that and saw that we weren't horizontal. I experienced information overload for the first time, and decided that I wasn't meant to fly small aircraft. I get the same feeling looking at the Lady Heather screens that have appeared in this list. There is an information density that begs for a VR display, and even then it would take more years than I've got left to become comfortable with it. This is no criticism of Mark Sim's work. It tells you all you ought to know. I just have trouble assimilating it. Good luck. Bill Hawkins -Original Message- From: Frank Howell Sent: Monday, May 22, 2017 4:05 PM Hi Folks, Great list...I'm learning a lot. Could I trouble you for suggested readings on the display content and interpretation from Lady Heather? Yes, I've read the PDF and the lines of codeand studied the websites of leapsecond.com, KO4BB.com, and the Dec 2014 thread on the time-nuts archive which basically asked this same Q. Any updates to that answer which was basicallyread a bunch of stuff and figure it out? I can do that but thought I'd politely as the listserv once again. 73, Frank K4FMH ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Looking for info on Trimble 16634-10
FWIW, that looks like aviation equipment (gov't or civil), with a locking connector. That stuff is designed for minimum size and weight. You might find the inside of the box quite cramped. Buying aviation parts is even more expensive than buying boat parts. Bill Hawkins -Original Message- From: time-nuts on behalf Of Bob Bownes Sent: Friday, May 19, 2017 10:48 PM Pretty sure that connector is an off the shelf Amphenol part. If you can't find it, however, you can replace it with an off the shelf one that will fit in the same hole. (If your lucky, you can even re-use the pins.) The replacement will run you about $30-40 for the pair, chassis and plug. Check Mouser, etc. > On May 19, 2017, at 23:21, Bob kb8tq <kb...@n1k.org> wrote: > > The mating side of that 22 pin connector isn't going to be cheap. It > looks like something out of their government systems group back in the late 90's. If it is, you may have a hard time getting info on it. > I'd pop it open and see what's inside. At least that will give you an > idea if it's 20 years old or 5 years old. Knowing the era should help in the search for information. > > Bob > >> On May 19, 2017, at 10:21 PM, Scott Armstrong <aa...@vntx.net> wrote: >> >> I acquired a Trimble 16634-10 receiver. A search of the web has >> turned up nothing so far. >> The unit is in a steel box built like a tank. SMA connector for >> antenna input and a 22 pin circular connector for the I/O and power >> ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Machining some aluminum help!
These threads where there is not enough information to define the problem can grow forever, because they are based on speculation, not facts. Corby, you have decided what you need based on what you know, but the rest of us need a more general statement of the problem. Unless, of course, that is something you do not choose to reveal. Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP10811 Oscillator Thermal Fuse
Labs could have used a common gas heater for the crystal ovens, with a bit of rewiring. No fire hazard there - you've got a chimney. Also, flame safety is well developed for gas heaters. Would have required throttling gas flow control. Bill Hawkins Another possibility is circulating hot water. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob kb8tq Sent: Thursday, May 11, 2017 6:25 AM Ultimately it all came to no good. The energy conservation rules simply took over. Shutting down everything during off hours became the way a lot of outfits did things. Don't turn off all your bench gear and you get a nasty note. I am not aware of full power being dropped during off hours. That tends to take out things you really do not want to shut down (fire sensors .). ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Austron/ Systrom Donner 8181 Time Code Reader
There is usually a power dissipation reason why a resistor becomes toast, and the reason is frequently a shorted bypass cap or a shorted device. Have you measured the resistance to ground of the end of the resistor opposite the power supply? Sometimes inputs get high voltages and short the amplifying device. Sometimes that is reason the units were for sale. Hope I'm wrong. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Dave Wood Sent: Saturday, April 22, 2017 8:43 PM Anyone on the list own the above Time Code Readesr. I have one of each, they are identical with the same issue. I need to identify the correct value of a resistor in the power supply that provides 27 volts to the input amp. They are both toast in my units and I do not have a manual. Thanks in advance! Dave ___ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] TAPR TICC boxed (input protection)
There are other ways that light can cause unexpected behavior. In 1983 I worked on a process control system whose maiden installation was in a corn processing plant, with lots of big valves and motors being controlled. The cards that did A/D and D/A conversion of control signals had UV erasable EPROMs for their microprocessors. There were a lot of those cards. One day the plant operators began complaining about the equipment misbehaving on a large scale. The problem went away when the guy taking flash pictures of our equipment stopped taking pictures. We put black tape over the UV lenses. Ob timenuts: This system later had a pulse frequency input card that I connected to the power line. Used the operator's trending display for process variables to watch line frequency change over time. It also had pulse outputs, and a little work got it to play "Daisy, Daisy" like HAL 9000 in "2001: A Space Odyssey." Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob kb8tq Sent: Sunday, April 09, 2017 1:34 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] TAPR TICC boxed (input protection) Hi If anybody gets into this sort of thing in the future - There are black / optical blocking die coat materials out there. They are silicone based and quite stable. We used a *lot* of the stuff on watch modules after it was discovered that the watch died when exposed to a heavy dose of sunlight (right through the LCD and into the chip . poof!!) Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Car Clock drift - the lowly 32kHz tuning fork crystal specs
Nice article in Wikipedia. Didn't see any familiar names in the reference list, though. Seems to me inhibition compensation is useful for compensating for the variation in purchased crystal frequencies, but not for temperature compensation. Also seems to me that a watch spends 2/3 of a day at wrist temperature and 1/3 at bedroom temperature, which varies with the seasons. Would a ceramic capacitor crafted for a certain temperature coefficient work? Can the fork have a crafted tempco? Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Ron Bean Sent: Sunday, April 09, 2017 12:05 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Car Clock drift - the lowly 32kHz tuning fork crystal specs >In your case, the car sits in an environment that matches their test >setup well. In my case ?\200? not so much. FWIW, mine drifts pretty badly. It's in an aftermarket stereo, and I don't remember when I bought it (I moved it from my previous car). I assume that all quartz clocks and watches these days use "inhibition conpensation". https://en.wikipedia.org/wiki/Quartz_clock#Inhibition_compensation ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Line Frequeny Stablity
Perhaps I should have clarified that while the synchronous machines all run at the same frequency, that frequency depends on the balance of steam (or hydraulic) power to the turbines that spin the generators and the aggregate power demand. When the power is not balanced, the frequency of the coupled system will change, but very slowly in proportion to the size of the network of generators. I don't know the effects of the DC tieline inverter, which can run at any set frequency, but any difference in frequency has to affect the power out of or into the tie line. As to doing the clock adjustment around quitting time at 5 PM, my experience is different. A system that took a frequency input and showed it as a function of time revealed that the frequency sagged during the workday and the air conditioning day, but was increased to make up the lost cycles during the minimum load time around 4:30 AM. In 1955 or so, The Air Force determined that the time of minimum human activity (and hence the maximum probability of attack) was at 4:30 in the morning. Independent research with traffic counters revealed a sharp dip in traffic at that time of day. Adjusting the cycle count at the time of minimum activity also minimized the cost of making that adjustment. Sorry, I have no recent data, but it sure feels lonely to be up at 4:30 AM. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Jeremy Nichols Sent: Wednesday, April 05, 2017 6:57 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Line Frequeny Stablity A fun way to monitor the state of the grid is to watch the web site of the Power Information Technology Laboratory <http://powerit.utk.edu> at the University of Tennessee <http://www.utk.edu>, Their site lists in both tabular and graphical (map) form the frequency of the grid. Most of it is USA-based but there are a few other countries also monitored. I have one of the monitors (in the table display page < http://fnetpublic.utk.edu/tabledisplay.html> my monitor is #853 in the Western Interconnection-I'm in California). The monitors, about the size of a thick hardback book, plug into a convenient AC line outlet, connect to your Internet router, and have a small puck-style GPS antenna so that it knows the time and where it is. The unit has an LCD display of date, time, line voltage, and line frequency. The voltage is shown to 3 decimal digits of resolution and the frequency to four digits. I got my monitor from the U of T after I sent them a report on my home-made monitor's results. It's interesting to watch the frequency wander up and down but always average very close to 60.000 Hz. They saw I had an interest and offered me one of their toys. The only thing it doesn't do is connect to my PC so I can monitor it long-term. I suppose if I were clever with network stuff there'd be a way to tap into its data stream. Jeremy, N6WFO On Wed, Apr 5, 2017 at 2:12 PM, Bob kb8tq <kb...@n1k.org> wrote: > Hi > > Back in high school, one of the radio club members figured out that > the "clock adjustment" took place locally between 4:30 and 5:00 PM. > Needless to say, pretty much everybody spent the next week listening > to WWV and watching the clock's second hand go out of sync with the beeps. > This was back in the late 1960's > and the idea of a grid was a bit looser than it is today. Indeed it > was post 1964 so there *were* grids big enough to take out the whole > north east section of the US. Since we were very much in that area the > topic of grid sync came up. Nobody ever really had a good answer to > that question. That included the guys who ran the local power company. > > Bob > > > On Apr 5, 2017, at 3:05 PM, Hal Murray <hmur...@megapathdsl.net> wrote: > > > > > > preilley_...@comcast.net said: > >> When I installed power plants in the 1970's they has a special "clock" > that > >> showed the cumulative error in terms of clock time. > > > > How big were the grids back then? > > > > What was the typical range of error over a day or month? > > > > > >> If the generator ran a little too fast the clock would move forward. > As > >> the operator observed the clock moving away from zero he would > >> reduce > the > >> plant's power and the clock would move backward toward zero. ... > > > > Does that operator control a single generator or a whole grid? > > > > Does having a human in the loop help the control loop stability? > > > > > > > > -- > > These are my opinions. I hate spam. > > > > > > > > ___ > > time-nuts mailing list -- time-nuts@febo.com To unsubscribe
Re: [time-nuts] Line Frequeny Stablity
The rotary generators in a system of connected generators are synchronous machines. There is no frequency difference between them, only phase angle, and not much of that - if the system is stable. The ocean liner analogy is correct, as there is only one captain directing the ship's course. If each plant set its own power levels it would be very difficult to maintain stability, due to the springiness of long transmission lines. A set of connected generators is controlled by regional dispatchers, who tell their plants how much power to generate in order for the day to average out to 60.000 cycles per second. They count cycles instead of measuring the frequency. You can count cycles with a synchronous clock. This becomes less tidy when DC tie lines are used, because inverters have to be adjusted to get the correct power flow. Hope I got most of that right. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Peter Reilley Sent: Wednesday, April 05, 2017 7:42 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Line Frequeny Stablity Think of it as an ocean liner trying to keep a dead straight course to it's destination. It weighs many tons and wind and waves may drive it off it's path but the captain can correct for this. It eventually arrives at it's destination and is only a few feet from the dock. The total rotating mass of all the generators in a network is many times the mass of an ocean liner. The operators do their best to keep them running at the correct frequency. Unexpected load changes can cause some divergence, but over time the average is dead on. When I installed power plants in the 1970's they has a special "clock" that showed the cumulative error in terms of clock time. The clock had two inputs, one from the utility power and the other from some reference, possibly WWV. Normally the "clock" was pointing up at zero and not moving. If the generator ran a little too fast the clock would move forward. As the operator observed the clock moving away from zero he would reduce the plant's power and the clock would move backward toward zero. His goal was to keep the clock at zero and not moving. Thus, your bedside clock was always on time even if there were temporary excursions fast or slow. Pete. On 4/4/2017 5:28 PM, Thomas D. Erb wrote: > Thanks for the info. > > > So that tells me how data is recorded - but not how the frequency is kept stable ? > > Is the line frequency now directly tied to GPS clock - with no drift ? > > Thomas D. Erb > t...@electrictime.com<mailto:t...@electrictime.com> / Electric Time > Company, Inc. > Office: 508-359-4396 x 117 / Fax: 508-359-4482 > 97 West Street Medfield, MA 02052 USA ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Hunting dark matter with GPS data
Before you go looking for flaws in space, read the comments to the sciencemag article at the link. Thomas Lee Elifritz is informative. It's amazing what you can do with math if you make a few simplifying assumptions. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of André Esteves Sent: Friday, March 24, 2017 3:30 PM To: Discussion of precise time and frequency measurement Subject: [time-nuts] Hunting dark matter with GPS data People in the list may be interested in replicating the work... Cheers, Aife http://www.sciencemag.org/news/2017/01/hunting-dark-matter-gps-data Hunting dark matter with GPS data By Adrian ChoJan. 30, 2017 , 2:30 PM WASHINGTON, D.C.A team of physicists has used data from GPS satellites to hunt for dark matter, the mysterious stuff whose gravity appears to hold galaxies together. They found no signs of a hypothetical type of dark matter, which consists of flaws in the fabric of space called topological defects, the researchers reported here on Saturday at a meeting of the American Physical Society. But the physicists say they have vastly narrowed the characteristics for how the defectsif they existwould interact with ordinary matter. Their findings show how surprisingly innovativeand, in this case, cheapmethods might be used to test new ideas of what dark matter might be. It is so interesting and refreshing and exciting, and the cost is basically zero, says Dmitry Budker, an experimental physicist at the Johannes Gutenberg University of Mainz in Germany, who was not involved in the work. Its basically the cost of the students analyzing the data. Astrophysicists think that dark matter makes up 85% of all the matter in the universe. Yet so far they have inferred dark matters existence only from its gravitational pull. For decades, many physicists have tried to directly detect a promising candidate for particles of dark matter, so-called weakly interacting massive particles, or WIMPs. But enthusiasm is waning as ever-more-sensitive detectors have failed to find the particles floating through our galaxy and passing through Earth. So many physicists are thinking more broadly about what dark matter might be. For example, instead of a new subatomic particle, dark matter could be something far bigger and weirder: macroscopic faults in the vacuum of space called topological defects. Topological defects are best explained with an analogy to magnetic materials such as nickel. Nickel atoms act like little magnets themselves, and below a certain temperature, neighboring atoms tend to point in the same direction, so that their magnetic fields reinforce one another. But that orderly alignment can suffer defects if, for example, atoms in different regions point in different directions. When this happens, the regions meet along a craggy surface called a domain wall, which is one type of topological defect. There can be pointlike and linelike defects, too. A similar thing might happen in space itself. Some theories predict that empty space is filled with a quantum field. If that field interacts with itself, then, as the infant universe expanded and cooled, the field may have taken on a value or phase, which would be a bit like the direction in which nickel atoms point. Regions of space with different phases would then meet at domain walls. These domain walls would have energy and, through Einsteins famous equivalence, E=mc2, mass. So they would generate gravity and could be dark matter. Now, Benjamin Roberts and Andrei Derevianko, two physicists at the University of Nevada in Reno, and their colleagues say they have performed the most stringent search yet for topological dark matter, using archival data from the constellation of 31 orbiting GPS satellites. Each satellite carries an atomic clock and broadcasts timing signals. Receivers on Earth use the timing information from multiple satellites to determine how far it is from each of them and, hence, its location. To use those data to search for dark matter, the researchers had to invoke another bit of speculative physics. Theory suggests that within a topological defect, the constants of nature will change. In particular, the passing of a topological defect should fiddle with the so-called fine structure constant, which determines the strength of the electromagnetic force and the precise frequency of radiation that an atom will absorb or emit as an electron in it jumps from one quantized energy level to another. But an atomic clock works by measuring just such a frequency. So were a GPS satellite to pass through a topological defect, the defect should cause the satellites atomic clock to skip a beat. One jump in one atomic clock wouldnt be proof enough for topological defects. So the researchers looked for a stronger signal, the wave of time shifts that would sweep across the whole 50,000-kilometer-wide GPS network if Earth passed through a large domain wall
Re: [time-nuts] Antique precision timing device without electronics
There is a power amplifier that was available at the time. It's called a relay. It would probably take two or three stages to get enough power to drive the motor. Were there any relays in the box? Conservation of power says some must be taken from the fork to operate the contacts. This would reduce the Q, but only while the fork was touching the contacts. When the battery is switched off, amplitude would decay until the contacts were no longer touched. Then you'd get over a minute for it to stop. At least, that's how it looks to this mechanical engineer. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bill Hawkins Sent: Thursday, March 16, 2017 1:05 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Antique precision timing device without electronics Hi Morris, If there's no active devices (and you'd be sure to see them, not solid state) where does the power to operate the motor come from? Is it the same contacts that drive the fork? It's amazing that there is high Q when contacts must be operated by the fork. Did it come with instructions for setting the weights at the end of the fork tines? Best regards, Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Morris Odell Sent: Thursday, March 16, 2017 4:23 AM To: time-nuts@febo.com Subject: [time-nuts] Antique precision timing device without electronics Hi all, I was recently asked to resurrect this interesting device by a colleague who collects antique scientific instruments. It's a "Chronoscope" made by the H. Tinsley company in London in the early 20th century and used to measure time intervals with the precision of those days. It's large and heavy in a polished wooden case with a top deck that hinges up to reveal the innards. The timing reference is a large tuning fork about 30 cm (1 foot) long and running at 25 cps. It's normally in a glass fronted housing (removed for the video) that includes a pair of hinged mechanical arms for starting it. It's maintained in oscillation by an electromagnet and contact arrangement powered from a 12V DC supply. The fork amplitude is controlled by a rheostat - too much and the tines impact on the magnet. The video frame rate makes the fork look slower than it actually is. I was able to extract a signal and measure the frequency with a modern GPS disciplined counter - it's 0.007% off its specified 25 Hz! The frequency is too low for my HP 5372A so I was not able to easily get an idea of stability or do an ADEV measurement. The fork has quite a high Q and takes over a minute to stop oscillating after the power is turned off. There's a built in higher voltage AC power supply, probably a mains transformer, potted in beeswax in a polished wooden box inside that is intended to energise a large neon strobe lamp used to adjust the fork. Unfortunately the lamp was not with the unit and is no doubt irreplaceable. The 25 Hz signal is filtered by an LC network and used to run a synchronous motor in the Chronoscope unit. Synchronous motors not being self-starting, you need to tweak a knob to get it going - there's a joke in there but I can't for the life of me think what it could be ?? The "Contact" switch and associated socket on the back controls an electromagnetic clutch that connects the clockwork counter mechanism to the motor and the contact "on" time is indicated on the dials with 10 mS resolution. There's not a single active device in there and after a clean and lube it runs very nicely from a modern 12V DC plugpack. My friend is very pleased with it and it will take pride of place in his collection. I'd be interested to know if any time nuts have knowledge or experience of this lovely instrument. A video of it is at https://youtu.be/i5S8WS9iN_E Enjoy! Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Antique precision timing device without electronics
Hi Morris, If there's no active devices (and you'd be sure to see them, not solid state) where does the power to operate the motor come from? Is it the same contacts that drive the fork? It's amazing that there is high Q when contacts must be operated by the fork. Did it come with instructions for setting the weights at the end of the fork tines? Best regards, Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Morris Odell Sent: Thursday, March 16, 2017 4:23 AM To: time-nuts@febo.com Subject: [time-nuts] Antique precision timing device without electronics Hi all, I was recently asked to resurrect this interesting device by a colleague who collects antique scientific instruments. It's a "Chronoscope" made by the H. Tinsley company in London in the early 20th century and used to measure time intervals with the precision of those days. It's large and heavy in a polished wooden case with a top deck that hinges up to reveal the innards. The timing reference is a large tuning fork about 30 cm (1 foot) long and running at 25 cps. It's normally in a glass fronted housing (removed for the video) that includes a pair of hinged mechanical arms for starting it. It's maintained in oscillation by an electromagnet and contact arrangement powered from a 12V DC supply. The fork amplitude is controlled by a rheostat - too much and the tines impact on the magnet. The video frame rate makes the fork look slower than it actually is. I was able to extract a signal and measure the frequency with a modern GPS disciplined counter - it's 0.007% off its specified 25 Hz! The frequency is too low for my HP 5372A so I was not able to easily get an idea of stability or do an ADEV measurement. The fork has quite a high Q and takes over a minute to stop oscillating after the power is turned off. There's a built in higher voltage AC power supply, probably a mains transformer, potted in beeswax in a polished wooden box inside that is intended to energise a large neon strobe lamp used to adjust the fork. Unfortunately the lamp was not with the unit and is no doubt irreplaceable. The 25 Hz signal is filtered by an LC network and used to run a synchronous motor in the Chronoscope unit. Synchronous motors not being self-starting, you need to tweak a knob to get it going - there's a joke in there but I can't for the life of me think what it could be ?? The "Contact" switch and associated socket on the back controls an electromagnetic clutch that connects the clockwork counter mechanism to the motor and the contact "on" time is indicated on the dials with 10 mS resolution. There's not a single active device in there and after a clean and lube it runs very nicely from a modern 12V DC plugpack. My friend is very pleased with it and it will take pride of place in his collection. I'd be interested to know if any time nuts have knowledge or experience of this lovely instrument. A video of it is at https://youtu.be/i5S8WS9iN_E Enjoy! Morris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] advice
In the confusion, I forgot that we are concerned with gravitational time dilation, not time of flight. The University of Minnesota has a lab about 2500 feet down in the Soudan mine. The following is their brief description: "The Soudan Underground Laboratory is a general-purpose science facility, which provides the deep underground environment required by a variety of sensitive experiments." Here's a link to the Soudan page: https://www.physics.umn.edu/outreach/soudan/tour/ Why is it named Soudan? The original miners found northern Minnesota to be extremely cold at times, so they named the town for someplace warm. Let me know if you are seriously considering this, and I will find a contact for you. Bill Hawkins -Original Message----- From: Bill Hawkins [mailto:bill.i...@pobox.com] Sent: Tuesday, February 21, 2017 8:08 PM Neutrinos? Look up the OPERA experiment that measured neutrinos going faster than light. Turned out to be a loose optical fiber connector to a timing instrument. Fermi Lab has/had the MINOS experiment going 500 miles from Chicago to a mine in northern Minnesota. The generated neutrinos go through Wisconsin but are not noticed there, AFAIK. Bill Hawkins (Resident of Minnesota, but not a physicist, just a BSME) -Original Message- From: Bob Stewart Sent: Tuesday, February 21, 2017 1:48 PM Hi, Have you been in touch with Fermi-Lab? They run a neutrino experiment with a receiver somewhere underground in Wisconsin. At least that's what I recall. I used to live next to a Physics professor who has a minor part in the experiment. I'm not even sure what sort of data they collect there; whether it's time or something else. Bob Stewart (Not a physicist) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] advice
Neutrinos? Look up the OPERA experiment that measured neutrinos going faster than light. Turned out to be a loose optical fiber connector to a timing instrument. Fermi Lab has/had the MINOS experiment going 500 miles from Chicago to a mine in northern Minnesota. The generated neutrinos go through Wisconsin but are not noticed there, AFAIK. Bill Hawkins (Resident of Minnesota, but not a physicist, just a BSME) -Original Message- From: Bob Stewart Sent: Tuesday, February 21, 2017 1:48 PM Hi, Have you been in touch with Fermi-Lab? They run a neutrino experiment with a receiver somewhere underground in Wisconsin. At least that's what I recall. I used to live next to a Physics professor who has a minor part in the experiment. I'm not even sure what sort of data they collect there; whether it's time or something else. Bob Stewart (Not a physicist) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] HP5065A Rubidium question
Well, if it was not working when you acquired it, the physics package had probably reached the end of its life. If it had been working recently and is not now, it might be repairable. Others on this list know more about repairing than I. Bill Hawkins -Original Message- From: David Scott Coburn Sent: Sunday, February 19, 2017 4:42 PM I have an HP5065A Rubidium Frequency Standard which is not working. All of the oven temperatures look OK. The power supply voltages look OK. The ~60 MHz going into the RVFS package looks OK. The 5.000 MHz and the ~5.315 MHz signals are within a few Hz. (The unit is running open loop only.) The A7 AC amp looks to be working OK. The A8 137/234 Hz signals look OK. There is 20 VDC feeding the RVFS lamp oscillator. But, there is no current coming from the photodiode. (Maybe a few picoamps of dark current, certainly not the expected ~50 microamps of DC, and no 137/234 Hz signals). It seems the most likely problem is that the Rb lamp is not coming on. Maybe possible that the photodiode is faulty, or a broken wire, etc. Any other possibilities I should check before setting off into the innards of the RVFS package? Thanks in advance! Cheers, Scott ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Power Problems Lucent KS-24361, L101 & L102
See https://www.febo.com/pipermail/time-nuts/2014-October/087670.html Pin 1 is Plus, pin 2 is Minus to an isolated power supply. All other pins have no connection. Hence, no damage. Schematics are not available, but many people have discovered what it takes to make them work. Time nuts is an adventure, but it's best to check the pipermail/time-nuts archive for previous work. Good fortune on your quest for knowledge. Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Low CostTemperature sensor
Perrier, Google finds a Siemens NI1000 sensor that follows the nickel curve. Nickel is popular in industrial control for cost, but not as accurate as platinum. Converting the platinum curve to accurate temperatures requires a second order equation, but has been done with 0.1% analog converters. Digi-key has ZNI devices as surface mount parts. Sparse data said nothing about a platinum curve. I'm curious because my former employer did very well selling platinum RTD sensors, usually 100 ohms at the triple point. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Perry Sandeen via time-nuts Sent: Monday, January 16, 2017 9:33 PM To: time-nuts@febo.com Subject: [time-nuts] Low CostTemperature sensor List, A while back there was much discussion about temperature sensors. One simple inexpensive one to consider would be the ZNI1000Temperature sensor. It's 1K ohms at 0C and it replicates the temperature curve of the Pt 1K ohm sensors. It's about $3 from Digi-Key. FWIW YMMY Regards, Perrier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] wifi with time sync
I haven't read the entire thread, but this may be relevant. If not, you know where to find the delete key. I live in a life care community - one of 450 people in 300 apartments on 3 floors. When I moved in a year ago, I could get Internet from the house cable, and they provided the modem. I bought wired and wireless 802.11n dual band routers for two apartments, a two bedroom for us and an alcove for my shop. There was plenty of noise from other such routers, but no problem within an apartment. I couldn't use a wireless keyboard, though. The cursor wandered around with the noise. Last month, a company experienced in wiring hotels for wireless put DSL to RJ-45 and 11n wireless access points in each apartment on the second floor, adding 100 transmitters to the mix. DSL with existing phone wiring was far cheaper than running new cable. The intent was to provide universal public Wi-Fi for the children of the residents. They might as well have installed 100 jammers. There were complaints of unusable cordless phones (most in the 2.4 GHz range) and lost Wi-Fi connections that simply reverted to the default IP address range and failed to reconnect. I got a home copy (this is my home) of InSSIDer software and surveyed the halls at 2.4 GHz with a Windows 7 laptop (you need a larger screen to see the signal distribution) I could see 10 to 20 of the new access points, as well as the occasional excursion to -10 dbm (top of scale) as nearby routers and printers kicked in. Great stuff. There are environments where time sync with Wi-Fi hasn't got a chance. Jim Lux was looking for a COTS solution to time sync, and this might work in a controlled environment. Don't even think about consumer radio clocks that sync from unknown Wi-Fi environments. Bill Hawkins (John Hawkins son) bill.i...@pobox.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lavoie WWV Frequency Comparator available
Had one of those before downsizing. Very clever circuit, if you are describing the vacuum tube unit. The small CRT does a circular sweep based on the reference standard with brightness modulated by the strength of the received signal, so that no rotation of the half bright half dark pattern proves a match. >From Minnesota, under good conditions, I could see the pattern change phase between Colorado and Hawaii as propagation conditions changed. No room for one now, but it was the most interesting WWV receiver I ever owned. Disclaimer: Absolutely no relation to Martin - thought you should know more about its capabilities. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Martin VE3OAT Sent: Saturday, January 07, 2017 3:40 PM To: time-nuts@febo.com Subject: [time-nuts] Lavoie WWV Frequency Comparator available I have a Lavoie Labs WWV Frequency Comparator that is surplus to my needs. It is s/n 450 but is not marked with the model number, although I believe it is an LA-800D. I also have a photocopy of the operation and service manual, including schematic and parts list. The device gives an oscilloscopic display of the phase difference between your local frequency standard and the received WWV signal on either 5 or 15 MHz. The beast still works although the electrolytics need replacing (symptom -- one of the power transformers gets very warm after a few hours of operation). And it could probably benefit from a proper RF/IF alignment (I have never bothered to do this). The unit is too big and heavy to ship by any normal means, so "local pick up only". However, I could meet you "half-way", provided it is within 200 km of Ottawa, Ontario. Free to a good home. ... Martin VE3OAT (near Ottawa, Canada) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Line Voltage - USA
Wonder if these cases could be used on social media to create enough fear that there would be a market for AC crowbars capable of blowing line/pole transformer HV fuses? There's a few hits with Google, mostly for DC crowbars. Too bad relays are so slow. Bill Hawkins -Original Message- From: Jeff AC0C Sent: Wednesday, January 04, 2017 10:42 AM The electric company in OKC repaired a pole problem at my parents house there a few years back. Somehow they managed to hook up the 240 across a single leg of the 120. Fried most of the electrical stuff in the house and caused enough damage to the house to require a complete rewiring. Parents lived in a motel for about a month while the work was done. The insurance company and the utility were transparent, covering all costs including replacement with new similar products without issue (other than the inconvenience). I think the electric company was especially glad that a fire did not result and there was no legal action as a result. 73/jeff/ac0c www.ac0c.com alpha-charlie-zero-charlie -Original Message- From: Hal Murray Sent: Wednesday, January 04, 2017 2:42 AM > Did the utility replace the damaged equipment? A friend lived in a building when the city crew working on a transformer put 440 on the line. It blew out all the electronics in 12 condos - mostly TVs. I think toasters and refrigerators were OK. There wasn't any question that the city was at fault. I don't remember how much paperwork they had to go through to get reimbursed. It might get sticky for something like a time-nut with a lot of used gear that may not be easy to replace at the original price. (Could be a good excuse to clean up and start over.) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] New stuff in my Tindie store
Seven segment displays have an interesting property. The display of 52 minutes or seconds looks like a mushroom cloud. When I am ready to get out of bed, I avoid initiating action while the display is 13 or 52. So far, that has saved me from many bad things happening. ;-) "Its a joke, son" as Foghorn Leghorn would say. Happy Holidays, Bill Hawkins -Original Message- From: Nick Sayer via time-nuts Sent: Monday, December 26, 2016 9:41 PM It has 7 seg LEDs for hour, minute, second and tenth of a second ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] [Summary] HP 115CR Clock Powerup / Documentation
Got a 113BR clock many years ago because it looked like the clock in the Smithsonian. Used a 103 precision OCXO for the source. It is noisy. That's part of why it has a heavy metal case. I expect that a rebuilt stepping motor might have been quieter. I kept it in a larger wooden box lined with R19 fiberglass insulation. I used an insulated wooden front door held by magnetic catches to close the box, had to remove the door to see it. The manual reset is a feature. If the clock stops for any reason, it stays stopped. If it restarted by itself it would authoritatively show you the wrong time. A battery and float charger are required if you want to see how much it varies in a year. If all you want is a technically attractive clock, talk to a watchmaker about driving it with a synchronous clock motor. Or do your own 10 Hz stepping motor (or whatever gear ratio is easy). Best of luck Bill Hawkins -Original Message- * Divider circuits need to be manually started using internal switches [snip] Similarly the motor must be manually started. "These clocks are not a lot of fun to live with. They sing along quite loudly at 1KHz." ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Nutty time-nuttery with WWVB
Please see http://support.ntp.org/bin/view/Main/SecurityNotice or Google "NTP security" But perhaps you meant to create a local NTP network with no connection to the Internet. In that case, SNTP is sufficient for wall clocks. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Clint Jay Sent: Friday, November 11, 2016 2:15 AM Rolling it yourself like that would allow you to negate the security risks associated with IoT as you'd have control of the security aspects. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Need some wisdom from the cesium beam tube gurus out there
Well, they cancel if they're at the same temperature. Bill Hawkins -Original Message- From: Mike Millen Sent: Friday, November 11, 2016 12:28 AM It would work as well if you used a pair of regular copper wires to connect the meter to the thermocouple... The junctions created by all the new connections will cancel out. Mike ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Nutty time-nuttery with WWVB
There are some problems with the Internet of Things and security. For example, look up the Mirai botnet and the DDoS attack on DNS provider Dyn last month. To understand the situation better, read Bruce Schneier's "Secrets and Lies", available as a PDF. The book was written in 2000 when things were simpler and easier to understand, but it still applies. The man has a sense of humor. Schneier makes the point that it is difficult to test software functionality but impossible to test for security. Buffer overruns were a problem back when Morris wrote the first worm. They are still a problem because software vendors can write legal license agreements that say the vendor is not responsible for any failures caused by the software. Basically, you bought it on an "as-is" basis. So the software ships, bugs are discovered, and sometimes the vendor fixes the bugs, especially if they are made public. Vendors don't spend money doing things they don't have to do. IoT devices are made as cheaply as possible. They are made user friendly by not burdening the user with security configuration, so user names and passwords have well-known defaults. The device has no anti-virus application. The simple routers offer little protection, as they have their own issues with default keys to their configuration. Marketing departments have gotten very good at stampeding buyers for things of little value. So good that companies that make the control systems for the nation's manufacturing plants and utilities have embraced the Industrial IoT. That should have been the Industrial Distributed IoT (IDIoT). Previously, control systems had no connection to the Internet, and so there was no need for Internet Security concerns. Now there are many security services, so the IDIoT has created jobs, as well as sales of routers. The air gap and the data diode have been discredited since Stuxnet, which was spread by strewing the parking lot with USB drives. Schneier emphasizes that the difficulty of providing security increases with the complexity of the system. As you may have noticed, each new revision of an operating system provides about a 4X increase of lines of code (in the case of Windows). Security is always in a catch-up race with the ability of criminals to find and exploit faults. Please pardon this intrusion into the world of precision time, but the issue was raised here. As a designer of industrial control systems, I've made it a point to study security, and found Schneier to be a fount of information. Perhaps a disclaimer is in order. I do not know Schneier and receive nothing from plugging his work. Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Fluke Voltage Standards.
Had the HP equivalent for a while. Required special cords to bring the voltage to the DUT. Buyer Beware. Haven't seen a Fair Radio catalog in years, not since I sold the R-39x equipment. There's a big difference between the accuracy of a voltage standard and a time standard. Perhaps this is because there are no satellites broadcasting voltage standards. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Perry Sandeen via time-nuts Sent: Wednesday, November 09, 2016 6:26 PM List, Fair Radio which has been in the surplus electronics business almost forever has two models of Fluke standards for sale. They have a sterling reputation. FLUKE-332A $100 Voltage Standard - Used Reparable FLUKE-332B $125 Voltage Standard - Used Reparable IIRC, this means they will work but are not calibrated. If interested one can email them for exactly what Used Repairable means. FWIW Regards, Perrier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] I love the smell of tantalum in the morning
So what are the odds that the failed cap would be C13? Is this cause for triskaidekaphobia? ;-) Please pardon this random excursion outside the bounds of precision time. Bill Hawkins (who learned not to let kakorraphiophobia lead me to osphresiolagnia [bad odors, not erotic] in college) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Satellite TV messed up, how is GPS time
Satellite TV (Dish, Direct, etc) has been having trouble for 10 hours or so, sometimes losing some channels and occasionally all of them. Fox News is consistently down, so it could have a human cause, but Space Weather says we have unusual solar activity. I no longer have GPS time receivers, so I wonder how GPS is doing. Thanks for any comments. Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Temp/Humidity control systems?
Looking at it as a problem in thermodynamics, which has equations for the flow and storage of heat, it might have a simple solution. If you can have your equipment closet hotter than the basement will ever be, we can use basement air for cooling the closet. The basement air can be held to about +/- 5 degrees F with conventional heating and cooling. You should dehumidify to 50% or less if that is a problem. 30% is a reasonable minimum. You should have a fan or two to stir the basement air. Install the biggest standard air filter you can find in an inside wall of the closet, which will filter incoming air. Install one or more exhaust fans on the wall opposite the filter. At least one of the fans must be variable speed. Or you could use an array of small fans with individual switches to get controlled air flow - better yet, make two of the fans in the array variable speed. Shouldn't be a problem if you use common 12 VDC fans. Now for the control system. You need sensors for closet temp and basement temp and humidity, and also one for the power flow into the closet. Electrical power leaving the closet on 50 ohm cables is assumed to be negligible. You need a D/A converter to control the speed of the fans. You know the temperature of the closet air (maybe want an average) and you know the temp and RH of air available to cool the closet. The RH will affect the heat capacity of the air. Now you calculate the amount of basement air needed to balance the heat flows at the desired temperature, and adjust the fans to provide it. Think of the fun you'll have determining the heat flow model constants for the system. In particular, there's no air flow sensor because they are expensive. You'll need to determine the relation between fan speed and air flow. I'd do this myself to determine the attainable precision, but I live in an old folks apartment now. Let us know how it turns out. Bill Hawkins I know you wanted a COTS solution, but I think this is what you need for 1 degree control. You can't do it with on/off control. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] What would be the proper equipment and procedure?
Ah, you might not have meant that for this list. You are a man of many talents. Dimethyl mercury has given elemental mercury a bad name it doesn't deserve. As a youth, I used it to turn pennies into silvery dimes. Father said he'd ingested a teaspoon to see how fast it would go through him. In his day, beryllium pliers were used around explosives because they were non-sparking. We both lived many years afterwards. People who don't understand the difference between elements and compounds insist that cleaning up after a broken mercury thermometer be done wearing moon suits. So it goes - as time goes by. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Mark Sims Sent: Friday, October 28, 2016 10:26 PM To: time-nuts@febo.com Subject: [time-nuts] What would be the proper equipment and procedure? I don't know if it the proper way but I used a very nice fume hood. Measured the metals (high purity), melted them in a quartz crucible, stirred with a quartz rod, and cast it in a ceramic block with a spiral pattern machined into it with a ball mill. You don't want to contaminate the mixture with other metals, etc. That "Things I Won't Work With" article was about dimethyl cadmium, not metallic cadmium. Reall Nasty Stuff. Metallic cadmium and cadmium plating has been used for ages without killing too many people. It's not something to take lightly, but I've had the pleasure of working around far worse things. For even more extreme nastiness check out dimethyl mercury... one drop, goes through rubber gloves like they aren't there, sure-fire rather horrible death. Derek Lowe's "Things I Won't Work With" series is some of the best reading out there... Unfortunately, I don't think that he is still doing them. His old web site has disappeared. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 1PPS to 32.768 khz
Hi Lee, We all had a first time posting on this list and survived it. No problem. You need to know more about phase locked loops. In this case, you need a voltage controlled crystal oscillator that a simple binary divider can take down to 1 PPS. That 1 PPS is compared to the GPS 1 PPS with a simple flip-flop, which produces a pulse width that can be filtered to be the control voltage for your VCXO. The resulting feedback loop causes your VCXO to track GPS. Now then, this is a great oversimplification of the process for getting very low timing errors. However, human time constants for observation of a clock do not require very low timing errors. Very few people would notice a 50 millisecond error. To get a useful answer from this group, you need to specify the accuracy required. If you want picosecond errors, you are into big bucks. Nanosecond errors are expensive but can be found on eBay. Microsecond errors still need a good GPS receiver (not cheap). Millisecond errors are not normally the subject of this group, although there has been a thread on receivers barely capable of that. Lurk and learn, grasshopper. The cost is low until you decide on the level of accuracy you wish to reach. Best regards, Bill Hawkins P.S. I was afflicted with the desire for accuracy down to the Caesium standard level. Hydrogen masers remained beyond my means. Now I live in an apartment in an old folks community, which required severe downsizing. The return on investment was negative. The older I get, the less I require precision time. YMMV. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Lee - N2LEE via time-nuts Sent: Tuesday, October 18, 2016 9:03 PM To: time-nuts@febo.com Subject: [time-nuts] 1PPS to 32.768 khz First let me say this is first time I have posted to the group so go easy on me. :) Secondly I want everyone to know that you guys make me feel so NORMAL for wanting to use and understand accurate timing devices. I thought there was something seriously wrong with me now I know there are others affected with the same disease. hehe Now my questions. 1. Does anyone know of a device that will take a 1PPS GPS timing signal and generate a 32.768 kHz sine wave output ? I have big digital clock that uses an 8 bit micro processor and an external 32.768 crystal. Obviously the external crystal is awful for accuracy. I have searched every where using as many search terms as I can think of and can't believe there is not a device that performs this function. I have found a couple of Epson RTC chips that might come close that 1pps but I don't think that corrects the 32khz just the clock time. 2. 10 Mhz Freq Standard I am not in the same league as the majority of the list members and just starting to dabble in GPSDO stuff. I have tried to find a thunderbolt as a starting device but it appears those are either dried up or people want too much money. I wanted to get the opinion of anyone who has tried the Leo Bodnar GPSDO ? For the money it appears to offer a beginner a lot of features. Thanks and reading the daily digest of what you guys are working on. I have a feeling if I am not careful you guys could cost me a lot of money. hehe Lee ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Moving GPSDO
The Motorola receivers in Lucent gear won't output a time signal if they don't have an initial survey. I make this assertion because the RFTG I had would not lock. The Motorola bag of bits decodes to say there's no position fix because enough satellites have not been acquired. Too bad I lived in a valley. Let us know how this turns out, starting from an initial survey. Bill Hawkins -Original Message- From: Joseph Gray Sent: Sunday, October 16, 2016 11:20 PM I'm curious to know how accurately a GPSDO will keep its 10 MHz output while moving. No initial survey to set a position would be done. I don't care about the UTC time. Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] A new take on the all-hardware GPSDO concept
What kind of capacitor is used for the 10 µF cap - electrolytic or film? Bill Hawkins -Original Message- From: Nick Sayer via time-nuts Sent: Monday, September 26, 2016 11:18 PM With a short TC loop filter, the PLL does lock up, but obviously the jitter of the Venus 10 MHz output comes through. With a longer TC, the PLL never locks - or at least if it does lock, its locking significantly off frequency. Thats with a 10 µF cap and varied resistors between 10k and 1M. The best I got was at 200k - a TC of 2s. That resulted in this video. Unlike other videos Ive made comparing two GPSDOs, this one is not a time-lapse. The reference is an OH300 based GPSDO. https://www.youtube.com/watch?v=hiHRp0dCJ64 <https://www.youtube.com/watch?v=hiHRp0dCJ64> A time constant of 10s (1M resistor) just doesnt work at all. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Vintage Quartz Crystal Manufacturing
I watched the video when it first hit the list and found it interesting, as I would any complex industrial process. I've seen another crystal film that was available a few years ago as a file, but can't find the reference. The people who can't believe people ever worked under those conditions with those primitive (today) tools need some historical perspective on the rate of technical change. My grandfather grew up before automobiles. My father grew up before jet planes. I grew up before computers, and worked with them as they changed. And the 'S' curves keep coming . . . [See "Rise of the Robots."] One other thing - the comments contained one about the matter-of-fact presentation being so different from what passes for explanations of technology on TV today. I'd quote it, but I couldn't find it in the comments today. It hit home, though. Today the presentation would have half a dozen people of varying ethnicity and sex, each making some lame joke along with a shallow explanation of what was going on. Compare the Science channel's new "How Do They Do It" to the older "How It's Made" shows. I blame it on the advertisers who control TV programming who want to maximize eyeballs by going as low as they can and still find people who can change a TV channel. Be glad to discuss this with anyone off the list. And now, back to precision time. Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent RFTFm-II-XO
As to what you would see, find the manual for the Motorola receiver for details. I don't have the link, but somebody else does. You get some info about the device and info about each satellite. You can use a 422 to USB converter or clip on either wire with a digital scope that decodes simple serial streams, like PicoScope. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Wednesday, September 14, 2016 6:13 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Lucent RFTFm-II-XO Hi These days, a RS-422 to USB adapter is a sub $20 item, even from a "name brand" outfit with real drivers. . If you shop a bit, you can get some dirt cheap USB to 422 adapters at the risk of having issues with the drivers (now or down the road). Bob > On Sep 13, 2016, at 11:44 PM, Chris Waldrup <kd4...@gmail.com> wrote: > > Hi, > > Regarding the Lucent box- I wanted to let everyone know that once it locked to satellites, I have a 10 MHz out. > The output was a square wave with some ringing, but I built a three element low pass filter and now I have a really nice 10 MHz sine wave. > Thanks to all! > > Last question I see it has a RS-422 output on one of the connectors. If I build or buy a 422 to 232 converter can I expect to be able to view the unit's data output with something like Lady Heather or Tboltmon? Or at least see an output with Hyperterminal? > > Thank you. > > Chris > KD4PBJ > >> On Sep 6, 2016, at 16:42, Bob Camp <kb...@n1k.org> wrote: >> >> Hi >> >> One might *think* a redundant system would work fine with the plug yanked. >> In this case .. nope. It needs to have a dummy connector on it to get >> the device running. I agree that this is an "interesting" way to do >> it. Regardless of that, they did the units need the signals from the >> other box (or fake signals) before they will do useful stuff. >> >> Bob >> >> >>> On Sep 5, 2016, at 10:22 PM, Bill Hawkins <bill.i...@pobox.com> wrote: >>> >>> Fake connections? Isn't a redundant system supposed to allow one box >>> to be disconnected? >>> >>> Bill Hawkins >>> >>> -Original Message- >>> From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob >>> Camp >>> Sent: Monday, September 05, 2016 8:20 PM >>> To: Discussion of precise time and frequency measurement >>> Subject: Re: [time-nuts] Lucent RFTFm-II-XO >>> >>> Hi >>> >>> If you only have one box, you need to be sure the "fake" connections >>> on the interconnect are correct. If they are not, you will not get >>> it to operate correctly. >>> >>> There also is a survey process if you have not had it running in >>> your location before. That could take a few hours to a few days >>> depending on your antenna. >>> >>> Bob >>> >>> >>> ___ >>> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to >>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >>> and follow the instructions there. >> >> ___ >> time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to >> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >> and follow the instructions there. > ___ > time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent RFTFm-II-XO
Fake connections? Isn't a redundant system supposed to allow one box to be disconnected? Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Monday, September 05, 2016 8:20 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Lucent RFTFm-II-XO Hi If you only have one box, you need to be sure the "fake" connections on the interconnect are correct. If they are not, you will not get it to operate correctly. There also is a survey process if you have not had it running in your location before. That could take a few hours to a few days depending on your antenna. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Heathkit clock available
There are two systems that affect line frequency anywhere in the world. One is the use of multiple power producers generating steam for turbines that turn huge generators. The generators are synchronized by the distribution networks that connect them. A generator rotates at the frequency determined by all of the other generators, If its turbine is receiving less energy than is required to keep up, the generator will take the balance of power from the network. If the turbine produces more energy than is required, it will cause the line frequency to increase a very little bit. Change 'steam' to 'water' for hydro-electric plants. A networked connection of generators and loads requires a perfect balance of power produced with power consumed to maintain constant frequency. This can only be done for very small networks. You cannot put a PID controller on each turbine and set it for a GPS derived frequency. The control actions would fight each other and destabilize the network. In the early days, each power station had a clock driven by the generators and a reference clock. An operator would increase steam to the turbines a bit if the station clock fell behind the reference clock, or decrease steam slightly if it was gaining time. There was (is) no way to predict the behavior of the loads, except from general experience of the effects of weather and holidays. Today's networks are much too large for control by station clocks. A large region has a central power dispatching station. A dispatcher tracks the difference between network time and GPS time. If the network is losing time, the dispatcher calls the necessary number of generating plants and asks them to increase power. It is common to lose time as the loads of the manufacturing day increase and to make it up after 4 AM or so. (During the 50s, the Air Force determined that 4:30 AM was the time of minimum human activity, and so a probable time for an enemy to strike with missiles.) I visited the Pennsylvania, New Jersey, and Delaware (PennJerDel) region's dispatch center in the seventies. Very impressive wall maps of major generation stations and load centers with their data. It is expensive for a plant to change power, and so they hatched the plan to stop trying to hold the time difference to zero over a day. There was sufficient outcry to abandon the plan. The other system comes from the use of high voltage DC tie lines to exchange power between networks isolated by geography, such as the West Coast and Texas. The DC lines use high voltage, high power solid state inverters to convert DC to AC or reverse the direction when power could flow the other way. The inverter frequency can be precisely controlled, but it is controlled to balance the power flow, not hold the line frequency. A network pays for the tie line power it produces or consumes. Different regions can have different phase behavior. I have only seen West Coast plots on this list. When I did some work with this in Minnesota in the eighties, the phase variation was only about 6 seconds during a day and zero from day to day. This is my understanding of the system. People with more knowledge, please correct my misconceptions. Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Heathkit clock available
The GC-1000 was the Most Accurate Clock. This new GC-1006 is Most Reliable without mentioning accuracy. The ad says that the standby oscillator can be calibrated by pushing some buttons on the back. Wondering how they do that almost makes me want to buy a simple clock that is $100 per pound. Perhaps there is a motor that turns a tuning capacitor to make the standby oscillator match the line frequency. More likely software changes the number of counts of some inexpensive XO per cycle. I have an alarm clock with 2" seven segment LEDS that I can read without glasses. Its backup oscillator is LC, and somewhat faster than the line. It has carried me through the short outages I've experienced. There's not enough info on what's behind the Santa Cruz rebirth of Heathkit. If I thought they were solid, I'd buy a kit to help prime the pump, so to speak. As it is, I'll be looking for neon-colored seven segment arrays a bit taller than those in the GC-1006. No doubt, there are many schemes for disciplining 60 (or 50) Hz oscillators with 1 PPS. TIA for any helpful comments. Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS antenna selection - lightning
This thread grows old, so here's one person's summary: There are two ways to be damaged by lightning: 1. A direct hit pumps 100 kiloamps of electrons into an ohm or so of your local wiring. There is no way to survive a direct hit except to implement stuff only the Military can afford. The probability is so low (outside of Florida and mountain tops) that your homeowners insurance may cover it. 2. A 100 KA strike goes to ground near you, with two effects: a. The ground resistance allows a large range of volts per meter to kill cows but not golfers with their feet together. b. A mighty electromagnetic pulse (EMP) induces voltages in anything inductive that is not shielded or twisted. Case 'a' argues for a single point earth ground. When the ground voltage goes up, you want all of your equipment to go up with it, as if it was on an isolated ground plane. It seems best to use the Electric Power Company's house ground for that reference point in your home. If you use a UPS for a set of equipment, everything on it should ground to that UPS (which should have a high capacity surge arrestor). You are left with telephone cords, TV cables, and antennas as peripheral connections to protect with surge arrestors. Marine supply stores sell rolls of 4 inch wide copper strap for connecting the mast on the wheelhouse cabin with the keel of fiberglass boats. This is also the ground for all electronic equipment. The strap is considerably less inductive than a wire. Case 'b' argues against long wires inside the area that contains the common ground and the surge arrestors at its periphery. Surge arrestors have energy ratings that refer to the energy of the EMP that caused the surge. I have no idea how that relates to lightning EMP energy so I buy the most capacity I can afford. I used these principles in a home that had a pair of HP GPS antennas four feet apart on a twenty foot mast of six inch plastic pipe, using N connectors and 50 feet of RG-8 to a pair of Z3801A receivers. The neighbor's tree took a direct hit (was split apart) less than 100 feet away. He had extensive electrical damage originating at the outdoor flood light six feet from the tree. I lost the GPS antenna closest to the tree but nothing else. FWIW, I had wireless G access points separating the area connected to the antenna from the rest of the house network. No attempt was made to beef up the grounds. Regards, Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] The home time-lab
Years ago I knew exactly how Sola regulators worked. That has faded, but what remains is that the regulation was done by varying the saturation of the core. That's why there is a slot in the laminations. I find it hard to believe that a partially saturated core can produce zero harmonics. In any event, the LC circuit does not filter anything. Possibly the circuit counteracts the change in saturation as the line voltage changes. I wouldn't expect it to effect the high frequency components of spikes. Any power supply that has a diode bridge and capacitor to create DC only draws power from the line at the voltage peaks, when the diodes become forward biased. I don't know of any choke input supplies, as were used to reduce the peak current of vacuum tube rectifiers. I know nothing about power factor correction for a bridge and capacitor, whether or not it is followed by a switching regulator. Make of it what you will. Bill Hawkins -Original Message- From: Alex Pummer Sent: Sunday, July 24, 2016 7:29 PM That is interesting, since the Sola device has a to the line frequency tuned tank circuit in it, thus the output should not have to many higher harmonics and should look reasonable close to sinusoidal see here: http://www.rdrelectronics.com/russ/jun16/vs2.PDF 73, K6UHN Alex ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lucent boxes
No, it does not work, unless you can reprogram the microprocessors. I
speak from experience.
The older boxes used a GPS receiver that reported up to 6 satellites.
The newer boxes report 8.
The messages that report satellite health have different lengths.
If the micro reports an error in the message, the box goes into
"flywheel" mode (aka holdover).
The oscillators are undisciplined, wasting all of that GPS info.
An external PPS signal, if you could couple it in, would be ignored
because the micro won't even try to use it.
Bill Hawkins
Note: I can't reprogram micros with unknown code.
-Original Message-
From: Douglas Baker
Sent: Monday, July 18, 2016 4:39 PM
Chris,
The RFTGm ("m" for miniature even though still a large box) is a later
version of the RFTG line. The XO unit houses the GPS receiver which is
essential for disciplining. Both boxes operate at 24 VDC and there is
an interface cable drawing on line at KO4BB's web site. Never tried to
hook them up together, but it might work. Maybe others here may know.
Good luck with it.
73's Doug
On Jul 18, 2016 12:52 PM, "Chris Waldrup" <kd4...@gmail.com> wrote:
- snip
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Re: [time-nuts] OXCO Spurious Output at Line Frequencies
Just to clarify - AC motors are either synchronous or induction. Induction motors must slip away from line frequency to develop the magnetic field they need to carry a load. The name plate speed is for rated load and the number of magnetic poles in the rotor. A 2 pole motor spins near line frequency - 4 poles at half. 1750 is for a 4 pole motor. And so on ... Bill Hawkins -Original Message- From: Hal Murray Sent: Tuesday, July 12, 2016 7:24 PM Most of the medium sized motors run at slightly below line rate, and often at half of line rate. I'm thinking of the classic squirrel cage induction motor vs a synchronous motor. A quick google search found 1725 and 1750 RPM. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS for Nixie Clock
Well, it's late and I've nothing else to do. I sympathize with you, but my Nixie clock is a computer display made years ago by Jag Air Clockvault. One of these Windows OS upgrades is going to refuse to run it. You say it has an FPGA for the display. What provides the numbers to be formatted? A line frequency clock has no time info - it has to be set. Do you have raise/lower buttons or just raise? Good luck doing a simple conversion from GPS receiver time to numbers the FPGA can convert. Much simpler to count 1 PPS pulses, but like line frequency, there's no adjustment for leap seconds. Reclocking the 1 PPS with 10 KHz seems like overkill for a clock to be read by humans. GPS reception and accuracy falls off quickly if the antenna can't see a large part of the sky. It won't function if it can't see several satellites. I know this empirically. WWVB has no such requirement, and it's accuracy is a better match for human precision. Could you give us a link to a picture of your solid walnut Nixie clock? Got any more walnut? Bill Hawkins -Original Message- From: John Swenson Sent: Sunday, July 10, 2016 10:55 PM I'm thinking about converting a Nixie clock I built years ago into using GPS for the time base. No real NEED, just for fun. The clock uses an FPGA for formatting and display, using the 60Hz line frequency as the time base. The case is a single hollowed out block of walnut. I'm looking into a TU36-D400-020 receiver. This seems to be optimized for timing purposes rather than navigation, it has 1PPS and 10KHz outputs. I'd be getting it from RDR Electronics, which says it it uses the Motorola command set. This seems fine for me, it has the information I need, specifically UTC time so I don't have to worry about leap seconds. I have a few questions about this receiver: The data sheet lists two serial ports, but I don't see any information about which to use. Are they identical, do I have to use one for some functions and the other for other purposes? What are the serial port parameters? 9600-8-N-1? Or something else? Which is better to use, the 1PPS or the 10KHz? I can easily go either way. The clock display just goes down to seconds so 1PPS would work. I could also re-clock the 1PPS with the 10KHz. What antenna to use? I would prefer something mounted inside the case. It is wood so an internal antenna will hopefully work. The board comes with a pigtail but it is not SMA. Any other hints for using this? I've never done a GPS interface before so I'm not sure about how I calibrate the time coming from the message over the serial port. Is it something like "the time is such and such at the rising edge of the next PPS, or the previous one? Or is there some other mechanism for calibrating when the second changes on the display to something close to reality? I previously toyed with the idea of using an X72 rubidium oscillator just for the bragging rights, but I would still need the GPS to get the time, I decided the TU36 on its own is probably just fine. Thanks, John S. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Visiting Greenwich
Hi Morris, The idea of the author of "A Brief History of Time" telling the time briefly has a certain appeal. Can you share some construction details? Even a parts list would be useful. Thanks, Bill Hawkins -Original Message- From: Morris Odell Sent: Wednesday, July 06, 2016 5:32 PM This is a terrific thread. I have been to Greenwich too and also some of the clock exhibits in London. There's a beautiful pendulum master and slave clock set up in the British Museum, and there's an original huge Caesium (British spelling!) frequency standard in the Kensington Science Museum. The last time I was there in 2013 there was also a special feature exhibition about Alan Turing and the Bletchley code breakers. I did pass through Bletchley station on the train about 20 years ago when I was in the UK but regrettably didn't have the time to stop there. I can recommend the climb up the hill at Greenwich to anyone - it's definitely worth the effort. They didn't allow photography of the Harrison clocks but I did manage to sneak one or two before the minder got to me :-) I'd love to have a genuine electro-optical speaking clock. There's one in the Australian Telecom museum not far from where I live. There's also a terrific display of a complete electromechanical telephone exchange including a speaking clock in the telecommunications museum in Stockholm but as I don't speak Swedish I couldn't understand what it was saying. I've just finished making a speaking clock using more modern technology, it uses a 30 year old speech synthesizer chip and sounds just like Stephen Hawking. Morris Melbourne, Australia ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] over-determined clock solution
Try overdetermined as one word. Also include GPS in the search string. Google has many hits. In timing receivers, once the position has been determined the receiver switches to using timing information from all of the satellites that it can see. Like the man with too many clocks, the clock time solution is calculated from too many satellites. That's what it looks like to me, anyway. Bill Hawkins -Original Message- From: Steve Sent: Saturday, June 25, 2016 9:08 AM The phrase "over-determined clock solution" is used in the Trimble Thunderbolt user manual in describing operation of the Thunderbolt GPS receiver. The manual does not discuss the phrase in any detail, appearing to assume the reader understands its meaning. An internet search on "over-determined clock solution" did not turn up any substantive hits. What does "over-determined clock solution" mean? Thanks. Steve, K8JQ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT stuffing boards: Saving the thread
The problem is editing out all of the redundant material. It's tedious by hand. Anyone got a program to do that? Say, in perl . . . Bill Hawkins -Original Message- From: John Ackermann N8UR Sent: Friday, June 24, 2016 1:36 PM You know, this thread has had a tremendous amount of practical information, with actual URLs, etc. Would someone be willing to consolidate the info on a web page somewhere? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Simple solution for disciplining OCXO with 1 PPS
Well, if you're open to something completely different, consider using a motor-driven potentiometer that provides a trim voltage to the OCXO. Adjust the motor at long intervals, leaving it off the rest of the time. It's called sampling control. You'll need to have an analog phase comparator for 1 PPS that has enough volts/degree to provide a useful error signal to the motor controller. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bernd Neubig Sent: Sunday, May 22, 2016 12:41 PM To: 'Discussion of precise time and frequency measurement' Subject: [time-nuts] Simple solution for disciplining OCXO with 1 PPS Hello Fellow time-nuts, I am looking for a simple solution to discipline my 10 MHz reference OCXO in my private lab with an 1 PPS signal from a separate GPS receiver. I am curious if there is a solution possible without programming a microcontroller, as I am an old-fashioned "analogue" guy ;) I am well aware, that such a solution would have a lot of disadvantages, as it cannot effectively compensate for short-term variations. However I would be happy if such a KISS solution could achieve a stability (STS) of better 1E-10 over an hour. I know this is a damned long integration time for an analogue integrator... If that sounds too weird, I am open to receive advises for a microcontroller based solution. Thanks a lot for your comments to come. BTW: you need not to teach me about basics of short-term stability. I just want to evaluate the limits of a possible analogue solution. For sure, that's not real disciplining, but more like a long-tau integration PLL Best regards Bernd DK1AG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GENIUS by Stephen Hawking (PBS TV), with 5071A cesium clocks
Well, Tom, you did get an active part in the show, and Stephen Hawking credited your worldwide reputation. Wow. You even sounded as natural as the actors used to give emotional depth to a science story. What troubles me is that we have the instruments to detect a 20 nanosecond difference in atomic clocks, but we have no way of measuring the effect on living cells. At least, not until we have devices that will transport us near the speed of light. Meanwhile, here I am on the third floor of a retirement community, possibly living faster than those on the first floor. Not that it approaches a significant fraction of a second per year; it's the principle of the thing. :-) Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Temperature controlled TCVCXO
Note that the 3450B has an accuracy of 10E-5. You're probably looking for something a lot better than that. Bill Hawkins -Original Message- From: David Sent: Friday, May 13, 2016 8:28 PM On Fri, 13 May 2016 11:38:06 -0500, you wrote: >David wrote: >> I was thinking of holding the temperature right at 25C or maybe a >> little higher at an inflection point to minimize the possibility of >> condensation. The difficulty is that the ambient temperature could >> vary above or below that so the TEC has to both heat and cool but >> that is a solved problem. > >The HP 3450A & B model digital multimeters used a Peltier device to >control the temperature of the voltage reference zener diode. You can >download the manual for the "B" model from Keysight's web site to get >an idea of the control circuitry >(http://www.keysight.com/main/techSupport.jspx?searchT=3450B=3450B:e psg:pro=3450B:epsg:pro=US=eng). >There's also a sales bulletin for that model that gives a bit more >information about the Peltier device and chamber >(http://www.ko4bb.com/getsimple/index.php?id=manuals). Search for 3450A >on that site. > >The chamber is controlled to 43C by the Peltier device, allowing quite >fast warmup times for the instrument, and operation above normal >environmental temperatures. > >Cheers, >Dave M It figures that HP would have done this if anybody had. I am not that familiar with their design history so thanks for bringing this to my attention. I did not find anything in the theory section of the original service manual although it does have the schematic but K04BB has a supplement which discusses the 3450A peltier chamber and circuit in detail. They even sort of mention that the gain of the peltier differs significantly between heating and cooling. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] What is "accuracy"? (newbie timenut, hi folks!)
Well, I'll take a crack at this, although I'm no expert. I hope it provides a base for others to build on. First the basics. Accuracy is a property of the thing being measured. Precision is a property of the measuring instrument. A digital voltmeter may have a precision of one millivolt and an accuracy of a tenth of a volt. You know what the meter reads to one millivolt, but you only know the voltage to an accuracy of 0.1 volt. Time and frequency are mathematically related. If you know one, you know the other. They can be measured to an accuracy that is very near the precision of the instrument because there is no analog to digital conversion, as required by most physical values. The accuracy is somewhat degraded by the zero crossing detector. Otherwise, measuring frequency and time is simply a matter of counting cycles of an oscillator. A clock is a cycle counter with a fixed period of repetition. When you want to know the accuracy of a clock with respect to a standard, you are really interested in how well they match over a period of time. You can watch your wall clock slow down with respect to WWV or some other national standard. Then you can say the clock is accurate to some value of minutes per day or other counts per period of time. I've never really looked at Allan Deviation, but it seems to be a statistical method for displaying variations in accuracy with time. Perhaps ADEV is what you need. Regards, Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of BJ Sent: Thursday, May 05, 2016 8:34 PM To: time-nuts@febo.com Subject: [time-nuts] What is "accuracy"? (newbie timenut, hi folks!) Hi Time Nuts, I'm fairly new to the fascinating world of time and frequency, so I apologise profusely in advance for my blatant ignorance. When I ask "what is accuracy" (in relation to oscillators), I am not asking for the textbook definition - I have already done extensive reading on accuracy, stability and precision and I think I understand the basics fairly well - although, after you read the rest of this, you may well (rightly) think I am deluding myself. It doesn't help matters when some textbooks, papers and web articles use the words precision, accuracy and uncertainty interchangeably. (Incidentally, examples of my light reading include the 'Vig tutorial' on oscillators, HP's Science of Timekeeping Application note, various NIST documents including the tutorial introduction on frequency standards and clocks, Michael Lombardi's chapter on Time and Frequency in the Mechatronics Handbook and many other documents including PTTI and other conference proceedings). Anyway, you can safely assume I understand the difference between accuracy and precision in the confused musings that follow below. What I am trying to understand is, what does it REALLY mean when the manufacturer's specs for a frequency standard or 'clock' claim a certain accuracy. For ease and argument's sake let us assume that the accuracy is given as 100 ppm or 1e-4 As per the textbook approach, I know I can therefore expect my 'clock' to have an error of up to 86400x1e-4= 8.64 s per day. But does that mean that, say, after one day I can be certain that my clock will be fast/slow by no more than 8.64 seconds or could it potentially be greater than that? In other words, is the accuracy a hard limit or is it a statistical quantity (so that there is a high probability that my clock will function this way, but that there is still a very small chance (say in the 3sigma range) that the error may be greater so that the clock may be fast/slow by, say, 10 seconds)? Is it something inherent, due to the nature of the type of oscillator (e.g. a characteristic of the crystal or atom, etc.) or does it vary so that it needs to be measured, and if so, how is that measurement made to produce the accuracy figure? Are environmental conditions taken into account when making these measurements (I am assuming so)? In other words, how is the accuracy of a clock determined? Note that I am conscious of the fact that I am being somewhat ambiguous with the definitions myself. It is my understanding that the accuracy (as given in an oscillator's specs) relates to frequency - i.e. how close the (measured?) frequency of the oscillator is to its nominal frequency - rather than time i.e. how well the clock keeps time in comparison to an official UTC source but I am assuming it is fair to say they are two sides of the same coin. Does accuracy also take stability into account (since, clearly, if an oscillator experiences drift, that will affect the accuracy - or does it?) or do these two 'performance indicators' need to be considered independently? I am guessing that the accuracy value is provided as general indicator of oscillator performance (i.e. the accuracy does REALLY just mean one can expect an error of up to, or close to?, a certain amount) and that stability (as i
Re: [time-nuts] Building a mains frequency monitor
The schematic is too simple. There is noise on the power line from switching things on and off, leakage from dimmers and switching power supplies, and the occasional animal that gets across the HV distribution line, not to mention lightning, induced or direct. A simple capacitor will reduce high frequency stuff. The purist will invest in an L and C that resonates at 60 Hz. Alternatively, use a synchronous motor driving a load with sufficient inertia in combination with a slotted disk and photo pickup. Perhaps an old record turntable will do - but not one with a regulated DC motor. The science fair folks got enough interesting data without all that, but the precision is not known. The link didn't have any reference to code at all. This is a way of looking at frequency variations with natural causes that does not require expensive equipment, if done right. Bill Hawkins -Original Message- From: Nick Sayer Sent: Friday, April 08, 2016 7:20 PM The instructable I wrote about it is at http://www.instructables.com/id/Science-fair-How-accurate-is-the-AC-line -frequency/ There's code for the Arduino and the Linux side as well as schematics. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Building a mains frequency monitor
Phase noise? The line frequency shifts phase every time a major electrical load is added or dropped from the power line. Seems to me this effect swamps every error in the measurement system. You are looking for parts per thousand at most. Precision GPSDO 10 MHz is overkill. In my humble opinion, that is. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Jay Grizzard Sent: Wednesday, April 06, 2016 8:22 PM To: time-nuts@febo.com Subject: [time-nuts] Building a mains frequency monitor Since it seems to be a week for new projects on time-nuts... ;) So I've been wanting to set up a power line frequency monitor for a while, and now(ish) seemed to be a good time for me. %< --- I appreciate any comments / feedback / pointers! -j ___ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Advise on building a DIY GPSDO?
No disrespect intended, but it seems to me that human technology is built on the published experience/mistakes of others. A newbie would do well to read the experiences of others before investing the first penny in hardware. TVB, Magnus Danielson, Bob Camp, Jim Lux, Attila Kinali and others have been there and done that. So have I but I wouldn't compare myself to them. First I got the $300 HP Z3? GPSDO units, then I tried some equally expensive Lucent units. I did get the $750 HP Rubidium and learned from the construction and operation. Then I got the $1200 Caesium standard and learned that I'd have trouble shipping it. That stuff is all gone now, much of it to paid junk haulers. I don't regret it, though. Education can be expensive. The high point was talking to a Minnesota professor of physics about the FTL neutrinos. Time and frequency can be measured to a precision/accuracy that is not possible for volts, amps, and ohms. It's exciting stuff, and correspondingly difficult. FWIW Bill Hawkins -Original Message- From: Alexander Pummer Sent: Monday, April 04, 2016 4:49 PM Building it cost you time and money, most likely much more than to buy, but you gain experience and you learn the limits of the different techniques, what you would not get to know other way 73 KJ6UHN Alex ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Advise on building a DIY GPSDO?
Perhaps you should quantify your goals - unless you are simply looking for the best you can do with the money you have. Then discover Tom Van Baak's website www.leapsecond.com - There is very little that he has not tried at one time or another. The short answer is that you use crystal oscillators for the short time constant accuracy that is not available from Rubidium. Good fortune. Bill Hawkins -Original Message- From: Nicolas Braud-Santoni Sent: Sunday, April 03, 2016 5:04 PM To: time-nuts@febo.com Subject: [time-nuts] Advise on building a DIY GPSDO? Hi, I've been slowly becoming a fellow timenut over the last few years, though said nuttery had yet to go beyond adding some wiring to get the PPS signal out of my GPS and into my NTPd. %<--- [snip] ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Reliability of atomic clocks
Taking Alan Melia's point that there aren't enough of these devices to establish good statistics and Bob Camp's point that temperature can cause components to fail before the physics package, I'd suggest that there is a need to specify the thermal environment for the 15 year run. How large was the heat sink? Did it have a fan? Also, the M-100 is the military version of the FRK-L that Collins used in its Omega navigation receivers, which were rated for commercial aircraft, probably with redundancy. Mil-spec parts would be somewhat more reliable than commercial parts. In my experience with industrial process control systems, anyone who needed reliability used redundancy, and hoped that the fail-over software would work. When safety was a concern triple redundancy was used with 2 of 3 voting for output values. FWIW Bill Hawkins -Original Message- From: Rob Sherwood. Sent: Sunday, March 27, 2016 11:34 AM My Efratom M-100 has been running for about 15 years 24/7. I have no idea if that is typical. It was purchased as NOS for $300. Rob NC0B ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] quartz thermometers
It may be that the need for that kind of resolution died out. The next step up from quartz thermometry is resistance thermometry. The linearization equation for platinum has enough terms to make it uncertain around .01 C. Temperature calibration baths usually use platinum resistance sensors. It may be that the triple point of water does not have the certainty to reach '0.0001C' Disclaimer: I only worked with industrial sensors from Rosemount, Inc. as an employee. Bill Hawkins -Original Message- From: Alan Ambrose Sent: Friday, March 11, 2016 11:42 AM Hi, I hope this is still relevant and not too off-topic...but since it involves crystals and tempco... Quartz thermometers (e.g. the HP 2804A) with their 'linear cut' crystals and '0.0001C resolution' seem to have been a thing from the mid-60's to the mid-80's: http://www.hparchive.com/Journals/HPJ-1965-03.pdf There still appear to be some manufacturers making the crystals: http://www.statek.com/products/pdf/Temp%20Sensor%2010162%20Rev%20B.pdf Anyone know why they died out? Did a better technology replace them? TIA, Alan ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Old xtal filter
Look up the Collins CV-157. This 1950s unit converted the IF output of an R-390 receiver into upper and lower sidebands, which could be further demodulated by existing land line multiplexing techniques, such as 4 RTTY on each sideband. It heterodyned the R-390 IF to 100 KC and filtered that with a 10 CPS bandwidth filter. A mechanical servo tuned the heterodyne oscillator to hold 100 KC. It was a marvel of technology at the time. Didn't use the Knights filter, though. Possibly the heaviest converter Collins built. Had 44 tubes. Had one once, but time passes. Bill Hawkins -Original Message- From: Joseph Gray Sent: Sunday, March 06, 2016 1:32 PM Assuming I made the pictures small enough, attached are two images of an very old crystal filter that a friend found. The strange thing about it is the bandwidth - 100 Hz. What could this have been used for, with such a narrow bandwidth? Joe Gray W5JG ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LIGO detects gravitational waves
If it were possible for time nuts to measure time differences to 10E-21, could they have seen the effects of the gravity wave? Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LIGO detects gravitational waves
IMHO, the decay seems backwards because we are watching the growth of the event as the black holes approach each other, reaching a maximum at collision. Don't know why the signal drops off after the collision. May be because gravity stops changing, or maybe because the resulting object left the universe - well, not if mass and energy are conserved. Or did the wave contain all of the radiated energy? Disclaimer: My field of study was not physics. Bill Hawkins -Original Message- From: Bob Stewart Sent: Saturday, February 13, 2016 2:35 PM Hi Tom, Thanks for posting this. I'm looking at the timelab plot, and the only thing I can relate that to is a musical note played backward. IOW, the decay seems backwards to me. Bob - AE6RV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] moon bounce for synchronization
And on the top left, a fan-fold paper printer for the data. Imagine handling all of that data manually instead of getting it in a disk file. Bill Hawkins -Original Message- From: Jeremy Nichols Sent: Saturday, January 30, 2016 12:43 PM To: time-nuts@febo.com Subject: Re: [time-nuts] moon bounce for synchronization Ooh! Ooh! Not only a 5245 with a 5265 voltmeter plug-in but a 5360 Computing Pig! Great picture, thanks for posting it. Jeremy N6WFO On 1/30/2016 6:16 AM, jimlux wrote: > This month's historical picture from JPL > http://beacon.jpl.nasa.gov/historical-photo-of-the-month > > This atomic clock was used at the Goldstone Time Standards Laboratory > in 1970, to synchronize clocks at Deep Space Network stations around > the world. This master clock was accurate to plus or minus two > millionths of a second, when compared to clocks maintained by the > National Bureau of Standards and the U.S. Naval Observatory. In the > late 1960s, JPL had developed a moon bounce technique to transmit > signals from one deep space antenna to another. Experiments included > periodic measurement of timing signals that were reflected from the > surface of the moon, to find out if the station clocks were within > allowable limits for accuracy. > > Time-nut will recognize, of course, that none of the things in that > picture are actually an atomic clock, although they are thing that are > useful if you have an atomic clock. > > > Note the sophisticated temperature monitoring system. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Downsizing dilemma, HP 3335A
MIT had a reasonably famous EE professor there circa 1950 - Harold Edgerton, known for his strobe lights and stop-motion photography. He also designed sonar pingers. Both depended on triggered capacitor discharge energy. There is now an Edgerton Center at MIT that teaches the practical art of soldering using simple circuits. The class size was about 25 when I visited about 10 years ago. Not enough MIT students attended, so they opened it to area high schools. Today's EE students can be productive if they know how to direct technicians. That's a skill that is learned on the job. I expect most of us know what happens when the boss doesn't know what the techs are doing. In my experience, you don't get good designs if you don't know how they are built. But then, there are people who think the Universe is based on mathematics rather than the other way around. Bill Hawkins P.S. My thanks to those who took my time instruments (3335A). I won't have junking them on my conscience. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Rob Sherwood. Sent: Wednesday, November 11, 2015 5:26 PM To: 'Discussion of precise time and frequency measurement' Subject: Re: [time-nuts] Downsizing dilemma, HP 3335A The EE department at the University of Colorado has an enlightened professor. http://ecee.colorado.edu/faculty/popovic.html Zoya required her students to not only get a ham license, but to build a Norcal 40A. http://ecee.colorado.edu/~ecen2420/Files/NorCal40A_Manual.pdf Most of the EE students had no idea what a resistor really was, let alone have any experience in soldering a resistor or capacitor on a PC board. One student stuffed the PC board, bent all the leads 90 degrees without cutting any of them off, and then in effect flow soldered the whole bottom of the PC board! One wonders how EE grads today can actually get a job and be productive with so little hands-on experience. Zoya belongs to the Boulder (Colorado) Amateur Radio Club, and our monthly meetings are in the EE department. It is too bad this is likely an unusual example of what happens on campuses today. Rob NC0B -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Pete Lancashire Sent: Wednesday, November 11, 2015 10:01 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Downsizing dilemma, HP 3335A I can understand the downsizing, someday it will happen to me. And where I live there is pretty much zero interest in anything electronic. The two local schools Portland State and Reed both have EE but the students done seem to have any interest in anything physical. they believe everything they need or have interest in can be simulated on a computer. I helped one of the PSU EE's one day, just finished his 2nd year, had an old Kenwood stereo distorted left output. He pretty much had no idea what to do, and when 'we' found the bad transistor, he didn't really know how to replace it. BTW I know a Comp Sci graduate from PSU that can not write a program in any language that outputs "Hello World" -pete Sad On Thu, May 23, 2013 at 5:08 AM, paul swed <paulsw...@gmail.com> wrote: > Bill > It is unfortunate when the time comes to downsize. Even worse as time > goes by at least for me each piece of test equipment from HP seems to > get heavier. Must be dust building up inside. So as Ed says if you > need that fine grain resolution you need them. > But you are also running into the age thing in the gear and that there > are failures that creep in that are really a big problem to figure out. > Especially if some form of programmable logics involved. > Lastly sending them to the dumpster is the worst thing. But then the > ole reality really sets in selling packing and shipping the stuff. > I guess the good news is that today there is a lot of replacement gear > that will do reasonably well thats cheap respectively consumes little > power and can easily be controlled by usb so you don't have to > actually stop experimenting. > Regards > Paul > WB8TSL > > > On Thu, May 23, 2013 at 2:32 AM, ed breya <e...@telight.com> wrote: > > > You don't save these kinds of synthesizers for high frequency > > coverage, but for their 10 to 11 digit frequency resolution. If you > > anticipate needing that, then of course they should be kept and > > fixed. The long-obsolete telecom standard connectors and ranges are > > pretty much useless - sacrifice that one first if you need parts for the others. > > > > If you need to justify keeping them, you can use them for practical > > everyday applications. For example, each one can store a telephone > number - > > as long as the power doesn't go out. > > > > Ed > > > > > > __**_ &
[time-nuts] HP 3335A for the impoverished experimenter
Group, I have the subject frequency synthesizer and the expanded foam shipping container it arrived in. I also have to move to an apartment in a life care community in two weeks. True, the focus of this list seems to be on 10 MHz, but if you'd like to experiment with precision frequencies between 200 Hz and 80 MHz, this is for you. The instrument has been checked with a few minor repairs. It is fully functional as measured with a Racal 1992 counter and rubidium external standard. Amplitude was checked with a Triplett 630 VOM, so accuracy of the measurement was 5% and didn't go down to millivolts. A scope could see that there was output that low and seemed to follow the dB ratios. I'm asking $200 for it shipped in continental US. The Racal counter is available for $100 shipped. At this point I don't care if it goes to a dealer who sells it for $1500. But if there are multiple requests, it goes to the best impoverished experimenter story. Please reply directly to b...@iaxs.net, not the list. It's been fun. Bill Hawkins P.S. Also have a 3335A parts unit and an Efratom FRK L rubidium pulled from a Collins Omega navigation set, oh, and a set of the older Lucent RFTG XO and RB units. The newer units don't have RB oscillators. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How did they distribute time in the old days?
The book "Einstein's Clocks, Poincare's Maps" describes a pneumatic time sync method for the public clocks on poles in the city of Paris, France in the late 1800s. Pneumatic clocks were made and used in the US for a while. Got one from the four letter auction site and dreamed of making a pneumatic pulse generator synched to 10 MHz. Sadly, the diaphragm in the pneumatic mechanism had rotted away, so I gave the clock to a friend who could make it work, but didn't. One pulse advanced the clock one minute. There was no auxiliary clockwork to keep it running between hourly sync pulses. I don't know of any mechanical clocks that sync once a day. IIRC, Western Union had to send people to advance or retard the hour hand when daylight savings time became common. There is something about those clocks that makes a time nut want to restore one. Bill Hawkins -Original Message- From: Nick Sayer via time-nuts Sent: Wednesday, October 14, 2015 11:42 AM The WU standard time service goes back further than the turn of the 20th century. It started in 1870. I've always wanted to get my hands on one of those clocks and come up with a circuit to recreate the synchronization signal for it, probably with a Raspberry Pi running ntpd and a big ol' MOSFET. The problem is that at this point, those clocks are quite expensive once they're reconditioned. My understanding (perhaps incorrect) was that the sync pulse was once daily and, as you said, would cause the hands to "snap" to 12. The trailing edge of the pulse was synchronized and would release the clock to operate normally. That they had something as accurate and widespread as it was so early is astonishing. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] UPS for my time rack
My apologies in advance for further putting tension on this OT thread, but one of the great stories from the early days of Usenet concerned a really large UPS system for a data center. In the late 80s the Digital Equipment Corp VAX computer was among the most powerful you could buy. If you can accept that amount of time travel, follow this link: http://www.hactrn.net/sra/vaxen.html or Google "vaxen immortal power" The reference to October 19, 1987, is to the first computer failure to have a major effect on the stock market. Enjoy, as they say Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] UPS for my time rack
>From experience, here's a story about a very quiet (RF-wise) pretty good sine wave UPS device. I acquired a Liebert 2KVA UPS for data centers in 1999 when our division was declared redundant. The cost when new would be prohibitive, but this one was junked when it stopped working. I got it, found a bad electrolytic cap (from the stains) and replaced it. Worked well. Never did get a manual, had to trace the switching stuff. This was from the days when data centers could afford the best in immortal power. The line feeds a regulated DC supply that runs the sine wave inverter and maintains battery charge. The inverter runs in sync with the line, but a relay connects the line to the load while the inverter idles. When the line fails, batteries supply the inverter and the relay switches it to the load. Then a cooling fan starts up. This machine required eight 12 volt batteries for 96 VDC nominal, higher on float charge. I bought 15 amp-hour batteries and wired them to a connector on the back intended for external batteries. Lethal voltage, of course. Requires proper protection. Also had a line voltage relay and toggle switch that would bypass the UPS and connect the time rack directly to the line. This allowed the UPS to be replaced when its warranty ran out. Batteries lasted six years, did not invest another $500 in them. Good luck. Bill Hawkins -Original Message- From: Chris Waldrup Sent: Saturday, October 10, 2015 8:20 AM To: TIme Nuts Subject: [time-nuts] UPS for my time rack Hi, I have decided I'd like to get a UPS to put on the rack containing my Thunderbolt, the laptop that runs Lady Heather, and frequency counter. Has anyone had bad experience noise wise with the APC brand units like are available on Amazon and at Staples? I'd like to get one that doesn't generate lots of RFI. Thank you. Chris KD4PBJ ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] KS-24361 REF-0 standalone
Actually, the Lucent software uses RAIM, and reports the value in its status message. If the position appears to have drifted off, or there aren't enough satellites to calculate the position, the software declares the oscillators to be free-wheeling, an expression meaning that the oscillators are free from discipline and are now drifting. So yes, the positioning aspects matter. Disclaimer: I haven't studied RAIM (or TRAIM) enough to know exactly what goes on, but that's the behavior I've observed. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Gregory Beat Sent: Friday, October 02, 2015 6:07 PM To: time-nuts@febo.com Subject: Re: [time-nuts] KS-24361 REF-0 standalone Dan - I have been following your experimentation with the surplus Lucent KS-24361 REF-0 module, to transform it into a standalone GPSDO. The original usage of the classic Oncore UT+ GPS receiver for KS-24361 REF-1, by Symmetricom / Datum for Lucent, was deliberate. For usage at a cellular data/telecom site, the focus was on the timing and frequency discipline from the GPS satellite transmission, rather than the position or dead reckoning aspects -- used by smartphones, automobiles, and other GPS applications on the market. === A couple of comments. While I can appreciate being economical (main criteria) and selecting the NEO-6M receiver, I believe that a u-Blox timing specific module (like LEA-6T) would be more desirable in this application. In addition, the u-Blox 6-series is the trailing edge of product support (market demand dictates its continuance), while the 7 and 8-series are their current modules (largely for the cellular / mobile industry (smartphones or cell sites themselves) u-Blox 6-series Timing Application Note (using the LEA-6T) https://www.u-blox.com/sites/default/files/products/documents/Timing_App Note_%28GPS.G6-X-11007%29.pdf IF you successfully adopt the u-Blox module to correctly "mimic" the Oncore UT+ GPS receiver command suite, THEN you open up a larger audience of "time-nuts" and Frequency Standard users (HP Z3801A frequency standard universe) as a receiver alternative. http://www.realhamradio.com/GPS_Frequency_Standard.htm These users may desire a "newer" GPS receiver that has more channels (8-channel); latest generation receiver; access to the newest GPS constellations. TAPR might be interested in sponsoring, as a kit/module, if a wider audience existed. The Heol Designs N024 receiver (France) accomplished this replacement role for the Trimble ACE II/III GPS receiver used in the Symmetricom/Datum TymServe TS2100. Their solution resolved shortcomings in the mid-1990 Trimble receiver design and giving this Symmetricom NTP server, time IRIG-B time code generator, and 10 MHz reference appliance a new lease on life (no longer a door stop). http://www.heoldesign.com/index.php?module=products=catalog=1 4=54 w9gb ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] algorithms and hardware for comparing clock pulses
The role of the diode is to break the current path to the cap when S1 shorts the current to ground when PPS 2 occurs. With the diode, S1 does not short the cap to ground. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Alex Pummer Sent: Thursday, September 24, 2015 3:58 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] algorithms and hardware for comparing clock pulses the role of the diode is just to have a voltage drop? 73 KJ6UHN Alex On 9/23/2015 11:31 PM, Bill Hawkins wrote: > Perhaps I can do this in words, as I have no schematic software. > > Start with the input to your favorite microprocessor's A/D converter. > Connect it to a suitable (more later) capacitor to analog ground. > Connect a cmos switch across the cap and call it S2. When S2 is on, it > discharges the cap. > > Now build or buy a constant current generator connected from a > suitable positive voltage to another cmos switch called S1. > When S1 is on, all of the current generated flows to analog ground. > > To make it all work, connect the anode of a diode from the junction of > the current source and S1 to the cap and analog input. > > When S1 is on, no current gets to the cap. When S1 is off, all of the > current gets to the cap, if S2 is off. This causes a linear buildup of > voltage across the cap, for a suitable time. > > When 1 PPS pulses are compared, suitable means one second to charge to > almost the maximum that the micro A/D supports. > The value of I is chosen to overwhelm diode leakage and A/D input > current. The value of C follows. > > All that remains for a working system is a pair of flip-flops to > control > S1 and S2. > FF 1 is set by PPS 1 and cleared by PPS 2, and by power on reset. When > FF1 is on, S1 is off. > FF 2 is set by PPS 1 and cleared by an output from the micro when the > A/D conversion is done. When FF2 is on, S2 is off. > > And so C will charge from PPS 1 to PPS 2, hold the value while the A/D > conversion occurs, and be reset to zero volts when the micro is done > processing the input. > > This gives the micro a linear conversion of pulse difference time > rather than an RC exponential value. > > Feedback controllers do better with linear error signals. > > But all of this is wasted if the PPS signals are not accurate due to > things that affect pulse rise and fall times. > > If the above was not adequately clear, please ask for clarification. > Or do a schematic and ask for corrections. > > Bill Hawkins > > P.S. This will not work well for small differences between PPS 1 and 2. > It will work if the goal is 50% difference, or 90 degrees phase shift. > > > -----Original Message- > From: Can Altineller > Sent: Wednesday, September 23, 2015 2:56 AM > > %< -- > > 4. I think an analog solution like Bill Hawkins described, would be > best suited for this task. But I have not understood it enough to build it. > > Best Regards, > C.A. > > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] algorithms and hardware for comparing clock pulses
Don't know why I was referenced on this. The simple approach is what I was trying to improve. But I was only looking at a way to covert pulse width time to voltage for further processing. Perhaps linearity is not required in this application. It's been my experience that controllers with proportional terms such as PID do a better job with a linear error signal, unless the thing being controlled (crystal frequency) is so nonlinear that the integral term does most of the work. Wish I could do the experiment, but no longer have a lab. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Thursday, September 24, 2015 6:37 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] algorithms and hardware for comparing clock pulses Hi Simple approach: Use a pair of tri-state buffers. Both have their outputs hooked to the cap through resistors. One (call it A) has its signal input grounded. The other (call it B) has its signal input tied high. Both of the tri-state controls normal sit in the "off" (= output is tri-state) condition. When I turn A on, the cap discharges. If instead, I turn B on, the cap charges. If neither is on, the cap changes voltage only due to leakage current. Let's say I have a long R/C on A and simply use it to discharge the cap to zero. It's there only to set a starting value on the cap. The R/C could be just about anything. Let's also say that I feed a variable width pulse into B. While the pulse has the gate control "on" the cap charges. The voltage on the cap is proportional to the well known R/C time constant formula and the width of the pulse. Once the pulse is gone, I fire up the A/D and read the voltage. After I have the voltage I put the cap back to ground with A. So what can go wrong? 1) I have the cap in the "both gates off" state to long and all I'm reading is the impact of leakage current. 2) My pulse is to wide and the R/C maxes out. 3) My pulse is long enough that my resolution goes below my desired resolution target. 4) The resistance is low enough that the gate output R gets into the act. 5) The C is so small that trace stray C (and input C's) get into the act. 6) The current into the R is so high that the gate current limits at the start of the charge cycle. 7) The caps or resistors are not stable so the system is not repeatable. 8) Your ADC has some pathogenic thing it does when it converts that shorts the cap to ground. ( = you have a really weird ADC). Except for leakage current, everything is controllable in the design. Some of the stuff above can be modeled (or measured) to minimize it's impact. There are more subtle issues like the fact that the gate has a different propagation delay low to high than high to low. That will stretch the pulse a bit. If you get really fast on the pulse, the output of the gate gets into the act a couple of ways. Bob > On Sep 24, 2015, at 2:31 AM, Bill Hawkins <b...@iaxs.net> wrote: > > Perhaps I can do this in words, as I have no schematic software. > > Start with the input to your favorite microprocessor's A/D converter. > Connect it to a suitable (more later) capacitor to analog ground. > Connect a cmos switch across the cap and call it S2. When S2 is on, it > discharges the cap. > > Now build or buy a constant current generator connected from a > suitable positive voltage to another cmos switch called S1. > When S1 is on, all of the current generated flows to analog ground. > > To make it all work, connect the anode of a diode from the junction of > the current source and S1 to the cap and analog input. > > When S1 is on, no current gets to the cap. When S1 is off, all of the > current gets to the cap, if S2 is off. This causes a linear buildup of > voltage across the cap, for a suitable time. > > When 1 PPS pulses are compared, suitable means one second to charge to > almost the maximum that the micro A/D supports. > The value of I is chosen to overwhelm diode leakage and A/D input > current. The value of C follows. > > All that remains for a working system is a pair of flip-flops to > control > S1 and S2. > FF 1 is set by PPS 1 and cleared by PPS 2, and by power on reset. When > FF1 is on, S1 is off. > FF 2 is set by PPS 1 and cleared by an output from the micro when the > A/D conversion is done. When FF2 is on, S2 is off. > > And so C will charge from PPS 1 to PPS 2, hold the value while the A/D > conversion occurs, and be reset to zero volts when the micro is done > processing the input. > > This gives the micro a linear conversion of pulse difference time > rather than an RC exponential value. > > Feedback controllers do better with linear error signals. > > But all of this is wasted if the PPS signals ar
Re: [time-nuts] algorithms and hardware for comparing clock pulses
Perhaps I can do this in words, as I have no schematic software. Start with the input to your favorite microprocessor's A/D converter. Connect it to a suitable (more later) capacitor to analog ground. Connect a cmos switch across the cap and call it S2. When S2 is on, it discharges the cap. Now build or buy a constant current generator connected from a suitable positive voltage to another cmos switch called S1. When S1 is on, all of the current generated flows to analog ground. To make it all work, connect the anode of a diode from the junction of the current source and S1 to the cap and analog input. When S1 is on, no current gets to the cap. When S1 is off, all of the current gets to the cap, if S2 is off. This causes a linear buildup of voltage across the cap, for a suitable time. When 1 PPS pulses are compared, suitable means one second to charge to almost the maximum that the micro A/D supports. The value of I is chosen to overwhelm diode leakage and A/D input current. The value of C follows. All that remains for a working system is a pair of flip-flops to control S1 and S2. FF 1 is set by PPS 1 and cleared by PPS 2, and by power on reset. When FF1 is on, S1 is off. FF 2 is set by PPS 1 and cleared by an output from the micro when the A/D conversion is done. When FF2 is on, S2 is off. And so C will charge from PPS 1 to PPS 2, hold the value while the A/D conversion occurs, and be reset to zero volts when the micro is done processing the input. This gives the micro a linear conversion of pulse difference time rather than an RC exponential value. Feedback controllers do better with linear error signals. But all of this is wasted if the PPS signals are not accurate due to things that affect pulse rise and fall times. If the above was not adequately clear, please ask for clarification. Or do a schematic and ask for corrections. Bill Hawkins P.S. This will not work well for small differences between PPS 1 and 2. It will work if the goal is 50% difference, or 90 degrees phase shift. -Original Message- From: Can Altineller Sent: Wednesday, September 23, 2015 2:56 AM %< -- 4. I think an analog solution like Bill Hawkins described, would be best suited for this task. But I have not understood it enough to build it. Best Regards, C.A. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] algorithms and hardware for comparing clock pulses
Group, Seems to me that what's needed here is a current source for linear volts vs. time and the cmos switching to control the duration of the capacitor charge while the phase flip-flop is on. When it turns off, it interrupts the processor and isolates the capacitor so it acts as a sample-and-hold device. The processor can take its own sweet time reading the capacitor voltage (although this sets minimum limits on the pulse duration). When the reading has been captured, the micro toggles a FF that shorts the capacitor with a cmos switch. The short is removed when the phase FF toggles on. This is a lot of analog circuitry, but it will operate as fast as the parts are capable of switching and not at the whim of whatever the micro is doing. Hope that's useful. Probably already been done. Bill Hawkins -Original Message- From: Magnus Danielson Sent: Tuesday, September 22, 2015 3:32 PM Jim, I had the intent to try this, but never got around doing it. Thanks for reminding me. Please share any enhancements. I did exchange some emails with Lars, but as that project never got off the ground, it faded out. Cheers, Magnus On 09/21/2015 10:02 PM, Jim Harman wrote: > Hi Can, > > For a simple analog solution, you might try a 74HC4046 phase detector > followed by a diode and RC network as used in Lars Walenius' GPSDO, > described here in the archives: > > https://www.febo.com/pipermail/time-nuts/2014-February/082820.html > > The phase detector produces a pulse whose width equals the time > difference between the two pulses. The RC network converts this to a > voltage proportional to the time difference, which you then measure > with the MCU's A/D converter. Using the rising edge of the signal at > pin 14 as the interrupt source triggers the A/D converter at the end > of the pulse, which corresponds to the peak of the analog signal.. The > 1 meg resistor discharges the capacitor between pulses. > > Lars' code also includes a filtering algorithm which does a nice job > of controlling one of the oscillators to match the 1-PPS generated by the GPS. > I have enhanced this if you are interested. > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Z380XA The saga of the aging 10811
Interesting. There may be a use for the OCXO units in the old Lucent boxes with the insensitive GPS receivers. The OCXO is an Efratom part # 023005-001. Some of those boxes were never used. Google can't find the specifications for the XO. I expect they're not as good as a functioning 10811, but they're better than a bad one if you've become attached to your Z38xx. Alternatively, you could try an LPRO-101 Rubidium with EFC if you don't need the short term stability of a crystal. The EFC loop tuning constants might be different, though. Either Lucent box can be shipped (in the USA) in a USPS large Fixed Rate Priority Mail box for $18. Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Benward Sent: Saturday, September 05, 2015 1:19 PM To: Time Nuts Subject: [time-nuts] Z380XA The saga of the aging 10811 Hi All, I would like to convey the saga of my Z3801A and my Z3805A. I purchased a Z3801A a few years ago at the Dayton Hamfest. I got it running and a few months later the unit lost it's GPS lock. I did some trouble shooting and finally realized the unit ran out of EFC range. I opened the double oven 10811 and retuned the unit to the lower end. The unit ran for another year or so, and then the oscillator died. The frequency was close, but the amplitude dropped too low for the circuitry to lock on to. I put the Z3801A aside and purchased a Z3805A from China (I think from Yixunhk). -%<- On another tangent, I tried hooking up a Morion to the Z3805A. I used an inverting amplifier for the EFC since the coefficient is positive and on the 10811 is negative. I never achieved good control before the Morion itself died. I will probably continue working on marrying a new OCXO to the Z380XA control board. I need an alternate source for the OCXO without depending on used double oven 10811s. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FLL errors
Ah, Magnus, source of so much solid and useful information, I don't see a time loop as valid. Frequency, yes, social time, no. A clock (purveyor of time) consists of an oscillator and a counter. In olden times the oscillator was a pendulum and the counter was a set of gears driven by the tick-tock of the escapement. Today we have electronic local oscillators providing one pulse per second (or whatever is needed) to electronic counters and displays. As an old timer, I prefer neon Nixie tubes. The problem we struggle to solve is to relate our local oscillator to some widely recognized standard frequency, preferably derived from an inordinately expensive generator based on the bouncing of atoms under controlled conditions. The very best way to transfer the standard (not At the tone, the time is ...) is to use an electronic phase comparator, error amplifier, and filter time constant that will cause the local oscillator to track the standard *frequency* usually propagated by GPS. The remaining problem is to get the counter to agree with our preferred version of time display (UTC, TAI, etc.). If the display electronics permit adjustments such as adding a second at a predetermined time, or adjusting by an hour for summer or winter time, then our needs for social time can be satisfied. I don't see the need to yank the oscillator around for social time with a time loop. Best regards, Bill Hawkins P.S. We're moving to a life care community that has no room for a time lab. The Junk Genius truck arrives at 10300 Colorado Road, Bloomington, MN 55438, at 11 AM on 1 September. If you can get here before that you can have anything you see. There are only antiques, except possibly the HP 3335A synthesizers and Racal Dana 1882 counters. I've tried to sell a few times but have had no takers. I won't ship (no time) but you can hire someone to pick it up. -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Magnus Danielson Sent: Saturday, August 29, 2015 9:47 PM To: Discussion of precise time and frequency measurement Cc: mag...@rubidium.se Subject: Re: [time-nuts] FLL errors Hi, On 08/29/2015 11:24 AM, Neville Michie wrote: A PLL locks on to the nearest cycle, is a Time Locked Loop different? Yes and now. In a signal conveying time, rather than letting a rising edge denote 0 degrees of phase you have some even time measure occuring, of some known nominal rate. You know what time it was on the time-scale, so that you know how much your local replica time-scale is off when compared. This time difference does go beyond the nearest cycle, but typically for locked situations is the nearest cycle. Don't ask how I know, I just know. If the decoded time from a GPS system is used discipline an oscillator then leap seconds would have to have a frequency transient to maintain lock. No, as GPS time in itself does not have leap-seconds, it's nominally the TAI time-scale offset. GPS signal conveys the difference between GPS time and UTC, and thuse the UTC can be conveyed. If you use the output to say drive a radio telescope monitoring a distant object you would want Earth's rotation to be phase or sidereal Time locked. I realise that for such a task far more complex computation would be required. So is a time locked loop a valid concept? Yes, whenever the enumeration of cycles to some time-scale is relevant. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] KS-24361 REF-0 standalone
Bob Camp has done a fine job of explaining the recent Lucent hardware. I have two of the old pairs with Rb oscillators and poor early Oncore receivers. Then I got a new pair with crystals and better GPS. I got the idea to use a new crystal unit to pair with an old RB unit, so I did some research on the messages required to do that. The data was acquired with a Pico Scope set to display the bytes as ASCII characters. The displays can be saved as text files, which can be edited with explanations of the data. I have no skills with microcomputers, and after many years working with computers have no desire to acquire them. The messages decoded easily enough with the 1996 Oncore manual. The problem with mixing old and new units is that the old Oncore had six channels while the new one has eight. The messages don't match. The only difference is two more groups of satellite data. I have text files (MS Word 2003) with the contents of the messages. Considering the low level of interest in this subject, please write to b...@iaxs.net for further details. If you'd like to experiment with the hardware, please make a reasonable offer for any of it. The new units have been assembled with a 28 volt 3 amp supply into a mini-rack using aluminum angle. My time lab is being downsized due to a move to senior living apartments. There's other stuff. Bill Hawkins Bloomington, MN 55438 -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Bob Camp Sent: Saturday, August 08, 2015 6:33 AM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] KS-24361 REF-0 standalone Hi As far as I know, the Symmetricom / HP designs that were done in the SA era (this is one of them) did not use the sawtooth correction information. The signal spreading (at the time they were designed) was just to great to make it worth playing with. I have no authoritative source for that, but it does sound reasonable. As with any absolute statement, there are sure to be exceptions .. == For the strings, you need the right status bits in the right locations. The KS does not care that it always sees the same sats at the same locations directly over its own north pole location. It just wants data in the field. It does care about the TRAIM status and probably a few other bits here and there. None of them appear to be hard to guess. All of the specs for the Oncore strings are something Mr Google knows a lot about. If you do try to synthesize *real* strings off something like a uBlox, remember that each of these guys had a slightly different idea about when the PPS fired relative to things like correction data and the time label on that PPS. Getting the time label wrong is pretty easy to fix. I (unfortunately) have more than ample empirical evidence of what getting the sawtooth correction off one second does. Its far harder to track down when only looking at the outside of the device. Bob On Aug 7, 2015, at 8:18 PM, paul swed paulsw...@gmail.com wrote: Dan exactly my thinking. I will guess it wants the string that says I have a 3d position lock. Something like @@ and 30-40 characters that would be fixed.I think there is a CRC at the end. But all of the message can be copied from a real oncore or simply monitor what comes out of the KS GPS unit. Hard to say whats needed but a good discussion. Be it any number of uProcs they can all easily do a fixed string. Regards Paul WB8TSL On Fri, Aug 7, 2015 at 5:13 PM, D W watsondani...@gmail.com wrote: Yes, I'm hoping that it just wants a dummy string to say GPS is ok, and doesn't actually use any information in it. If that's the case, code can be developed for PIC and AVR that will work for just about anyone, using a ~$1 chip. Even if the string does need to contain real GPS info, it should still be quite easy to do. A while back I wrote some code to parse the serial string from a Jupiter-T and display the information on a 4 line LCD display. It worked very nicely but I never did anything useful with it. I think I'll take Bob's notes and incorporate the REF-0. That would make for a very compact setup. Dan On Aug 7, 2015, at 2:06 PM, paul swed paulsw...@gmail.com wrote: Looking forward to the notes. Yes it could be fairly simple if what ref 0 wants is a string that essentially says the system is fixed with 3 d accuracy. Perhaps after that the ref 0 makes no checks other then the string keeps coming with the correct quality. Not to push a particular proc but any of the low end ones will do that stunt very easily. That would be pretty sweet. Paul WB8TSL On Fri, Aug 7, 2015 at 10:13 AM, Bob Camp kb...@n1k.org wrote: Hi Ok, I will write something up and post it here. It will probably take a few days to get it all into a form that answers most of the questions. What you will need: 1) A working REF-0 2) A PIC or other micro to get things going 3) A GPS with a PPS output
Re: [time-nuts] NPR story on coupled pendulums
They talk about sound pulses affecting the pendulums. Sounds more likely that the mechanical vibration transmitted through the aluminum bar affects the escapements. Perhaps the 'tock' side generates the strongest pulse, and the 'tick' side is sensitive enough to be affected by that pulse. That would soon have the clocks synchronized out of phase, provided the mounting arrangement did not absorb too much of the pulse energy. The situation is similar to synchronizing a TV vertical oscillator (running a bit slow) with the received sync pulse from the broadcast station, no? Bill Hawkins -Original Message- From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Hal Murray Sent: Tuesday, July 28, 2015 10:55 PM To: time-nuts@febo.com Cc: Hal Murray Subject: [time-nuts] NPR story on coupled pendulums University Of Lisbon Scientists Solve Pendulum Clock Mystery Two professors at the University of Lisbon say they have discovered why the pendulums of clocks set on the same surface will eventually swing together in opposing directions. http://www.npr.org/2015/07/28/427178282/university-of-lisbon-scientists- solve- pendulum-clock-mystery I thought the NPR story was not very interesting. (But it probably wasn't targeted at time-nuts. :) -- Here is the paper: Huygens synchronization of two clocks http://www.nature.com/srep/2015/150723/srep11548/full/srep11548.html -- These are my opinions. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] 60Hz line data
Gotta get some answers from my relative in a PA gas fired plant. A year ago he told me that the plan to deregulate the number of cycles in a day had been abandoned. The referenced documents are older than that. OTOH, there's no other explanation for Hal Murray's observation of the West Coast grid variation. Seems to me that all of the rotating synchronous machinery connected to a grid is constrained by all of that heavy rotating machinery to change speed quite slowly, like starting to change the direction of a ship heading to a port about 5 miles out. There are at least three grids in the US that are independent of each other in frequency. That reduces the strains on a grid from distant changes. Power is transferred using high voltage DC transmission lines. Really large solid state inverters convert between AC and DC. Each inverter can make any frequency it wants to, subject to the constraints of all that synchronous machinery. Frankly, I'm puzzled by the graphs that relate to the time offset. All that's available to the observer is the line frequency. Relative time may be inferred with a cycle counter. How is that counter set to UTC? How can you tell the difference between time error from some reference point, and cycles gained or lost in the counting equipment - due to noise and/or computer interrupt servicing routines? When I asked for data from parts of the country east of the Rockies (on 7/10), I got one reply from a person who is not a member of the list but reads archive sites. He sent his long term graph for Texas and the link to a real-time statistics page that gave him the data for the graph. The statistics are at (strip the stuff after com/ to get the home page and further details): http://www.ercot.com/content/cdr/html/real_time_system_conditions.html His chart (with permission) is at: http://home.earthlink.net/~schultdw/power/all.png In this case, the time reference was given by the power company. No cycles were counted. Regards, Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
