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" Date: 2017/1/17 21:20:23 To: "Discussion of precise time and frequency measurement";"Perry Sandeen"; 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 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
me-nuts and follow the instructions there. -- --------- Javier Herrero Chief Technology Officer EMAIL: jherr...@hvsistemas.com HV Sistemas S.L. PHONE: +34 949 336 806 Teide 4, Núcleo 1 Of. 0.1 FAX: +34 949 336 792 28703 San Sebastián de los Reyes - Madrid - 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] 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 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 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] 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] 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 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] 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.
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] 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 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.
[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] 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] 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] 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] 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-40MHZ<http://www.ebay.com/itm/New-AD9850-module-modest-capacity-AD9851-DDS-Function-Generator-up-to-40MHZ-/400422353936?pt=LH_DefaultDomain_0&hash=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_0&hash=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%2FCL&pnid=372732&stock=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] 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?
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 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] 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] 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] 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.
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 wrote: 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) 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-nuts<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<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<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.
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) 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-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] 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] 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] 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 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] 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 Albertson 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 Watzlavickwrote: 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...
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 Herrero 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] 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] 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. Forster 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 Harris" 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)
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] 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)
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 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 13:19, Azelio Boriani escribió: The Xilinx and Altera have their embedded CPUs (Microblaze and Nios) IP. I'm not familiar with them and don't know how much they cost. Until now I have developed on Xilinx 50Kgates FPGA and 128 cells CPLD with the Xilinx's free tools. Mostly expensive for amateur use, although reduced free versions exists (for Nios-II it is Nios-II/e without MMU and no cache, I suppose that something similar for Microblaze). But both are closed-source. There are open-source soft processors like LatticeMico32 and LEON3. I'm moving to one of these for a next project (not yet decided which one, since in this case it will be a bare-metal application, with no operating system, but I would like to use a processor that is supported by Linux distribution for the future). Linux is ported to both, and for LM32 (not sure if for LEON3), RTEMS also (see www.milkymist.org , an open source hardware and software project with an LM32 implementation on a Spartan 6 FPGA using RTEMS. Also there is a plethora of soft implementation of several processors in OpenCores (ranging from 6502 to OpenRISC) and also somewhere I read about an implementation of a Cray-1 in a Spartan-3 :) 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 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.
Re: [time-nuts] Opera coordinator has resigned
El 02/04/2012 16:14, J. Forster escribió: If the FTL neutrino "discovery" had been kept quiet until fully vetted, he probably would not have had to resign. I suppose so... Also, things would have been completely different if the 60ns error would be of the opposite sign, that would lead to the believing that neutrinos are a bit slower than light and not a bit faster. This of course would also have been of big impact in the physics community, but not so big :) and also would not have take even a single line in the newspapers and other media, except on the specialized ones. Anyway, I think that it was keep quiet during some time and only made public when though that it was fully vetted... but as we have seen a couple of details were overlooked. In the positive side, as Javier Serrano said, it has been the first time that neutrino speed has been measured with this precision. 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
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] Opera coordinator has resigned
El 30/03/2012 16:55, Javier Serrano escribió: On Fri, Mar 30, 2012 at 3:07 PM, 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=slides&confId=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] 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] 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 ?
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] 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)" 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
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 Herrerowrote: 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 Murray 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] 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 Murray 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
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 Murray 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] 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 Danielson wrote: From: Magnus Danielson 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] 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 Corbolante 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
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.
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
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.
[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.
Re: [time-nuts] Low-Cost Rubidium Performance
El 10/02/2012 00:13, Javier Herrero escribió: El 09/02/2012 22:28, Magnus Danielson escribió: Consider that it is de-modulated and then low-pass filtered. Also, it is the alternating rate and not 1400 Hz difference in DDS setting which is the key parameter here. The 1400 Hz gives a hint of the Q-value however, which seems to be lower on these than on any of my larger rubidiums, but it is maybe to be expected. Yes, you're right... I was thinking on the alternating rate (that in fact I measured, at 416...Hz, but the other number came first ;) ), and in the fact that the FRS, that uses 127Hz as alternating rate, has notorious spurs at 127 and 254Hz (al at a lot of their harmonics), so I was expecting someting similar for the FE5680A at 416.Hz and harmonics, but seems not to be there (or the spur forest makes not easy to see these trees :) ) I answer myself. Perhaps they are there quite notoriously, since in the spectra plots that I took when I got mine, now it is clear why there are two peaks at around -70/-75dBc at somewher that seems very near +/-416.7Hz: http://www.nebulosa.org/images/FE5680A/FE5680A4.jpg Probably in the phase noise plot they are masked by all the phase noise floor and other spurii that are not so apparent in a quick measurement with the spectrum analyzer 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] Low-Cost Rubidium Performance
El 09/02/2012 22:28, Magnus Danielson escribió: Consider that it is de-modulated and then low-pass filtered. Also, it is the alternating rate and not 1400 Hz difference in DDS setting which is the key parameter here. The 1400 Hz gives a hint of the Q-value however, which seems to be lower on these than on any of my larger rubidiums, but it is maybe to be expected. Yes, you're right... I was thinking on the alternating rate (that in fact I measured, at 416...Hz, but the other number came first ;) ), and in the fact that the FRS, that uses 127Hz as alternating rate, has notorious spurs at 127 and 254Hz (al at a lot of their harmonics), so I was expecting someting similar for the FE5680A at 416.Hz and harmonics, but seems not to be there (or the spur forest makes not easy to see these trees :) ) 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] Low-Cost Rubidium Performance
Hello, El 09/02/2012 21:06, Magnus Danielson escribió: I was just thinking about that. For these more modern 5680A, just the Q of the resonance and the loop filter / loop bandwidth would not allow for so much high frequency side-bands of the DDS to pass through. The loop filter at least should have good rejection to the 1400Hz frequency presumed to be used for the detection... although in the phase noise plots I've not seen a very significant spur at that frequency. The low frequency DDS variations will go through however. Yes :) I'd expect that the DDS noise creeps onto the 10 MHz signal one way or another, such as the CPLD or other location where separation is poor. It would be a bit fun to hunt around and see where the noise creeps in. Quite a bit. Would be helpful to see how bad is the 60MHz signal available inside :) All those 1Hz spaced spurs (and multiples...) could be originated by the CPLD. It would also be fun to see what a mixer based PI-loop OCXO cleanup (using say a spare 10811) would do. Using a pre-filter and mixer (to avoid severe intermodulations) while still getting a decenting filtering effect. Also... perhaps using the 60MHz instead if it is cleaner... I've a spare 10544 and a 10811 that would love to use for cleaning up the output (but lack of time for now to play around as much as I would like :) ) 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] FE-5680A's suitability for use as a 10 MHz reference for microwave transverters
El 09/02/2012 01:40, Bob Camp escribió: Hi Here is a little more on how much of a problem you have. If you would like the spurs to be down 70 dbc at 10 GHz. They go up by 20 log N. in this case N is 1000. That gets you 60 db. Spurs at 10 MHz would have to be down at -130 dbc to make it at 10 GHz. As a side note (since I've just asked by), does the phase noise also go up by 20 log N when multiplying? 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] Rubidium Performance
El 05/02/2012 22:27, John Miles escribió: John Thank you for your effort. It would be nice if you could confirm the 4 to 5 Hz dither that seems to be the loop time constant and long term aging that will influence the GPS/Rb control loop time constant setting. I did see 1 E-12 per month which may be unique to that unit. Bert Kehren There's a lot of impulse-like structure in the 10 MHz signal from the units I have, certainly. You can see the spikes here that are associated with the spurs at multiples of 1 Hz in the earlier PN plot, as well as some even stronger pulses that show up about every 28 seconds. They might correspond to the grand repetition rate of the DDS. The DDS self-update is around 28.4s, so for sure these spikes are related... and seems quite strong. 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] Rubidium Performance: DDS noise effect on 10 MHz
Hello, John, Your phase noise plot seems quite similar to that sent by Said some time ago (4 Jan), that looks like a lot of spurs quite evenly separated. It is likely from the price and p/n that your unit is one of the "newer" ones with 60MHz xtal and the DDS inside the loop - and I would think that the pn from the DDS would be removed by the loop. But since the division from 60MHz is done by a CPLD, perhaps the signal is corrupted by this CPLD, or perhaps it is corrupted by a switching regulator inside the unit. The 60MHz signal is available inside the unit, in a small coaxial connector. Perhaps it would be interesting to also analyze it. Regards, Javier El 04/02/2012 10:43, John Miles escribió: From your comments, it sounds like you may be measuring one of the earlier 5680A's that could be tuned over a large range with a DDS output. These earlier ones had a 50.25 MHz internal osc which was locked after multiplication to the rubidium frequency. Then there was a DDS on the output that could be programmed over a wide frequency range. That sounds plausible. I haven't taken the time to bring myself 100% up to speed with the many different variations and options for these little boxes, but I could swear I'm looking at a low-resolution, unfiltered, uncleaned-up DDS. The newer ones have a 60 MHz internal oscillator. This is multiplied up to 6840 MHz and subtractively mixed with ~5.3125 MHz from a DDS to get to the rubidium frequency. The feedback from the rubidium cell locks the 60 Hz which is divided by 6 for the 10 MHz output. No DDS on the output generation. The DDS in the loop can digitally adjust the rubidium lock frequency that tunes the 60 MHz, to fine tune the output only around 10 MHz. Do you know which type of 5680A you are measuring? This one is marked S/N 0339-65969, purchased from http://www.ebay.com/itm/260930018124 . It seems to have the pinout documented at http://vk2xv.djirra.com/tech_rubidium.htm for serial 0127-96634 (pin 1=V+, pin 2=GND, pin 3=+5V, pin 7=RF out.) However, VK2XV claims that s/n 96634 was non-programmable. I haven't tried hooking up a serial terminal to mine, but I did notice that there was some negative voltage on one of the other pins (9?) that might correspond to an RS-232 signal level. Can't complain too much at $40/each, anyway I believe the seller's claim that these are new or nearly so, even though they look like they've been removed from an installation. The internal foam insulation is usually discolored from heat, while it looks great in the two units that I bought from this seller. -- john ___ time-nuts mailing 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] New Rubidium Frequency Standard Group
Me too. I think that this is a transient that will surely decay... and that also is leading to several constructive sub-threads that are not directly related with the FE-5680A but nevertheless very interesting and very "time-nut" related. I'm not interested to subscribe another list that probably will became without activity quite soon. Regards, Javier El 02/02/2012 15:27, iov...@inwind.it escribió: I would disagree. The traffic on the FE-5680A took some of the group's bandwidth only in the recent weeks in coincidence with the appearance of cheap units on the auction site. Why to force time-nuts to jump to and fro one group and another? I have only been a member of the time-nuts group for a short while. It seems like 75% of the posts here have to do with the FE-5680A Rubidium Frequency Standards and there use and modification. This seems like the most popular subject and takes up allot of the group's bandwidth. There is a new Yahoo Group called " Rubidium " that just was recently started. I wonder if all the Rubidium traffic and posts would be better at that group. Send posts to : rubi...@yahoogroups.com Just a suggestion. ___ time-nuts mailing 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] FE5680 DDS plot
I forgot... have you had the opportunity to check if the difference between the two DDS programming words is the same in all cases? All my readings leds to 1400.00x Hz, I've not looked at it but probably the difference in DDS counts is constant. Regards, Javier El 02/02/2012 10:13, Javier Herrero escribió: Great plot :) I've a dump of the SPI transfers during a night taken with the logic analyzer... but have found no time yet to process the dump to extract the transfers. Of course it is easier to take it from the serial port data :) The adjustment looks quite closely related to the temperature. Regards, Javier El 02/02/2012 06:15, Scott Newell escribió: Javier Herrero's exciting DDS discovery led to this plot of the unit tweaking the frequency (cmd 0x22): http://n5tnl.com/time/fe-5680a/graphs/dds_autotuning.png It appears to make an adjustment even before lock! ___ time-nuts mailing 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] FE5680 DDS plot
Great plot :) I've a dump of the SPI transfers during a night taken with the logic analyzer... but have found no time yet to process the dump to extract the transfers. Of course it is easier to take it from the serial port data :) The adjustment looks quite closely related to the temperature. Regards, Javier El 02/02/2012 06:15, Scott Newell escribió: Javier Herrero's exciting DDS discovery led to this plot of the unit tweaking the frequency (cmd 0x22): http://n5tnl.com/time/fe-5680a/graphs/dds_autotuning.png It appears to make an adjustment even before lock! ___ time-nuts mailing list -- time-nuts@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 trimming resolution
El 31/01/2012 21:47, Attila Kinali escribió: This was exactly the device i intended to use. But it doesnt really have 32bit timers. They cascade two 16bit timers to get 32bit, but then all kind of restrictions apply which make the timers unusable. And when using 16bit timers, i'll get an overflow every 800us (at 80MHz clock). I see... for edge count and edge time, only individual timers and not concatenates. I've had a look to the LM3S9D96, and it is more or less the same (the exception is that it is marketed as 4 32-bit timers that can be used as 8 16-bit timers :) ), and I suspect that all the family will have similar behaviout. A pity... since for Ethernet it includes the LAN and PHY on-chip. 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] FE-.5680A trimming resolution
El 31/01/2012 20:43, Attila Kinali escribió: My current progress is that the uC i wanted to use does not do what i want. Can anyone recommend a uC with 32bit timers and IEEE 1588 support? You can have a look on these http://www.ti.com/mcu/docs/mculuminaryfamilynode.tsp?sectionId=95&tabId=2597&familyId=1756 Some of them have IEEE-1588, like the LM3S9B96 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] GHz output from fe5680a
El 31/01/2012 02:52, Magnus Danielson escribió: On 31/01/12 02:20, Bob Camp wrote: Hi Simple answer is don't bother. More complex answer - of course you can. You will get a forest of spikes (every 5, MHz or so ). Also, since the 5,3 MHz is modulated, 1,4 kHz apart is the two signals, and then a skirt of side-bands as the frequency modulation is relatively quick. It's not clean. BTW. A fun hack would be to hook up the 63,8976 MHz OCXO in replacement of the 60 MHz and then re-adjusting the DDS to 2.35645 MHz, as the 107s overtone of the OCXO minus the new DDS frequency hits the Rb resonance. Cheers, Magnus And then we will have a not less fun 10.6469MHz and 0.939Hz outputs :) However, if the DDS can easily be reprogrammed to large offsets (and the output filter is a simple lowpass...), that idea is very useful if you need an strange frequency and have an OCXO at 6x that extrange frequency ;) 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] FE-.5680A trimming resolution
El 30/01/2012 03:19, Chris Albertson escribió: On Sun, Jan 29, 2012 at 10:19 AM, Javier Herrero wrote: El 29/01/2012 14:45, Bob Camp escribió: My next intention is to replace the OCXO in one of my Thunderbolts with a Rb and use a small microcontroller to get the voltage correction from the Thunderbolt through the serial port and convert to a 5680A offset. I probably will use a Luminary since I've some small evaluation boards around, and I only have to add a MAX3232-class interface IC for the serial ports. My plan is simpler. I'll compare the phase of the Rb and t-bolt and send rs-232 commans to the Rb to keep the difference as small as possible. This will run on an Arduino. I'm also thinking of porting over much of the Lady Heather t-bolt monitoring stuff to the Arduino. My idea is to let the thunderbolt do all the things, replacing the oscillator, but letting it do all the comparisons, time constants, etc. since it also enables to set oscillator slope, time constant, and also do all the monitoring. So the uP, for now, will be simply a "protocol converter", sniffing the DAC value from the Thundervolt and converting it to an offset to the FE-5680A, using a EKK-LM3S9B96 I've lying around. I've more ambitious plans involvign a more capable embedded processor... (too many plans for so limited free time to play with things :) ). 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] FE-.5680A trimming resolution
Hello, Also I expect that the range would be somewhat limited by the unit software, since the control word is 32-bit, same as the DDS program word with, and I don't think that the little thing would enable to program the DDS from zero to 32-bit. In any case, my idea was first to only monitor the DDS word (at serial port) and serial port offset message limits, and also to test in that way the lock range of the 5680A - this can be a bit tedious since when I programmed a 10Hz offset, the unit unlocked ant took several seconds to lock again. Regards, Javier El 29/01/2012 21:41, Bob Camp escribió: Hi If you try to do full scale, check the range of your VCXO first. The digital test is much easier if you already know where your VCXO stops tuning. Bob On Jan 29, 2012, at 1:45 PM, Javier Herrero wrote: I'm now gathering the unit self-updating of DDS data, that will take somewhat long... so I will try later or tomorrow. Since we have seen that the DDS values are reported back in a response to a command, it is easy to do without the need to have anything hooked to the SPI bus :) Regards, Javier El 29/01/2012 19:37, Scott Newell escribió: At 05:45 AM 1/29/2012, Javier Herrero wrote: For example, the following data has been gathered: Serial offset 00 00 00 00 DDS A word: 44 02 62 F6 = 1141007094 = 5 313 228.32219 Hz DDS B word: 43 FD CC 8E = 1140706446 = 5 311 828.32085 Hz Can you do a test at +/- fullscale offset as well? This is a very exciting discovery. Nice work! ___ time-nuts mailing 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] FE-.5680A trimming resolution
I'm now gathering the unit self-updating of DDS data, that will take somewhat long... so I will try later or tomorrow. Since we have seen that the DDS values are reported back in a response to a command, it is easy to do without the need to have anything hooked to the SPI bus :) Regards, Javier El 29/01/2012 19:37, Scott Newell escribió: At 05:45 AM 1/29/2012, Javier Herrero wrote: For example, the following data has been gathered: Serial offset 00 00 00 00 DDS A word: 44 02 62 F6 = 1141007094 = 5 313 228.32219 Hz DDS B word: 43 FD CC 8E = 1140706446 = 5 311 828.32085 Hz Can you do a test at +/- fullscale offset as well? This is a very exciting discovery. Nice work! ___ time-nuts mailing list -- time-nuts@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 trimming resolution
El 29/01/2012 14:45, Bob Camp escribió: Hi Very interesting. It sounds like dithering would be needed to get down to parts in 10^-14. If we do that from an external device (PC / PIC / FPGA / whatever) it would be useful to know the delay between the serial command and the DDS update. The more variable the delay, the less accurate the dither. Bob Since I've all the things powered on the bench table, it is easy to measure: 21ms from the start of the serial message, to the end of the last DDS programming word. I've repeated several times, the time does not seem to have submitted to latencies, it is very constant. The automatic update rate of the DDS in the unit is somewhat around 28.5 seconds (I misread an inter-word delay of 671.5us as a 671.5 seconds interval). I'm trying to get a long capture from the logic analyzer to try to plot the DDS programming variations, but then I need to post-process it since the analyzer has no SPI decoding so I'm gathering the bit streams. My next intention is to replace the OCXO in one of my Thunderbolts with a Rb and use a small microcontroller to get the voltage correction from the Thunderbolt through the serial port and convert to a 5680A offset. I probably will use a Luminary since I've some small evaluation boards around, and I only have to add a MAX3232-class interface IC for the serial ports. Now... my question is to decide which of the two Thunderbolt will be converted to Franken-Thunderbolt. I've bee monitoring both from some time, feeding them from same GPS signal, and both looks quite the same (I was trying to see if one of them has a worse OCXO than the other. One is from the past group purchase, and the other has been purchased not long ago - but both are very similar, with same firmware and the Trimble OCXO, and monitored with Lady Heather they are really very similar). Next... clean-up the Rb output with an OCXO (the one from the Trimble or a 10811A I've around). But this depends on other things I must do... with more priority :) 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] FE-.5680A trimming resolution
El 29/01/2012 13:57, Magnus Danielson escribió: Hi Javier, On 01/29/2012 12:45 PM, Javier Herrero wrote: Hello, As it has been discussed in the past days, the architecture of the newer FE-5680A that has been recently purchased by a lot of us does not led to a trimming resolution through the serial port of 1.7854e-7Hz, but rather leds to think that the trimming resolution is in fact 6.80789e-6Hz (relative frequency resolution 6.807e-13). I've hang a logic analyzer to the DDS SPI bus, and an SPI message appears inmediately after updating the offset through the serial port. I've found that the DDS is programmed in two frequencies, separated 1400Hz near exactly, for each serial port offset setting, and that one bit increment in the serial port offset setting is translated to a one-bit increment for both DDS frequencies. The DDS frequencies are alternated at 416.666Hz rate through FSELECT pin, at an invariable 50% duty cycle, presumably to perform synchronous detection in the same way as explained in the FRS-C manual. For example, the following data has been gathered: Serial offset 00 00 00 00 DDS A word: 44 02 62 F6 = 1141007094 = 5 313 228.32219 Hz DDS B word: 43 FD CC 8E = 1140706446 = 5 311 828.32085 Hz Serial offset 00 00 00 01 DDS A word: 44 02 62 F7 = 1141007095 = 5 313 228.32685 Hz DDS B word: 43 FD CC 8F = 1140706447 = 5 311 828.32550 Hz Serial offset 00 00 00 02 DDS A word: 44 02 62 F8 = 1141007096 = 5 313 228.33151 Hz DDS B word: 43 FD CC A0 = 1140706448 = 5 311 828.33016 Hz I've seen that these values seems to vary slightly from time to time in the less significative digits, I've been then change in the order of 2-3 units from one data take to a different one minutes later. I've checked that the unit updates each several seconds the DDS control words, and I've seen changes in the lower significant bits at minutes intervals, although most of the times, same previous words are sent. I suspect this is some form of unit self-compensation, perhaps to temperature changes. Last, I've sent an offset of 1468879 units, that shoudl correspond to a 10Hz frequency change assuming a trimming resolution of 6.90789e-6Hz, and after a temporary unit unlock, it has locked exactly at 10 000 010.000 Hz. So I can conclude that these units are not fully compliant with the manual we are handling, and that the trimming resolution is 6.80789e-6Hz and not the stated 1.7854e-7Hz. Good work Javier! It also makes perfect sense from the hardware architecture of these newer 5680A. It's nothing wrong with it, it's just different. Somebody put this up on the wiki. I will receive new 5680A when I pickup the packet on Monday, I only have an older variant with serial port and DDS output. Cheers, Magnus I've just gathered the following message from the unit using the serial tool: Cmd 0x22 0x0D byte reply: [22] [0D] [00] [2F] [44] [02] [62] [EF] [43] [FD] [CC] [87] [3E] Cmd 0x22 ASCII (.): D.b.C... Cmd 0x22 ASCII ( ): D b C It seems that these are the current DDS values. Since now they are a slightly different of what I've logged before, I suppose that they are updated and are not some stored start-up values. So another reverse-engineered commad :) I'm currently logging with the logic analyzer the SPI activity to the DDS, it seems to be updated at a somewhat outrangeous interval of 671.5 seconds or something like that. It will take several hours to fill the analyzer memory :) Regards, Javier, EA1CRB ___ time-nuts mailing 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] FE-.5680A trimming resolution
Hello, As it has been discussed in the past days, the architecture of the newer FE-5680A that has been recently purchased by a lot of us does not led to a trimming resolution through the serial port of 1.7854e-7Hz, but rather leds to think that the trimming resolution is in fact 6.80789e-6Hz (relative frequency resolution 6.807e-13). I've hang a logic analyzer to the DDS SPI bus, and an SPI message appears inmediately after updating the offset through the serial port. I've found that the DDS is programmed in two frequencies, separated 1400Hz near exactly, for each serial port offset setting, and that one bit increment in the serial port offset setting is translated to a one-bit increment for both DDS frequencies. The DDS frequencies are alternated at 416.666Hz rate through FSELECT pin, at an invariable 50% duty cycle, presumably to perform synchronous detection in the same way as explained in the FRS-C manual. For example, the following data has been gathered: Serial offset 00 00 00 00 DDS A word: 44 02 62 F6 = 1141007094 = 5 313 228.32219 Hz DDS B word: 43 FD CC 8E = 1140706446 = 5 311 828.32085 Hz Serial offset 00 00 00 01 DDS A word: 44 02 62 F7 = 1141007095 = 5 313 228.32685 Hz DDS B word: 43 FD CC 8F = 1140706447 = 5 311 828.32550 Hz Serial offset 00 00 00 02 DDS A word: 44 02 62 F8 = 1141007096 = 5 313 228.33151 Hz DDS B word: 43 FD CC A0 = 1140706448 = 5 311 828.33016 Hz I've seen that these values seems to vary slightly from time to time in the less significative digits, I've been then change in the order of 2-3 units from one data take to a different one minutes later. I've checked that the unit updates each several seconds the DDS control words, and I've seen changes in the lower significant bits at minutes intervals, although most of the times, same previous words are sent. I suspect this is some form of unit self-compensation, perhaps to temperature changes. Last, I've sent an offset of 1468879 units, that shoudl correspond to a 10Hz frequency change assuming a trimming resolution of 6.90789e-6Hz, and after a temporary unit unlock, it has locked exactly at 10 000 010.000 Hz. So I can conclude that these units are not fully compliant with the manual we are handling, and that the trimming resolution is 6.80789e-6Hz and not the stated 1.7854e-7Hz. Best regards, Javier, EA1CRB ___ time-nuts mailing list -- time-nuts@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 FAQ update: question about frequency synthesizer architecture
Another though... The FE5680A manual says that the most basic unit outputs 50.255+ MHz (1/136 the Rb oscillation frequency). I suppose that this is the "other" style of units, that uses a 50.255MHz crystal to excite the cavity. 50.255MHz/2^48 is 1.785416^-7Hz, the claimed resolution for these FE-5680A. I'm starting to suspect that the claimed resolution of 1.7854^-7Hz is only for a serial protocol compatibility reason, and that really the effective tuning step for these Rbs is in fact around 6.81^-6Hz. Regards, Javier, EA1CRB El 28/01/2012 20:44, Javier Herrero escribió: I've checked now that they do not seem to be any activity on the DDS SPI lines during normal operation. I've tried with several small offsets through the serial port, and the square wave at FSELECT seems to be same square, no appreciable duty cycle variation. Regards, Javier El 28/01/2012 20:32, ed breya escribió: The lower bits can be pulse width modulated to get finer resolution, but it gets harder to maintain monotonicity. Eventually you run out of processing resolution, or the control signal falls into the noise floor, whether the system is digital, analog, or both. Ed Javier Herrero wrote: Sat Jan 28 18:38:53 UTC 2012 It can be... but the resolution of the center frequency of two DDS frequencies would be limited to half DDS LSB... so not enough. I will try to monitor FSELECT and also to extract some SPI data if I found some free time today or tomorrow :) ___ time-nuts mailing 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] FE-5680A FAQ update: question about frequency synthesizer architecture
I've checked now that they do not seem to be any activity on the DDS SPI lines during normal operation. I've tried with several small offsets through the serial port, and the square wave at FSELECT seems to be same square, no appreciable duty cycle variation. Regards, Javier El 28/01/2012 20:32, ed breya escribió: The lower bits can be pulse width modulated to get finer resolution, but it gets harder to maintain monotonicity. Eventually you run out of processing resolution, or the control signal falls into the noise floor, whether the system is digital, analog, or both. Ed Javier Herrero wrote: Sat Jan 28 18:38:53 UTC 2012 It can be... but the resolution of the center frequency of two DDS frequencies would be limited to half DDS LSB... so not enough. I will try to monitor FSELECT and also to extract some SPI data if I found some free time today or tomorrow :) ___ time-nuts mailing 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] FE-5680A FAQ update: question about frequency synthesizer architecture
Only to note that I measured at the wrong place... the reference frequency to the DDS is 20MHz, not 10MHz as I stated :) Regards, Javier, EA1CRB El 28/01/2012 15:21, Javier Herrero escribió: El 27/01/2012 19:27, beale escribió: I added a bit to the "electronics" section of the FE-5680A FAQ as below. http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_faq#electronic (Note- until today, I had the 8 and 6 digits transposed, calling it the fe5860a. But no one noticed :-) The updated section is below. I measured the 20 MHz input and 5.3 MHz output of the DDS, but I'm puzzled by how the tuning resolution (4.6 mHz) of the DDS output is divided by such a large factor to achieve 0.18 uHz resolution at the final 10 MHz output. Can any frequency synthesizer gurus explain how this is done? The frequencies inside the unit are quite similar to those found in the FRS-C, 60 and 5.3125MHz. The FRS-C excites the cavity at 60MHz x 114 - 5.3125MHz = 6.8346875GHz (a bit over the 6.834682608GHz Rb natural resonance - so I suppose that the resonance is driven to 6.8346875GHz using the C-Field), so I understand that the FE-5680A operates in the same way. Since in the multiplication process the 60MHz frequency is multiplied by 114 and the 5.3125MHz only by one, 1Hz offset in the 5.3125MHz frequency will need 1/114Hz offset in the 60MHz signal to obtain the same resonant frequency. I've checked that the DDS is driven by 10MHz, not 20MHz (I've just checked it), so the 5.3125MHz is probably an image and not a fundamental DDS output. Hence, the minimum DDS step is 2.23mHz. A change of 2.23mHz in the 5.3125MHz frequency is compensated by an approximately 20.45uHz change at the 60MHz frequency, and so, a 3.41uHz at the 10MHz output, i.e. one part in 3.41^-13. This lets to a factor of 19 between the adjustment attainable directly by modifiying a 1LSB and the claimed 1.7854^-14 adjustment. Probably this is done by modifying the duty cycle of the FSELECT signal. I suspect that the 416.667 signal at FSELECT is used to produce the modulation on the cavity excitation to perform a synchronous detection (the same way it is done in the FRS-C at 127Hz), to obtain a null, so the null can be slightly "moved" by variying the duty cycle at FSELECT. I will try to play a bit more this evening :) 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] FE-5680A FAQ update: question about frequency synthesizer architecture
It can be... but the resolution of the center frequency of two DDS frequencies would be limited to half DDS LSB... so not enough. I will try to monitor FSELECT and also to extract some SPI data if I found some free time today or tomorrow :) Regards, Javier, EA1CRB El 28/01/2012 15:35, Azelio Boriani escribió: And I think it depends on the two frequencies loaded too. The FSELECT selects between two phase accumulator steps. Maybe the word sent to the Rb is manipulated to obtain two symmetric values to load. On Sat, Jan 28, 2012 at 3:21 PM, Javier Herrerowrote: El 27/01/2012 19:27, beale escribió: I added a bit to the "electronics" section of the FE-5680A FAQ as below. http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_faq#electronic (Note- until today, I had the 8 and 6 digits transposed, calling it the fe5860a. But no one noticed :-) The updated section is below. I measured the 20 MHz input and 5.3 MHz output of the DDS, but I'm puzzled by how the tuning resolution (4.6 mHz) of the DDS output is divided by such a large factor to achieve 0.18 uHz resolution at the final 10 MHz output. Can any frequency synthesizer gurus explain how this is done? The frequencies inside the unit are quite similar to those found in the FRS-C, 60 and 5.3125MHz. The FRS-C excites the cavity at 60MHz x 114 - 5.3125MHz = 6.8346875GHz (a bit over the 6.834682608GHz Rb natural resonance - so I suppose that the resonance is driven to 6.8346875GHz using the C-Field), so I understand that the FE-5680A operates in the same way. Since in the multiplication process the 60MHz frequency is multiplied by 114 and the 5.3125MHz only by one, 1Hz offset in the 5.3125MHz frequency will need 1/114Hz offset in the 60MHz signal to obtain the same resonant frequency. I've checked that the DDS is driven by 10MHz, not 20MHz (I've just checked it), so the 5.3125MHz is probably an image and not a fundamental DDS output. Hence, the minimum DDS step is 2.23mHz. A change of 2.23mHz in the 5.3125MHz frequency is compensated by an approximately 20.45uHz change at the 60MHz frequency, and so, a 3.41uHz at the 10MHz output, i.e. one part in 3.41^-13. This lets to a factor of 19 between the adjustment attainable directly by modifiying a 1LSB and the claimed 1.7854^-14 adjustment. Probably this is done by modifying the duty cycle of the FSELECT signal. I suspect that the 416.667 signal at FSELECT is used to produce the modulation on the cavity excitation to perform a synchronous detection (the same way it is done in the FRS-C at 127Hz), to obtain a null, so the null can be slightly "moved" by variying the duty cycle at FSELECT. I will try to play a bit more this evening :) 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. ___ time-nuts mailing 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] FE-5680A FAQ update: question about frequency synthesizer architecture
El 27/01/2012 19:27, beale escribió: I added a bit to the "electronics" section of the FE-5680A FAQ as below. http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:fe5680a_faq#electronic (Note- until today, I had the 8 and 6 digits transposed, calling it the fe5860a. But no one noticed :-) The updated section is below. I measured the 20 MHz input and 5.3 MHz output of the DDS, but I'm puzzled by how the tuning resolution (4.6 mHz) of the DDS output is divided by such a large factor to achieve 0.18 uHz resolution at the final 10 MHz output. Can any frequency synthesizer gurus explain how this is done? The frequencies inside the unit are quite similar to those found in the FRS-C, 60 and 5.3125MHz. The FRS-C excites the cavity at 60MHz x 114 - 5.3125MHz = 6.8346875GHz (a bit over the 6.834682608GHz Rb natural resonance - so I suppose that the resonance is driven to 6.8346875GHz using the C-Field), so I understand that the FE-5680A operates in the same way. Since in the multiplication process the 60MHz frequency is multiplied by 114 and the 5.3125MHz only by one, 1Hz offset in the 5.3125MHz frequency will need 1/114Hz offset in the 60MHz signal to obtain the same resonant frequency. I've checked that the DDS is driven by 10MHz, not 20MHz (I've just checked it), so the 5.3125MHz is probably an image and not a fundamental DDS output. Hence, the minimum DDS step is 2.23mHz. A change of 2.23mHz in the 5.3125MHz frequency is compensated by an approximately 20.45uHz change at the 60MHz frequency, and so, a 3.41uHz at the 10MHz output, i.e. one part in 3.41^-13. This lets to a factor of 19 between the adjustment attainable directly by modifiying a 1LSB and the claimed 1.7854^-14 adjustment. Probably this is done by modifying the duty cycle of the FSELECT signal. I suspect that the 416.667 signal at FSELECT is used to produce the modulation on the cavity excitation to perform a synchronous detection (the same way it is done in the FRS-C at 127Hz), to obtain a null, so the null can be slightly "moved" by variying the duty cycle at FSELECT. I will try to play a bit more this evening :) 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] FE-5680A FAQ update: question about frequency synthesizer architecture
El 28/01/2012 00:17, claudio.gira...@virgilio.it escribió: Hello John, thanks for maintaining the 5680A FAQ; regarding its frequency resolution, have you checked the DDS FSELECT pin (and maybe also PSEL0/1) to see if they are doing some kind of "dithering" of the DDS frequency ? I've just checked it... yes, it does. In the unit I've at hand, a quick check shows a square wave at FSELECT, rate 416.666...Hz, duty cycle 50% (exact as per a fast check, will try to measure with higher detail later). I've not reprogrammed the frequency adjustment on this unit, so I suspect that the adjustment is done by a combination of varying the duty cycle at FSELECT and reprogramming the DDS. Next step: to snif the SPI buts to the AD9832 :) 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] finding time astronomically.
El 23/01/2012 21:43, Jim Lux escribió: One is where you "lay the iphone on the table" in a fixed position. One could use the internal accelerometers to determine "level", but I don't think you could tell orientation, unless, perhaps, you can see circumpolar stars? That is, by watching the movement of the stars/planets through the field of view over some hours, could you figure it out? Or is there some fundamental ambiguity. I don't know about the iPhone, but I've seen an HTC with a funny application that, when you point anywhere in the sky, it shows you the constellations that are there. Even if you point it to ground, it shows you the constellations in the other hemisphere :) I don't remember if the application is this http://www.google.com/mobile/skymap/ or something similar, but in any case, the phone knows its orientation quite good (well... also depends on the phone to have the right time, of course... :) ) 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] Thunderbolt GPS TimeKeeper
El 23/01/2012 19:29, Chris Albertson escribió: So back to time. If the goal is keeping good time then it is best not to use Microsoft Windows. There are good technical reasons having to do with the way MS Win. keeps and adjusts time. The bottom line is that you will never be able to do better then about the millisecond level even with a directly attached GPS. Using another OS, BSD or Linux you can do almost three orders of magnitude better. (Three orders is huge.) The OS and software is free and all you need is any computer that has a physical serial port, not USB but a real DB9 connector. This is a good use for a 10 year old notebook PC. (The computational load is trivial so even a 486 class computer is OK) Hello, I agree at all at not thinking on MS Windows for any precision timing task (even low precision). We have some systems with a Windows based workstation and Meinberg ntp distribution, and several linux embedded processors taking the time from the workstation using ntp in a LAN (with very very low traffic, also). This works well if you only need relative precision (i.e. 1 second) time difference to the workstation, but once we tried an application that required a synchronization between the linux processors and the windows system in the order of 10ms, and this never worked reliably. This is trivial to put into work in a LAN using ntp or chrony. By orders of magnitude. And that to not speak about the windows time server, not fully ntp compatible but partially (to make things more confusing - the usual MS way of taking an industry standard and pervert it on its own way - rather imaginative also). You only need to have a look to this: http://support.microsoft.com/kb/939322 amd particularly to the paragraphs "We do not guarantee and we do not support the accuracy of the W32Time service between nodes on a network" and "The W32Time service cannot reliably maintain sync time to the range of 1 to 2 seconds". This explains all... 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] Help on processing some data
Hello, I've several data sets of frequency measurements taken at 500us intervals, and would like to extract phase noise data from them. In order to do a consistency check with my processing, could I request some help from any of you that have available Stable32 or other similar tool to process one file? Best regards, Javier, EA1CRB ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Lady Heather for a noob
El 13/01/2012 04:57, brent evers escribió: Hijacked thread. Yes - this would be great to see done on a linux machine. I don't know that much about LH, but something done cross platform (PyQt or such - could make binaries for win, linux, and mac) in a server/client config would be great. I don't know much about NTP other than pointing machines to NTP servers for time, but having the server side provide also be an NTP server would be the cats ass for me. Pretty big wish list for someone who can't write code out of a wet paper bag huh? It would be nice, but if no graphic i/f is used for the server side, I think it would be better to implement it in standard C instead of PyQt, for portability reasons, so the server could be easily rebuilt for running in a non-PC class embedded linux computer (like those using ARM) For providing ntp, probably the best way is to use ntp :) As far as I remember, since I've not played around it since some time, the LinuxPPS driver is implemented as a character driver, so several applications can read it, and as other has pointed, ntp i/f to the GPS can be implemented using shmem. ntp can also be recompiled for running in almost anything (I've put it into work both in Nios-II uClinux-MMU and Blackfin uClinux-nonMMU, also taking time from an M12 using Linux-PPS) 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] FE-5680A arrived
Hello, What kind of power supply are you using for it? If a switching one, perhaps this is the origin. Regards, Javier, EA1CRB El 12/01/2012 11:39, Chuck Forsberg WA7KGX N2469R escribió: I received my Ebay Tek 2712 spectrum analyzer Monday and I have been throwing software to read its data via GPIB. Here is a spectrum I got connecting the Rb 10 MHz to the 2712. Nice little spurs. I don't see anything to account for these anywhere else. The 2712 is a big step up from Ham radio fish finders and I'm still learning things about the 2712. It would be nice to have original easy to read printed manuals and/or a high quality PDF. The black and white (no greyscale) PDFs on the internet are hard on the eyes and not searchable. ___ time-nuts mailing 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.
