Re: [time-nuts] nuts about position
In message , Mark Sims writes: >The effects of things like antenna position changing a couple of cm due to >expansion and humidity effects are swamped by the receiver accuracy and noise. Short term: Yes. Long term: No. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] nuts about position
In message , Mark Sims writes: >The next thing I want to try is a receiver self-survey vs the post processed >results... I fell into that trap many years ago as well :-) The post processed result eliminates and compensates for a lot of effects which are invisible to the receiver, that is the entire point of post processing. But if your goal is to get good 1PPS out of your receiver, forcing it to hold a "perfect" position, means asking it to deal with effects it cannot measure, and as a result you get *worse* 1PPS performance than if you use the "wrong" self-survey position. That said, there are certainly a lot of issues with how the self-survey position should be calculated *and* maintained, because it really needs to change over time for optimal performance. Almost any suboptimal antenna-position means that you should vary the position-hold coordinates over the orbital period (but see below), but over longer periods also environmental factors come into play. For instance if you put the antenna on a wood-construction, be it a pole or a house, it coordinates will vary at the cm level over the seasons as the wood expands and contracts. The good news is that the receiver gives you the input data to work and model these biases, the bad news you don't get a lot of data. I did some experiments when ten Oncore M12+T's passed through my lab many years ago: I plotted the reported "residuals" vs. satellite position, and I tried to update the held position on a daily basis using the trend, and the results were measurable at the several ns level: http://phk.freebsd.dk/raga/sneak/ I didn't persue this further, because my latitude is particular unfavourable to the simple (N/S+E/W) approach (no birds north of me) and with only a single receiver the amount of input data is too low for such a crude algorithm. A more complex geometrical model could probably get more mileage out of the sparse data, as would tracking more birds than the 12 the M12 could track. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] HP 5372A TIA Question
In message , Magnus D anielson writes: >Consider that you need to swap the cables to verify that it is static >with the setup and does not follow the cables. Run long series of measurements with the HP5372A OCXO free-running and with it slaved to the DUT clock. Any imperfection in the interpolator will show up as different noise characteristics in the two results. There is a test in the service manual which will give you a good indication how well tuned the interpolator is, run that before touching anything, and don't attempt to tune the interpolator unless you can follow the procedure in the manual *exactly*. PS: I do not recall it being mentioned, but the 1 MOhm input pods are horribly unstable compared to the 50 Ohm input pods, which are basically just a stripline and a BNC connector. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 Request to the List
In message <59219f88-52bb-d127-29de-1ea0ccc2b...@febo.com>, John Ackermann N8UR writes: >It's much better to have one thoughtful post than a dozen written on the fly. See also: http://bikeshed.org -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Sawtooth correction: next or previous PPS
In message <20180522011345.4db43406...@ip-64-139-1-69.sjc.megapath.net>, Hal Mu rray writes: > >hol...@hotmail.com said: >> One thing to look out for when messing with sawtooth messages is the >> question of does the message come out before or after the PPS pulse... good >> look finding the answer in the receiver documentation... > >Has anybody asked the manufacturers? It is trivial to measure with a HP5370: Capture a series where you measure the 1PPS against a good 10MHz and record the serial datastream. Then offline apply the negative sawtooth and plot the result. If you get ugly spikes at the turning points of the "hanging bridges" you're doing it wrong. For the UT Oncore etc. it is predictive of the next 1PPS flank. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Cesium Clock Avialable
In message <b17ed93d-0178-456f-b448-a93697e44...@n1k.org>, Bob kb8tq writes: >Cs is classified rightly as a hazardous substance. Transporting and shipping >hazardous stuff is indeed regulated (as it should be). For various silly >reasons >the minute amount of Cs inside a virtually indestructible container in a Cs >standard falls into the hazardous category. The reason for this is actually not very silly. Very potent Cs137 sources are used in borehole characterization in disturbingly high numbers, and they are licensed and tracked by the relevant national regulatory agency, NRC.gov in the USA. The HAZMAT regulations used to be different for Cs137 (nuclear concerns) and Cs133 (chemical concerns) but smartasses in the oil industry discovered lower costs if they "couldn't remember the number". I belive HP used to have an exemption for shipping factory new CS-tubes *from* their factory, but not for shipping new or used tubes *to* their factory, because customers could not be trusted to pack according to spec. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] HP 5372A
If want to exploit what the 5372A can do in FMT-context, you should feed it the amplified and band-pass filtered RF (rather than some down-converted and otherwise mangled version of the signal) and capture timing of the actual zero-crossings and post-process that. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Simon Winchester: The Perfectionists
In message <20180508073640.64e72406...@ip-64-139-1-69.sjc.megapath.net>, Hal Mu rray writes: >about the clocks in Oxford chiming midnight in friendly disagreement. Terry Prachett has a lovely description of how the clocks of Ank-Morpork chimes in "Men At Arms": Noon in Ankh-Morpork took some time, since twelve o'clock was established by consensus. Generally, the first bell to start was that one in the Teachers’ Guild, in response to the universal prayers of its members. Then the water clock on the Temple of Small Gods would trigger the big bronze gong. The black bell in the Temple o Fate struck once, unexpectedly, but by then the silver pedal-driven carillon in the Fools’ Guild would be tinkling, the gongs, bells and chimes of all the guilds and temples would be in full swing, and it was impossible to tell them apart, except for the tongueless and magical octiron bell of Old Tom in the Unseen University clock tower, whose twelve measured silences temporarily overruled the din. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Better quartz crystals with single isotope ?
Silicon comes in a number of isotopes but 95% of it is Silicon-28. When you make pure mono-crystaline silicon, you get 50-60% better thermal conductivity if you only use Silicon-28 atoms. Yes, you read that right: 50-60% improvement for removing the remaining 5% other silicon isotopes, and for this and other reasons, sorting silicon atoms by isotope is now a thing, which amongst other side effects have made the Advogardo Project possible. I can't help wonder if there may be similar interesting effects in quartz crystals, if they were monoisotopic ? Several relevant mechanisms can be imagined, lower internal damping, higher stiffness etc. etc. We know a LOT about quartz and have a very good theory for its behaviours, but i find no signs anybody has ever touched monoisotopic Quartz. The obvious experiment is not rocket-science, nor does it demand inordinate resources for amateurs, see for instance from 03:35: https://archive.org/details/59554KrystallosCF But it is clearly beyond what I have time to persue. Do we know anybody in the quartz business who needs a really cool research project ? Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Any guesses as to how Citizen is claiming ±1 second/year with using this AT-cut 8.4MHz XTAL?
In message <02d201d3d1b1$d7318640$859492c0$@joshreply.com>, tn...@joshreply.com writes: >That comes out to about 30ppb, and this is a pocket watch so they don't seem >to depend on the temp stabilization of being attached to a human wrist. For an application where neither phase noise nor jitter matters, it is certainly feasible to measure the tempco of the X-tal at the factory and let a micro-power computer use temperature measurements to model the "perfect" frequency and phase. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Weird Stuff Warehouse shutting down
In message <8bcc9dcc-fa97-b531-d658-2051c094c...@bluefeathertech.com>, Bruce Lane writes: > Heh... So much for Google's favorite "Don't Be Evil" motto I wonder what happens when the googlers realize that they could have had WeirdStuff on their campus...? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 longwave time service planned in India
In message
Re: [time-nuts] quartz / liquid nitrogen
In message <299B45118C9248498D7B4F3AFE72231E@pc52>, "Tom Van Baak" writes: >Has anyone tried running a quartz oscillator at liquid nitrogen >temperatures: -196 C (-321F, 77K)? It's probably impractical >commercially, but maybe something of value to a time nut. Whispering gallery sapphire resonators at cryogenic temperatures is a thing for phase-noise, but those are dielectric (microwave) resonators, not piezoelectric resonators. > Would that dramatically lower temperature improve phase noise & > short-term performance? Yes it will reduce your thermal noise as a source of PN, and dramatically so. But I doubt short and long term performance will improve. Even if you can find a zero-turnover cut at a convenient temperature, I don't think anybody know how to produce mK temperature *stability* at cryogenic temperatures ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] There goes LORSTA Jan Mayen
http://jan.mayen.no/nyheter/destruksjon-av-loran-c-long-range-navigation/ -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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
In message <1520456485.3091982.1295242984.442b4...@webmail.messagingengine.com>, Pete Stephenson writes: >On Wed, Mar 7, 2018, at 9:28 PM, Mark Sims wrote: >> A more detailed explanation of what is happening: >> >> https://arstechnica.com/tech-policy/2018/03/ovens-across-europe-display-the-wrong-time-due-to-a-serbia-kosovo-grid-dispute/ > >This explains why my oven clock and the time/temperature display >on the building outside my apartment in Switzerland are six minutes >slow since January. It was a great mystery to me. Can you get a picture of this ? It would be wonderful to have for future discussions... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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
In message <5a9c4644.5030...@yandex.com>, Charles Steinmetz writes: >Some times, "just because it's better" is a sufficient >reason to overdesign, particularly where the incremental cost is low and >especially where the projected number of units is low, both of which are >true WRT the improved A9 board. I fully agree, and if it were me, I would absolutely use the best capacitor I could find at a non-insane price. But that was exacly my point: The only thing you (might!) get by spending an *insane* amount of money on that capacitor is PTFE and its better dielectric absorption. But there are three good reasons not to. First, they are HUGE, typically a couple of inches in diameter and four or five inches long[1] Second, there are no reputable suppliers of ~5µF PTFE capacitors that I have been able to find, there are only audiohomoeopaths. *Nowhere* have I seen anybody buy an audiohomoepathy PTFE capacitor and publish a traceable DA measurement for it, much less information about tolerance, lot variations etc. I am certainly not going to shell out $785.07 for what is claimed to be a newly produced PTFE capacitor[2]: https://www.v-cap.com/cutf-capacitors.php Neither am I going to shell out $34.70 for something which may or may not be USSR army surplus and which may or may not be PTFE[3]. https://www.ebay.co.uk/itm/Lot-of-1-piece-K72-11-Teflon-Capacitors-0-22uF-4-7uF-125V-1000V-NOS-Tested/132443841947?hash=item1ed644a59b:m:mPF1aOO4F7dJXTSF0qHKcSQ And third, the difference in DA between PTFE and Polystyrene is barely a factor five and it is from 0.05%(PS) to 0.01%(PTFE). That is simply not going to make *any* difference in an HP5065A. The trick here is to do the math on the S/N ratio of the optical signal: The A9-capacitor is primarily a low-pass filter, and pretty much any sane capacitor can do that. Poul-Henning [1] Almost any other type of capacitor is wound from two layers of insulator on which a thin layer of metal has been deposited by evaporation or sputtering. PTFE must be wound from two PTFE films and two metal films, which means a lot more metal, because it must have the mechanical strength for the winding operation. [2] Notice the claimed "dielectric coefficient of 1.45" ? Either he means "Dielectric Absorption" in which case the number is in % and *horrible*, or he means "Dielectric Constant" in which case the number is physically impossible. [3] Because USSR wasn't very good at PTFE to begin with. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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
In message <cab+jonc9hvv9826ocwmtdtec-mr8jj+g-vw_teso4bnmo0b...@mail.gmail.com>, Wayne Holder writes: >>> The only thing I could provok, was that almost all capacitors I >>> tried were sensitive to touch. > >Most ceramic caps are sensitive to "micro phonics" via the piezoelectric >effect, which can translate mechanical stress into electrical noise. Yes, and unlike plastics, their mechanical resonance is sharp and at frequencies where microphonics matter a lot. Even then, a 4.7uF SMD multilayer ceramic mounted with two "looped" wires for stress-relief worked just fine. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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
In message
Re: [time-nuts] "Super Rubidium" filter mod for PRS-10?
In message
Re: [time-nuts] Replacement A9 boards for the HP 5065A
In message <aabpkd8mdat36...@smtpout03.dca.untd.com>, cdel...@juno.com writes: >Any guess as to what type it is? > >Polycarbonate, polypropylene, ??? I think the manual says polypropylene in the parts list ? >Just wanting to find a good modern replacement for its use. (Integrator >with a 50ms time constant.) The audiohomeopathy crowd claims to have PTFE/Teflon capacitors available in these kinds of sizes and I've been meaning to buy one just to see if it truly is PTFE or not, but list-prizes has nothing to do with reality. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] HP 5065A super
In message <2a6c14a0-823a-4177-aefd-bed8bcea8...@n1k.org>, Bob kb8tq writes: >It turns out that the nickel’s really awful magnetic properties at RF [...] The semiconductor industry has serious problems with electromigration of very tiny copper conductors. A large company in the business spent an awful lot of money failing to get Cobalt to work, before somebody said "But wait, isn't that one of the magnetic elements ?" It now seems to become Wolfram instead. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] HP 5065A super
In message <20180222160256.68d832a88fc2d7da91602...@kinali.ch>, Attila Kinali w rites: >Ah.. this looks significantly different than my 5065 service manual shows. > >So, I guess you want to build a new board that replaces this? > >Then i would go for the LTC6240HV with a +/-5V power supply. Offset voltage (stability) is a, if not the, *very* important parameter for the integrator. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] LED instead of discharge lamp for Rb vapor cell standards
In message <20180221184928.1c9b4c3a4d2e762970b5b...@kinali.ch>, Attila Kinali w rites: >So the Rb85 "notch" filter might not get rid of all the unwanted light >and some of this might depopulate the excited state of the Rb87 >that are in the RF cavity. I have a hard time seeing how you can not get worse S/N that way. If you want to do it with a LED, I think it needs to be a stabilized LED-Laser. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 "NAKED" 5065A optical unit
In message <20180221163511.b8d6eec26415fe16e66e4...@kinali.ch>, Attila Kinali w rites: >On Tue, 20 Feb 2018 09:36:49 -0700 >Mark Goldberg <marklgoldb...@gmail.com> wrote: > >> I don't know anything about these devices, but for TCXOs, the power supply >> noise significantly affects the phase noise of the output. An LM317 is not >> well specified for noise and I expect is is orders of magnitude worse than >> something like an LT3042 low noise regulator. > >It's >30dB for broadband noise, according to Gerhard Hoffmann's measurement: >https://www.flickr.com/photos/137684711@N07/24070698809/in/album-72157662535945536/ Just to point out that you are rapidly heading down a blind alley from where this topic started: I was talking about driving the single-transistor UHF generator which ionizes the Rb in the lamp, so far I have not even established if this voltage affects the HP5065 performance in the first place. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 "NAKED" 5065A optical unit
In message <aabpjy7pfajkd...@smtpout01.dca.untd.com>, cdel...@juno.com writes: >Here is a PIX of the optical unit from a 5065A totally removed from the >shield assembly. Nice! >Left to right: > >Lamp assy >lamp oven cylinder >lamp reflector/convection block/diffuser >Rb85 filter cell It looks like there is a square filter of some kind between the reflector and the filter cell ? I've been thinking a little bit more about power for the lamp assembly. Since I have the lamp on the bench-supply I am going to plot lamp voltage vs. photo-I because it looks like a threshold rather than a linear relationship. If that is the case, I think it will make sense to give the lamp its own adjustable voltage regulator (LM317), so the power can be reduced to what is optimal/necessary without having to take the lamp apart and change a resistor. A 1R resistor between the 22-30V supply and the LM317 will make it easy to monitor lamp current, and a 300mA short-circuit protection is a nice bonus. If need be, the regulator could start out at 20V and drop to something lower in a matter of minutes. Actually, now that I think about it, I should try to measure if it is gives better stability if I drive the lamp with constant current, constant power, constant voltage or constant photo-I... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Receiving the MSF time signal on cheap radio modules
In message <cagj4f+6jbu6t0rvfdf5z4gfmv6nyknkgzm9q0mhjlzb60mk...@mail.gmail.com>, "Deirdre O'Byrne" writes: >I've updated my paper, which now contains the attached graph. (I did a >linear regression analysis to see what the correction for the receivers >should be, and I applied receiver 2's correction to both receivers to >generate this graph). Yes, these cheap "clock-receivers" vary a lot and they are usually also very temperature sensitive. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Anyone have experience with this antenna?
In message <875e4bc6-32c3-4724-afcd-086553ae5...@n1k.org>, Bob kb8tq writes: >Water wise, one might note the large piles of snow sitting on my antennas at >the moment. Yes, I >could go knock it off, but somehow it just keeps coming back. Weird how winter >works …. There >is no perfect solution. Somebody at BIPM told me that their antennas were heated and thermostatically kept at constant temperature. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Anyone have experience with this antenna?
In message
Re: [time-nuts] Receiving the MSF time signal on cheap radio modules
In message <CAGJ4F+697SyXwm3yWG-XczN4zF7r2RAmXzAcEm=dhaqbjc_...@mail.gmail.com>, "Deirdre O'Byrne" writes: >MSF disciplined oscillator?! I don't trust these receivers to any better >than about the 20ms mark, so such a disciplined oscillator would have quite >a long integration time! It's actually more complicated and better than that. The low-pass filter dominates, so the falling flank at second N depends on the pulsewidth at second N-1. I can't remember the numbers I got when I "sorted" DCF77 pulses depending on the previous pulse being short or long, but it was a fair bit better than 20ms. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Receiving the MSF time signal on cheap radio modules
In message <20180206225742.67030406...@ip-64-139-1-69.sjc.megapath.net>, Hal Murray writes: >> Since MSF *is* on 60 KHz, you do indeed get dead spots. > >If the two signals are not encoded identically, there should be an >interesting signal when one of the transmitters is off and the other is on. >Has anybody looked for that sort of pattern? I have seen signs of that in my data in the shape of phase-shifts, and that sort of made me concentrate on DCF & LORAN. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Receiving the MSF time signal on cheap radio modules
In message <a2b31a8c-147b-4d35-bdc2-8d64d3743...@n1k.org>, Bob kb8tq writes: >If you want to get even more “nutty", look at the “seed” that you likely >already have >for the computation. In this day and age, you probably know what day / month / >year it is. So, some of us think of that as cheating :-) >Since you might not (say) know the hour, you have a +/- 1 day sort of >tolerance on that. It rolls >into month and year in some cases. The seed adds complexity, but probably makes >things more robust. I tried it, and it gave surprisingly little benefit. Unless very fast initial aquisition is your goal (why?!) you get a more robust result by not "cheating", since in real life at some point your RTC chip will contain bogus values. If you go the SDR route and decode DCF77 and MSF (and 162kHz France, WWV/B, the japanese signal at 40kHz and the russian at 200/3 kHz for that matter) in parallel, it is perfectly fair to expect them all to have the same date (modulus timezones). And yes, I would really *love* to se a colaborative project that produced an "all-world VLF timecode SDR-receiver"... >One cute thing is that this stuff is (in general) not very compute intensive. >If data past the >minute tick is being looked at, you probably can afford to run multiple >parallel solutions (even >on a < $5 MCU). The NTPns ran on a Soekris4501 and I was never able to measure a difference in power having the DCF77 blame code running or not. After all, it's only sixty trival patterns to match once a second... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Receiving the MSF time signal on cheap radio modules
In message <cagj4f+54sxqc34fpnefnw3q3emhmq+uc-v-lfc5bnfk7h7q...@mail.gmail.com>, "Deirdre O'Byrne" writes: >With a blame algorithm in place it should be possible to recover these signals. Yes, easily. At distance MSF is significantly harder to receive than DCF77. One of the reasons is that USA also operates two 60kHz transmitters also very precisely on frequency, so there are areas of the world where the three signals cancel and areas where they reinforce each other. I tried to model this many years ago, but I don't trust the result, somebody with better HF-propagation chops than me should look at it. In addition to that problem, switch-mode designers seems to just *love* 60 kHz, and at least here in Denmark there is a lot more "hash" around 60 kHz than 77.5 kHz. Finally, the modulation scheme of MSF is a bit on the overengineered side, which makes pulse discrimination needlessly hard - as you have also found out. The big advantage of the blame algorithm is that since it is so tolerant of missing pulses, you can be throw everything away which isn't 100% clearcut. If you look at the top of the dcf77.c file, you can see how I did that for DCF77, but the complex modulation of MSF needs a much more complex state engine there. Finally, many of the small "clock-receivers", like the one you use, are optimised for battery-life and therefore they use very resonant filters, often crystal-filters, and heavy low-pass after demodulation, and that trows away a LOT of information which would be useful to have to discriminate the pulses. If you go for the SDR approach, you will have much more information available, and can use much more well-behaved filters to detect the pulses, and one added advantage of carrier-tracking is that the power-modulation is carrier-synchronous, which makes them much easier to spot. So really: Get yourself an 1MSPS ADC chip and go that route instead. (In theory, certain modern sound-cards should be usable for this if you can rip out their low-pass filters. Havn't tried.) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Receiving the MSF time signal on cheap radio modules
In message
Re: [time-nuts] Receiving the MSF time signal on cheap radio modules
In message <CAGJ4F+6Nvic=rouh7eozhklcdzibtormgu0ikj-sk6ixjw+...@mail.gmail.com> , "Deirdre O'Byrne" writes: >I've been trying to see if I could design a decoding algorithm that >would be more noise-tolerant than the algorithms I've seen out in >the wild. You can: I baptised it "the blame algoritm". The trick is not to try to accept pulses as valid but to try to throw out pulses which are impossible. Imagine you have a 120 second long shift-register, and you feed your received pulses into it. Then try brute force, for every one of the newest 60 positions if that can be the start of a minute or not, by testing all the constraints you can think of, and there are surprisingly many. Some are obvious, the bits encoding the hour cannot contain "39", but that is a remarkable weak filter that seldom kicks in. A much stronger filter is that the bits encoding the hour must be the same as in the previous minute *unless* minutes were 59 in the previous minute *and* zero in this minute. If you count it up, that is a strong and very peculiar relationship on all the hour-bits and all the minutes-bits and if even one single of them are wrong, you can definitively discard that theory for the start of the minute. A similar thing holds for the date bits, the time in the previous minute must be 23:59:59 and in this 00:00:00 for there to be any difference between the dates, and even then, only a small number of possible changes in the date bits are valid. If you look in http://phk.freebsd.dk/phkrel/NTPns.20080902.tgz you will find a file called dcf77_blame.c with my code, here is a couple of the simpler tests: /* LSB of minutes must be different from previous minute */ j = ip->shiftprev[(offset + 21) % 60]; if (j * ip->shiftreg[(offset + 21) % 60] > 0) FAIL((why, " 0")); /* * If the LSB of minutes was '1' in previous minute * the next higher bit must have changed, if it was * a '0' it must not. */ if (j * ip->shiftreg[(offset + 22) % 60] * ip->shiftprev[(offset + 22) % 60] > 0) FAIL((why, " 1")); When using this algorithm, missing pulses is almost a non-issue up to around 40% of them missing, and even in an enviroment like that, it is not uncommon to see the algorithm lock on to the minute in about 34 seconds and know the full time in less than 3 minutes. If you make your pulse width discriminator *really* selective, which you might as well, you can "blacklist" disproved minute positions for the next many minutes as the risk of a '1' and '0' being confused is close to zero. That will get you minute lock, even with 70%-90% missing pulses, in a matter of minutes if you use a longer shift register. I did a parallel prototype for MSF, but I didn't need it so I never completed it, not sure I have it around any more. I should really write an article about that code... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Rakon HSO-14
In message <ee82321b-3176-4d0d-b0bc-64625dce8...@n1k.org>, Bob kb8tq writes: >If you try “normal” machining techniques on a resonator, you are very >likely to create micro cracks in the material. Those are *really* bad for >aging and a few other issues ….. So that brings me to another question: We use quartz crystals in very simple geometries, usually cylinder slabs, with very perfect surfaces - for all kinds of good and sane reasons. But mostly we use simple geometries because that is what we could make work, with the pretty crude production mechanisms in second world war. On the other side of the business we have SAW resonators which uses very complex conductor patterns on the surface to do their thing. If we can/could etch quartz in *precise* complex patterns at will, regardless of crystal orientation, sort of like the stuff we do in silicon wafers already: https://www.micralyne.com/fabrication-capabilities/etching/ Would that open up any interesting possibilities, or is the simple cylinder slab by definition the best ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Rakon HSO-14
In message <480971424.644410.1517715556...@webmail.xtra.co.nz>, Bruce Griffiths writes: >It has been used to machine/polish crystal quartz waveplates and >to machine/polish the surface of silicon wafers before uses for >MEMS fabrication. Its even been used to carve channels in silicon >wafers in such applications. The images on this page gives a good impression about the current skill-level in that area: https://www.azonano.com/article.aspx?ArticleID=2740 I'm pretty sure that it is not the machine control but rather the metrology that would be the challenge. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Rakon HSO-14
In message <0f9a9acc-4cdf-780f-e633-616262264...@earthlink.net>, jimlux writes: >> [1] Surprising to me is that modern dentists are highly kitted for >> CNC-ing very hard ceramic materials at high precision. > >But, small "tooth sized" pieces - how big is your crystal. Well, they appearantly make a mouth-full at a time, so that is covered... I don't think the dentist machines are precise enough though, as I understood it, the state-of-the-art stuff has built in laser-interferrometers etc. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Rakon HSO-14
In message <31183984-ed9d-60e1-6528-76dfde5f3...@rubidium.dyndns.org>, Magnus D anielson writes: >The slots and thus the remaining bridges seems to have been a relatively >simple stage of the process. Orientation of the blank seems to have been >simple. The shapes for the electrodes seems to have been worse. I heard a talk about "microfluidic system production" last year, those are basically hydraulic systems on micrometer scale, mostly for medical diagnostic applications. There was some banter about available tools[1] and some of the ones mentioned immediately rang the "BVA" bell in my mind. It sounded to me like there are machines commercially available today which could spit out very repeatable BVA assemblies in one single operation. I have no idea if the result would actually work and be on frequency, or for that matter, where I can borrow one of those machines, but... The prices mentioned were not prohibitive in the context, you would break even well before a thousand units at the prices mentioned. Poul-Henning [1] Surprising to me is that modern dentists are highly kitted for CNC-ing very hard ceramic materials at high precision. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] minimalist sine to square
In message <eb956eca-4534-0463-031b-232f8bdbd...@earthlink.net>, jimlux writes: >> I played with that, I used a small transformer to balance the signal >> and then into LVDS receiver through a voltage divider. Worked well, >> but I didn't measure the jitter, it was just for a micro-controller. > >You can also do it with capacitive dc block to one side, and some >resistors - the ap notes describe it. The receivers are a fairly high Z >input, so you pick the voltage divider resistors to make the termination >resistance right for the incoming signal. Yes, but that doesn't give you galvanic isolation, which I think is almost mandatory unless it is a metrology situation. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] minimalist sine to square
In message <63ae173b-93f4-ffe4-ddf1-655761665...@earthlink.net>, jimlux writes: >On 1/19/18 11:31 AM, Tom Van Baak wrote: >You do want to watch the common mode voltages - some of the parts are >not good about having the signals swing near the rails (or beyond). Also be aware that specs are for balanced input signals, if you tie one of the inputs to a threshold voltage, published specs may not apply, in particular speed. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] minimalist sine to square
In message <898171c2-0e9a-6a2a-dcfc-b7d893f89...@earthlink.net>, jimlux writes: >What about the plethora of LVDS receivers - they're basically a >differential input thresholder, with deliberate hysteresis, looking for >a 300 mV shift across a 100 ohm resistor. I played with that, I used a small transformer to balance the signal and then into LVDS receiver through a voltage divider. Worked well, but I didn't measure the jitter, it was just for a micro-controller. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Stable32 now available
In message <canx10hazfmb+0kktwcacrkjd6u7fihr0-dy9ebg5zfk+x3f...@mail.gmail.com>, "Dr. David Kirkby" writes: >those platforms, because otherwise non-portable code will be introduced. >That's been my experience, both on projects I have managed, and the >SageMath mathematical software. Yes, "Trust but verify" :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Stable32 now available
In message
Re: [time-nuts] Stable32 now available
In message <d5ecc3fb-ecaa-875f-f599-4b484d33b...@rubidium.dyndns.org>, Magnus D anielson writes: >If we rather focused on maintaining and extent it into the >future, that would be a great way to take care of the heritage. I can >see myself contributing to that. Ditto. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 "PulsePuppy" Pot Selection
In message <d9bb2fe5-c3fa-4fe0-9f32-676d7a006...@att.net>, "Brian, WA1ZMS" writes: >I have seen similar issues to Dana's and have told myself it must >be torque left in the gear-train within the pot. Maybe all in my >mind as well, but it seems real to me on some equipment. Or simply that you are too impatient and your previous correction has not fully been effected yet. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 "PulsePuppy" Pot Selection
In message <CAKn+a3sNg3fE-C8=g-_utwj3ibmeujgvpfapv5yvr7cnn8f...@mail.gmail.com>, Mark Goldberg writes: >When the pot is used as a voltage divider, theoretically it should have >the same TC throughout, so temperature effects should not affect the divide >ratio or the output. I researched this a bit a couple of years ago in relation to HP5065 C-field tempco The major tempco in pots are mechanical in nature. Plastics have *horrid* tempcos, most in the hundreds of PPM and the best (nylon) barely making it under 20 PPM. Mind you, that is usually measured on relatively large linear extrusions, not small bits of geometrically complicated plastic, like you would use to encapsulate a trimpot. There are trimpots on the market which claim 5PPM ratio stability, but the conditions under which that is measured are not very easy to implement in practice. If you want anything close to 1PPM trimpots, hunt eBay for "ESI dekapot" -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] ergodicity vs 1/f
In message <ec6c7c98-5788-4acd-ee06-116a0ff98...@rubidium.dyndns.org>, Magnus D anielson writes: Years ago I ran into this paper: https://fas.org/irp/agency/dod/jason/statistics.pdf What is amazing about it, is that back in 1992 they nailed the odds of climate change to north of 100k, in a statistically rigorous manner. They can do this because "Extreme Value Theory" is an extremely sensitive way to determine if a process is static or if it fits your (noise-)model. I've often wondered about EVTs applications to oscillator noise, but Real Life have kept me busy with other things, so I'll happily pass this ball to anybody else who might want a go... Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Performance verification for time counters
In message <20171130181024.832c6adfd3cea0658ba43...@kinali.ch>, Attila Kinali w rites: >What puzzles me here is, the reason why someone would care >about sub-1Hz frequencies in a telephone system? IIRC POTS >did cut off somewhere areound 100-300Hz anyways. They did not. Most carrier frequency facilities had bottom frequencies in the 50kHz area or higher. Bob brought up the sub-Hz stuff, I pressume he knows what it is used for. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Performance verification for time counters
In message <42a2f881-1631-402c-8ed6-2c863f6fe...@n1k.org>, Bob kb8tq writes: >>> Needless to say *demonstrating* this 0.001 db sort of gain flatness on a >>> repeater >>> out to crazy low frequencies is a bit involved. It *is* a great gig if you >>> happen to be >>> a consultant … >> >> demonstrating 0.001 dB (or would that really be 0.1 mB or 100 microBels) >> precision in *any* application is a bit involved. That's 0.03% >> > >Yup, now do it at some silly low frequency ( 0.(some number of zeros)1 Hz …. >great way to waste a lot of time. Sorry, I don't see the challenge: HP3458A in sampling mode, careful cabling, done. At RF frequencies where you have to think about impedance however... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Performance verification for time counters
In message <9793f6fa-cb78-4bf1-bc80-6b1a593fc...@n1k.org>, Bob kb8tq writes: >Needless to say *demonstrating* this 0.001 db sort of gain flatness on a >repeater >out to crazy low frequencies is a bit involved. It *is* a great gig if you >happen to be >a consultant ... No consultants were involved, they did it in mass production at WE. Remember, they needed thousands of repeaters per *coax* and there were handfulls of coax'es in each cable. This is the relevant article about the amplitude: https://archive.org/details/bstj53-10-1935 -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Performance verification for time counters
In message <409346f4-60e1-4cae-8602-84fb1c061...@n1k.org>, Bob kb8tq writes: >>> The HP3336 with its outstanding level-control is a much >>> overlooked bargain for this kind of stuff. >> >> I looked for the manual, and it seems to have ROM feeding values to a DAC. >> Is that not DDS? That is for the level control, not for generating the signal. The level control has a custom HP-chip with two matched thermal converters, so you can compare the power of two signals with it. One signal is the RF output, the other comes from a DAC. The 3336 is as far as I know one of the the most precise instruments when it comes to amplitude, and it was built specifically for the last two generations of the Carrier Frequency Coax telephone network (L4 and L5) where up to 10.800 4kHz telefone channels were stacked over each other in a single coax cable. Because the top frequency were near 70 MHz, they needed a repeater for every mile of cable which is up to 4000 repeaters for a call across the US. If every one of those repeaters had a systematic dip of 0.01dB at the same frequency, That would amount to 40dB attenuation in total, so the amplitude tolerances were almost insane, in order to keep the amount of equalizing manageable. Google: bstj53-10 site:archive.org It's an amazing story... The HP3336 and the HP3586 level meter go together to measure these lines: The 3586 measures the received signal and when it is done it tells the 3336 to step 4kHz up to the next channel. The crucial trick is that the 3336 produces the exact same output level for all 10800 channels. See: HPJ May 1980. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Performance verification for time counters
In message <5e3f68620fdb8f2e5d62e9907a44c6eb.squir...@email.powweb.com>, "Chris Caudle" writes: >On Wed, November 29, 2017 3:51 pm, Poul-Henning Kamp wrote: >> While it is tempting and probably easiest to use a DDS style >> generator, I recommend a synthesized one instead, to avoid >> trouble with numeric spurs. > >Can you describe the distinction you are making between a synthesized >generator, and a direct-digital synthesized generator? I do not >understand what would be meant by a synthesizer which is not DDS. What used to be called a "Synthesized Signal Generator" was a almost or even entirely analog beast, which means almost all distortion is harmonic (2f, 3f, 4f, ...) This is a good place to start, in particular the App-note at the bottom: http://hpmemoryproject.org/news/5100/hp5100_page_00.htm DDS is "Direct Digital Synthesis" where you basically generate the desired signal with a computer and D/A converter. Because this discrete rather than continuous in time, there are all sorts of "weird" distortion products, and aliasing artifacts. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Performance verification for time counters
In message <f413435c-c5a8-4cc4-9912-2ac7e7662...@radioengineering.com>, Andy ZL3AG via time-nuts writes: >HP 5359A Time Synthesiser? If we're only talking 1PPS timestamping and nothing better and more flexible is available, then yes. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Performance verification for time counters
In message <5602c647-1251-4d78-b82e-798bfcd8b...@leobodnar.com>, Leo Bodnar writes: >Now, what would be recognised procedure for sweeping external input pulse >delay over few hundred ns in a controlled, measurable and repeatable way? When I did this (20 years ago :-), I used a signal generator. Lock it to the same frequency as your reference signal, but set it for pure sine output slightly offset in frequency (10.10/9.90 MHz), so that your know your TI sweeps the entire window. Until you get a god "box" distribution, there is no need to do anything more complicated. Be aware that flaws in the box shape can come from either the sig-gen or your counter: This is basically a "vernier" style of measurement, and very few sources hold up to that kind of scrutiny. Next run as high a sampling rate as your device supports and look for samples which "leap-frog" each other, in theory you should have none. Next, siggen=ref frequency, but adjust the phase (relative to the common clock reference) and the amplitude, and see if the zero-crossings behave the way you expect. In particular check if the noise (= stddev) is even throughout the window. Finally you can use PM/AM/FM modulation with different shapes (triangle, square, sine etc) and idicies of modulation, in each case you can calculate what distribution to expect. While it is tempting and probably easiest to use a DDS style generator, I recommend a synthesized one instead, to avoid trouble with numeric spurs. The HP3336 with its outstanding level-control is a much overlooked bargain for this kind of stuff. Poul-Henning -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Some more info on the 5065A optical unit
In message <2b66d682-15cf-465f-9a34-d7f7e7929...@n1k.org>, Bob kb8tq writes: >Straight cardboard *is* an issue on RF coils in humidity. The C-field coil is DC only. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 ISO8601 ?
In message <4bec82c4-583e-4632-8589-d898cc2bd...@n1k.org>, Bob kb8tq writes: >I had never realized there was a format for expressing “I think it was 1967 >but it’s >all a bit of a blur”. I think that is one of the major reasons for the revision. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] New ISO8601 ?
Seems there is an ISO8601 revision in progress ? https://www.loc.gov/standards/datetime/ -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 C-field mods and optical unit mods
In message <1159987519.5777361.1511296831...@webmail.xtra.co.nz>, Bruce Griffit hs writes: >What is the effect of the C-field coil dimension tempco? I have not been able to measure it. The C-coil is located thermally close to the temperature controlled parts of the physics package. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 C-field mods and optical unit mods
In message <5AC3D7F0C1F14BAB8B7BE4A552034FCC@dell370>, ws at Yahoo via time-nuts writes: >C-fields are current sensitive, so if they are wound with copper wire, any >small change in their temperature, even when temperature controlled, could >have a effect much greater than 1PPM on that current when driven from a >fixed voltage thru a resistor. > >Does anyone use current drive? The standard circuit is current drive... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] AD9544 clock chip
This beast may have some interesting uses: http://www.analog.com/en/products/clock-and-timing/clock-generation-distribution/clock-synchronization/ad9544.html -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Room temperature control (was: Holdover, RTC for Pi as NTP GPS source)
In message <20171101190841.366058d77e544d256b862...@kinali.ch>, Attila Kinali w rites: >The best we can do today is to have a well insulated room (no windows >with whith unknown power flows) and measure the temperature at a few >strategically choosen points. Then control the heat influx and >outflux using an approriate control loop. This will still result >in deviations of 1-2°C when somone walks in. It is a matter of energy balance. Humans emit heat on the order of a hundred watts and the only way to have that not affect the room temperture, is to "wash" it away in airflow with much higher energy content, as is typically done in clean-rooms. That still leaves you with the thermal radiation imbalance from the higher temperature of the human skin, which is why "nano" laboratories sometimes are kept at an uncomfortably warm temperatures. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] NTP linked PC clock is slightly ahead of Lady Heather GPS time
In message <sn1pr11mb102409ef442d98a98bfec447ce...@sn1pr11mb1024.namprd11.prod.outlook.com>, Mark Sims writes: >The next release of Heather has an audible tick clock mode where >it ticks at hh:mm:ss.000 This can be used to set your watch more >accurately, etc. Consider the potential for people to attach wires to the PC-speaker as a means to get an electrical signal also. These days the speaker is almost the last usable interface for this. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Novatel Dual frequency GNSS receivers on ebay
In message <6C47315934DF482EB10A679D10C09093@pc52>, "Tom Van Baak" writes: >I'm guessing this product is >mostly designed for the PN part of PNT (Positioning, Navigation, Timing)? At least with the firmwares I have had a chance to test, that is clearly the case. I don't know if they have firmware revs focused on timing, but even if they do, the hardware for the PPS output doesn't seem particularly well geared towards real-time uses, but more for post-factum correction. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Another LORSTA mast bites the dust...
In message
[time-nuts] Another LORSTA mast bites the dust...
LORSTA Jan Mayen this time: http://jan.mayen.no/nyheter/loran-c-masten-gar-ned/ -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] HP 5065 Meter readings after restoration and adjustments: 2nd Harmonic Problems ? (II)
In message <881182040.5268197.1504868987...@mail.yahoo.com>, Ulf Kylenfall via time-nuts writes: > >2nd Harmonic level has gone down from 18 to 14 in a few hours.Needle is >nervous in the way that it wiggles about one needle-widthin a random but slow >pace. >All other readings are stable. >Rotating the knob back and forth restores the previous readings. >I am considering a fault in the 137 MHz circuitry. It can also be the synth which bounces up and down in frequency if the delay-line has drifted. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] HP 5065 Meter readings after restoration and adjustments: 2nd Harmonic Problems ?
In message <125529892.249004.1504854237...@mail.yahoo.com>, Ulf Kylenfall via time-nuts writes: >The meter is not stable and the needle is somewhatnervous. When tapping the >instrument with a smallscrewdriver, this value jumps up and down. If the jumps are always the same place on the scale, it is probably a mechanical issue in the meter, if it is all over the scale it could be the rotary switch which selects what the meter shows. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Atomic clocks and Wassenaar agreement
In message <20170820181537.a7a834e32b848ea3f63d3...@kinali.ch>, Attila Kinali writes: >On Sun, 20 Aug 2017 11:28:17 + >> [1] I've always wondered about that rule and I suspect it is a >> mistake. Knowing who is on this list, I imagine that the next >> revision will read the far more sensible: "Non-rubidium *or* >> having ..." > >Yes, singling out Rubidium is kind of weird. I see that rule as a way to carve out telco-class rubidiums, and that's why I think "or" would make much more sense than "and". -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Atomic clocks and Wassenaar agreement
In message <20170820120742.c48c69758cc9fa4856ab0...@kinali.ch>, Attila Kinali writes: >On Sun, 20 Aug 2017 08:50:59 +0000 >"Poul-Henning Kamp" <p...@phk.freebsd.dk> wrote: > >> >Bob your right its interesting that the sales locations are in China and >> >India. Perhaps a larger opportunity for a RB reference today. >> >> Could be because hydrogen masers are dual-use under the Waasenaar >> Arrangement ? > >As far as I can tell, there is no explicit mention of atomic >clocks. There very much is: 3. A. 2. g. Atomic frequency standards being any of the following: 1. "Space-qualified"; 2. Non-rubidium and having a long-term stability less (better) than 1 x 10 -11 /month; or 3. Non-"space-qualified" and having all of the following: a. Being a rubidium standard; b. Long-term stability less (better) than 1 x 10 -11 /month; and c. Total power consumption of less than 1 Watt; The product in question drives directly through the loophole in point 2[1] >But the list of dual use electronics is long and broad. >E.g. Section 3. A. 1. b. 10. covers basically all low noise >frequency sources. Including just a simple low-noise XO. >Does anyone have more specific knowledge? Knowledge ? No. Some Experience ? Yes. The people who wrote the list very much know why they put things onto it, and in the process of narrowly tailoring the restrictions often give more away than they probably should. Depending on your hobbies, you can get some pretty interesting project ideas by reading the list[2]. (3.A.3 anyone ? or how about 9.B.6 ?) The civil servants who administer the lists in the foreign ministries are seldom rocket engineers and will usually administer the list strictly to the letter, rather than talk to one. Poul-Henning [1] I've always wondered about that rule and I suspect it is a mistake. Knowing who is on this list, I imagine that the next revision will read the far more sensible: "Non-rubidium *or* having ..." [2] http://www.wassenaar.org/wp-content/uploads/2016/12/List-of-Dual-Use-Goods-and-Technologies-and-Munitions-List-Corr.pdf -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] (no subject)
In message
Re: [time-nuts] Can I haz an anti-hydrogen maser now?
In message <20170805130056.58880...@aluminium.mobile.teply.info>, Florian Teply writes: >The obvious trick would be to choose their distance such that >only their noise cancels... But the good news is that if you mix their output, you would have the worlds most precise DC signal :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] time-nuts Digest, Vol 156, Issue 35 (5065A Pwr Xfmr - Too high output voltage)
In message <1826314051.766978.1501316001...@mail.yahoo.com>, Ulf Kylenfall via time-nuts writes: >That was a brilliant idea... >...until I realized that I needed 115V for the XO quick-heaterand >we use 230V in Europe... The quick-heater isn't that important, unless you are a very impatient person. It is also, as I understand it, the primary reason for fried out OCXOs... See also: http://phk.freebsd.dk/hacks/HP5065A/20150925_ocxo_preheat/index.html -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 5065A - Looking for AC XFMR PAECO 9100-2742 specification
In message <675538475.428966.1501176257...@mail.yahoo.com>, Ulf Kylenfall via t ime-nuts writes: >Removing that board I discovered that the "24-32V" raw DC was some >40 Volts. That's a bit on the high side, but not excessively so. HP tended to let the linear regulators shave a big slice in precision instruments, probably to make sure that absolutely no ripple makes it through. If I were you, I would ditch the transformer entirely, and go with an external DC PSU and put a high-quality DC/DC converter in the HP5065A See: http://phk.freebsd.dk/hacks/HP5065A/20150930_dcdc/index.html -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 milestone approaches
In message <F81132F1D0FB46429C7D5C2FA77F65C6@system072>, "Bill Hawkins" writes: >On Thursday night, 21:40 PM CST, it will be exactly 1.5 billion seconds >since Jan 1, 1970 UT, the Unix EPOCH. We threw a big "uptime(1)" party for the entire UNIX ecosystem here in Denmark back when 1e9 seconds rolled around :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] J06 HP-59992A time interval calibrator for HP-531xx counters
In message <8fdafefb-3563-94be-e68d-63fe00164...@earthlink.net>, jimlux writes: >On 7/9/17 10:27 AM, Bob kb8tq wrote: >> Hi >> >> People *have* been known to sort MiniCircuits parts and use the “extras” in >> something else. A certain major oscillator manufacturer once bought a bunch >> of RPD-1’s , sorted them for the “one in a hundred” examples, and then >> returned >> the rest for credit…… Somehow I doubt HP didi it quite that way. > >Some manufacturers will cherry pick for you. Maybe the datasheet says >gain is 14 to 18 dB, and you order a batch that you want to be 15.5-16.5 >dB.. They'll pick those out, but of course, now the remainder have a >hole in the distribution. Particularly when you're buying high-rel or >space grade, where they have to 100% test anyway. I've been told by somebody from HPs manufacturing in Europe that there were one or two "magic" components where the manufacturer would send their entire production to HP. HP would test, measure and sort into four bins: "Failed", "Good", "Really good" and "HP". The first three bins got shipped back to the manufacturer. He suspected that back at the manufacturer, the "Really good" got a "MIL-GRADE" stamp :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] J06 HP-59992A time interval calibrator for HP-531xx counters
In message <dm5pr1101mb21057d2e3c55e34307a0fde2ce...@dm5pr1101mb2105.namprd11.prod.outlook.com>, Mark Sims writes: >Also coax and RF relays cost a lot. Pretty soon your BOM cost >is over what a 59992A will run... assuming you can find one. The crucial feature of the 59992A was support for DC-bias, and that seems to have dictated its design. If you have no need for DC-bias, an 8-pin microcontroller with a stable crystal and suitable resistor networks on the outputs will do fine. TI measurements on top of DC-bias was important in development and manufacturing of disk drives: Measurement of jitter of mechanical origin must happen on the analog side of the differential read amplifier, which usually balances a couple of volts up for cost reasons. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] 5370B Question / help needed
In message <caot1cqj4k8uynvfp8ajolgjd57pm31lnzt_jro44j4zhesv...@mail.gmail.com>, Thomas Allgeier writes: >Going through the motions of measuring TI with it's own 10MHz ref as input >(as described in the manual) I don't get 100 ns, but around 15 ns. So this >is with the switch set to START COM. Oddly enough I get the same 15 ns with >the switch set to SEP, and going through a 6 ft cable between start and >stop. Have you checked the trigger polarities ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 Connectors and D-Subs...
In message <1317347843.1873959.1498418740...@mail.yahoo.com>, Ulf Kylenfall via time-nuts writes: >Why not take a look at mixed D-Sub connectors? Because they cost a fortune ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] uC ADC resolution (was: Poor man's oven)
In message <b90b65d3-5e09-4c1c-ade1-100a0a26d...@n1k.org>, Bob kb8tq writes: >If you want the controller noise to *not* be the limiting factor at an ADEV >floor of 1x10^-12, >that drives you to a noise floor of < 0.1 mK. You can then work through the >various thermal >gains to come up with a level of DAC bits that you need. You could equally as >well decide >on a 1x10^-13 floor and / or might have a 1x10^-9 sensitivity. Which gets us back to what SRS does for low noise: Implement the low noise stuff, the PI(D) loop, in analog, but tune/calibrate/adjust the analog circuitry with DAC's set (infrequently) by a uC. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] uC ADC resolution (was: Poor man's oven)
In message <73a71ef4-eb76-4965-b3d5-53f9dd5bf...@n1k.org>, Bob kb8tq writes: >If we want to hold the oven at some temperature +/- 0.1 C, the control loop >needs to go from full on to full off over that range. ...ehhh, what ? >You will map (somehow) the full range of the output into a 0.2 C input range. Uhmm... no ? The full DAC range maps to the heat you need for supply at the two ambient temperature extremes. For instance if you were building a -40...+70C OCXO, *ideally* DAC code 0 should correspond to +70C and DAC code 65535 to -40C ambient That means that one DAC step corresponds to a change in ambient temperature of (+70 - -40) / 65536 = 1.7 milliKelvin. A more realistic temperature range for a time-nut build would be +10...+40C. DAC bitsmK 10 29.3 12 7.3 14 1.8 16 0.5 10 bits would cause I-hunting in your PI(D) but the measurement noise would probably dither that for you. 12 bits would allos a trivial implementation. If you go for a double or tripple oven/dewar design, you probably need 14 bits. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] uC ADC resolution (was: Poor man's oven)
In message <017ac7d5-751b-4084-a3b3-e5132509c...@n1k.org>, Bob kb8tq writes: >You may well use a custom set of control parameters for the warmup phase. The easiest way to avoid overshoot is to use a properly damped PI(D), which is _exactly_ the same thing you want once you are out of the warmup phase, so why bother with two different code paths ? But related to this is the question of output/heater resolution[1]. While it is tempting to use a PWM output, it is a recipe for noise injection, and I would not even try it. Delta-Sigma strategies for spreading the noise-spectrum are interesting, but will not save you if the required heater power ends up being a small rational fraction (1/2, 1/3, 1/4 ...) of the full scale. So a proper DAC is called for. I wonder if a "4-20mA" DAC like the AD5421 is a usable programmable heater ? [1] It is relevant to point out that, as *always* the 'I' term should not be enabled until the P(ID) *output* is no longer clamped. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] uC ADC resolution (was: Poor man's oven)
In message <3897c09a-d76c-474c-8907-9ea25f8c3...@n1k.org>, Bob kb8tq writes:
>The “limited range” part of it is why the op-amp makes so much
>sense. If the ADC can “see” +/-10C that’s way more than will ever be useful.
Most uC's have a pile of mux'ed ADC inputs, so do all of the above:
AI0 = Full range
AI1 = +/- 10C
AI2 = +/- 2C
A big upside to this is that you will not need to invent heuristics
for clamped inputs in your PI(D) controller, something which is a bit
harder than most people realize.
Assuming a 10-bit ADC, the code will look something like this:
double
get_temp(void)
{
T = read_AI2();
if (T > 50 && T < 975) {
T += T2_offset;
T *= T2_scale;
return (T);
}
T = read_AI1();
if (T > 50 && T < 975) {
T += T1_offset;
T *= T1_scale;
return (T);
}
T = read_AI0();
if (T > 50 && T < 975) {
T += T0_offset;
T *= T0_scale;
return (T);
}
abort("You have problems...");
}
--
Poul-Henning Kamp | UNIX since Zilog Zeus 3.20
p...@freebsd.org | TCP/IP since RFC 956
FreeBSD committer | BSD since 4.3-tahoe
Never attribute to malice what can adequately be explained by incompetence.
___
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Re: [time-nuts] backfill
In message <593a4677.5080...@yandex.com>, Charles Steinmetz writes: >The insides of mains alternators are almost entirely metal -- tons and >tons of copper tubing, and the casings and rotor shaft are steel. And >the alternators must operate at a relative humidity of absolute zero. This is close to to being "not even wrong". There is no requirement for "a relative humidity of absolute zero", which is theoretically impossible if there is any iron around. There are however stringent requirements for non-corrosion, dielectric potential, cooling, corona behaviour etc. etc. Cooling the stator is a no-brainer, it is almost always water-cooled. If they could afford to use helium to cool the rotor, they would jump on it instantly, but the cost is prohibitive at their leakage rates. Pure water would also be workable, but its high density means it cannot be used to cool the rotor without a serious hit to efficiency. Next down the line is hydrogen, which comes with a shitload of issues. Apart from all the obvious issues, lube-oil degradation, polymer degradation, fire-risk, risk of explosion, health-risk etc. hydrogen has "interesting" solubility in metals. If you want to purify hydrogen, you press it trhough a filter consisting of a solid slab of palladium, and that takes a lot less pressure than you would expect. For iron in particular, hydrogen means embrittlement, so a major focus in rotor design is to keep the hydrogen away from the iron. If you Google "generator hydrogen seal" and and you will find little love for hydrogen cooling. In 1993 Siemens put the first 170MVA air-cooled generator optimized by computer simulations of the flow-fields and since then the hydrogen cooling has been confined to an ever-decreasing top tier of name-plate power. Today fan cooling will take you to approx 400MVA and pressured air cooling will take you to about 600MVA. Above that, you are, almost by definition, in a nuclear power plant, and all problems from hydrogen cooling of your single huge generator pale in comparison to having a handful of smaller generators in parallel. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Poor man's oven
In message <cabbxvhuzd5riv+sbqa0cnsvfczvb7ub-dfljltob0tzt-pr...@mail.gmail.com> , Chris Albertson writes: >The next step up the complexity scale would have you place an I2C >interlaced ADC inside your oven. These don't cost much and have several >ADC channels. ISOtemp made a version of their OCXO-107 which a built in DAC, but I've been told the result was less than stellar. When you do stuff like that, you need to pay a lot of attention to noise. Personally I would avoid I2C, in preference for SPI to avoid the sharp flanks required by I2C. I would also run the SPI as slow as I possibly could and put low-pass filter the digital signals at the boundary. SRS uses an interesting trick in several of their instruments, where they shut down parts or even all of the digital circuits when not needed, see for instance their digital "all analog" lock-in amplifier. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Poor man's oven
In message <a9e08db0-2cb4-46ee-bc6f-3f3f9bc65...@n1k.org>, Bob kb8tq writes: >In an OCXO design, the gotcha >is matching the PTC oven temperature to the crystal turn. You can do that if >you have a substantial inventory of material and custom fab the oven after >the crystal is built. Bob, you of all people must be able to answer this: OCXO's have specified temperature ranges for instance -40...+70°C for the heavy duty stuff. But I cant imagine the ovens used are so perfect that they have the same regulation performance at all temperatures. I can choose the exterior temperature, which I should prefer ? Disregard aging of electronics and materials, we all know that stuff, what I'm interested in is at which exterior temperature OCXO ovens work best ? -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)
In message <canx10ha776qb1y_j+t7mcawsn6vrp0velv5k13hhs6kdda9...@mail.gmail.com> , "Dr. David Kirkby (Kirkby Microwave Ltd)" writes: >I can't find it now, but I know someone said thermocouples are obsolete. I >spoke to a friend tonight who services industrial boilders. He said >thermocouples are far from obsolesce, at temperatures of a few hundred deg >C, as nothing else works. Thermocouples are not obsolete. If nothing else because they are cheap and can be made on the spot and in all sorts of weird shapes. The only thing which competes with thermocouples in high temperature is platinum, which is horribly expensive by comparison and more prone to noise than thermocouples. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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 sensors and quartz crystals (was: HP5061B Versus HP5071 Cesium Line Frequencies)
In message <20170605133013.526e8505158e68b6a8091...@kinali.ch>, Attila Kinali w rites: >> Where do digital sensors (e.g. ds1820 and some more recent parts from TI) >> fit into this ? > >AFAIK, these are all band-gap temperature sensors. The Ds1820 is based on the frequency difference between two free-running silicon oscillators with different physical design. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies
In message <3ca81847-63c4-f803-994d-8e07c9973...@earthlink.net>, jimlux writes: >Modern RTDs all are 0.00385 ohm/ohm/degree at 25C. Typically, you have >a 100 ohm device (although there are Pt1000s), so it's changing 0.385 >ohm/degree. 1 part in 3000 Depending how much money you want to spend, you can also get pt10k and even pt100k RTD's, to satisfy particular needs for resolution, self-heating, inductance, mass and the many and varied noises. And if course, we cannot talk PT100 and fail to repeat the old pun: "PT100 is the gold standard for temperature measurement" :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies
In message <cabxq0zczlhbjpzwt+jtxtgr+xgprao9x9ewkwxs+jaye2h8...@mail.gmail.com> , "Donald E. Pauly" writes: >Electronic thermal coolers did not exist then http://www.thermoelectrics.caltech.edu/thermoelectrics/history.html >Electronic temperature sensors did not exist either. https://en.wikipedia.org/wiki/Resistance_thermometer#History -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Fwd: HP5061B Versus HP5071 Cesium Line Frequencies
In message <c8fbcbc0-8cbc-16be-f956-b729abdd1...@earthlink.net>, jimlux writes: One final detail about TEC's which people usually don't have to worry about, is that they're not happy about switching directions. You generally end up with them mechanically tearing themselves apart if you use them for mixed cooling/heating. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Next Aug 21 eclipse and time flow
In message
Re: [time-nuts] Next Aug 21 eclipse and time flow
In message <cagp4rdnjxgfwgqubokfdugec90-dp2a2cnsdwypx8vs_btb...@mail.gmail.com> , Michael Wouters writes: >The effect you're looking for depends on a comparison of two different >kinds of atomic clocks eg Cs vs H-maser so the maser comparison presumably >will be a null measurement. It would have to be between clocks where the clock-atoms have very different masses (for instance Cs vs. H) but it would *also* have to be clocks where the clock-photons have very different energy. So the best setup would be H-maser Cs or Rb foundtain and an trapped ion optical clock. Since any physicists at NIST will be keenly aware of the Nobel Prize dangling in front of any competently measured effect, I think we can trust them to be on the ball :-) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] HP 1820-0313 4.2V Logic (Flip-flop)
In message <1580810140.741428.1494966823...@mail.yahoo.com>, Ulf Kylenfall via time-nut s writes: >That the 1820-0313 is unobtanium I can understand.Has anyone created >an equvalent based on discretesor is there a suitable SMD "single" >flip-flop like single gatesthat could be suitable? I did a divider board for the LED clock: http://phk.freebsd.dk/hacks/HP5065A/20160112_working_clock/index.html -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Counter Internal Oscillator Importance with External Reference?
In message <54ee7bdd-0a49-cc49-540d-2812e70dd...@rubidium.dyndns.org>, Magnus Danielson writes: >Wither it is proper side bands or other systematic noise, it is bad >indeed, [...] It's more subtle than that, it can be things like thresholds in the counters trigger being sensitive to the phase of the internal clock because of (very slight) cross-talk. I reported data on this a couple of years ago, as I recall my setup were something like this: House-10MHz --> HP3336C clk-in and HP5370B clk-in. HP3336C output -> HP5370B start then 3m coax then HP5370B stop. Measure TI(start->stop), for different settings of output phase angle on the HP3336C. Theoretically that plot should be a flat line. In practice it is not even close. I think I convinced myself that the majority of the problem was trigger-noise the HP5370B, but my notes are not accessible at this time. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Counter Internal Oscillator Importance with External Reference?
In message <60c74d75-41e5-7112-d8b6-721664b89...@rubidium.dyndns.org>, Magnus Danielson writes: >Indeed. On the other hand some measurements is hard not to do that way. >One should think about how isolation is created if needed, and this >includes AC and DC, common mode and differential mode. Isolation >amplifier should be part of the arsenal. EMI is part of it, but there raw synchronism is a significant source of systematic errors because the "noise" is no longer gaussian. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Counter Internal Oscillator Importance with External Reference?
In message <bad861e5-00a6-5ffc-e031-be6372a13...@rubidium.dyndns.org>, Magnus Danielson writes: >Also, there is a reason that you can buy different internal oscillators, >this is one of them. For labs with their frequency distribution there is >no need to waste money on stand-alone performance. Please don't forget that running the counter of the same signal as the circuits being measured runs the risk of masking noise processes. I'm sure that modern counters like 53230 are better at this than the 5370, but you should always sanity-check your measurements using the counters internal, undisturbed timebase. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Anthorn eLoran
In message <a3865.7ccf4f2a.4642c...@aol.com>, GandalfG8--- via time-nuts writes: >Is anybody monitoring eLoran from Anthorn? I don't see it here in Denmark either. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Fwd: HP5061B High Ion Current/Tubes Out of Cesium
In message
Re: [time-nuts] The ultraAtomic clock for home
In message <cad2jfah1frkzt0m6onoug6g5t_hziunhgdvvsotyceareog...@mail.gmail.com> , paul swed writes: >I suspect if there is one of these some other vendors and even perhaps La >Crosse may have other models at a lower cost. Will not comment on the >technical quality of these products. They're probably based around one of C-max chips: http://www.c-max-time.com/products/showProduct.php?id=17 (This is the old Temic technology that has wandered all over the place...) -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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] Single ended or differential input to TDC chip
In message <20170327180513.307125ed395c80e4e6490...@kinali.ch>, Attila Kinali w rites: >Now, the TDC expects a differential input, but the system gets single-ended >pulses as input (50R coax input, level likely to be CMOS 3.3V, but level not >fixed yet, ie can be freely choosen). I can either convert these single-ended >signals into differential off-chip or on-chip. Unfortunately, I lack knowledge >and experience to judge either approach. The issues I see are: I would give the chip differential inputs, because that way it can also be used, without loss of performance, on future differential signals. -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 p...@freebsd.org | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. ___ 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.
