[time-nuts] Opening for an analogue design engineer in our team at CERN
Dear all, Sorry in advance for the slightly-OT message. We are looking for an analogue designer to help us with signal conditioning in data acquisition applications and also in low-jitter clock signal generation and distribution for White Rabbit <http://www.ohwr.org/projects/white-rabbit/wiki/> applications requiring very high precision. Since much of what I have learnt about this subject in the last years comes from this list, I thought I'd post it here. It is a relatively exotic profile these days, so we need as much help as we can get in trying to find good candidates. If you know somebody who could be interested, could you forward them the link? http://jobs.web.cern.ch/job/12582 I take the opportunity to thank all people sharing their knowledge and experience in this list, and in particular the creators/maintainers/moderators for nurturing such a fantastic community. Many thanks in advance for your help, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT: Eagle PC CAD now Autodesk, $500/year
On Fri, Jan 20, 2017 at 4:52 AM, Richard (Rick) Karlquist < rich...@karlquist.com> wrote: > > Still, the question arises: are there any affordable alternatives? > Don't have to be entirely free. I am looking for any trends out > there as to what tool will attract a critical mass of users in > the future. There is strength in numbers. > > Disclaimer: the section I lead at CERN has been contributing to KiCad development [1] since 2011. Our main driver is to facilitate sharing and collaboration [2] in the domain of Open Source Hardware. As others have said, there is quite some momentum behind KiCad these days. If you want to give it a quick try, I think Chris Gammell's simple "Getting to blinky" tutorial [3] is a very good place to start. Chris also runs a very lively forum where people can ask questions [4]. KiCad does have its quirks [5] like all other EDA tools, but it's progressing quickly and the developers are quite receptive to constructive criticism. We want to take KiCad beyond the hobbyist realm, and we are especially interested in feedback from people in the designers-we-admire category like you. Cheers, Javier [1] http://www.ohwr.org/projects/cern-kicad/wiki [2] https://giving.web.cern.ch/content/kicad-development-1 [3] https://contextualelectronics.com/learning/getting-to-blinky-4-0/ [4] https://forum.kicad.info/ [5] See e.g. the list we keep at http://www.ohwr.org/projects/cern-kicad/wiki/UI_improvements ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How to create a super Rb standard
Hello, And about temperature, in this article http://www.dtic.mil/dtic/tr/fulltext/u2/a495520.pdf there is an interesting point, in the last page: Riley answer to the question "You mentioned larger cells. Where there any other things done go get these fantastic results? Regards, Javier On 18/01/2017 13:12, Bob Camp wrote: Hi You would need to redesign the Rb to work in a vacuum. There is a lot involved in doing that. They depend on the air inside the package to properly operate the heating in the physics package. Different parts of the package are at different temperatures. Without the air cooling the temperature offsets could not be properly maintained. There are a *lot* of differences between the GPS Rb’s and the ones we buy on eBay. The fact that they operate in pretty far down the list of significant differences. The most simple answer to “why” the Rb is better is that the design requirements on the two standards were different, as were the design teams. Coming up with an Rb with better short term stability is the way that all worked out. That short term stability is better than other large cell Rb designs, but not by a crazy amount. How much better it is depends a lot on which large cell Rb design you compare to. It also depends a bit on which specific unit you are looking at. All that said, space benign is indeed a pretty quiet environment. It certainly does help a bit if you operate there. There is also data on the GPS Rb’s that show them doing quite well on the ground. So no, it’s not all space, but space does not hurt their performance. Bob On Jan 18, 2017, at 12:23 AM, Li Ang <379...@qq.com> wrote: Hi I am wondering if anyone tried to put a Rb unit into a vacuum container. And how much the performance is improved? Someone told me that's why the Rb clocks are more stable than Cs clocks on the GPS satellites. LiAng ---Original--- From: "Bob Camp"<kb...@n1k.org> Date: 2017/1/17 21:20:23 To: "Discussion of precise time and frequency measurement"<time-nuts@febo.com>;"Perry Sandeen"<sandee...@yahoo.com>; Subject: Re: [time-nuts] How to create a super Rb standard Hi Since the physics package in the small Rb’s is different than the stuff in the large units, you have some basic limits on what you can do to improve them. The main things people have done are to modify them to turn off the temperature compensation and replace it with some sort of precision controlled thermal enclosure. Pressure compensation is a good idea on any of these parts (large or small). How much your particular unit benefits is a “that depends” sort of thing. Bob On Jan 16, 2017, at 10:24 PM, Perry Sandeen via time-nuts <time-nuts@febo.com> wrote: List It looks like their is as infinitely small chance of being able to get 5065. So what can be done with the telco Rb's (mine are analog tuned) to wring the best possible performance from them? Sooper Duper power supplies, Peltier (sp) cooling modules? Regards, Perrier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] hm H Maser
Hello, Two kind of clocks were developed and qualified, a Rb and the PHM, and it seems that this is the cost for the development of both (since it mentions two on-board clock technologies). And this includes the development of breadboards (EBBs, really full-fledged prototypes with no qualified parts) and of qualification models ( http://www.spectratime.com/uploads/documents/ispace/PTTI_FCS_RAFS_PHM_2005.pdf ), designed and manufactured with flight-quality components since the EQMs are submitted to all testing (thermal vacuum, vibration, life, EMC...) to levels a lot more estringent than those applicable for a commercial-use maser. Taking into account that GIOVE-B (used as the in-flight test bed for the PHM) cost was 72M€, surely excluding launch and deployment costs, I suppose that excluding the PHM itself, it seem that 100M€ is the order of magnitude for the development including in-flight testing platform. Regards, Javier On 10/01/2017 17:22, Ole Petter Rønningen wrote: "The European Commission and the European Space Agency have approved the Galileo GNSS programme. Two experimental satellites will be launched in late 2005 or early 2006. Atomic clocks are critical for satellite navigation. After more than ten years of development and an overall budget of € 30M, two onboard clock technologies have been qualified. The author considers their current status and performance." https://www.gim-international.com/content/article/onboard-galileo-atomic-clocks Ole Den 10. jan. 2017 kl. 14.18 skrev ewkehren via time-nuts <time-nuts@febo.com>: Do we know what the PHM development for Galileo cost? Sent from Samsung tabletBob Camp <kb...@n1k.org> wrote:Hi On Jan 10, 2017, at 2:45 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <drkir...@kirkbymicrowave.co.uk> wrote: Once 9 Jan 2017 12:59, "Bob Camp" <kb...@n1k.org> wrote: Hi Ok here are some rough numbers: On Jan 9, 2017, at 4:35 AM, Dr. David Kirkby (Kirkby Microwave Ltd) < drkir...@kirkbymicrowave.co.uk> wrote: It would be interesting to see your breakdown of the costs and man hours for an H2 maser. I suspect that others would find cheaper/faster solutions. $100M for the H2 $25M for the Rb With all due respect, and I apprectiate you have a good knowledge of this field, but that's not a breakdown of costs or man hours I wanted to see, but a cost which appears to be plucked from the air. Hardly plucked from the air. The last Rb design that I was involved with was roughly 5X that expensive. There's a BIG difference between a volunteer effort where * Salaries are not paid * Items of test equipment are likely to be borrowed or people provide access to them for no charge etc, * Academics are likely to provide consultancy for free, in return for being on papers published. * Software licenses could probably be obtained free, or enough people get trials. That’s where the 5:1 cost reduction comes from. compared to a commercial company building a maser where * Salaries are paid * All equipment is purchased new * Bench power supplies with 3.5 digit displays are sent out for calibration each year. * No outside body will do anything except at a commercial rate. * Flights are booked for meetings which could be done over the Internet. * High end software licenses are huge. $500M for the fountain. But on what basis do you arrive at that figure? The numbers that the people who have done it come up with when you talk to them. To get sponsorship for anything remotely close to those numbers, you need to have some massively good credentials. Bob Yes agreed at $500M. But someone like Tom, who does have massively good credentials, could perhaps get $500,000, and perhaps that wisely spent could get a fountain built. Without knowing how you arrive at $500M, it is not possible for anyone to look at ways of shaving that cost. This is *not* a cheap field to be doing things in …. Bob The Lovell Telescope at Jodrell Bank in the UK was built on a shoestring budget. It was at the time the world's largest steerable radio telephone. Half a century later only 2 larger ones have been built. Maybe I am too nieve. Dave. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mail
Re: [time-nuts] Fw: Optical transfer of time and frequency
On Sun, May 1, 2016 at 5:44 PM, Tom Van Baak <t...@leapsecond.com> wrote: > This particular issue -- how to synchronize (or, at least phase compare) > multiple oscillators by a two-way laser link over a few km to within 500 ps > -- is really quite interesting. It would, for example, allow me to do live > monitoring of 5071A Cs time dilation on my next mountain-valley relativity > experiment. Maybe Koruza [1] could be a good starting point for such a development. It does not meet the distance spec in its current state but it is not too expensive and it's all open source hardware (and software of course). I am pretty sure the Koruza team would be happy to collaborate. Cheers, Javier [1] http://koruza.net/ ___ 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] Fw: Optical transfer of time and frequency
On Sun, May 1, 2016 at 9:50 AM, Magnus Danielson <mag...@rubidium.dyndns.org> wrote: > If I recall correctly, there where some White Rabbit stuff available from > vendors, was it only Ethernet switches or also cards? Yes, the switch is available from two vendors that I know of. They are referenced at [1]. For nodes, we have a page describing what hardware support is needed [2]. Then there are various boards available commercially which implement that hardware support, like [3]. For the particular case of WR-enabled TDCs, one could use the SPEC PCIe carrier [3] with a TDC FMC [4] or a simple DIO FMC [5], delegating then the TDC function to the FPGA on the carrier, using an HDL core like [6]. Or roll your own, of course. Has anybody experienced with free-space optical gigabit Ethernet links? I am curious about whether the transceivers have a fixed latency or at least a latency one can easily quantify online. This is the trickiest part for adding WR support on top of a given physical layer. Cheers, Javier [1] http://www.ohwr.org/projects/white-rabbit/wiki/Switch#Commercial-producers [2] http://www.ohwr.org/projects/white-rabbit/wiki/WRReferenceDesign [3] http://www.ohwr.org/projects/spec/wiki [4] http://www.ohwr.org/projects/fmc-tdc/wiki [5] http://www.ohwr.org/projects/fmc-dio-5chttla/wiki [6] http://www.ohwr.org/projects/tdc-core/wiki ___ 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] Optical transfer of time and frequency
On Sat, Apr 30, 2016 at 8:06 AM, Bruce Griffiths <bruce.griffi...@xtra.co.nz> wrote: > So far I haven't found an existing free space optical implementation of White > Rabbit. There are two groups working on that subject that I know of: Jean-Pierre Aubry [1] and his colleagues in EPFL (Neuchâtel campus, in Switzerland). They started around one year ago. Javier Díaz [2] in the University of Granada (Spain). Javier just visited Neuchâtel with a PhD student (Paco Girela) who is supposed to start working on free space WR soon, if I understood correctly. Tell me off list if you would like me to connect you. Cheers, Javier [1] https://people.epfl.ch/242679 [2] http://www.ugr.es/~jda/ ___ 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] CERN hosted 9th White Rabbit workshop, presentations online
Thanks for the kind words Achim! On Thu, Mar 17, 2016 at 12:25 PM, Achim Vollhardt <avoll...@physik.uzh.ch> wrote: > CERN has hosted this week the 9th White Rabbit workshop. Actually our friends at Nkhef [1] hosted the event in Amsterdam. Nikhef is a really cool institute. In the same building you have people working on neutrino detectors to be installed at the bottom of the Mediterranean (KM3NeT) , the Cherenkov Telescope Array, the Square Kilometre Array and Gravitational wave detection. The lab tour was one of the highlights of the event. I recommend it to anybody going to Amsterdam. > White Rabbit is a open hardware fiber-based network which allows for > precise (sub-ns) time transfer over fiber lengths of up to 10km (and > even more) between attached nodes. Indeed, 10km were our initial specs. Then through the magic of open source and some very gifted individuals, WR specs are being stretched in many directions. The longest link to date is the one done by fellow time-nut Anders Wallin [2], around 1000km! Cheers, Javier [1] https://www.nikhef.nl/en/ [2] http://www.ohwr.org/attachments/4271/4_WR-workshop_2016_wallin.pdf ___ 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] Tait reference
Hello, Tait T800 is a series of mobile radio repeaters, so probably the T801 could be a unit intended for iso-frequency networks, in which there are several repeaters are distributed in a wide area operating all at the same frequencies with a very tight tolerance. BNCs and 13.8V power supplies are very common in the mobile radio networks world. Regards, Javier On 11/01/2016 4:00, Bob Camp wrote: Hi Unless we are looking at different auctions, that one appears to want 13.8 V at <= 5A as the supply. The BNC’s are also a fairly rare item in the Telco inventory (but not unheard of). If I had to bet, I’d say it’s a piece of mobile video gear. I would not bet anything over about a nickel on that being correct. It’s very much a mystery item other than possibly having an offset frequency translation function. Bob On Jan 10, 2016, at 8:35 PM, paul swed <paulsw...@gmail.com> wrote: What little I can tell is they are telco references so there may be something good inside OCXO or RB. It looks like it runs on -48VDC from the ebay pix. Its output could be any of the typical telco references that are not 5 or 10 MHz. These are pure guesses. The Price seems reasonable. Good luck Paul WB8TSL On Sun, Jan 10, 2016 at 6:48 PM, Adrian Godwin <artgod...@gmail.com> wrote: Are these the references with a rubidium oscillator ? They seem to have similar models with OCXOs etc. http://www.ebay.co.uk/itm/111862884745 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Why would Keysight UK uncertainty measuring 1 MHz be as high as 7.6 Hz?
Hello, The calibration certificate does not indicate that the measurements were done with the frequency counters referenced to the 5071A at the time of calbiration (if so, it would be listed under the Calibration Equipment Used table). It says that the 53132A were calibrated against the 5071A. If for your calibration they have used 53132A witout the oven oscillator option it is very probable that its uncertainity is 7.6ppm as indicated in the certificate. Since the maximum error tolerable for the LCR meter is 100ppm (+/-100Hz @ 1MHz), it makes sense to perform the measurement with an instrument with an uncertainity of 7.6ppm, and not to use the better counter in the lab for that purpose. Regards, Javier On 28/08/2015 22:48, Dr. David Kirkby (Kirkby Microwave Ltd) wrote: My LCR meter came back from Keysight UK last week, where it was calibrated. This instrument works at various frequencies from 20 Hz to 1 MHz, so obviously has some sort of oscillator in it. But I don't think the absolute accuracy on frequency is important on this, as it does not even have the ability to set to an arbitrary frequency. There are only 8000 or so steps, and at the high end, some of those steps are more than 100 kHz apart!!! So clearly frequency accuracy on this instrument is not that important. Anyway, the cal certificate, a copy of which I put here http://www.kirkbymicrowave.co.uk/cal_certificates/Keysight-standard-calibration-with-uncertainties-for-4284A-precison-LCR-meter-18-08-2015.pdf shows on page 5 that it was checked at 1, 8, 20, 80, 400 kHz, and 1 MHz. But the uncertainty reported (7.6 Hz) seems extremely high, given they used a 53132A counter as a working standard, and a 5071A primary frequency standard. Why should the uncertainty be so high? Am I missing something? When they done my VNA last year http://www.kirkbymicrowave.co.uk/cal_certificates/Keysight-standard-calibration-with-uncertainties-for-8720D-vector-network-analyzer-16-09-2014.pdf the uncertainty on frequency was about 5 orders of magnitude better than that. The 10 MHz timebase was measured with an uncertainty of 0.0010 Hz. I checked the Keysight UK accreditation (by UKAS) for frequency http://www.keysight.com/upload/cmc_upload/All/UKAS_S_2015-08-14_Eng.pdf and see over the range 0.1 Hz to 500 MHz, which covers the LCR meter, their accreditation is 6.0 in 10^11 + 0.020 nHz. I can't believe they are unable to measure better than 7.6 ppm on frequency, so are wondering why the uncertainty is so high, even though I am sure such an uncertainly is very acceptable for this application. It is either an error on the cal certificate, or I am missing something. I expect it is the latter, and hoping someone here can fill me in. Dave ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] looking for SMT oscillator SC cut, with no oven
Hello, Jim, I suppose that one of the alternatives that you've explored are the ABLNO from Abracon http://www.abracon.com/Precisiontiming/ABLNO.pdf They say that they are 3rd overtone, but it seems more an AT-cut than a SC, and anyway is around 10dB poorer than your requirements. An I suppose that to make surgery in an AOCJY (that fully meets your requirement) to remove the oven will not be adequate :) Also it is a bit bulky... Regards, Javier On 26/08/2015 20:23, Jim Lux wrote: For a project at work, I'm looking for a good close in phase noise oscillator (better than -100dBc@ 10Hz, -120dBc would be nice) at 100 MHz in a SMT form factor. But it doesn't need good temperature stability. There's tons of SMT OCXOs out there with reasonably good performance, but they draw watts. My application is actually quite temperature stable already AND I have an external reference to measure against. Most of the lower powered oscillator modules are TCXO, and have, maybe, -80dBc at 10MHz. I guess we could go to a discrete design with a crystal and amplifier, but a little clock module would be a simpler solution. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] Leap Second in press
Hello, This is an article published in one of the main newspapers in Spain, about the timekeeper at ROA, the institution responsible of legal time in Spain. http://www.elmundo.es/ciencia/2015/06/30/559189c622601d6b4e8b4594.html It is in spanish, but has pictures :) Regards, Javier ___ 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] Good references on holdover?
This is a great list. Thanks everyone! Much of the material relates to cases where good holdover needs to be maintained for several hours, but there's a lot of insight to be gained from the reading, and I am sure those techniques will come in handy for other projects. Thanks again! Javier On Fri, Feb 6, 2015 at 2:58 PM, Attila Kinali att...@kinali.ch wrote: On Fri, 6 Feb 2015 10:21:08 +0100 Javier Serrano javier.serrano.par...@gmail.com wrote: We would like to start working on holdover performance for White Rabbit [1]. This is a new domain for us. Our main use case is a WR switch losing its reference because someone disconnects a fiber. We can have redundancy, but it will take some time for a switch to change over to another reference. During this time, the oscillator in that switch will be free-running. We want to minimize the phase drift during that interval, which we think should be a couple of seconds maximum. We have never worked on holdover, and I am wondering if we can do something smarter than the obvious feeding of some constant voltage to the VCXO, based on averaging during the locked state. Does anybody know of any good references on holdover? I think you are looking for something like [1]. I think [2] could be also of help, although it's not as good as the Nicholls paper. Zhou's paper [3] seems to be very similar to what Nicholls did (i have not fully read it yet). HTH Attila Kinali [1] Adaptive OXCO Drift Correction Algorithm, by Nicholls and Carlton, 2004 http://dx.doi.org/10.1109/FREQ.2004.1418510 [2] A Frequency Model for OCXO for Holdover Mode of DP-PLL, by Hwang, Shin, Han, Kim, 2000 http://dx.doi.org/10.1109/SICE.2000.889649 [3] Adaptive Correction Method for an OCXO and Investagion of Analytical Cummulative Time Eror Upperbound, by Zhou, Kunz, Schwartz, 2011 http://www.sce.carleton.ca/faculty/schwartz/abstracts/HuiPaperschwartz.pdf -- It is upon moral qualities that a society is ultimately founded. All the prosperity and technological sophistication in the world is of no use without that foundation. -- Miss Matheson, The Diamond Age, Neil Stephenson ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Good references on holdover?
Thanks for your ideas. On Fri, Feb 6, 2015 at 11:09 AM, Hal Murray hmur...@megapathdsl.net wrote: Is your PLL analog or digital? I'll assume digital since it's hard to hold analog voltages stable for several seconds. Yes, it is digital. It's even software. It runs on an LM32 [1] soft core inside an FPGA. Then there's a DAC and a VCXO. Our goal is to achieve sub-ns synchronization with respect to a master reference even during switch-over between redundant paths. Cheers, Javier [1] http://www.ohwr.org/projects/lm32 ___ 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] Good references on holdover?
Dear all, We would like to start working on holdover performance for White Rabbit [1]. This is a new domain for us. Our main use case is a WR switch losing its reference because someone disconnects a fiber. We can have redundancy, but it will take some time for a switch to change over to another reference. During this time, the oscillator in that switch will be free-running. We want to minimize the phase drift during that interval, which we think should be a couple of seconds maximum. We have never worked on holdover, and I am wondering if we can do something smarter than the obvious feeding of some constant voltage to the VCXO, based on averaging during the locked state. Does anybody know of any good references on holdover? Thanks! Javier [1] http://www.ohwr.org/projects/white-rabbit/wiki ___ 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] FOSDEM 2015 has a time-track
On Tue, Jan 13, 2015 at 9:04 AM, Attila Kinali att...@kinali.ch wrote: I'll be at FOSDEM, Friday to Monday. Do any of the present time-nuts care for a meetup (like some drinks or dinner)? That'd be great! I will be at FOSDEM but unfortunately I will miss the Time track because I am organizing the Electronic Design Automation devroom the same day. Cheers, Javier ___ 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] STEL-1173/CM Source
Hello! On 18/12/2014 5:37, Magnus Danielson wrote: Ed, On 11/15/2014 04:38 PM, Ed Palmer wrote: Yes, I'm sure. I did check the cabling. :) If I was somehow measuring the Tbolt or 4065A against itself, there wouldn't be any frequency offset. The Oscilloquartz 3210 (which appears to be an OEM'd 4065A) is spec'ed at 3E-13 @ 100K seconds. The 4065C is even better at 8.5E-14 with a noise floor of 5E-14. My OSA 3210 is not the same core as 4065A. The Oscilloquartz that has the same core as the 4065A is the 3120 (EUDICS 3120 they call...), not 3210. I'm now doing a comparison of a Lucent KS-24361 against it, and have not yet enough data for 100K seconds although it is showing an ADEV there around 3e-13. Regards, Javier ___ 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] Digital Mixing with a BeagleBone Black and D Flip Flop
Hi Simon, I am the initiator and leader of the White Rabbit project, which in the context of these discussions is more a disqualifier than anything, since I do very little technical work these days, unfortunately. Please forgive me if I have misunderstood what you are trying to do. Some tentative answers below: On Wed, Oct 15, 2014 at 1:58 PM, Simon Marsh subscripti...@burble.com wrote: On 15/10/2014 10:29, Bruce Griffiths wrote: The use of a synchroniser loses no information apart from fine details about the metastability response of the sampling flipflop. With a 10Hz offset and a 10MHz clock the sampling resolution is 100fs with the phase difference between the flipflop clock and data input transitions changing monotonically by 100fs between successive active clock transitions. Phase noise/jitter between the flipflop and data input transitions will typically result in a burst of state transitions at the synchroniser output rather than a single transition when the active clock transition and a data transition coincide.. Right, this is my understanding of what the white rabbit articles refers to as glitching and is why I know I have something wrong when I see no noise at all. Do you have a precise idea of what the offset in frequency is between your DUT(s) and the slightly-offset oscillator? If that offset is too big compared with the jitter of your clock signals and your flip-flops, that would explain why you see no glitches. Locking to your DUT frequency is a good way to make sure you control the offset. Small frequency offsets are typically implemented by multiplying by (N-1)/N with N big enough. There is a trick (from NIST I think) for achieving high N by cascading two PLLs which multiply by M-1 and M+1 respectively. The effective multiplication factor is then (M^2 - 1). Making M^2=N and inserting the divide-by-N in between the multipliers gives you the global (N-1)/N. We don't use this trick, but it can be handy in some circumstances. BTW, does anybody have a pointer to the original reference for it? What I'm less sure about is what I should expect to see as the clock/data phase steps through the unstable region of the sampling flip flop's response. Whilst the synchroniser will ensure I get an output of some sort at each cycle, its going to take many cycles @100fs to step through before the sampling flip flop is stable again. Is this likely to appear as (random?) state transitions at the synchroniser output ? perhaps this region just gets lost in the mush of clock jitter ? You should indeed use a synchronizer made of a chain of FFs of length at least two. You should see the typical glitch pattern after the first FF and also after the second, i.e. what you should see in an oscilloscope should pretty much look the same for both FF outputs. Only in the very infrequent cases where you hit the metastability window of the first FF there should be a difference between what you see after the first FF and after the second one (except of course for the fixed one cycle latency). Notice I am abusing the word 'glitch'. These are pulses of at least one clock cycle duration. The current implementation used in WR was developed by Tomasz Wlostowski in the frame of his MSc thesis, following the ideas of Pablo Alvarez which Bruce pointed to earlier. As you can see in Tomasz's dissertation [1], there was not a lot of investigation on optimal strategies for DDTMD noise. The precision at the time was deemed more than adequate. It is very timely that you bring up this subject now, because I hope to start looking at ways to optimize phase noise in WR in the coming months, and noise coming from the DDMTD phase detector is definitely something I want to look at. I will be very interested in your ideas and findings regarding optimal strategies for the de-glitcher. Cheers, Javier [1] http://www.ohwr.org/documents/80 ___ 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] F*watch
On Sun, Oct 12, 2014 at 12:28 AM, Chris Albertson albertson.ch...@gmail.com wrote: On Sat, Oct 11, 2014 at 1:50 PM, Javier Serrano javier.serrano.par...@gmail.com wrote: It's as free-as-in-freedom as we could make it: schematics, layout, case and code, all using free tools. That is really the best part. But I wonder what it would cost to build a copy using your design files. Or what would it cost to build a run of say one dozen?Apple prices their watch at $350 which at first seemed really high but then I started thinking if that was a high price or not I haven't done the math myself, since our objective was never to save money, but I am pretty sure you can convince yourself by looking at the parts list and contacting your favourite distributors (and excluding your own time to learn about it and make it) that the f*watch can be made cheaper than Apple's watch. Having said that, I think you would be comparing apples and oranges ;) Our main objectives with this development were others, in order of decreasing priority: - to give our colleague a gift and a departure party he would remember forever. I think we succeeded on this one! :) - to give him something which would keep him coming back to us to do what he likes best (aside from hiking): hack low-level software. - to explore the limits of what a bunch of hackers can do meeting irregularly on Friday evenings and working intermittently at night and on weekends for a few months, using only free tools. - to start eating our own dog food. We have been contributing to KiCad for some time now [1], and we wanted to evaluate how far we still are from being able to use it at work without a big productivity penalty. So I don't look at the f*watch as a way to save money (and even less, time!) but as a great platform to experiment and have fun. Cheers, Javier [1] http://www.ohwr.org/projects/cern-kicad/wiki ___ 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] F*watch
Friends, This is a GPS watch we designed after working hours as a surprise gift for a colleague who just retired: http://www.ohwr.org/projects/f-watch/wiki It's as free-as-in-freedom as we could make it: schematics, layout, case and code, all using free tools. Cheers, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] What sort of oscillator is this?
On 28/09/2014 17:44, Dr. David Kirkby (Kirkby Microwave Ltd) wrote: BTW, you may note Keysight's uncertainty for measurement of the 10 MHz reference in September 2014 is 0.0010 Hz, whereas Agilent's was 0.00080 Hz in August 2013. They 5071A primary frequency standard. I assume the fact that the ID number is UK13623 on both certiciates, means it is actually the same standard, rather than two of the same model number. It seems the same unit, I doubt they will maintain the ID if replacing it, but it has been re-cablibrated between both certificates, so its uncertainity has evolved from the previous calibration to the last one. Regards, Javier ___ 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] Oscilloquartz 3210 Cesium Standard
It seems that later, they decided to shameless use the FTS/Datum/Symmetricom FTS-5045 module http://www.gigatest.net/datum/5045txt2.pdf The OSA-5585 I've has one inside, labeled Symmetricom everywere, and the Oscilloquartz contribution is a subrack containing the DC-input and AC-input power supplies, a controller that manages the FTS-5045 through its serial port, and some clock synthesis and distribution cards to provide PPS, 10MHz and 2.048MHz, with a spectral quality a lot worse than the output from the FTS-5045. I find the Oscilloquartz part of the equipment not very good nor very usefult to my purposes, to a point I'm thinking on to remove it completely an control/monitor directly the FTS-5045 with whatever thing with a serial port and a display (my Blackfin module, a Beaglebone o whatever similar) Regards, Javier On 29/08/2014 1:23, Magnus Danielson wrote: FTS had a patent on microcontroller steered cesium, which could naturally have limited the spreading time of that technology. Oscilloquartz at the time where more focused on the telecommunication market and meeting the ITU-T G.811 PRC quality requirement, keeping within +/. 1E-11 in frequency, and that is achievable with the analog design, so no rush changing it. FTS and HP where more into time-keeping, so therefore improving the design made more market sense for them. Anyway, that's about how I have perceived the market at the time. Cheers, Magnus On 08/28/2014 11:47 PM, Chris wrote: On 08/28/14 19:53, Javier Herrero wrote: Hello, Then it is a quite different beast to the EUDICS 3120, that they also call OSA-3120... I note now that yours is a 3210, not 3120 :) Regards, Javier The 3210 looks like a much earlier design, prior to the inclusion of microprocessor control. Date codes look mid eighties, by which time companies like FTS did have microprocessor control. Maybe their later design products ran in parallel because of gov or esa contracts. In theory, the more straightforward hardware design should make it easier to keep running, tube life permitting, assuming the info can be found. Thanks for sending it anyway - it all adds to the sum of knowledge... Regards, Chris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Oscilloquartz 3210 Cesium Standard
Hello, Then it is a quite different beast to the EUDICS 3120, that they also call OSA-3120... I note now that yours is a 3210, not 3120 :) Regards, Javier P.S. no, there is no known cure to the time nuts things interest. It becomes chronic, and only gets worse ;) On 28/08/2014 16:33, Chris wrote: On 08/28/14 05:03, Javier Herrero wrote: Hello, Here is the manual I've. I have also some other documentations, and some Oscilloquartz software for the OSA-5585, but I don't know if they are very useful. Regards, Javier Hi Javier, Thanks for that and for the other replies. The 3210 looks like quite an early design, with no sign of microprocessors at all. There's a 8 slot card cage with a load of discrete analog circuitry, 741 op amps etc and a couple of boards full of 14 / 16 pin ssi cmos / ttl devices, which I guess would be the synthesiser logic and perhaps a state machine style startup sequencer. Apart from that, the rest is power supply related and what looks like an alarm board with optoisolator discete outputs to a 25 way D connector. The step recovery diode (?) multiplier into the microwave cavity is a really neat gold plated assembly with what looks like a 50r termination (setup tap for spectrum analyser ?) and an adjustment trimmer, but am not touching that or the many trimpots on the boards or any adjustments until I have more info. The tube is from FTS, part number / model 7101. It seems strange that the 2nd harmonic, meter #9, is zero, since even with a tube approaching eol, one would expect at least some indication, which is why I think there may be an electronic fault. Perhaps the hv power supply module feeding the electron multiplier. Will try to measure that, but the area around the tube is really heavily rivetted and screwed down in all directions. Looks like a lot of the left hand side of the case will need to be disassembled just to get at the tube connections. It also had the battery backup option, with 4 sets of 3 x cyclon type cells, but with a date code of 1984, are seriously dead and have been removed. This time nuts things seems to be a growing interest and wonder if there is a cure ? :-). Recently bought a 1970's era Tracor 304D rubidium standard. Again, no lock, but a very well engineered and screwed together piece of kit and should be fixable. Collection now includes the Z3816, from Ebay US around 7 years ago, a Z3815 currently being repackaged, an HP103 with open circuit oven heater elements and the 3210... Regards, Chris ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Oscilloquartz 3210 Cesium Standard
Hello, I've some manuals from an OSA-5585, one of them for the EUDICS 3120. The thing that Symmetricom calls EUDICS-3120 really is a FTS-5045 module (Symmetricom in my case), that I think that it is the same that is inside the FTS-4060. It seems that one common problem with these, discuted some times in the list, is an STEL-1173 IC that has a failure mode in which the outputs stop working (one after another, not all at same time :) ). Regards, Javier On 27/08/2014 23:09, Chris wrote: Hi, I recently bought an Oscilloquartz 3210 cesium standard and although it does power up, it does not lock. All the parameters on the meter look sensible, other than the 2nd harmonic, #9 parameter, which shows zero. Quart oscillator output looks almost spot on in comparison with the lab Z3816. I have no info on this unit at all, so this may either be a dead tube, or other electronic fault on one of the many pcb's in the system. Ion pump had a small reading on power up, but now dropped back to zero. I am looking for a user guide for this unit, or even better, a manual with theory of operation and setup info. Can anyone help with this, or perhaps suggest a source ?. Year of manufacture estimated 1984/85, from date code on ic's. I notice that the tube is from FTS, the same construction as in the FTS 4060, but different part number and wonder if this was original fitment, or has been replaced at some stage... Regards Thanks Chris Quayle Oxford, England . ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Symmetricom 1111C OCXO question
Hello, Supply voltage is 24V. I've no information of the control voltage range and slope. Regards, Javier On 26/07/2014 7:02, davidh wrote: Hi All, Can anyone advise the supply voltage and range of the control voltage for these gadgets? Cheers, david ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] temperature sensor
Hello, There are two types of NTC thermistors that are (very) frequently used in spacecrafts, the Measurement Specialties (traditionally YSI, Yellow Spring Instruments) 44907 and 44908, that are 10k @ 25ºC NTC: http://meas-spec.com/downloads/44908.pdf and http://meas-spec.com/downloads/44907.pdf Both are specified in error against temperature, being ±0.1ºC for the 44908 and ±0.2ºC for the 44907, in the 0-70ºC range. I suppose that these ones are obscenely expensive, but the civilian versions are the 44006RC and 44031RC, with the same specified tolerances, and the same calibration curve, and readily available (e.g. from Farnell). I suspect that the difference between the space qualified ones and the others are quality control and traceability, and perhaps (only perhaps) a different low-outgassing epoxy coating, but probably the sensor material is the same in all of them. The advantage is that you get a quite good intial tolerance, so calibration can be simplified, since you only need to calibrate the resistance measurement device with known resistances to obtain a ±0.1ºC error from the sensors. The qualification mandated by NASA for these sensors refers mainly to MIL-PRF-23648 standard, that describes a load life test, consisting in application of maximum power specified for the themsitor during 1000h, intermittently (30min. on, 30min. off) and checking at 250, 500, 750 and 1000h that the thermistor remains in the specified tolerance in the applicable specification sheet, so I suppose that these thermistors are quite good wrt long-term stability. In applications where more stability is required, also Pt thermistors are used in spacecrafts (mainly Pt1000 and Pt2000, also others), but the problem is that depending on the wire run, they shall be measured using 4-wire techniques, and also initial calibration is not so tight (when it is so tight, they tend to be also very expensive) and not so easy (a Pt1000 has a rough variation of 3ohm per ºC). Regards, Javier On 21/07/2014 16:12, Attila Kinali wrote: On Mon, 21 Jul 2014 04:39:51 -0700 Alexander Pummer alex...@ieee.org wrote: NTC are not that very stable, they are amorphous material winch could recrystallize slowly and therefore change it's electrical behavior , PT100 style is more reliable since it is pure metal How long is the time constant for NTCs? I guess, it wouldn't matter for most of the measurements we do, as NTCs need to be calibrated before precision measurements anyways. Unless one measures over several months, or years. But on this timescales, i wouldn't really trust an off the shelf PT100 either. Not unless i measure its stability For use in GPSDOs and OCXOs, i guess it doesn't really matter, as long as the NTC stays within spec. There an external loop corrects for the variation/drift of the measurement. While we are at it: what is a good way to calibrate/characterize temperature sensors that is available to hobbyists? Attila Kinali ___ 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] Sad news Ulrich Bangert
On Fri, Jun 20, 2014 at 10:52 PM, Hartmut Paesler timen...@paesler.de wrote: unfortunately I have to deliver the sad news that Ulrich Bangert, DF6JB passed away on 11/06, aged 59. I always enjoyed reading him, both in form and in content. He was special to many people he never met or heard about. Please tell his family and friends if you meet them. Javier ___ 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] Weather/units question for European members
Hello, Wind speed usually in meters/sec (when used for scientific data) or km/h (used in the news, so the people can compare with car speed ;) ) Pressure in millibars. Meteorologist also usually refers to hectopascals, but it is more for representing something at a given altitude (for example, winds at 700hPa) than for managing pressure data. Temperature in ºC Precipitation in liters/squared meter or millimeters (it is a 1:1 equivalence) Best regards, Javier On 24/05/2014 3:16, Mark Sims wrote: I am building a weather sensor that includes a ultrasonic anemometer to measure wind speed, direction, and air temperature. It uses 4 cheap ($1 each) HC-SR04 ultrasonic rangefinder modules that output a pulse width proportional to the time of flight of the sound signal (topic is time nut related since it simultaneously measures the speed of sound in 4 directions to a pretty good accuracy/resolution using a cheap-ass microprocessor - ATMEGA328 (like and Arduino)... and does so without using any counter-timer channels). Now the question... I would like it to be able to output data in imperial or metric units. In what units is the typical wind speed reported (meters/sec, km/hour, ?). Also air pressure (millibars/hectopascals/pascals/?). ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] STEL 1175 vice 1173
Hello, I think that not as a direct replacement of the 1173. The 1175 has 32-bit phase increment resolution and 10-bit DAC output. The 1173 has 48/12 bit. Regards, Javier On 14/05/2014 17:13, cdel...@juno.com wrote: Hi, I found two PLCC STEL 1175 in a rack mounted synthesizer I have. I'd be willing to sell the chips. Would they work? Cheers, Corby ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Very slow freq. counter / event counter
On 18.04.2014 19:17, Andrea Baldoni wrote: Hello. In the lab, I would like to have an event counter that can double as frequency/period counter, with maximum clock rate in the order of the tens of Hz or so, better with TIC function (aka chronometer). Resolution need not be better than 1/100s, counts to , but the input should be simple and permissive, something like 0-5V or 0-12V, or short-to-activate. I own a Racal-Dana 1995 than can count periods to 1700s, but can't be used as event counter and the inputs are delicate, needing care and attenuators. I also have an Agilent 34401 that can count frequency; the input is very versatile but, for whatever reason they limited the lower frequency to 3Hz so it can't measure slow signals. It also can't be used as event counter or as TIC. I know there are some industrial timer/counters (for example the chinese Sommy /Autonics CT series) but I would like more to have a laboratory instrument, with binding post in the front, mains power, etc... A vintage would be good also, just maybe not so vintage to use dekatron tubes :) (nixie are ok, but it should not weight a ton or shipping to Italy would be prohibitive) Someone has a suggestion? Hello, One alternative could be a HP 5334A/B. They can be found rather unexpensive, I think that it has all your required functionalities, and a wide input voltage range (+/-50V with x10 att on) Regards, Javier ___ 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] Acam TDC's
On 07.04.2014 18:51, Dan Kemppainen wrote: At which resolution do you wish to get 40Msps? Tell me the single-shot jitter figure. So far we had only several ksps of throughput in our TDC circuit, but the bottleneck lies within a computer interface. Anyway, it is not an easy task to get some 200MB/s into the computer in a sustained fashion. (And to process such amounts of data in real time is hard, too.) The plan was to pair it with a FPGA to make decisions on the data. The result of the decisions would have been passed further down the digital signal chain. In order to achieve what we needed to see, we would have had to measure time with a resolution on the order of 50pS, at a rate of 30 to 40 million times per second. Eventually we went to a high bandwidth analog system, and were able achieve our goals. It would have been nice to do it digitally, though. That was a few years ago, and it feels like ancient history now! :) Nowadays you could use the TSH788 from TI, 200Msps @ 13ps if I remember well. Once was commented on the list, and I've one piece lying around, but have not yet found time to play with it. Regards, Javier ___ 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] Symmetricom 1111C OCXO question
Hello all, I've a C OCXO (inside a Symmetricom 5045A that is inside an Oscilloquartz OSA 5585) that refuses to start. It seems that one voltage regulator is not operating, with only 2V at its output while it should have (I think...) around 12V. I've partially analyzed the circuit, and it is nothing from other world: a 6.9V reference diode, driving an operational amplifier, driving a NPN transistor. But the 6.9V reference diode is biased from the regulator output, so... if the regulator does not provide output, the zener is not biased, and then... the regulator does not provide output. So it must be some kind of start-up circuit, that makes the transistor to conduct a bit, or to bias the diode, when power is applied. I've been looking around, but not found it yet. I have make a quick test by placing a 6k8 resistor between the collector and the base of the transistor to make it conduct, and then the regulator starts, provides adequate output (12.5V), and also the 5MHz output appears. Any idea is welcome :) Best regards, Javier ___ 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] Symmetricom 1111C OCXO question
Hello! Yes, I was thinking something like that, but was not able to find it. After analyzing somewhat more, I'm finding that the problem seems more subtle. Since the gain of the operational is 1, and there is a positive feedback (the diode bias from the output), the output voltage should build up until reaching the zener threshold and then stabilize. But it only reach 2V, and remains there. The zener is biased using a 2k resistor. A further examination reveals that the zener also supplies a reference voltage to three sections of a quad X9241 digital potentiometer, through resistors (1k for each of two sections, 10k for the other). The X9241 receives a 5V supply from a MIC5205-5 regulator, that takes its input also from the output of the main regulator. The X9241 is non-volatile, and has the I2C bus accesible from outside the oscillator. When the output voltage is locked at ~2V, the output of the MIC5205 is also ~2V and in this condition is seems that the resistance to ground of the X9241 sections (nominally 10k each) is a lot lower, so they load too much the reference diode, and makes the voltage at the zener not to go up more. So I suspect that the output of the MIC5205 is activated too early, and when ramping up, it creates the lock-up. I've tested to put a 1000uF capacitor at its output to try to delay its turn-on, and then the circuit starts up OK - the voltage at the reference diode is the expected, the output of the regulator is ok, the output of the oscillator is ok. The MIC5205 has an enable pin, but it is tied to the input, and also has a bypass pin in order to connect a bypass capacitor to enhance its noise performance and power supply noise rejection, and this capacitor also has an effect on the regulator turn-on time. There is in fact a ceramic capacitor connected there. So tomorrow I will test to add some capacitance in parallel with it and see what happens. Normally I would doubt that the ceramic capacitor is bad, but I would also be surprised that the design of the circuit is so marginal that a slightly faster turn-on time in a secondary regulator is able to create this havoc :) Best regards, Javier On 03.04.2014 23:41, Bob Camp wrote: Hi Normally that sort of circuit has a “boot strap” pull-up resistor that weakly biases the diode to get things running at start up. Bob On Apr 3, 2014, at 11:08 AM, Javier Herrero jherr...@hvsistemas.es wrote: Hello all, I've a C OCXO (inside a Symmetricom 5045A that is inside an Oscilloquartz OSA 5585) that refuses to start. It seems that one voltage regulator is not operating, with only 2V at its output while it should have (I think...) around 12V. I've partially analyzed the circuit, and it is nothing from other world: a 6.9V reference diode, driving an operational amplifier, driving a NPN transistor. But the 6.9V reference diode is biased from the regulator output, so... if the regulator does not provide output, the zener is not biased, and then... the regulator does not provide output. So it must be some kind of start-up circuit, that makes the transistor to conduct a bit, or to bias the diode, when power is applied. I've been looking around, but not found it yet. I have make a quick test by placing a 6k8 resistor between the collector and the base of the transistor to make it conduct, and then the regulator starts, provides adequate output (12.5V), and also the 5MHz output appears. Any idea is welcome :) Best regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Symmetricom 1111C OCXO question
On 03.04.2014 18:25, Azelio Boriani wrote: Other idea than leaving the 6K8 resistor? Yes... I would prefer to know why the little thing has stopped working. The 6k8 resistor has also probed to be a marginal solution. The operational amplifier is a Burr-Brown one (don't have the p/n at hand now), and since it was my first suspect, I replaced it with a similar (but not the same) part from Linear Technology that I had at hand. With this one, I tested the resistor trick. After concluding that the original opamp was ok, I have put it back. With the original one, the resistor trick did no longer work, so it was not only a dirty solution, but also very marginal. So... I would prefer to find and solve the real failure :) Regards, Javier ___ 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] Trimble Thunderbolt 1pps
On 27.01.2014 15:08, Attila Kinali wrote: In practice, the receiver chip only has one power supply. It would take extra work to make the switching threshold below ground. That's not correct. Standard transceiver chips (like the MAX232 family) have an integrated charge pump to get a negative power supply. Hello, The venerable MC1489 does not need a negative supply, and can have a threshold below ground, without too much complication. http://www.onsemi.com/pub_link/Collateral/MC1489-D.PDF (the receiver circuit diagram is shown) On the other side, the MAX232 has positive thresholds in the receiver side http://datasheets.maximintegrated.com/en/ds/MAX220-MAX249.pdf pag. 6 Regards, Javier ___ 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] Trimble Thunderbolt 1pps
On 27.01.2014 19:33, Robert Atkinson wrote: All the receiver chips I've looked at, ancient and modern, have only positive thresholds. Most have single supplies and clamp the input at 1 diode drop negative WRT common after an input current limiting resistor, see the MC1489 datasheet. Hello, Not exactly. If you check the MC1489 datasheet from On Semiconductor, the thresholds can be programmed with the response control resistor and can in fact be negative. (Figures 6 and 7 in the datasheet). The serial input resistor forms part of a resistive divider with the feedback resistor and the external resistor - not simply a current limiter to the diode. Regards, Javier ___ 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] Generate 1 PPS signal on serial port
Hello, On 06.08.2013 17:25, Chris Albertson wrote: The current Linux kernel has a PPS GENERATOR. See pps_gen_parport Put WHY would you need this? The documentation for pps_gen_parport suggests only using it for crude synchronization of sevel computers but NTP would in every case work better for that purpose. But for whatever reason Linux does PPS in both directions Be warned that any software PPS gignal will not be great, expect a few microseconds or error There are applications for that... I had to do that some time ago, since I was required to send a PPS signal aligned to UTC, and a time-stamp of this PPS signal using MIL-1553 (surely this is familiar to some people in the list). The time was the UTC time at the computer (well, in this case an embedded one, ntp sync'd through LAN). Since at that time (not that long ago) there was not a pps generator available in the linux kernel, I developed a small kernel module to drive an ouput pin. It worked nicely enough, with a few microseconds of error - completely tolerable in that application. Regards, Javier ___ 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] Industrial control systems and IEEE 1588v2 time sync
On Wed, Jul 31, 2013 at 6:19 AM, Bill Hawkins b...@iaxs.net wrote: Microsecond accuracy is impressive, but what does it cost? A colleague of mine had a non-exhaustive look at the market 1.5 years ago [1]. The cheapest PTP switch she could find was the Hirschmann MACH1000, selling for 5.7 kCHF with 16 ports. Cheers, Javier [1] http://www.ohwr.org/attachments/948/WRintro.pdf or animated PowerPoint at http://www.ohwr.org/attachments/949/WRintro.pptx ___ 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 subtraction with D-flip flops
On Tue, Jun 25, 2013 at 4:36 AM, ed breya e...@telight.com wrote: 4. It seems to me that whenever fd is much higher than fc (fdfc), that fd could be used instead to trigger the second DFF, which would reduce the metastability of the first DFF somewhat, and also synchronize the output signal closer to the edges of fd - but with some metastability from that too. Clocking the two FFs of a synchronizer with different clock signals will not work against metastability. When the edges of fd and fc are very close in time, there is a slight chance that the output of the first FF will be in a metastable state for some time. By clocking the second FF with fc you allow for a full (guaranteed) period of fc for that output to stabilize to a solid '0' or '1'. If you clock the two FFs with two different clock signals you don't have that guarantee. There should be a big gain to be had somewhere else to do something like that, but I can't see it. I must say all my experience is with fc very close to fd in frequency, so maybe I am missing something about the fdfc case. Cheers, Javier ___ 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] Have 10 MHz need 19.2 MHz
On 07.06.2013 19:23, Perry Sandeen wrote: List, Another hardware possibility. Double the 10 MHz to 20 MHz. With another circuit of 74HC390’s divide 10 MHz to 200 KHz. Then double it twice to 800 KHz with LM 1496 DBM’s. Apply the two frequencies to a LM 1496 DBM and use a LPF to get the 19.2 MHz. Hardware complicated? A bit. Only a bit? Only the filter to rejetct the products that you will have spreaded in all places, spaced 200kHz, and mainly to remove the 20.8 MHz spurious that you will have as a result of the last mixing, makes this approach difficult. I would favour a PLL, and since for the application, short-term stability seems unrelevant, even using a conventional VCO and not a crystal would be enough. A 74HC4046 can reach 19.2MHz, and you only need a couple of dividers to get a 200kHz reference to feed it. However one doesn’t have to search for a microprocessor that you program and may not be available in a couple of years. The IC’s are cheap and have been and will be around forever. The LM1496 was discontinued long ago it was a second source of the MC1496 (that is in production). But never think it will be around forever (yes, as a hobbyist, surely you can find a single piece forever, more if price does not matter too much). Also, I'm not a bit fan of PICs, quite the contrary, but for example the PIC16F84 has been available from more that 16yr and it is on production... so following your LM1496 criteria, will be available forever :) IMHO sometimes an older *brute force* circuit proves that more can be less in implementing what you desire to accomplish. Brute force is usually brute :) Regards, Javier Regards, Perrier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] have 10MHz need 19.5Mhz
On 02.06.2013 20:59, Chris Albertson wrote: I thought of using an AD9850 DDS chip. You can buy these on break out boards very cheap on eBay but they need a 125MHz clock.I could drive the 9850 with a 120MHz clock that is multiplied up from 10MHz.what is the simplest 12x multiplier. I assume getting to 125MHz from 10MHz is to hard. New-AD9850-module-modest-capacity-AD9851-DDS-Function-Generator-up-to-40MHZhttp://www.ebay.com/itm/New-AD9850-module-modest-capacity-AD9851-DDS-Function-Generator-up-to-40MHZ-/400422353936?pt=LH_DefaultDomain_0hash=item5d3b083c10 Is there a smarter and more direct way to get 19.5MHz for 10MHz? Or use the AD9851 that is more or less the same, but includes an internal x6 multiplier for the reference. You can find also some at the same place: http://www.ebay.com/itm/1pcs-DDS-Signal-Generator-Module-AD9851-0-70-MHz-2-Sine-Wave-and-2-Square-Wave-/400352450150?pt=LH_DefaultDomain_0hash=item5d36dd9666 Regards, Javier -- Javier Herrero Chief Technology Officer EMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] (Datum) FTS-4040A cesium, and STEL-1173 NCO chip
Hello, These people seems to have them availabe at single quantities for $65... perhaps not in the right packaging: http://www.questcomp.com/questdetails.aspx?pn=STEL-1173%2FCLpnid=372732stock=Yes (I've never purchased from them... si I cannot encourage or discourage :) ) Regards, Javier On 29.04.2013 07:51, Stewart Cobb wrote: Guys, I'm working on a sick FTS-4040A cesium frequency reference, which is basically a box and power supply wrapped around the FTS-5045 cesium beam module. (Datum bought FTS, then Symmetricom bought Datum, but this 1995 device is too old to appear on the Symmetricom website. This was one of the first digital cesiums. It uses a microcontroller to drive a frequency synthesizer to sample many different points in the cesium tube's frequency response. Part of the synthesizer is a 12.6+ MHz DDS, built from a Stanford Telecom STEL-1173 digital numerically controlled oscillator (NCO) chip and an Analog Devices fast D/A chip. In my unit, the STEL chip seems to be broken. All the inputs seem to be correct, but the output bits to the D/A are all continuously low, so there is no 12.6 MHz signal and thus no lock. The unit also throws a fault code 11, which translates as 12.6 MHz signal power low, confirming this diagnosis. Web searching gives the impression that these STEL-1173 chips are known to be fragile. There was a reference on time-nuts in 2006 to repairing a cesium by replacing the STEL chip, In 2009, a Steve Swift who read the 2006 thread offered to sell some STEL chips to the thread originator, but the deal (if there was one) was conducted off-list and I can't find valid contact information for Steve Swift. So it's time to consult the hive mind: 1) Are these STEL-1173 NCO chips known to fail early? Are there ways to baby them so they don't fail early? 2) Does anyone know a source for replacement STEL-1173 chips? 3) Is there any detailed documentation (schematics, procedures, test points, etc) available for the FTS-5045 cesium module? (I have the 4040A operators manual, but it doesn't show much detail. 4) Is there a way to tell whether the cesium beam tube itself is good, without the frequency synth working? All other telemetry points (ion pump, electron multiplier, etc) seem to settle to nominal values after warmup, so I have some hope that the tube is still good. 5) Any other suggestions or hints for repairing this unit? Cheers! --Stu ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Releasing sources (was Re: Brooks Shera)
On 31.03.2013 17:32, Lizeth Norman wrote: All u guys that post code to push up your little ego and then don't help when it sucks need to see a shrink. Don't want emails, don't post. Keep your bad code in the folder were it belongs. Are you suppossing that anybody that releases any code must provide support to you for free and for life? Don't you think that is enough that they have released the code for free? If you think it sucks for you, you are free not to use it. Probably other people finds it interesting and useful, and if they have any problem, they try to solve it by themselves before trying the author to get their problems solved for free. Rgds, Javier ___ 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] Releasing sources (was Re: Brooks Shera)
On Thu, Mar 28, 2013 at 9:24 PM, Lester Veenstra les...@veenstras.com wrote: Start a discussion group associated with the publishing, possibly without direct contact information on the author. There is something seriously wrong if you cannot publish and share ideas without being swamped with support requests, to the point of having to do it anonymously. If a project is very successful, and support requests become a serious issue to the original developer, chances are it can be commercialized. There are many examples of Open Source Hardware projects with commercial support [1]. A high-precision Open Source GPSDO would certainly qualify. Sharing and discussing is great while it stays at a level which allows you to have fun. It is becomes a serious amount of work, and if users see a value in the support, they should be willing to pay for it. I think paid labor makes Open Source Hardware more scalable and sustainable. Cheers, Javier [1] This is e.g. a board we designed at CERN, which is commercialized by three companies (that we know of): http://www.ohwr.org/projects/spec/wiki ___ 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] Metastability (was Brooks Shera)
On Mon, Mar 25, 2013 at 11:16 PM, Tom Van Baak t...@leapsecond.com wrote: Both edges of the 24MHz clock gating pulse are asynchronous with respect to the signal being gated. Metastability can result with clock pulse widths that lie within a critical range. Bruce I don't disagree with your statement above, but my question was -- does it matter in a GPSDO; does it matter in this GPSDO? Occasionally missing a 24 MHz tick is a not a worry (all gated frequency counters share this feature). A one-count ambiguity is normal and expected, even welcome. Note also that the PIC will see only 0 or 1; there is no metastability in software. So where exactly is the problem? Properly designed gated frequency counters get the input pulses into their system clock domain by using a synchronizer. Then they use this synchronized pulse to freeze the value of their internal counters. In the process of synchronizing the input you do introduce a 1 clock tick uncertainty, and this is unavoidable unless you go to more evolved designs based on interpolation. I don't think this is what we discuss about when we talk about metastability. If my understanding is correct, what we are discussing is what happens if you try to freeze the value of a counter with a signal which is asynchronous to the clock of that counter. Imagine that you have a 32-bit counter and your async pulse comes when the counter is transitioning from 0x to 0x. *All* bits are changing state. Even without metastability involved, i.e. assuming you don't hit the metastability window in any of the 32 FFs you use for freezing the counter value, you have a problem which is not a 1 tick problem. This is because the delays of each bit going from the counter FFs to the freezing register FFs are never exactly the same, so at the moment of freezing you might sample e.g. 0xABCDABCD, i.e. something completely unrelated to the value you would expect. Metastability would only make things worse by making some of those bits undefined for some length of time. So this is a well understood problem with a standard solution. Designs which don't use this solution can still function well if the occurrence I described is not very frequent. It was said in the other thread that Brooks Shera got rid of outliers (defined by him as more than 30 ticks offset) in software. That still leaves a 30 tick uncertainty for the time tag. So again, there is a proper way of dealing with metastability, but that does not automatically imply that designs not using it will malfunction. It depends on how often it happens and what the specifications are for the given design. Still, coping with metastability properly is so simple and cheap that there is really no reason not to do it. Cheers, Javier ___ 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] Brooks Shera
On Mon, Mar 25, 2013 at 2:56 PM, Tom Van Baak t...@leapsecond.com wrote: I realize there are many cases where clock domain considerations are important. But why does it matter in a device that is simply doing long-term 1PPS statistical sampling? Could one of you clock domain specialists actually spell out the GPSDO problem for the rest of us, nanosecond-by-nanosecond? It's hard to discuss this generally, so let's take an example design. I don't know Brooks Shera's design at all, so I don't know how applicable the following example is to it. In any case it is an illustration of the type of clock domain problems one can have while designing a GPSDO. Imagine you want to know how many ticks of a 10 MHz source (such as a VCXO) there are between two rising edges of an externally provided PPS. By externally provided I mean it is not derived from the 10 MHz VCXO. Most people today would do it with an FPGA. One way of doing it wrong is the following: - Have a free-running counter clocked off the VCXO, counting +1 at each tick. If this is a 32-bit counter it contains 32 flip-flops (FFs) that you take the output from. These outputs also go to a bunch of gates which feed the D inputs of those FFs. These gates implement the +1. The VCXO output is hooked to the clk inputs of all FFs, so at every rising edge of the VCXO signal, a new value appears at the Q outputs of the FFs. This value is the old value plus 1. Sorry if I am explaining this at a too-easy level. The signals out of the FFs take some time to go through the gates, but the FPGA PlaceRoute tool knows (because you tell it so) that if the worst case combinational delay between any Q output of an FF and any D input of any FF is well below 100 ns, all is fine. This is the beauty of synchronous design. You tell the PR tool what your clock period is and it makes sure all signals at D inputs are stable by the time the next rising edge of the clock comes. - Now you say OK, I am going to freeze the value of that counter at every rising edge of PPS and store it, so a simple subtraction afterwards will tell me the period I am measuring. What happens if you tap the Q outputs of those 32 FFs and send these signals to the 32 D inputs of another bunch of FFs which are clocked by the PPS? The PPS rising edge can come anywhere withing the 100 ns period of your clock. Because of the different latencies for each line inside the FPGA, there are chances that some bits in the 32 bit word (as seen by the D inputs of the PPS-clocked FFs at the time of a PPS rising edge) have changed after a VCXO rising edge, while others still haven't. This can give you completely bogus values at the Q outputs of these FFs. You might think that you can do a software sanity check and fix the bogus values, but this is impossible. You cannot know which bits are wrong just by looking at this time-stamp. In addition to this problem, there is also the issue of metastability in FFs. If the rising edge of PPS as seen by an FF in its clk input is very close in time to a transition (rising or falling) in the signal hooked to its D input, the Q output can stay in a metastable state (neither '0' nor '1') for a long time. This is more or less important depending on what you are doing with these outputs further down in your design. It's generally very bad. So how do you do it properly? You bring the PPS into the VCXO clock domain. You can do this by feeding the PPS signal to a chain of three FFs clocked by the VCXO: - FF1 has its D input hooked to the PPS signal. - FF2 has its D input hooked to the Q output of FF1. - FF3 has its D input hooked to the Q output of FF2. The output of FF1 can be metastable from time to time, with a small but not negligible probability. The output of FF2 is for all practical purposes safe. For it to be metastable, you would need a doubly-unlikely event: that FF1's output has gone metastable in the previous clk tick and that the D input of FF2 is seeing an unsafe (far from '0' or '1', near the transition region) voltage at the time of the current tick's rising edge. Now if you tap the outputs of FF2 and FF3 and hook them to gates which implement (Q(FF2) and not Q(FF3)), the output of this combinational block is a nice 1-tick-long pulse which is '1' after detecting a rising edge of PPS. This pulse is in the VCXO clock domain, so you can safely use it as an ENABLE of the bank of 32 FFs you use to get a time stamp. This bank now gets clocked by the VCXO signal, so all FFs in the design are clocked by the same clock, and the PR tool can do its job properly. I hope I understood your question well and this answers it. Cheers! Javier ___ 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] GPSDO with a RaspberryPi
On Fri, Mar 1, 2013 at 12:47 AM, Azelio Boriani azelio.bori...@screen.it wrote: Javier: the 24bit counter is clocked only by the 10MHz and is running continuously, the PPS is the most important signal. The LSClock is the clock for the latch: this latch has to be clocked to shift out its content serially and has to be loaded with the PPS from the GPS (PPSReference). I see no other way to deal with this other than selecting the two clock sources for this latch/shifter. You need two registers: - One that takes a snapshot of the counter value when the Clk10MHz-synchronized PPSReference arrives. - One that gets read out using SClockIn. Ideally you would sequence things so: - Once the snapshot is taken you drive a data valid strobe (Clk10MHz-clocked) which gets detected in the SClockIN domain. - Then the snapshot is transferred to the second register mentioned above, using SClockIn. - Only then it gets read out, using SClockIn. When the chip select (CSelect) line is high, the PPS is selected as a clock, when the CSelect is low (SPI trying to read) the SClockIN is selected as a clock. I know it is not a good practice to use gated clocks but at times it seems there is no way out and the CPLD is only 64 cells wide... I am sorry I did not have time to read the whole material. I just went quickly through the VHDL. Seen in isolation, there are things that can go wrong if you don't control when the read-out happens, e.g. if CSelect goes to '1' in the middle of the PPSReference pulse you will have a spurious rising edge and a bad time stamp. But if you control when CSelect goes high then this could be a non-issue. I also did not consider CPLD gates available. Anyway, the biggest problem I see with the code as it stands is the clocking of the 24-bit counter output with an asynchronous signal (PPSReference). I think that really needs to be fixed in any event. Cheers, Javier ___ 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] GPSDO with a RaspberryPi
On Fri, Mar 1, 2013 at 10:40 AM, Azelio Boriani azelio.bori...@screen.it wrote: The metastability from the PPS latching the counter is indeed a problem: rarely do I see out of range numbers and have to filter them out. You cannot filter them out. One time you will have bit 10 wrong and you will be able to detect that, but what if it's bit 3, or bit 2, or both? How can you know? What I proposed in a previous message solves your problem: get the PPSReference signal into the Clk10MHz domain before using it. This is the tried and proven way to deal with metastability. I can provide a code snippet later if needed. Cheers, Javier ___ 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] GPSDO with a RaspberryPi
On Thu, Feb 28, 2013 at 1:26 AM, Azelio Boriani azelio.bori...@screen.it wrote: First try at a simple GPSDO for the RaspberryPi. See here: http://www.c-c-i.com/exchange/for the file PiAutoTIC1.zip Nice project Azelio! Here are a few comments after a cursory look at the VHDL: - Gated clocks (i.e. LSClock) are in general not a good idea. You can split things in two: the serial link clocked by SClockIN and the getting hold of the value of the counter in a separate process clocked by PPSReference (or for a better option, see below). - In any case you will have to deal with metastability properly [1]. Now you're clocking the 24-bit output of the counter (which is in the Clk10MHz clock domain) with the PPSReference signal (after gates). It would be better to synchronize the PPSReference input to Clk10MHz with three FFs and a synchronous edge detector (i.e. PPSRising = PPSRefd2 and not PPSRefd3 inside a CLK10MHz clocked process). Then you can look at the value of the counter when that 1-tick-wide Clk10MHz-synchronous signal (PPSRising) goes to '1'. - The CMDReg process is another place where metastability can occur in the current design. - Once you have reduced the number of clocks in your design you will need to watch carefully every place where clock domains are crossed and put synchronizers [1] in there. Cheers, Javier [1] I uploaded some useful references to http://www.ohwr.org/documents/22 ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] How far can I push a crystal?
On 18.01.2013 22:41, shali...@gmail.com wrote: 10.059 used to be a standard frequency for some 8051 microcontrollers. Should not be too hard to find. No, it was 11.0592 Regards, Javier ___ 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] OT question about liquid cooling
Hello all, Please excuse me for the OT, but since this list is plenty of very knowledgeable colleagues, I'm tempted to ask... I need to cool several resistive loads, in the order of 5kW, and I plan to use a cold plate and a liquid-to-liquid heat exchanger like the Lytron LCS-20, but this unit is quite big, and an overkill (it has 20kW capability). If someone could suggest me a smaller liquid-to-liquid heat exchanger, and preferably a rack mount unit (and share any experience), it would be most welcome. Since this has not too much to do with time and frequency, please answer off list. Thank you very much! Best regards, Javier ___ 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] RFX GPSDO - Anybody played with one of these?
El 01/10/2012 11:22, Hal Murray escribió: t...@westwood-tech.com said: information appeared to be non-existent. IMHO for pretty much *everything* that is for sale, if you have to ask for the price it is a scam. Yes, when it says call for pricing, I usually drop interest. But I wouldn't say scam. How about not targeted at my corner of the market? I can think of several reasons for not publishing a price. 1) The product doesn't really exist yet. They have done the research but haven't finished up and handed off to manufacturing. They are looking for initial customers so they can tune things to fit what customers really need (and are willing to pay for). You want the tall skinny version? Fine, we'll make that first. How tall? 2) The product is tricky to use. They want to make sure it will work well in your application. 3) The product has lots of interacting options/parameters. They only stock a few combinations. If you want to buy more than a handful, you can get a better price by picking the right options. 4) The price varies a lot as a function of the quantity. They prefer to quote you as a function of the volume you request, and don't want you to be dissappointed it they publish a 1000+ price and you only want 10, or to make you think that it is too expensive if you want 1 but you think that the price, based on single quantites, is too expensive 5) International marketing policies. They want, for example, their US distributor to quote you, and will not provide you a direct factory pricing. In fact, I think that the usual thing is not to publish a price if they are not selling it directly to you. We don't publish prices of our products, and they are not a scam, not outrangeously expensive, they exists, they are not (very) tricky to use, and has not so many options... mainly the reasons are 4 and 5 :) Regards, Javier ___ 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] RFX GPSDO - Anybody played with one of these?
I asked for a quotation to one spanish distributor about a year ago. It was quoted at 977 EUR for a single unit, for the newer Thunderbolt E. $465 seems not bad for that unit. Regards, Javier El 01/10/2012 18:53, Chris Albertson escribió: On Mon, Oct 1, 2012 at 9:27 AM, Don Latham d...@montana.com wrote: A single unit would set you back $465.00 and delivery would be in the region of 6 weeks. I Wonder what price the T-Bolts sold for new in single quantities. Maybe more than $465? Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] messy workbenches
El 29/09/2012 19:11, Joe Leikhim escribió: I would have to agree that a lot of engineer and tech types fall into these categories. If not, we would probably not have and GPS satellites, cellphones and supersonic planes.(where is my hoverboard?) Not sure. Asperger is a type of autism, and although some geniouses along the history also seems to have suffered some degree of this syndrome, there are a lot of non-so-brilliant people that also suffers it (but since they are not geniouses, nobody has learn about them). In other hand, there have been also a lot of true geniouses that are a lot far from suffering nothing similar to that (for example, Richard Feynmann). Two nice examples of fictional people with that syndrome are Sheldon of Big Bang Theory (although they deny it) and the detective Monk. Best regards, Javier ___ 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] Multiple Time Interval Counters to measure Transients?
On Mon, Sep 10, 2012 at 9:08 PM, Florian Teply use...@teply.info wrote: Apart from that, I'll also check with ACAM in Germany as they have ready-made chips that would do that, and 65 to 120 ps RMS accuracy is okay for the CMOS stuff. Maybe they sell their chips for only a few hundred euros each... ;-) You might also want to have a look at this FMC with an ACAM chip on it: http://www.ohwr.org/projects/fmc-tdc/wiki It is made to work with this FMC carrier in PCIe format: http://www.ohwr.org/projects/spec/wiki The FMC carrier is a mature product. The TDC FMC is soon going to be commercialized. The design is open, so it could give you some ideas in any case. We have also played with a TDC core in the FPGA (http://www.ohwr.org/projects/tdc-core/wiki) using the same FMC carrier with a simple digital I/O mezzanine (http://www.ohwr.org/projects/fmc-dio-5chttla/wiki). This core is based on delay lines inside the FPGA, using logic elements. In your case it looks like a solution which would enable more channels in the FPGA at the cost of some accuracy would probably suit better. You can do this by e.g. sampling inputs with different phases of clocks in the 200 MHz realm, using the internal PLLs of FPGAs. Cheers, Javier ___ 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] Re; New Wrist watch
Hello! El 10/09/2012 19:33, Tom Van Baak escribió: Ah, done with it you say? No, that only begins a whole new set of problems. Setting to UTC begs the question: what time frame are you in and whose definition of a second is your watch counting. Some time ago we supplied a customer in Germany a quite complex equipment, including a workstation whose time was set at UTC. One day he commented us that he had at first not noted that, and used the workstation time to check the time while he was working with the system... and that he noted the difference to the local time when he missed the lunch a couple of times because the company canteen was already closed when he arrived. Traveling across timezones with a good clock brings you interesting problems, at the sub-microsecond level at least, due to earth rotation and latitude and due to relativistic effects of altitude and velocity. Well, but since the $150 wrist watch class usually does not provide a microsecond hand, I suspect that this would pass inadverted :) Regards, Javier -- Javier Herrero Chief Technology Officer EMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] oscillators
El 30/08/2012 20:53, saidj...@aol.com escribió: There are some drawbacks to this type of SC-cut MCXO I would think, and it could possibly be replaced by a much higher performance Symmetricom CSAC, probably at a lower cost and higher availability: * Q-tech MCXO is ITAR controlled, CSAC is not * MCXO has 20ppb over temp stability, CSAC has 1ppb spec, typical units can be much lower than that. Our GPSTCXO has 75ppb over temp, not much more than the MCXO, but probably at 1/10th the cost. * The G-sensitivity of CSAC is at least 50x better than the MCXO (its so low, its very hard to measure) * Aging of MCXO is much higher (order of magnitude) * Symmetricom is a big player, Q-tech is relatively small and unknown * I remember that there are patents on the MCXO held by FEI? * Power consumption is very similar, future CSAC units will have much lower power than the MCXO. The MCXO does have lower phase noise, it's an SC-cut cyrstal after all. But with CSAC's now becoming available from multiple sources, why use an MCXO? bye, Said As you say about G-sensitivity, let time pass until the CSAC is also ITAR controlled ;) It will no take too much. Regards, Javier ___ 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] So, how did you spend your leapsecond?
After watching Blade Runner (the director cut) reposition on a TV channel, that ended just one minute before 2am local time, I watched my nixie clock to, as I was expecting, held 02:00:00 (local time) by two seconds. Surely its GPS (an M12T) sent the right time to the uC, 23:59:60 UTC... but I'm guilty of not taking into account leap seconds when I implemented the UTC to local time conversion, including automatic daylight savings (that was about 9 years ago, I think... not a time nut then ;) ). Well, I note the bug for the day when the daylight saving change and then I should upgrade the firmware :) It has been the first opportunity to me to watch a leap second (or so...) since those ones at the end of year ever finds me quite far from home and from any timing piece other than the clock at the square where I've traveled to for the new years eve :) Regards, Javier El 01/07/2012 02:07, Mark Sims escribió: ? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Clockwise.
See below, after /tvb ;) El 26/06/2012 15:08, Azelio Boriani escribió: Yes, and the reference? On Tue, Jun 26, 2012 at 2:32 PM, Tom Van Baak (lab) t...@leapsecond.comwrote: With four points one can compute ADEV... /tvb (iPhone4) ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Clockwise.
It can be a reference. I was not meaning a good one :) And surely it is not that bad as a clock. El 26/06/2012 15:32, Azelio Boriani escribió: OK, in my opinion the iPhone is not a reference but, well, if you say it is then OK. On Tue, Jun 26, 2012 at 3:20 PM, Javier Herrero jherr...@hvsistemas.eswrote: See below, after /tvb ;) El 26/06/2012 15:08, Azelio Boriani escribió: Yes, and the reference? On Tue, Jun 26, 2012 at 2:32 PM, Tom Van Baak (lab) t...@leapsecond.com wrote: With four points one can compute ADEV... /tvb (iPhone4) __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/**mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Thunderbolt won't set a stored position?
El 12/06/2012 08:50, Chris Wilson escribió: It has also always shown a Leap Second Pending minor alarm, but I believe this is quite usual? Hello, it is usual now since there is a leap second scheduled for next 30-Jun. After that day, it will disaappear... until next one :) Regards, Javier ___ 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] Dimension 4 and GPS time disagree, why?
El 12/06/2012 13:09, David J Taylor escribió: I run Dimension 4 as a time standard on my POC's, mainly for using JT65 digital radio communications. It polls tick.usno.navy.mil for the time. I have noticed since getting my ThunderBolt set up that the GPS time is about 15 seconds in advance of my PC clock, despite a correction via Dimension 4 immediately before checking the difference. Why is that please? Thanks. Hello, Probably you have the Thunderbolt displaying GPS time, not UTC time. GPS time offset is now 15 seconds (16 secons from next 1-Jul) Regards, Javier ___ 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] Different or defective FE-5680A?
El 09/06/2012 09:35, Chris Albertson escribió: On Fri, Jun 8, 2012 at 11:22 PM, Ed Palmer ed_pal...@sasktel.net wrote: ... It is programmable over a wide frequency range (typically 100 Hz to 15-20 MHz), but you have to bring out the signal yourself,... Any idea WHY someone would design something like that? A programable frequency standard where the frequency does not come out of the box. Customized part with only 1pps output, design and manufacturing mostly reused from standard unit or another customized unit :) What next and audio amplifier that only drives an internal dummy load? Light bulb with a metal envelope? That would be a nice infrared source :) Regards, Javier ___ 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] Neutrino Velocity
On Fri, Jun 8, 2012 at 1:51 AM, Marvin Marshak mars...@umn.edu wrote: Good morning from Japan, The Neutrino 2012 Conference is being held in Kyoto, Japan, this week. This morning's session is scheduled for 3 talks on neutrino velocity--one from the OPERA Experiment that initially reported the anomalous effect, one discussing other experiments at the Italian Gran Sasso Lab and a third talk from the MINOS Experiment (Fermilab to Soudan MN). The session will begin at 0915 Japan time. Hi Marvin, Someone told me the LNGS experiments reported just preliminary results (some more fine-tuning of calibrations needed) with central values of Dt ranging from 2 to 6 ns with statistical errors around 1 ns and systematics ranging from 3 to 6 ns (positive Dt means nu slower than light). Apparently MINOS presented only a reanalysis of the data accumulated from 2005 with Dt around -11 ns and a systematic error of the order of 15 ns. The analysis of more recent data collected after installation of the new timing system will probably be available after the Summer. Is this correct? BTW, we installed White Rabbit links redundantly to the existing LNGS and CERN timing systems for the two weeks of special beam (100ns-spaced 2ns-wide bunches). It was quite a rush so it is not fully documented. All the data we gathered can be seen at https://project-lngstt.web.cern.ch/project-lngstt/ (although it is quite useless without explanations of what the data actually mean). The important bit is that WR agreed with the legacy systems at least at CERN, OPERA and Icarus. Borexino and LVD have not checked yet against WR, but should do so in the near future. So in terms of redundancy we have: - Four different experiments in LNGS basically agreeing on the value of the neutrino speed, compatible with c. - Two different timing technologies (for internal lab distribution) agreeing at CERN and two different timing technologies agreeing in LNGS. - Two different GPS time transfer systems using two different software analysis tools agreeing with each other. The only bit of redundancy I see missing is in certain parts of CERN, like the length of the cable from the Beam Current Transformer to the digitizer, which is common mode to everybody. The MINOS data, when it becomes available should provide more reassurance on those last bits. Cheers, Javier ___ 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] Thunderbolt GPS rollover
Hello, There was a competitor, long ago, AIR (Atmospheric Instrumentation Research Inc.) that produced something similar. As usual, Vaisala bought that company in order to make it dissapear, like a lot others, but this is another history. I never had the details of how it worked (it was kept quite as a secret then), but the radiosonde GPS section was very very simple, without any digital signal processing. I remember something like an LNA and one or two mixers. I think that real sonde position was never calculated, only speed (probably 2D, since the sonde also had a pressure sensor for providing the height), by comparison of satellite doppler as received by the sonde and as received on ground, but as I said, it was never disclosed to me then, but I've found that Dave B. Call (then owner of AIR) did patented it, US patent nr 5347285, so perhaps it worths to read it (I will do as soon as I get a time slot available for it :) ). Of course, operating principle for Vaisala sondes can be different. Perhaps I've somewhere one of those sondes... but most surely I've lost it quite long ago. Best regards, Javier El 07/06/2012 22:08, EB4APL escribió: Maybe you can avoid COCOM limits: Vaisala radiosondes (the most used type here in Europe, see www.vaisala.com) include half GPS receiver on it and the other half is in the ground tracking program. The balloons go up to about 30 Km and while the speed is very low this height is above the limit. Maybe you can get a recovered sonde and use it either directly or modulating its telemetry on your radio. The receiving program SondeMonitor is licensed to amateurs by a small fee and can be downloaded free for evaluation. Ignacio, EB4APL On 07/06/2012 5:35, Robert Watzlavick.com wrote: Onboard gps units tend to drop out at high altitude and/or high velocities due to COCOM limits. Some will re-acquire at apogee but it doesn't always work. I'm planning for onboard telemetry but a multilateration system is the backup. I correspond with others on aRocket and unrestricted gps units still aren't available to the average person without a lot of paperwork and $$$. -Bob On Jun 6, 2012, at 22:13, Chris Albertsonalbertson.ch...@gmail.com wrote: Why not fly a tiny GPS inside the rocket? Either modulated the beacon with the GPS serial data or record it to a micro SD card. On Wed, Jun 6, 2012 at 7:33 PM, Robert Watzlavickroc...@watzlavick.comwrote: Sorry to resurrect an old thread but I also have a question about using the Thunderbolt in the future. I'm considering using 4 of them in a multilateration setup to track an amateur rocket with an onboard beacon. Chris Albertson Redondo Beach, California ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Javier Herrero Chief Technology Officer EMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS and Rubidium frequency standards and noise question (new...
Hello, El 03/06/2012 10:46, saidj...@aol.com escribió: The FEI-5680A Rubidium that we discussed here some time ago has a much worse phase noise plot of course, because the 10MHz is generated digitally through a DDS, not a 10MHz crystal oscillator.. There is a version that generates 10MHz directly through DDS, but the particular version we recently discussed a lot about generates the 10MHz signal from a 60MHz oscillator, and the DDS is used for generating the ~5.3125MHz signal for mixing with the 114th harmonic of the 60MHz to obtain the Rb resonance frequency. I don't remember if someone did a comparison in PN performance between the two FE-5680A flavours. Regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPS and Rubidium frequency standards and noise question (new...
Hi, Said, I think that all of the last cheap ebay lot are of the second variety (60MHz osc + 5.3125MHz DDS, very narrow tuning range through serial port message). I remember your phase noise and adev plots on them. But I don't know if the first variety (the ones with a 55MHz or so crystal oscillator and 10MHz DDS-derived output, with wide range of frequency settability through the serial port) are better or worse in the phase noise, spurious and adev sections compared with the second one. Regards, Javier El 03/06/2012 21:35, Said Jackson escribió: Hello Javier, I have a couple from that last Ebay lot , and the phase noise/spurs are so bad on these that I figured the 10MHz must have been generated by a DDS. I posted the phase noise and ADEV plots of this unit to this list earlier this year. bye, Said Sent From iPhone On Jun 3, 2012, at 2:19, Javier Herrerojherr...@hvsistemas.es wrote: Hello, El 03/06/2012 10:46, saidj...@aol.com escribió: The FEI-5680A Rubidium that we discussed here some time ago has a much worse phase noise plot of course, because the 10MHz is generated digitally through a DDS, not a 10MHz crystal oscillator.. There is a version that generates 10MHz directly through DDS, but the particular version we recently discussed a lot about generates the 10MHz signal from a 60MHz oscillator, and the DDS is used for generating the ~5.3125MHz signal for mixing with the 114th harmonic of the 60MHz to obtain the Rb resonance frequency. I don't remember if someone did a comparison in PN performance between the two FE-5680A flavours. Regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Javier Herrero Chief Technology Officer EMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Oh dear
El 07/05/2012 11:20, Attila Kinali escribió: But to bring this back to time nutty topics, have a look at http://www.colorfly.eu/product.html It's an MP3 player with high precision timing. It does not only use two TCXOs with 5ps Jitter.. No! It also employes a technique known as Jitter Kill for the ultimate mobile sound experience! :-) Attila Kinali It plays MP3 or uncompressed audio? ;). And the sliding potentiotemer... prone to all kinds of noises and imbalance, and the nice wood enclosure, hand engraved, of course manufactured in a controlled temperature and humidity environment, that no doubt has a very positive effect on the sound, probably as good as the EMC shielding that provides. Also I love this paragraph On month day of year, the technique of circuit named Jitter Kill was registered as a patent for the other special technique of the Pocket HIFI player. When was/will be month day of year? excellent accuracy :) I imagine Steve Wan and his team laughing out loud everytime their get a purchase order. Regards, Javier ___ 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] parking lot location (was2 (Spoofing))
No, there are a lot more messages from him since at least 2008 and last one in the chinese scopes thread some days ago. The e-mail origin seems quite authentic from the headers, so I suspect he has sent it to the list in error :) Rgds, Javier El 21/04/2012 00:50, Bill Hawkins escribió: [Parking lot location details deleted] While clearly not spam, the only other time Mr. Darlington's name appears in this group in the 12,459 low noise messages since 12/31/2010 was the following: -Original Message- From: Robert Darlington Sent: Tuesday, October 04, 2011 4:07 PM To: j...@quikus.com; Discussion of precise time and frequency measurement Subject: Re: [time-nuts] 2 (Spoofing) So that no more goes out to the list. It does nothing to stop the problem. I'd have to look at the headers but based on what I'm hearing it sounds like his mail server is wide open, OR, somebody on the same network/isp is spamming. -Bob On Tue, Oct 4, 2011 at 2:54 PM, J. Forsterj...@quikus.com wrote: I agree with that picture. The sad thing is that the spammer can do it to Jeff essentially forever. There is little that can be done, other than change his email address, because the spammer has both his email address and a list of sites where that email address is trusted. As a Moderator (not of this group) I immediately moderate any such spamming email addresses, so at least no further spam goes out. Best, -John From the looks of it: 1. The bad guys imported/stole Jeff's address book (via social networking ABI hijack, or PC infection). 2. The bad guys then spammed (from 84.27.224.19 in the Netherlands) to the contacts they stole from Jeff's address book (and spoofing as Jeff). This is troubling because it could happen to any one of us (if we have an address book and it gets hijacked). Per John's previous message, I would be leery of social network ABI (Address Book Import) for one thing. -Greg - Original Message - From: Chuck Harriscfhar...@erols.com Sent: Tuesday, October 04, 2011 2:04 PM Subject: Re: [time-nuts] 2 (Spoofing) I'm not convinced. Notice that the to: line contains a list of addresses that look like they would belong in a time-nut's address book. That wouldn't be beneficial, or necessary if the spammer was spoofing his way into febo's servers. I think this came from a spambot running on jeff's machine, and it emailed the payload to as many places as it dared... one of them happened to be the time-nuts address used for posting messages. -Chuck Harris gbusg wrote: The spam message in question was apparently spoofed and did not originate from Jeff's PC. In the message header, note the Originating-IP was [84.27.224.19]. That IP address originates from a server at [Netherlands Groningen Ziggo B.v]. Jeff's actual IP address (which I won't repeat here) is significantly different and is located in the U.S.A. Chuck, I think somehow the spoofers have overcome the obstacle you mention, unfortunately. (Otherwise how did the user of the Netherlands server manage to get spam through to our group?) -Greg This is the message that started it all: -Original Message- From: jeffh...@comcast.net Sent: Tuesday, October 04, 2011 4:42 AM To: lrode...@yahoo.com; ronru...@mindspring.com; smbi...@verizon.net; stacie...@comcast.net; time-nuts@febo.com; tryto...@gmail.com; warrensjmail-...@yahoo.com Subject: [time-nuts] 2 Have ever been to the best on-line shop? This is it! [link to a French ceramic pottery shop deleted]. End of old messages happens here. OB timenuts: Time hung heavy on my hands. Bill Hawkins ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts 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] Holy cesium clock, Batman!
El 09/04/2012 16:59, Tom Knox escribió: I have heard the definition of a Time Lord is someone who has more then one clock and still knows what time it is. Thomas Knox No, no, is someone who know what time it is without needing a clock :) Regards, Javier ___ 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] Holy cesium clock, Batman!
El 08/04/2012 04:31, Magnus Danielson escribió: Oups, there is currently 7 caesium clocks in my lab (not all mine) and I'm not there to protect them all. Lost count of rubidium... Hum. 7 Cs clocks and lost count of Rb... and you're not there to protect them all... give me the address, I would take care. If you later not found them there, don't worry. They are all well cared of ;) Regards, Javier ___ 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] FPGA GPSDO (Was: Re: NTP jitter with Linux)
On Sat, Apr 7, 2012 at 1:47 PM, Javier Herrero jherr...@hvsistemas.es wrote: RTEMS also (see www.milkymist.org , an open source hardware and software project with an LM32 implementation on a Spartan 6 FPGA using RTEMS. We use the LM32 (http://www.ohwr.org/projects/lm32) in the White Rabbit and other projects. Here's a LibreOffice presentation on why it was chosen: http://www.ohwr.org/attachments/download/559 It's smaller than the LEON3 and more capable than the ZPU. We found it to be a good compromise. The guys in GSI (a German Physics lab) developed a good debugging tool for it (http://www.ohwr.org/projects/phase). Our PTP stack (http://www.ohwr.org/projects/ppsi/wiki) will soon run on it. Cheers, Javier ___ 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] FPGA GPSDO (Was: Re: NTP jitter with Linux)
El 07/04/2012 18:17, shali...@gmail.com escribió: When you install the Altera tools, it automatically installs NIOS and gcc. I assume there are no restrictions for private use, but you may have to send $ if you make a commercial product. That remains to be checked. With the Quartus Web, you can use any Nios but in time limited form (1 hour or so) or as long as the debug cable is tied to the PC. The only Nios free for use (commercial or private) is the Nios-II/e version. The only NIOS really useful, NIOS-II/f (with MMU, caches, and faster) is commercial, and the license pack inclding the triple speed ethernet core is $995. Also other IPs are commercial (like memory controllers, etc.) Regards, Javier ___ 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] FPGA GPSDO (Was: Re: NTP jitter with Linux)
El 07/04/2012 16:02, Jim Lux escribió: On 4/7/12 4:47 AM, Javier Herrero wrote: I'm very familiar with the LEON and RTEMS, having managed a software development project with it for the last 3 or 4 years at work. http://www.gaisler.com/ for LEON http://www.rtems.org/ for RTEMS I will have a look to RTEMS And yes, there is a port (maybe two) of Linux for the LEON as well (A few years ago, we loaded up the Snapgear port, but since we went RTEMS, I haven't fooled with it). You'd have to check the Gaisler.com website. I've done. The Snapgear port is quite old now, but the other port is actively maintained and updated with current kernel. You can drop a LEON core into a Virtex II in about a day, and judging from the traffic on the LEON yahoo list (where the Gaisler folks hang out), lots of people are doing things like multiple cores and things on all manner of Xilinx eval boards. And also for Altera (for example, the Terasic DE2-115 with a Cyclone IV) and others. I've seen you int that list :) An I've seen implementations for smaller FPGAs like the Spatarn 6LX25 RTEMS wise... It's pretty well supported by the community, it's open source, it does all the stuff you want a RTOS to do. it's NOT a multitasking, dynamic loading OS like Linux. That is it doesn't support an MMU and process space isolation (although that might be possible in newer versions.. there's a lot of configurability). It's basically a statically linked single task with threads. They've got RAM (and disk) file systems, IP stacks, a shell, YAFFS, etc. Like all open source, there's quite a lot of interesting stuff available (not from rtems.org, but others) that is 90% complete. Somebody at Google Summer of Code or for their Masters decides to implement something cool, and gets most of the way done, then wanders away (the summer ended, they got their degree, the usual story). But there's also a core of users who are serious and rigorous and contribute back, so the main stuff in the distribution from Joel Sherrill at OAR (who make RTEMS) is pretty rock solid. I will learn more about RTEMS. For the application I've (and this links directly to the message from Javier Serrano), the hardware platform is one of the CERN Open Hardware ones, the SPEC. For the purpose and interface needs, really an operating system is not required (no filesystem, no TCP/IP needed, no multitasking, no framebuffer...), and certainly a Linux would have a very large footprint without providing any real help. And about the processor selection, the trade-off that Javier exposes are the same I'm confronting. Both are open-sourced and well supported, and in one side the LM32 is smaller, in the other the LEON3 has more capabilities that can be implemented or not (like MMU or FPU, and better multi-core support, although not currently needed in my project). I probably will take the LEON3 road, but also because it is more popular in my current field, but for now I usually do not need the FT version since I'm more related with GSEs. ESA has several rigorously verified flight qualified versions of RTEMS (in Portugal and Austria, as I recall) Yes, this is one of the reasons to gain experience in that road :) I have some tendency to stay in Linux because I'm very familiarized with it in the non-MMU implementations (for Blackfin) and also with MMU - and I've found that for a small embedded system, to have the MMU is not so important, even sometimes it is a drawback. In any case we are running a bit OT (except considering that this general discussion has timing applications, of course ;) ). Also I'm happy to have found a time-nut colleage in other list, and probably I will ask you some things about off-list in order to not increase noise, if possible. Best regards, Javier ___ 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] FPGA GPSDO (Was: Re: NTP jitter with Linux)
El 08/04/2012 00:21, Jim Lux escribió: On 4/7/12 10:08 AM, Javier Herrero wrote: El 07/04/2012 16:02, Jim Lux escribió: RTEMS might be just what you need. Kernel, basic OS calls for scheduling, queues, etc. It's nice when you decide you want threading to not have to graft it into a big loop no-OS style program. You can use native calls or POSIX style (I like POSIX, because I can develop on Linux and just recompile for the RTEMS target). There's all the usual GDB support as well. Yes, it is starting to seem that would fit my needs for this project very nicely. Device drivers are easy to write for RTEMS, and it has VERY fast ISRs. That's probably one of the big advantages.. I would say that one of the most important for me. Sometimes I've dealed with Xenomai/Adeos and uClinux when Linux latencies and worse, latency uncertainities, but things then start to be a bit complicated... It's a small footprint, stripped down RTOS, but because you can work with POSIX API calls, you can do most of your development in Linux (particuarly things like calibration interfaces and computational stuff) and then it ports very easily when you move it to RTEMS on the target. Looks very good for several of my usual applications, where bare metal sometimes requires too much work, and Linux requires too much footprint :) Also, to support POSIX style is a great advantage. I've had a quick look around www.rtems.org, and I see that it is also ported to Blackfin, so it will also fit my usual ADSP-BF532 based platform. I hope that the learning curve will not be too steep :) Thanks for the info. Best regards, Javier ___ 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] FPGA GPSDO (Was: Re: NTP jitter with Linux)
Hi, Jim, I will ask off-list to reduce noise... :) El 08/04/2012 00:29, Jim Lux escribió: If you need a 64 bit timer core with a bunch of latches and a programmable pulse generator, let me know. We've got one at JPL we're happy to distribute (for free). I take good note. This is the kind of things that comes handy from time to time :) Goddard Space FLight Center has a variety of SpaceWire cores (in VHDL), and we've got a Verilog wrapper for it at JPL. GSF SpW cores are available for free? Or are even available for non-US? One of the things that I plan to do sometime is an SpW implementation, mainly for instrument EGSEs - probably will try in the near future if one of my customers wins a project and contracts us the EGSE. We are currently using SpW cards from Dynamic Engineering, but sincerely I'm not too happy with their support. For internal use, we have a Star Dundee SpW USB brick, but I find that SpW boards from Star Dundee are expensive and only with 3 ports - and we usually need 4 (you know, nominal and redundant I/Fs to both nominal and redundant instruments :) ). There are some free SpW ESA cores. The fun part is that they are free except for a 5000 EUR management fee... Best regards, Javier -- Javier Herrero Chief Technology Officer EMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] NTP jitter with Linux
El 05/04/2012 12:20, Azelio Boriani escribió: On a side note, speaking of deterministic systems, why has no one built a GPSDO with an FPGA yet? Or an NTP server? :) Oh, I've done that (an NTP server, not GPSO) in a Cyclone III FPGA. But well... it has a Nios-II CPU and runs Linux, so I suppose it does not count too much :). A pure FPGA (without CPU) NTP server would be very fun, but I suppose that the development effort required would not worth it, taking into account that implementing a true ntp in an embedded linux is quite easy. I have recently put into work an application that reads and writes UDP packets for a relatively high speed (280Mbps) ethernet to ECSS-E-ST-50-01C TM transfer frames gateway. The Ethernet part was quite easy to implement (the RAM-based FIFOs and flow and error control were a bit more difficult, since you must have a continous uninterrupted 280Mbps output, and the input is Ethernet - with extremely variable latencies). Regards, Javier ___ 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 jitter with Linux
El 05/04/2012 00:58, gary escribió: That is the AMD speed step, but doesn't intel do the same thing? I suppose so. In any case, under Linux you can force off the speed step (i.e. force the CPU to a fixed clock). I did that some time ago in a Dell server with a dual quad-core Opteron with Fedora Core 10... but don't remember the procedure Regards, Javier ___ 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] Coax Connectors (was Re: Opera coordinator has resigned)
On Sat, Mar 31, 2012 at 9:24 PM, Achim Vollhardt avoll...@physik.uzh.ch wrote: I do work in high energy physics and we use LEMO and other standards. For some years now, I have started to advertise against LEMO (in particular the LEMO 00 size), as it is VERY sensitive to mechanical defects and partial connection (yes, you can ..). We have found very often defective LEMO connections, which could only be detected via time domain reflectometry. Or LEMO interfaces, which changed impedance significantly when rotating them in the fully mated position.. this list could be extended a lot more. And this famous click when mating is inaudible in typical high energy physics electronics barracks.. too much fan noise. In addition, for the very fast signals of modern DAQ systems, LEMO 00 is just not up to speed (literally) anymore. If size is not of ultimate importance, we switched to SMA, or SMC if size matters. I am very interested in this, since we just decided to use LEMO 00 over SMC in some of our designs: http://www.ohwr.org/projects/fmc-projects/wiki/SMC_vs_LEMO This is for ~100MHz work, so bandwidth was not an issue. Compatibility with legacy was the major criterion in our case. I would be interested in reading what people are using as coax connectors in space-constrained environments like FMC, and why. Cheers, Javier ___ 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] Pulsar Source?
El 30/03/2012 05:02, Jim Lux escribió: and orientation. Sort of like a super star tracker all in one! (You can see why NASA is interested..) And ESA. Last year they published an invitation to tender called Deep Space Navigation with Pulsars, with the following description excerpt: The activity will focus on the study of the use of Pulsars for Deep Space Navigation. Localization of spacecrafts in deep space is today very challenging and, in same cases, not enough precise and/nor reliable. Highly rotating neutron starts (also called Pulsars)generate pulses with high stable periodicity that can be used to locate an object in space. It had quite a low budget assigned... but seems that it had some interest. I think I can get the statement of work if somebody is interested. Best regards, Javier ___ 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] Opera coordinator has resigned
On Fri, Mar 30, 2012 at 3:07 PM, iov...@inwind.it iov...@inwind.it wrote: http://inagist.com/all/185697069783195648/ Personally I'm sorry about such an end of the story. There was a meeting in Gran Sasso on Wednesday. You can see some of the slides at http://agenda.infn.it/materialDisplay.py?materialId=slidesconfId=4896 I found particularly interesting the ones by Maximiliano Sioli, where he explained the two mistakes found in the OPERA data acquisition chain and how, after correcting for their best estimate of their effects, the time of flight is compatible with a speed of c. I saw the webcast of the event. Some people did give the OPERA spokesman a hard time, and he admitted to not having fully checked everything they could have. Ah well, everyone makes mistakes. There will be another run with neutrinos spaced by 100 ns in May. If all four experiments in LNGS give the same result this time, I suppose the case will be closed. It will also be very interesting to see the MINOS results. In any event, from a time-nut point of view this is quite exciting. It is the first time neutrino speed is measured with this precision. I think this will pave the way for future experiments using precision geodesy and time transfer. Cheers, Javier ___ 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] Opera coordinator has resigned
El 30/03/2012 16:55, Javier Serrano escribió: On Fri, Mar 30, 2012 at 3:07 PM, iov...@inwind.itiov...@inwind.it wrote: http://inagist.com/all/185697069783195648/ Personally I'm sorry about such an end of the story. There was a meeting in Gran Sasso on Wednesday. You can see some of the slides at http://agenda.infn.it/materialDisplay.py?materialId=slidesconfId=4896 Thanks for sharing them I found particularly interesting the ones by Maximiliano Sioli, where he explained the two mistakes found in the OPERA data acquisition chain and how, after correcting for their best estimate of their effects, the time of flight is compatible with a speed of c. The devil is ever in the small things :) It is truly very interesting I saw the webcast of the event. Some people did give the OPERA spokesman a hard time, and he admitted to not having fully checked everything they could have. Ah well, everyone makes mistakes. There will be another run with neutrinos spaced by 100 ns in May. If all four experiments in LNGS give the same result this time, I suppose the case will be closed. It will also be very interesting to see the MINOS results. In any event, from a time-nut point of view this is quite exciting. It is the first time neutrino speed is measured with this precision. I think this will pave the way for future experiments using precision geodesy and time transfer. This is true. And also perhaps the use of neutrinos for time transfer purposes :) Nowadays nort their generation in a controlled way either the detection is easy, but who knows in the future... Regards, Javier ___ 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] Opera coordinator has resigned
On Fri, Mar 30, 2012 at 7:42 PM, J. Forster j...@quikus.com wrote: There are failures and there are failures. A negative result is a failure that is worth reporting. A failure due to an improperly mated connector... not so much. That is saying to anyone who wants to do a similar experiment in the future that they need at least two redundant systems. I believe that is quite a valuable lesson. Concerning the OCXO, one has to bear in mind that this experiment was not meant to measure time of flight, but rather neutrino oscillations. The message for me here is that it's good to publish all your designs, including gateware sources, as soon as possible, but I don't know how compatible that is with today's highly competitive scientific world. So I think there is an important lesson behind each one of the two issues. Of course this is easy to see from outside and after the fact. Cheers, Javier ___ 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] Opera coordinator has resigned
I suppose that when it was photographed, nobody noticed it. After noticed that it was no correctly plugged-in, the past pictures were reviewed and found that in fact it was not fully plugged in :) El 31/03/2012 01:04, iov...@inwind.it escribió: May anybody out there explain why the connector was simply photographed, and not put in place, on October 13, that is one month before the updated version (Nov 17) of the Opera paper? Antonio I8IOV ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Distribution amp - Use a video amp unit ?
I was only kidding a bit, since for a lot of the most common JEDEC and also non-JEDEC conventional (as opposed to SMD) discrete components they are similar parts with a similar numbering in SMD, and the 1N914 is one of them - so I found it not the best example :) . However, the same argument could be applied to the MMBT3904... in the same sense, != 2N3904 since in the strict sense it is not TO-92. Anyway I was not intending to generate any deep discussion about this matter :) Regards, Javier El 26/03/2012 03:54, gary escribió: MMBD914 !=1n914. 1n914BWTm i.e. using a suffix, is something I haven't seen before, but technically 1N914BWT != 1n914. That is, in the strict sense, the 1n914 has to be a diode in that glass package. On 3/25/2012 5:48 PM, Javier Herrero wrote: El 26/03/2012 02:35, gary escribió: I forgot to mention that those old jedec part numbers specify a package and electrical limit under one part number. That is, you can't find say a 1n914 in SMD, but you can find direct equivalents with other numbers. You will find supply houses listing SMD versions of jedec parts, but technically that is not correct. Oh, you can :) MMBD914 (SOT-23), 1N914BWT /SOD-523F) and some more. Regards, Javier ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] LEA-6T Group buy
El 26/03/2012 22:30, Azelio Boriani escribió: 120CHF + the custom duties. Even if in the EU. Switzerland is not part of EU :) Although it is part of Schengen Area. Regards, Javier ___ 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] Distribution amp - Use a video amp unit ?
El 26/03/2012 02:35, gary escribió: I forgot to mention that those old jedec part numbers specify a package and electrical limit under one part number. That is, you can't find say a 1n914 in SMD, but you can find direct equivalents with other numbers. You will find supply houses listing SMD versions of jedec parts, but technically that is not correct. Oh, you can :) MMBD914 (SOT-23), 1N914BWT /SOD-523F) and some more. Regards, Javier ___ 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] Experience with THS788 from TI?
13ps resolution at 200Msps sampling rate and real 15.8Msps output data throughput? not too many around :) Regards, Javier El 21/03/2012 15:44, David escribió: I am surprised it is not more accurate and precise. Even old discrete designs can get down to 10ps or better. I wonder what market it is for where space is at that much of a premium. On Wed, 21 Mar 2012 14:47:28 +0100, Heinzmann, Stefan (ALC NetworX GmbH)stefan.heinzm...@alcnetworx.de wrote: I just discovered that TI makes a TDC chip called THS788, see http://www.ti.com/product/ths788 for more info. Interesting specs, but rather expensive. Has anyone from the list had a chance to experiment with this device? ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Neutrinos not faster than light
On Fri, Mar 16, 2012 at 11:44 PM, Javier Herrero jherr...@hvsistemas.es wrote: Hello, Javier Serrano can confirm it for sure, but I think that the article with the OPERA results is based on data from 2009 to 2011, not from data taken the previous day :) Exactly. OPERA first published a result based on several years of data taking prior to the summer 2011. These results were criticized on several fronts, most of which had to do with the 10us-wide proton distribution at the exit of CERN's Super Proton Synchrotron (SPS). Then it was decided to have a short run in December 2011 with 524ns-spaced proton bunches, so that neutrinos detected in Laboratori Nazionali del Gran Sasso (LNGS) could be unequivocally assigned to a single bunch. These bunches are around 1ns-wide. I think the four experiments in LNGS (OPERA, Icarus, Borexino and LVD) saw neutrino events during that run. For OPERA, these events confirmed their previous result, and they extended their original paper accordingly. This now is the publication of the Icarus results, based on 7 neutrino events. The time link between CERN's SPS and Icarus is different from the CERN-OPERA link only in the last stretch, where the dedicated OPERA and Icarus data-taking electronics reside. It's soon to conclude where the difference in results could come from. I personally don't know that last stretch well enough to comment. In any case, we will have another dedicated run with spaced bunches later in the Spring, and then all four experiments will be ready to publish a result quite quickly. In addition, our American friends in Fermilab and MINOS should be able to get a result as well some time in 2012. So we're entering now some very interesting months! Cheers, Javier ___ 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] Neutrinos not faster than light
I think that this is the article: http://arxiv.org/pdf/1110.3763.pdf It is not strange that the results are available now. These experiments are run during months, and generates a large quantity of data. Best regards, Javier El 16/03/2012 21:19, Azelio Boriani escribió: OK, that is, are they telling us that for an experiment concluded in 9/2011 the results are available today? On Fri, Mar 16, 2012 at 8:30 PM, Hal Murrayhmur...@megapathdsl.net wrote: Announcement from CERN: ICARUS experiment at Gran Sasso laboratory reports new measurement of neutrino time of flight consistent with the speed of light http://press.web.cern.ch/press/PressReleases/Releases2011/PR19.11E.html -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Neutrinos not faster than light
The paper is this one, dated yesterday: http://arxiv.org/ftp/arxiv/papers/1203/1203.3433.pdf Regards, Javier El 16/03/2012 21:50, Javier Herrero escribió: I think that this is the article: http://arxiv.org/pdf/1110.3763.pdf It is not strange that the results are available now. These experiments are run during months, and generates a large quantity of data. Best regards, Javier El 16/03/2012 21:19, Azelio Boriani escribió: OK, that is, are they telling us that for an experiment concluded in 9/2011 the results are available today? On Fri, Mar 16, 2012 at 8:30 PM, Hal Murrayhmur...@megapathdsl.net wrote: Announcement from CERN: ICARUS experiment at Gran Sasso laboratory reports new measurement of neutrino time of flight consistent with the speed of light http://press.web.cern.ch/press/PressReleases/Releases2011/PR19.11E.html -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] Neutrinos not faster than light
Hello, Javier Serrano can confirm it for sure, but I think that the article with the OPERA results is based on data from 2009 to 2011, not from data taken the previous day :) Regards, Javier El 16/03/2012 23:29, Azelio Boriani escribió: Well, I agree. Then Why the OPERA results were available at once? Why nobody had pointed out that there was the ICARUS data processing in progress? On Fri, Mar 16, 2012 at 10:03 PM, Javier Herrerojherr...@hvsistemas.eswrote: The paper is this one, dated yesterday: http://arxiv.org/ftp/arxiv/papers/1203/1203.3433.pdf Regards, Javier El 16/03/2012 21:50, Javier Herrero escribió: I think that this is the article: http://arxiv.org/pdf/1110.3763.pdf It is not strange that the results are available now. These experiments are run during months, and generates a large quantity of data. Best regards, Javier El 16/03/2012 21:19, Azelio Boriani escribió: OK, that is, are they telling us that for an experiment concluded in 9/2011 the results are available today? On Fri, Mar 16, 2012 at 8:30 PM, Hal Murrayhmur...@megapathdsl.net wrote: Announcement from CERN: ICARUS experiment at Gran Sasso laboratory reports new measurement of neutrino time of flight consistent with the speed of light http://press.web.cern.ch/press/PressReleases/Releases2011/PR19.11E.html -- These are my opinions, not necessarily my employer's. I hate spam. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] quartz crystal configuration in small cases
Hello, AT cut crystals can be manufactured both as a round disk or as a strip resonator, so probably they are AT. For example, these are: http://cfm.citizen.co.jp/english/product/pdf/HC-49_U-S.pdf and http://cfm.citizen.co.jp/english/product/pdf/CSA-310_309.pdf Regards, Javier El 13/03/2012 21:46, ALAN MELIA escribió: hi Magnus the only bar resonators I have actually seen were NT flexural bar. Modern cuts probably include all sorts of resonator modesbut are these AT cuts? Alan --- On Tue, 13/3/12, Magnus Danielsonmag...@rubidium.dyndns.org wrote: From: Magnus Danielsonmag...@rubidium.dyndns.org Subject: Re: [time-nuts] quartz crystal configuration in small cases To: time-nuts@febo.com Date: Tuesday, 13 March, 2012, 17:59 On 03/13/2012 06:35 PM, ALAN MELIA wrote: Hi Atilla, I dont have book availabe but AT cut is a thickness-shear vibration mode so plate area may not be an issue ?? Just harder to make :-)) One of the AT cut oscillators I use has a crystal bar rather than a circular plate. Being mass-produced in bulk, etched etc. It is just a different process. I'm sure the crystal oscillator folks here could point to some good sources on that. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ 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] Neutrinos not so fast? (defective connector)
On Fri, Feb 24, 2012 at 3:41 PM, iov...@inwind.it iov...@inwind.it wrote: Da: b...@lysator.liu.se Data: 24/02/2012 14.42 A: Discussion of precise time and frequency measurementtime-nuts@febo.com Is it known which GPS receiver type was used in the Neutrino experiment? It was a Septentrio PolaRx2e. See the paper on setup and procedures: http://dl.dropbox.com/u/13409775/cern-cal.pdf Here's a more official location with more information: http://www.ohwr.org/projects/cngs-time-transfer/wiki Cheers, Javier ___ 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] Neutrinos not so fast? (defectove connector)
On Wed, Feb 22, 2012 at 11:26 PM, Poul-Henning Kamp p...@phk.freebsd.dk wrote: 20m of extra fiber sounds *much* more plausible. Inventing an excuse about a loose connector to cover up the mistake sounds even more plausible. You really don't want to defend your phd dissertation, being known as the idiot who made a fool of both CERN and SanGrasso in one go. PHK come on, you can do much better than this :) I am sorry guys. I really owe this list a lot of knowledge and I try to give back every time I have an opportunity, but I will not be able to react to all suppositions in real-time. Also I am not even a completely reliable source of information myself because these things have been found in OPERA, and I only know of them indirectly. I only have two points: - Delays in fiber connections can be modified because of changes in input power (due to improper screwing), which turn into delay changes via the input capacitance of the photo-diode. This only has an effect on the final result if the calibration was conducted with the proper screwing (sure) and the experiment with improper screwing (not sure). - OPERA and CERN have followed the scientific method in an exemplary way all throughout the process. The published information is the result of a leak and has two problems: a) it's incomplete and b) it's too soon to publish anything meaningful, it would have been much better to study the effects of the two issues found, quantify them and then go public. Maybe there is virtually no effect on the final result, who knows. So please stay tuned for proper information. That's all I can say for now. Cheers, Javier ___ 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] FE-5680A firmware dump
Don forget the PSD813 :) It provides 128KB Flash and 8KB RAM... so it can be a bit more complicated Regards, Javier El 17/02/2012 11:09, Azelio Boriani escribió: In my opinion you don't need the power of an IDA-class disassembler to process an 8051-like code. The MCS51 family processors have only 128 or 256 bytes of RAM (and at most 64K ROM) and cannot host complex code. On Fri, Feb 17, 2012 at 10:27 AM, Elio Corbolanteelio...@gmail.com wrote: From: Mike McCauley I've been considering ripping the firmware from the mcu as well. I've not got beyond the consideration stages, but i have all the equipment here at work. When you say that the read option is not available. is this because the chip has protection fuses enabled? Id like to help with the disassembly if you can get the binary dump. Don't worry: when I will be able to dump the firmware I will let it on the public domain. BTW, I have the opportunity to use the IDA disassembler (a friend of mine is a licensed user) so I think the disassembly of the code will be rather good. Any knowledge of a public domain 8051 disassembler which can rival IDA in performance/code analysis? _ Elio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OCXO phase noise
Hi, Magnus, El 13/02/2012 09:06, Magnus Danielson escribió: On 02/13/2012 08:28 AM, Javier Herrero wrote: Hello all, I'm planning to use in an application this oscillator http://www.abracon.com/Precisiontiming/AOCJY.pdf in the 40MHz version. The phase noise data in the data sheet is for the 10MHz version. Is it possible to extrapolate these numbers to what I could expect in the 40MHz version? Any guideline? A quick and dirty analysis comes from assuming the same noise but chopped up differently by the frequency, then for original frequency f1 and target frequency f2 you get the scale-factor f2/f1. Similarly, the dB variant becomes 20*log(f2/f1) so for f1=10 MHz and f2=40 MHz you get the scale factor 4 which turns out about 12 dB higher. It's not perfect, but gives you a hint of what to expect. That is exactly my thinking, but I was looking for a second opinion :) We have anyway asked Abracon for pn data on the 40MHz version to be sure. Thanks! Best regards, Javier ___ 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] OCXO phase noise
Thanks for your answers, Magnus and John. For now, I will take the 12dB value as a starting point until further confirmation. Regards, Javier El 13/02/2012 10:32, Magnus Danielson escribió: On 02/13/2012 10:16 AM, John Miles wrote: That is exactly my thinking, but I was looking for a second opinion :) We have anyway asked Abracon for pn data on the 40MHz version to be sure. Most likely, the PN improvement will be somewhat better than the expected 12 dB close to the carrier, and somewhat worse than expected (if you see any improvement at all) farther out. The corner frequency that separates close in and farther out will be device-specific, but it'll probably happen between 100 Hz and 2 kHz. A more proper analysis would separate the effects of oscillator Q, resonator loop noise and the buffer noise and then scale them accordingly. Assuming the same Q (which isn't correct) the oscillator core 1/f^2 or 1/f^3 flips up on. The buffer noise then masks on top of that. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OCXO phase noise
I've an answer from Abracon. I had overlooked these plots: http://www.abracon.com/Precisiontiming/AOCJY%20Typ%20Phase%20Noise%20Plots.pdf The answer is that we can expect for the 40MHz unit a phase noise performance half way between the 10MHz and 100MHz units performance. That is, compared with the 10MHz unit, roughly a 20dB increase at 10Hz, a more or less 12dB increase at 100Hz, 6dB at 1000Hz, and around 3dB from that point. Regards, Javier El 13/02/2012 16:45, Javier Herrero escribió: Thanks for your answers, Magnus and John. For now, I will take the 12dB value as a starting point until further confirmation. Regards, Javier El 13/02/2012 10:32, Magnus Danielson escribió: On 02/13/2012 10:16 AM, John Miles wrote: That is exactly my thinking, but I was looking for a second opinion :) We have anyway asked Abracon for pn data on the 40MHz version to be sure. Most likely, the PN improvement will be somewhat better than the expected 12 dB close to the carrier, and somewhat worse than expected (if you see any improvement at all) farther out. The corner frequency that separates close in and farther out will be device-specific, but it'll probably happen between 100 Hz and 2 kHz. A more proper analysis would separate the effects of oscillator Q, resonator loop noise and the buffer noise and then scale them accordingly. Assuming the same Q (which isn't correct) the oscillator core 1/f^2 or 1/f^3 flips up on. The buffer noise then masks on top of that. Cheers, Magnus ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- Javier Herrero Chief Technology Officer EMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Los Charcones, 17 FAX: +34 949 336 792 19170 El Casar - Guadalajara - Spain WEB: http://www.hvsistemas.com ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] OCXO phase noise
Hello all, I'm planning to use in an application this oscillator http://www.abracon.com/Precisiontiming/AOCJY.pdf in the 40MHz version. The phase noise data in the data sheet is for the 10MHz version. Is it possible to extrapolate these numbers to what I could expect in the 40MHz version? Any guideline? Thanks! Best regards, Javier ___ 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.
