Re: [time-nuts] FE-5680A control programs
Hello, I'm still here, unfortunately my Rb are gathering dust and I cannot follow the list everyday. I wrote some scripts to automate data collection from FE5680 and my counter using python. They run in Windows and can be used and modified at will, I've not much time now, so I cannot give support on their usage, but it should be easy enough. I will check what I have... Il 2013-05-24 14:06 Ziggy9 ha scritto: A few months ago Fabio Eboli posted some Python functions that might be useful. I haven't used or tested them myself, but they might be of interest. Still up on pastebin at http://pastebin.com/download.php?i=VpZVuw0t I don't know if Fabio has done any further work on this but perhaps he'll chime in here. Paul On May 24, 2013, at 0:22, Chris Albertson albertson.ch...@gmail.com wrote: You have been collecting programs? I did not know there were any to collect. Do you have a list? I don't have much use for a .exe file but is your are source codes available that would be great. On Thu, May 23, 2013 at 4:44 PM, EB4APL eb4...@cembreros.jazztel.es wrote: Hello, Since I bought my FE-5680A (10 MHz, 1 PPS variety), I have been collecting control programs for it and keeping then in reserve. Now that I'm going to box it with a distribution amp I tried some of them, first of all to adjust the frequency against the GPS. I used Bob Campbel's VK4XV Fe5680Calibrator.exe with good results. I have other programs which interrogates the device and shows the hex dumps, but I would like to know if there is a windows program that allows to send other that the offset related commands to the device and get the responses not in hex but translated to plain language. In fact I don't know if there are housekeeping commands for reading thinks like the lock status or the lamp voltage like the analog outputs of the FRS-C and others. Thanks in advance, Ignacio EB4APL __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- 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.
Re: [time-nuts] FE-5680A control programs
Here the last revision for the interface script: http://pastebin.com/rVuDK3py This is an example of data logging using the previous functions: http://pastebin.com/H9sMT1GP I had somewhere also a script that put out nice real time graphs from the logged data, see matplotlib, numpy, etc... Hope this helps. I'm sorry I cannot keep working with Rb, (busy looking for new job now, no luck so far...) but if there are any questions I will try to answer as far as I can :) Ciao! Il 2013-05-24 14:06 Ziggy9 ha scritto: A few months ago Fabio Eboli posted some Python functions that might be useful. I haven't used or tested them myself, but they might be of interest. Still up on pastebin at http://pastebin.com/download.php?i=VpZVuw0t I don't know if Fabio has done any further work on this but perhaps he'll chime in here. Paul On May 24, 2013, at 0:22, Chris Albertson albertson.ch...@gmail.com wrote: You have been collecting programs? I did not know there were any to collect. Do you have a list? I don't have much use for a .exe file but is your are source codes available that would be great. On Thu, May 23, 2013 at 4:44 PM, EB4APL eb4...@cembreros.jazztel.es wrote: Hello, Since I bought my FE-5680A (10 MHz, 1 PPS variety), I have been collecting control programs for it and keeping then in reserve. Now that I'm going to box it with a distribution amp I tried some of them, first of all to adjust the frequency against the GPS. I used Bob Campbel's VK4XV Fe5680Calibrator.exe with good results. I have other programs which interrogates the device and shows the hex dumps, but I would like to know if there is a windows program that allows to send other that the offset related commands to the device and get the responses not in hex but translated to plain language. In fact I don't know if there are housekeeping commands for reading thinks like the lock status or the lamp voltage like the analog outputs of the FRS-C and others. Thanks in advance, Ignacio EB4APL __**_ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/** mailman/listinfo/time-nutshttps://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there. -- 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.
Re: [time-nuts] Low noise power supplies?
Hello, interesting discussion about noise. It's all way over my knowledge, so my contribution to discussion maybe is only noise :) Re batteries I agree with Mark, see below: Il 2013-01-31 06:42 Mark Sims ha scritto: A123 20Ah LiFePO4 cells have an internal resistance in the milliohm range. Their M1 26650 format cells are around 8 milliohms. Most high capacity (3000 mAh) 18650 style lithium cells are around 10-15 milliohms. I made some tests of high rate RC batteries, and their internal resistance seem to be below 10mOhm These are Li-ion pouch cells, their selfdischarge seem very low, but I dont have figures for this. Their cost is very low, and are used for RC airplanes or cars, only thing I'm expecting is that they will age and their internal resistance (and capacity) probably will worsen after some time. This is a graph of a 3-cell battery of 1.8Ah capacity, charged and discharged at 3.6A and 7.2A (red and blue curves): http://www.eevblog.com/forum/reviews/high-rate-li-ion-batteries/?action=dlattach;attach=31097 Here tested up to maximum declared rate: http://www.eevblog.com/forum/reviews/high-rate-li-ion-batteries/?action=dlattach;attach=31185 I report this here about noise, because I remember that while I was charging and discharging them, I was watching with awe the voltmeter stable readings. The power supply/load was an HP6632B and the meter a keithley 2015, the meter reading was stable up to last digit (10uV over 10-11V)and counting digit by digit up while charging or down while discharging, no missing codes sort of thing :) It was like watching a counter instead of a voltmeter. So I was wondering what could be the real noise of a chemical battery. Reading this discussion I'm learning that the batteries can be low noise voltage sources. Thanks, Fabio. ___ time-nuts mailing list -- time-nuts@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 noise power supplies?
Sorry, Poul-Henning Kamp, I answered directly to your mail address, I repost it here... Il 2013-02-01 18:09 Poul-Henning Kamp ha scritto: Content-Type: text/plain; charset=ISO-8859-1 In message 2bf4f4e8c8207ae0f94a7e1a1e63c...@quipo.it, Fabio Eboli writes: Il 2013-01-31 06:42 Mark Sims ha scritto: A123 20Ah LiFePO4 cells have an internal resistance in the milliohm range. [...] Low internal resistance in batteries is an indicator of low noise, but not a guarantee of low noise. I have no reason to disagree with your statement :) I was agreeing with Mark about the fact that there are new chemistries with low internal resistance, and nice characteristics like low cost, availability and low self discharge, and that some Li-ion can be built to be one of those. For instance in wet lead-acid cells, turbulence in the liquid as the density changes can lead to low-frequency noise, which incidentally sounds a lot like a pot of stew simmering. It would be interesting to see if there are references about noise in the li chemistries. Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] OT, looking for a good science forum
Il 2013-01-26 14:58 Bob Camp ha scritto: Hi Platinum RTD's are a pretty good bet for -80C, they hold up well down there. For calibration, ammonia and acetylene both have triple points in the vicinity. I'd probably try ammonia first, but not for any good Doesn't acetylene have a bad habit of dissociate when pure liquid? Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] One Kg Quartz Resonator
Hi As with the one kg resonator, you need to mount the bar *somehow*. The idea is generally to suspend the resonator at a point that least affects the resonance (a dead spot). With a large bar, making it manually adjustable is practical. Not so much with a smaller part. Bob Il 2013-01-23 01:54 jmfranke ha scritto: I also have two of the crystals. The discs are used to adjust the phase of the acoustic feedback to the resonator ends. John WA4WDL Thanks Bob and John, I gave a superficial read to one of the patents, as I understand the patent says that the plates are there to give predictable acoustic reflections (yes I know I should read before posting questions :) ) Bob the dead spot mounting is interesting (are they called nodal points, or I'm mistaking terminology?). The metallization on the 50kc rod is on top and bottom plates, while the 100kc is swapped, one electrode on top on one half and bottom on the other half rod. The suspension is also different, the 50kc is supended in the middle while the 100kc is suspended in two points. How are supposed to vibrate these bars? Will they inflect along the long axis? Or elongate? Or a mix of different motions? Thanks. Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] One Kg Quartz Resonator
Il 2013-01-23 13:39 Bob Camp ha scritto: the mode that the bar is resonating in, it's a bit hard to guess where the nodes will be. Just looking at the bar, you wouldn't *guess* that the end points would be nodes... Bob Sorry Bob I didnt understand last part. You say that the end faces are nodes that move very little? Or that it's hard to tell the way they move? I asked that because reading the patent, I understand that the plates are trimmed to stay near the rod and not touching it, to give costant air reflection behaviour. And talks about supersonic movement of the air, so I was wondering why that was only a problem on end faces and not on other long faces of the rod. Thanks, Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] One Kg Quartz Resonator
Il 2013-01-22 23:19 Tom Van Baak (lab) ha scritto: Yes, Don, those old quartz bars are rare and amazing: http://leapsecond.com/museum/gr676b-50kc/ http://leapsecond.com/museum/gr1190a/ What is the function of the (metal?) disc plates near the two ends of the rods? Their position seem to be trimmable. Thank, Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Counter OCXO behaviour
Il 2013-01-14 22:15 Charles P. Steinmetz ha scritto: Because the oscillators are sealed assemblies, I'm not aware of anyone who has taken one apart for analysis -- so the reason for this behavior must be considered unknown until we know what is going on inside. By the way, there is a non working unit on ebay in US just now, 58h to auction end. If it was in EU I would have picked it up just for dissection. Unfortunately for me shipping charges are a little high for an autopsy: ebay #251211816860 Best regards, Charles Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Counter OCXO behaviour
Robert, I asked the seller for the least expensive way to send that OCXO here (nothing to lose on a marginal packaging, let's assume the item is non working) and he quoted 12USD. I think I must refrain from spending 20USD (assuming I will be the only bidder) for a device to be dissected, althoug I've done worse things with my ebay account :) If it was a working OCXO I would have happily bought it, but thinking about it I would not dissect a working OCXO, for me it would be a crime :) I will see if he has something interesting (and light) in other items he listed, maybe I could share shipping cost between items. Il 2013-01-15 15:34 Robert LaJeunesse ha scritto: re ebay #251211816860 the seller is one I've dealt with a few times before, and had excellent service. I would not hesitate to deal with them again. FWIW according to the US Post Office web site a 1 pound package to Italy ships for $11.60. Bob L. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Counter OCXO behaviour
Il 2013-01-15 15:31 David C. Partridge ha scritto: Yes the 1992 4E adjustment is a bear. Mine behaves pretty much the same, ISTR it took me a few days to get it adjusted to my satisfaction and it was still drifting a bit. The strange thing is that mine now is changing frequency at more than 1x10^-10 per day, measuring a 10MHz reference this would be one digit per day, but before it was steady on last digit for long time intervals, last digit moved up and down only with day/night temperature variation. Is it possible that the OCO was sealed by so much time, opening it I changed the internal equilibrium? (humidity?). Interestingly I saw a 1992 with a built in Rb on eBay (I think in France) some years back but the price went way beyong my budget. I've about this on this list, option 04R: http://www.febo.com/pipermail/time-nuts/2011-November/060516.html Fabio. ___ time-nuts mailing 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] Counter OCXO behaviour
Hello, recently I tried to trim the Racal Dana 1992 04E internal reference, using the GPS pps as a reference. I'd like to ask a pair of questions... - First is about the method. I'm using the counter TI to measure it's own OCXO. The GPS is starting the count, the internal reference 10MHz (on the rear there is a reference output connector) stops the count and I log the result as I've done before with other oscillators. Is this a correct procedure? - Second, is about the behaviour of the OCXO after trimming. The OCXO seem not that stable after the trimming, like if the crystal started to age faster than before trimming, and now is slowly stabilizing. It's like the retrace of the crystals I've read about, but the instrument was never powered down in the last month. And it's oven has been on for the last year. Will a crystal retrace also after retrimming? The frequency of the crystal is slowing, in the first hours after the trimming rapidly, and now more slowly. After few days the frequency seem to be slowing somewhere around 1x10^-10 per day. Unfortunately I havent logged the counter for enough time before the trimming, but it measured the same Rb with less than 3 digits of difference (3x10^-10) in last 6 monthes. Thanks, Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Counter OCXO behaviour
I answer here to all, thank Ed David and Charles for your thoughts. David, LOL, you posted the pic of the exact counter in question. Not a similar unit, I mean it's exactly *that* 1992 that is being measured ;) The pictures on eevblog show the early measurements I made with the counter. One of the Rb wasmeasured to about 10MHz+60mHz. After a while (I think a pair of monthes) the reading was slightly over 10MHz+70mHz and remained there for more than 6 monthes, until I trimmed the counter few days ago. The trimming is very touchy, and the simple opening of the screw on the rear is traumatic: the frequency rises for a pair of minutes and then it takes a while to return to the previous level. Talking about this OCXO, how much is it good? I mean for who has eperience with many OCXO is this a good unit, or it's an average one? Is this the kind of stability and reaction that can be expected by an OCXO useful for GPSDO (less the EFC control of course)? Measuring this OCXO, just now I'm starting to feel the precision of the FE5680, or 5682. It's so easy to set the Rb to follow GPS closely for days... I have some pics of the measurements I made, they are a little messy, I hope can be fun and interesting to see: This was before touching anything, top right the phase between the GPS and OCXO: http://www.flickr.com/photos/14336723@N08/8382126024/ it was slow by about 7x10^-9. This was the first trim attempt: http://www.flickr.com/photos/14336723@N08/8382125734/ and this the last trims, the dips in phase are evident, they happen when I open the calibration screw on the rear: http://www.flickr.com/photos/14336723@N08/8381043177/ and at last these are logged after last trim action: http://www.flickr.com/photos/14336723@N08/8381044033/ I tried to extract more data from last log: http://www.flickr.com/photos/14336723@N08/8382126108/ Here I made the first and second derivative in time of the phase, data are heavily averaged, so are not very accurate. The 10MHz period error (vs. GPS) changed from -0.8x10^-10 soon after the trim, to +1x10^-10 after two days (top right). The OCXO period was rising from almost 2x10^-15 soon after the trim to 1.3x10^-15 after two days (bottom left). Seem the stabilization will take a while... Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Counter OCXO behaviour
Il 2013-01-15 00:08 Fabio Eboli ha scritto: Trying to be more clear: 10MHz period error (vs. GPS) changed from -0.8x10^-10 soon after the trim, to +1x10^-10 after two days (top right). Top right is change of phase in time, i.e. period error measured using GPS as reference. The OCXO period was rising from almost 2x10^-15 soon after the trim to 1.3x10^-15 after two days (bottom left). Bottom left is change of period error in time, 1.3x10^-15 per second is around 1.1x10^-10 per day, if I'm not mistaken, more than typical unit's aging stated by datasheet. Seem the stabilization will take a while... Fabio. ___ time-nuts mailing 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] Undocumented FE5680A commands, and a python script
Hello, I've read about undocumented FE5680A commands (On excellent Didier' FE5680 FAQ page). This python script is a collection of the functions I'm using to connect to FE5680: http://pastebin.com/VpZVuw0t And I will add to it more functions based on these new fields. I'd like to know if anybody have worked out more details about these commands. Thanks, Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FE5682A inside pics
I reassembled the failed unit and booted it up. The internal working voltage is 15.3V, the unis seem similar to 5680A, and has even the footprints for a DB9 connector in the same position of the 5680A. I will try to spot if it carries the same signals than that unit. As I was expecting the failed FE-5682A wasnt working, but fortunately the problem was that it was unable to lock: the 10MHz output wasnt crossing the 10MHz boundary, but was low. I had read from John Beale that a FE5680 with the same problem was healed touching the C217 trimmer: https://plus.google.com/u/0/photos/109928236040342205185/albums/5680473650837554113/5680683008490223330 So i tried to spot something similar in the FE5682, and the right candidate was C245 here: http://www.flickr.com/photos/14336723@N08/8331581900/ http://www.flickr.com/photos/14336723@N08/8331582154/ After retouching it, the FE5682A passed again the 10MHz limit, and after few minutes locked on the right freq. It has c-field adjust both with a trimmer accessible from an hole on the side, and to the connector, and both work. My counter is busy logging, so I cannot measure the regulation range of the EFC, but if it follows the LPRO-101 probably it will have the same 0-5V range. After a night powered up, the unit seem stable against one of the 5680, I have it sitting on an thin (1mm) aluminium plate and it is using 820mA at 20V. The diagnostic voltages are: Pin 5 lamp voltage that reads 3.4V Pin 9 crystal Vmonitor 5.7V That's all for now. Fabio. Il 2012-12-31 16:45 Fabio Eboli ha scritto: Positive update, in the broken unit the pin 10 goes to power module input, while the pin 8 goes to power module ground, and there is grounded. I powered the good unit and it locked in few minutes, wothout driving the EFC, the frequency seem very near the FE5680 I set against the GPS. The output 10MHz phase is influenced badly by input voltage up to 18V, and is stable after that, so the unit seem to be a 19-32V one. Now that the failed unit is still opened, I will try to check the inner working voltageon this, if anibody has any question or curiosity about the units, I still have it opened up... Fabio. Il 2012-12-31 14:46 Fabio Eboli ha scritto: By the way, about the psu the unit contains this module: http://www.farnell.com/datasheets/14431.pdf so probably internally it works at 12V. Fabio. Il 2012-12-31 14:44 Fabio Eboli ha scritto: Hello, in the last day of this ugly year I received a pair of FE5682A. ... ___ time-nuts mailing 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] FE5682A inside pics
Hello, in the last day of this ugly year I received a pair of FE5682A. The two have visibly different tags, probably are from differen age, and one has the word FAIL written on it. The pinut is similar to LPRO-101 see: http://www.febo.com/pipermail/time-nuts/2012-November/071937.html but the working voltage specs are unclear, so I decided to open up the FAIL one, here some pics, hope that can be interesting: http://www.flickr.com/photos/14336723@N08/sets/72157632394339366/ Happy new year :) Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FE5682A inside pics
By the way, about the psu the unit contains this module: http://www.farnell.com/datasheets/14431.pdf so probably internally it works at 12V. Fabio. Il 2012-12-31 14:44 Fabio Eboli ha scritto: Hello, in the last day of this ugly year I received a pair of FE5682A. ... ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] FE5682A inside pics
Positive update, in the broken unit the pin 10 goes to power module input, while the pin 8 goes to power module ground, and there is grounded. I powered the good unit and it locked in few minutes, wothout driving the EFC, the frequency seem very near the FE5680 I set against the GPS. The output 10MHz phase is influenced badly by input voltage up to 18V, and is stable after that, so the unit seem to be a 19-32V one. Now that the failed unit is still opened, I will try to check the inner working voltageon this, if anibody has any question or curiosity about the units, I still have it opened up... Fabio. Il 2012-12-31 14:46 Fabio Eboli ha scritto: By the way, about the psu the unit contains this module: http://www.farnell.com/datasheets/14431.pdf so probably internally it works at 12V. Fabio. Il 2012-12-31 14:44 Fabio Eboli ha scritto: Hello, in the last day of this ugly year I received a pair of FE5682A. ... ___ time-nuts mailing 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] Strange GPS behaviour
An update regarding the GPS module, simply shielding it from air currents improved the things: http://www.flickr.com/photos/14336723@N08/8327229820/ At 48000s I swapped references, hence the change in slope. I think the poor receiver module (Azelio, 20€, I think it can be considered cheap :) is not to be blamed too much, I mounted it raised from the PCB, and the only thermal contact were the few pins used to connect to it, and it was exposed to moving air. But usually it will be sodered directly on the PCB like an SMT component, and enclosed into a box. Il 2012-12-28 23:27 Fabio Eboli ha scritto: Like I mentioned in a precedent message (answering Magnus) I'm seeing some temp effects on my GPS module, see this message: http://www.febo.com/pipermail/time-nuts/2012-December/073310.html ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Testing the TAC, and a question about ADEV
http://ieeexplore.ieee.org/xpl/login.jsp?tp=arnumber=4030739url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D4030739 http://ieeexplore.ieee.org/xpl/login.jsp?tp=arnumber=4030739url=http%3A%2F%2Fieeexplore.ieee.org%2Fxpls%2Fabs_all.jsp%3Farnumber%3D4030739 is one of the best in that it gives guidance on selecting suitable test oscillator periods. It also details how the integral linearity can be derived from the test. There are a couple of minor errors in the paper. Bruce Thank you for the references, unfortunately I dont have an account to access to IEEE papers. P.S. The micro's adc is charachterized for total unadjusted error of +-2LSB Max at 25°C, 12bit total. It's s-h is 8pF with 1kohm in series, probably I can sync the sampling to open just before the pulse, and close after the fact. What error is that: As per the datasheet blah blah :) : the total unadjusted error (TUE) is defined as the maximum deviation between the actual and the ideal transfer curves. It is a parameter that specifies the total errors that may occur, causing maximum deviation between the ideal digital output and the actual digital output. It is the maximum deviation recorded between the ideal expected value and the actual value obtained from the ADC for any input voltage. see: http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/APPLICATION_NOTE/CD00211314.pdf pag 9, I was considering it the worse case error. gain error? +-1.5LSB offset error? +-1.5LSB integral nonlinearity? +-1.5LSB What about monotonicity or differential linearity? DNL +-1LSB See : http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00161566.pdf pag 76 A worst case assumption would be that the ADC is perhaps only monotonic for the 11 most significant bits. Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Testing the TAC, and a question about ADEV
Il 2012-12-28 21:43 Magnus Danielson ha scritto: The bucket statistic method is very simple. You divide a scale into a suitable set of ranges, equally wide. The you count how many hits you get within each of those ranges or buckets. By the way, since I've seen some contributors that are from Italy (Azelio...? :) what is the correct name of the tecnique in Italian, maybe it's something I've studied or seen somewhere. Thanks. Fabio. ___ time-nuts mailing 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] Testing the TAC, and a question about ADEV
Hello How could I test the time to analog converter we talked few posts ago? Something that can be done with things I have or can easily find. I was thinking that would be nice to try to feed it with signals similar to the real ones, but that can be controlled: PPS + 10MHz reference, without the PPS tipical jitter. To do so I was thinking to use the PPS from one of the 2 FE5680 and the 10MHz from the second ad use these to simulate the real signals. I can tune the frequency of the Rb with the serial interface (tested and working). I'd like to verify both the resolution and repeteability. I was trying to figure the approx jitter I will have using the Rb like I said above, so I'm giving an eye to this diagram from John Miles page: http://www.ke5fx.com/rb.htm If I'm understanding correctly, that 5680 at 1s should have most of the jitter (95% +-2sigma) into an interval +- 3.08x10^-11 wide, i.e. about 62pS on the PPS signal (non considering the PPS buffer inside the 5680). Is this how it work, or I'm mistaking? This is from only one unit, but both unit will have the jitter, how to take into account the jitter from both? Is there a better method to make this test? I could try to test the TAC alone feeding it with a 100 to 200nS pulse, but I dont know from where to start to generate a clean stable and repeteable pulse. I have the 2 5680, the counter with it's 10MHz inputs and outpus, and a Vectron OCXO that came with one of the 5680, with these markings: OCXO500-18 63.897600MHz 34537 A0715 and... soldering iron, solder and scrap electronics :) Thanks, Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Testing the TAC, and a question about ADEV
Bruce, Bob, now I have more questions than before :) First and most important: Where can I find references about the statistical method you mentioned? I tried to search online but didnt't find any info. What do you think about the simple setup I mentioned before (the 2 Rb osc)? If I set accurately the frequency difference (easy with a scope and a timer) I will know the cycle-by-cycle pulse increment (or reduction). Was the jitter estimation I made for the single Rb correct? Fabio. P.S. The micro's adc is charachterized for total unadjusted error of +-2LSB Max at 25°C, 12bit total. It's s-h is 8pF with 1kohm in series, probably I can sync the sampling to open just before the pulse, and close after the fact. Il 2012-12-28 19:53 Bruce Griffiths ha scritto: One potential source of non monotonicity is the ADC particularly those embedded in a microprocessor. The only cure being to either use an external ADC that is monotonic or truncate the ADC result until it's monotonic. Varying the synchroniser clock frequency (a 2:1 range should suffice to cover the range of interest) should allow non monotonic behaviour to be detected. Otherwise one has to resort to using calibrated delay lines. Bruce Bob Camp wrote: Hi The statistical fill approach is a cute way to go. The gotcha comes in when you have a structure that *may* not be monotonic. Bob On Dec 28, 2012, at 1:04 PM, Bruce Griffithsbruce.griffi...@xtra.co.nz wrote: Fabio Eboli wrote: Hello How could I test the time to analog converter we talked few posts ago? Something that can be done with things I have or can easily find. One method is to use a statistical fill the buckets technique to measure the linearity. To do this one needs to use an incoherent source to trigger the interpolator and plot a histogram of the results. A noisy RC oscillator would be useful for this but care should be taken to avoid injection locking. To achieve useful measurement in a reasonable time interval a trigger rate somewhat greater than 1Hz is required. If the interpolator has 1024 time delay bins then ~ 100,000 trigger events are required to achieve a bin width measurement error of 10%. Otherwise a series of measurements of a set of accurately known delays is required. Useful results can be produced by measuring the delay between various outputs of a shift register clocked at a sequence of different measured frequencies. I was thinking that would be nice to try to feed it with signals similar to the real ones, but that can be controlled: PPS + 10MHz reference, without the PPS tipical jitter. One should characterise the interpolator linearity etc first. To do so I was thinking to use the PPS from one of the 2 FE5680 and the 10MHz from the second ad use these to simulate the real signals. I can tune the frequency of the Rb with the serial interface (tested and working). I'd like to verify both the resolution and repeteability. I was trying to figure the approx jitter I will have using the Rb like I said above, so I'm giving an eye to this diagram from John Miles page: http://www.ke5fx.com/rb.htm If I'm understanding correctly, that 5680 at 1s should have most of the jitter (95% +-2sigma) into an interval +- 3.08x10^-11 wide, i.e. about 62pS on the PPS signal (non considering the PPS buffer inside the 5680). Is this how it work, or I'm mistaking? This is from only one unit, but both unit will have the jitter, how to take into account the jitter from both? Is there a better method to make this test? I could try to test the TAC alone feeding it with a 100 to 200nS pulse, but I dont know from where to start to generate a clean stable and repeteable pulse. You dont need one (see above) as long as you have the means to accumulate the results of 100,000 measurements or preferably more. I have the 2 5680, the counter with it's 10MHz inputs and outpus, and a Vectron OCXO that came with one of the 5680, with these markings: OCXO500-18 63.897600MHz 34537 A0715 and... soldering iron, solder and scrap electronics :) Thanks, Fabio. Bruce ___ time-nuts mailing 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] Testing the TAC, and a question about ADEV
Little update about the PA6H GPS. I was having problems with periodic abrutp change in drift. I didnt like the psu of the Rb, so modifed them and started logging temperature and voltages. Now I have some early evidence of the suspect: the GPS receiver seem upset by rapid changes in temperature. When I have a temperature variation on the GPS, I see a drift change in the PPS logged signal (against Rb reference). It seems that the drift changes by a magnitute proportional to the rate of change in temperature (dT/dt). Is this something I should expect from a GPS receiver or is a feature of my model? What process could generate this problem? It's like if there is a big delay in the pulse inside the module, that is temperature dependent and changes with unit temperature, driving the PPS back and forth several 100's of nS when the temperature changes. I should ballast thermally the GPS, or I will have to thermostabilize it :( Hello Magnus, It should be a good way to sweep through the various delays in a sequence, which with fairly simple post-processing would reveal both the jitter and non-linearity. I've seen that with the scope I can set the two Rb to march the edges almost exactly. Noise jitter adds like power, so same noise would give you a 1.41 multiplication up. So if my units are like the one in that test, I will have somewhere around 90pS for 95% of the samples. Not Bad. So, you just want to produce a 1 PPS, so a PIC divider such as TADD-2 would be suitable if you don't have PPSes on your 5680s. Fortunately my units have the PPS, I'm also thinking to mod them and remove the LP filter on 10MHz so I can have the logic level edge without squaring the signal. soldering iron, solder and scrap electronics :) You could do a bit of damage with that :) No need of these things to to damages, when I was child some fertilizer and too much curiosity was enough... I survived a pair of near miss events before I changed interests :) ___ time-nuts mailing 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] Strange GPS behaviour
Like I mentioned in a precedent message (answering Magnus) I'm seeing some temp effects on my GPS module, see this message: http://www.febo.com/pipermail/time-nuts/2012-December/073310.html In this graph there are the FE5680 voltages and temperatures, and the temperature sensed on the PCB near the GPS: http://www.flickr.com/photos/14336723@N08/8318815981/ At time 2s I heated the GPS receiver directly with hot air gun and the drift started to change rapidly. At 25000 I heated the FE5680#2 I was using as reference, but no visible effects, (apart the slight variation in it's voltage :) At 3 33000 35000 seconds I heated the GPS with a resistor placed near the PCB, this generated more gradual temperature variation on the GPS. Here can be seen the results of the heating on the drift, (logging GPS PPS against Rb): http://www.flickr.com/photos/14336723@N08/8318816213/ the hotair generated so much variation, that the script was unable to unscrable the data. The resistor heater generated slower temperature variation on the GPS, it's visible a glitch everytime there was a temperature variation, and the drift magnitude seem to follow the variation of the temperature in time (dT/dt). I will try to reduce temperature sensivity incrementing the thermal capacitance and isolating the GPS from the ambient. Is this normal or it's a defect (feature) of my unit? I'm also curious about what internal structure can generate this wander in PPS. Like I said before it's like if the PPS pulse (for intervals of few 100's of nS) depends on something that is very temperature dependent. Thanks, Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Questions about TAC frontend, and some measurements
Hello, hope you all had a happy Christmas. Back to the topic. Bob Camp asked: Hi One very simple question - how good would it do if you just did it all with logic gates? Tri-state buffers and things like that…. Now that you are up to a 100 to 200 ns long pulse, a lot of the fiddly stuff about can't get a 2 ns pulse through it goes away. I'm not suggesting you tear up what you have. It's just something else to try and compare Bob Bob, are you hinting to something like the last mail from Bruce? I.e. to use a tristate buffer to charge the capacitor? If not can you explicit what are you thinking? :) Thanks also to Alan Melia and Tom Miller for the details about bjt saturation . Bruce, about the tempco of the current generators, There is the led in series with a BE junction. The blue leds should have a tempco in mV per °C similar to th BE junction, dont know the red ones. Would it be better to use something like a 4.7 or 5.1V zener? If I remember correctly these zener voltage shuld cancel most of the BE tempco. And what about a TL431 instead of the led+bjt? The Avago diodes are pretty costly :) Is that circuit working like the internals of ECL logic families? The simplest (lowest part count and least number of power supplies) consists of a tristate buffer driving an RC circuit. The PPS signal is connected directly to the buffer input whilst the output of the PPS synchroniser (at least 2 stages to minimise the probability of metastabilty at the synchroniser output) drives the buffer tristate control input. A 2 stage syncronizer is composed of 3 FF? I.e. clock in parallel to 3 FF, PPS to the first D, Q from the first to D of the second, same from the second to the thid, and Q from the third to out. Let's assume that the inputs from PPS and 10MHz are fast enough, what can still generate metastability? Setup time violation? The RC network starts charging when the PPS signal goes high and stops when the synchroniser output goes high. The capacitor charging is nonlinear but this is easily corrected in software. The capacitor is connected between the input of a capacitive charge redistribution ADC and ground. Software correction for the effect of charging the charge ADC input capacitance is also required. I see you are stressing the fact of using a capacitive charge redistribution adc. I dont know much about the internals of the ADC devices, can you suggest a partnumber for an example? Suitable fast single gate tristate drives are readily available. With low tempco resistors and capacitors the TAC gain tempco can be 200pmm/C or less. The only disadvantages are the increased software complexity and the need for an extra bit of ADC resolution to maintain TAC resolution. The 3-state buffer + R-C seem an elegant solution for a microcontroller based thing, I'v given an eye to logic buffers, and seem that all suggest that the Hi-Z state leackage current is not very well specified, but something around 1uA, that means that cap's voltage after the pulse can rapidly (and unpredictabily?)change due to leackage. I imagine also that the leackage of the buffer will vary with temperature. The ADC of the micro is pretty fast, I shuld check the datasheet but I remember around 1uS per conversion, what would happen connecting directly the micro ADC to the charged cap? And sync the ADC to sample immediately (few uS) after the pulse. Could the loading from the s/h capacitance be corrected in fw? Bruce By the way, I updated my miserable schematic, I tried a simple mod to avoid the saturation of the switches. Only because I had it already built: http://pastebin.com/9VHkhmSv Now I'm chasing the origin of the drift variation, logging the temperatures and voltages. More on this as soon as I have some data. Thank you all, Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Questions about TAC frontend, and some measurements
Il 2012-12-23 11:36 Bruce Griffiths ha scritto: The simulation indicates that the TAC capacitor charging current is far from constant whilst charging. This is due to the use of saturated switches rather than current steering switches. The capacitor charging current is poorly controlled. So in this respect your circuit fails miserably. So if I'm understanding correctly, the non linearity is due to the uncontrolled current flowing from the collectors to the bases of saturated transistors, that changes the magnitude of charging current in uncontrolled way. I was trying to use a sungle supply, but now I'm starting to see the limits of my implementations. Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Questions about TAC frontend, and some measurements
Il 2012-12-23 07:42 Bruce Griffiths ha scritto: The classic TAC using current mode switching is similar to the attached circuit schematic. Bruce I tried to replicate the circuit you attached, the pic was low resolution so I tried to figure the values. This is the circuit asc text http://pastebin.com/EkgqmgfE If you have time please check it, and tell me the errors, thanks. *I wish to all the members of the list a happy Christmas* Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Questions about TAC frontend, and some measurements
When it comes to phase, your interpolator may also be sensitive. Dont know if I was clear enough, just in case I wasnt able to explain well before: the data I collected didnt came from the analog interpolator, but from the OutD that is a digital out. The interpolator is still in it's infancy. So if I'm understanding you are suggesting to measure on the second 10MHz edge, instead of the first, I would have 100 to 200nS instead of 0 to 100nS. I didnt think about this, I like the idea! Indeed. Some even let one more edge go and measure between 200 and 300 ns. I modified the schematic this way to use the second edge: http://www.flickr.com/photos/14336723@N08/8297438155/ Like that you try your interpolator wings! Sorry, I didnt undestand this part. Trivial, I like that you experiment and build your own interpolator design, build experience. Thanks, I like to experiment directly when I can. This puts me in front of the real problems. And by the way playing with the interpolator is something that I'm enjoing; that few transistors are making something that was sort of magic for me before: converting nanoseconds pulses in something that can be easily read. In this work I'm only starting and I'm already on the edge of my little knowledge on electronics, and I'm learning much from the resources and contributors to this list. Good luck and look forward to your progress reports. I will happily keep sharing the work. You got me inspired to try something myself. :) Wow :) Thank you, Fabio. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Questions about TAC frontend, and some measurements
Hello, Bruce Using saturated transistors as switches in the current source and elsewhere isn't conducive to fast switching. The traditional arrangement using current mode switches is much faster and more predictable. This is something I'd like to understand better. I'm referring to this schematic here: http://www.flickr.com/photos/14336723@N08/8293076065/ Q2 and Q5 are saturating toward the end of the ramp pulse, when the ramp capacitor C1 starts to go up. I was prepared to see the circuit I designed fail miserably on switch time, but it seem to be working, as far as I could see on the DSO. As far I can understand, the fact that Q2 and Q6 don't saturate, saves the circuit, since at the end of the ramp, when Q1 and Q5 are into saturation, Q6 is able to steer the current to ground, and reverse bias BE (and CB) of Q5. Is this correct, or I was only lucky with the specific parts I used? Buffering the ramp with an opamp requires that the opamp settling time be known so that the opamp has fully settled before a sample is taken. With a charge redistribution ADC that has a sampling switch connected to a capacitor array a buffer isnt usually necessary. Bruce I was planning to read the voltage with a microcontroller's ADC. I will set a fixed delay from the PPS rising edge and start sampling there. To do so I need that the voltage on integrating capacitor to stay reasonably stable during the delay. Fabio ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] MT3339 PA6H and Racal Dana GPIB, update
Thank you all for the advices. I will prepare the setup for a longer logging session, using an inverter and a battery for power backup. Now I'm starting building of a clock shaper and a divider for the 10MHz signal, I will use 7AC gates for both the squarer and divider, since I have many of them here, no need to buy anything. The question is: watching the previous log, how much will the results be influenced by the GPS antenna and it's cabling ? (now I'm using this one: http://www.mirifica.it/store/gps-antenne/347-globaltop-fgpane-sma-5-m.html) Thanks, Fabio. Azelio Boriani azelio.bori...@screen.it ha scritto: Yes, this is the typical GPS receiver PPS wander. It is usable for a GPSDO as it seems of timing quality (the Motorola M12M is -20nS..+20nS over 10 days). See: http://www.jackson-labs.com/assets/uploads/main/Motorola_M12.pdf on page 7. On Thu, Dec 13, 2012 at 2:47 PM, Bob Camp li...@rtty.us wrote: Hi Ok, those plots look much more real. Thanks for sharing. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Fabio Eboli Sent: Thursday, December 13, 2012 7:58 AM To: time-nuts@febo.com Subject: Re: [time-nuts] MT3339 PA6H and Racal Dana GPIB, update Bob, timenutters here are the first results, hope I'm not boring the members with these posts, for most participants these are basic things. Now I'm trying to understand if the setup is working or I have to modify some things. The logging is at 47000 samples and going, the script is working well now, and I dont have glitches so far. Raw data, time interval between the pulses: http://www.flickr.com/photos/14336723@N08/8269800802/ Positive thing is that the drift seem consistent with the previous decimated pulse period data. Data corrected for linear drift and offset, the actual values are in the graph: http://www.flickr.com/photos/14336723@N08/8269800868/ Here I dont' like very much what I see, but surely I'm not knowledgeable enough to judge the data :) Some notes for who didnt read previous posts: Racal 1992 counter, start on pps from FE5680 #1 stop on gps pps from PA6H GPS module, Counter External standard is 10MHz from FE5680 #2. The Fe5680 #2 was powered one hour before the session start, and it's mounted near the FE5680 #1, so there is some thermal stabilization in the first hours. Also I dont have any signal amplification and squaring, the trigger on the counter is set at half the pulse peak voltage, both rising edges. Is the graph what I should expect from the gps signal, or I'm seeing some problems in the setup? Thanks, Fabio. Bob Camp li...@rtty.us ha scritto: Hi That approach works well. If you have them about a half second apart I'd stick with that setup. Bob This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing 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. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] MT3339 PA6H and Racal Dana GPIB, update
Bob, timenutters here are the first results, hope I'm not boring the members with these posts, for most participants these are basic things. Now I'm trying to understand if the setup is working or I have to modify some things. The logging is at 47000 samples and going, the script is working well now, and I dont have glitches so far. Raw data, time interval between the pulses: http://www.flickr.com/photos/14336723@N08/8269800802/ Positive thing is that the drift seem consistent with the previous decimated pulse period data. Data corrected for linear drift and offset, the actual values are in the graph: http://www.flickr.com/photos/14336723@N08/8269800868/ Here I dont' like very much what I see, but surely I'm not knowledgeable enough to judge the data :) Some notes for who didnt read previous posts: Racal 1992 counter, start on pps from FE5680 #1 stop on gps pps from PA6H GPS module, Counter External standard is 10MHz from FE5680 #2. The Fe5680 #2 was powered one hour before the session start, and it's mounted near the FE5680 #1, so there is some thermal stabilization in the first hours. Also I dont have any signal amplification and squaring, the trigger on the counter is set at half the pulse peak voltage, both rising edges. Is the graph what I should expect from the gps signal, or I'm seeing some problems in the setup? Thanks, Fabio. Bob Camp li...@rtty.us ha scritto: Hi That approach works well. If you have them about a half second apart I'd stick with that setup. Bob This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing 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] MT3339 PA6H and Racal Dana GPIB, update
Racal 1992 GPIB, to Chuck Forsberg: thank you, I will go to see your work. A little update, after about 20 hours this is the logging situation: http://www.flickr.com/photos/14336723@N08/8267828444/ Not bad, seem the GPS chipset jitter claim of 10nS is real, what do you think. Could this unit be a decent one for a GPSDO attempt? The values are the difference from 1s value in ns: Blue: (1-Period)*1E9, left y axis Red: Boxcar average 100 samples, right y axis Yellow: same as red 1000 samples. I had only few glitches, that are filtered out in the previous calculations: http://www.flickr.com/photos/14336723@N08/8266795789/ one with a reading of precisely 1,5s (the negative one) and a periodic lack of record, the positive values. This Rb unit seem pretty close to the mark, more than another unit I have. I'm thinking to try the other method Azelio Boriani advised me to do (26 november 2012), using the pps output from this Rb as a reference. If I understand well, I should use the Rb as start and the GPS as stop on the counter, measuring the phase, and I should see a very long time before the signals cross. The pulses relative position will be obtained with a little luck :) Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] MT3339 PA6H and Racal Dana GPIB, update
Bob Camp li...@rtty.us ha scritto: Hi 20 hours should be 20*60*60 = 72000 samples. The graphs appear to show about 17,000 samples. Hello Bob, unfortunately I'm not logging all the pps samples, I'm picking one sample every about 4 pulses, because I'm triggering the counter and waiting 4s before reading the result. So these are not consecutive pps periods. See my previous message of 11-Dec 23:36. Here I have two main problems I will try to solve for now: - I have to understand how to sync the logging script to the counter, so I can read all the values. - The counter cannot read every pps in period mode, but one every two, so I will try to use the start-stop method, since this FE5680 frequency is fortunately very close to the mark. If the results do cover a 20 hour period and do not have drift removed, that's a good FE5680. 1.4x10^-14 is an amazing number for one of those. Bob Sorry, here I don't follow you, maybe my graph is misleading, or I'm not understanding, but I see that the FE5680 frequency seem wrong by 3x10^-10 and goes up and down by 3 to 4x10^-10, it's not thermoregulated but simply mounted on an aluminium plate, into a room not thermoregulated. Fabio This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] MT3339 PA6H and Racal Dana GPIB, update
Bob Camp li...@rtty.us ha scritto: Hi Ok, so the data is already decimated and it does show a 20 hour period. Yes The way I'm reading things - the pps's start out at zero offset on the left side (yellow line at about sample 350). They still are at roughly zero offset on the right side (at about sample 17045). Total peak to peak in the yellow line is 0.5 ns. Total peak to peak in the red line is 1.4 ns. One ns over 20 hours would be 1.4x10^-14. I will think about this, now I cannot still figure it out :) So back to the original question - was drift in the pps removed before the graph was done? No, the only filtering was the removing of the glitches: the blue graph is the result of if Period is a number between 0 and 1,4s then plot (1-Period)x10^9 the other are the averaging, each sample is averaged with it's neighbours, 100 samples for the red (50 before and 50 after) and 1000 samples for the yellow (500 before and 500 after). Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] MT3339 PA6H and Racal Dana GPIB, update
Bob Camp li...@rtty.us ha scritto: Hi If you are driving the counter's frequency standard input with the FE5680 and simply measuring the period of the GPS output, then the data would make sense. Bob, the data make sense :) I'm using the FE5680 as ext standard for the counter, the pps is measured as period. I am assuming that the counter starts counting on the pps out of the FE5680 and stops counting on the pps out of the GPS. That way every sample is the time difference between the two. Not now. This will be the next try, at least now I know that I should be able to get enough room for non overlap the periods for some time. I have only a doubt: is the internal OCXO of the counter enough for the phase measurement or I should use the other FE5680 as ext standard for the counter? I will have the pps let's say 0,5 seconds apart, the counter will give 1nS resolution, and will be 2x10^-9 on that interval, pretty demanding I think. The better way will be to connect the PC to the FE5680 and drive it's pulse close to the pps, but I should bring out the serial lines. Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] MT3339 PA6H and Racal Dana GPIB, update
Thanks Bob, the next logging session will be setup as per your suggestion. Now I'm logging with the counter in time interval, Rb 1 is the start, GPS is the stop and Rb2 is the ext reference. The pulses are 670mS apart now. Fabio. Bob Camp li...@rtty.us ha scritto: Hi Yes, I would run the FE5680 into the counter's frequency standard input. For the real data, you can set up the counter to start on the GPS pps and stop on the 10 MHz output from the FE5680. You will only have 100 ns of range. You can unscramble the data after the fact. If you don't want to unscramble things, divide the 10 MHz down to 100 Hz and put that into the stop channel. Lots of fun. Bob This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing 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] MT3339 PA6H and Racal Dana GPIB
Hello, this afternoon the post(wo)man handed to me the little box with the PA6H GPS modules. I bought also an antenna with 5mt cable, so I can use it in the lab. The module is up and running, requiring only 3V3 supply, locking very fast, about 30s from cold start, here is it, working with ext antenna: http://www.flickr.com/photos/14336723@N08/8264614897/ And now I'm trying to setup a logging session to try to log interval measurements with the counter: http://www.flickr.com/photos/14336723@N08/8265684680/ Now this is what I have done, the goal is to try to have some jitter measurements for the PPS output: - A FE5680A is the timebase for the counter - the counter is a Racal Dana 1992 - the FE5680A 1Vpp output is connected directly to rear reference input of the counter - the counter measures the PPS signal from the GPS module, Time interval A, 9 digits (single shot) 1nS resolution. After fighting with the counter's GPIB interface now I'm logging a stream of time intervals. I'm not catching all the pulses, but only one each 2 or 3, depends. - Is this setup enough to get meaningful data? - If so how long should I log the data? - If not what should I modify? - Once collected the data, what kind of analysis should I do? And for who have ever used the Racal Dana 1992 with GPIB interface: I feel dumb, but I could not figure how to poll the instrument for the availability of last data. Now the sequence i do is this: - T1 - wait for trigger - T2 - trigger - wait 4 seconds - read result - T2 - trigger - wait 4s etc... Doing so I catch only part of the pulses, is there a way to make it better? This is a graph of the first thousand records: http://www.flickr.com/photos/14336723@N08/8265826150/ Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] STM32 based thing (was GPSDO Alternatives)
Michael Tharp g...@partiallystapled.com ha scritto: On 12/6/2012 4:26 AM, Fabio Eboli wrote: Are you using the pll to obtain 72MHz (x9) for the clock? Yes, the crystal oscillator is multiplied up to 72MHz which then drives the timer. Even though the particular timer peripheral I chose happens to be on the APB1 bus which is restricted to 36MHz, the timer itself is still fed with the 72MHz clock. Both PPS signals (generated from OCXO and received from GPS) are then independently timestamped. Ok, now I understand. How is faring the pll clock on 1s intervals? The datasheet reports 300pS jitter, that should be good. My plan for now is this: (sorry if my terms are not exact), i will start with a Rb instead of an OCXO. I want to try to measure the ratio between the GPS and the Rb, to do so I will use the Rb 10MHz clock a timebase for the pps. The first counter will be setup as input capture with external clock, the clock is the Rb 10MHz and the captured will be the rising edges of the GPS. This will give a count of around 10^7. Then I will use a second counter with internal clock that will start on the pps edge and stop on the Rb edge, the result will go from zero to 100nS/13.9ns=7 This count will give some interpolation. As far as I understood all this could be done in the internal hw, but it remains to be seen if there are problems with the actual hardware (bugs, silicon errata etc). The external hw for now will be a normal XO for the micro, and some logic to square the inputs, perhaps I will setup also a FF to have a pulse that starts with the PPS and stops with the first 10MHz edge, this will be useful for testing with the real counter and to eventually implement an analogue TAC. Just now I was simulating on ltspice some TAC interpolators, if the previous system will go I'm thinking to add an analog interpolator that will convert the 0 to 100nS edge difference between the Rb clock and the pps in analog value, to increment the single shot resolution. I was also thinking that for the disciplining I dont need to have the interpolator giving the exact time interval, but I need it only be sensitive and stable enough. The control loop is entirely another problem :) Ok now I need to start burning some flash to check if the thing can go somewhere. Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] STM32 based thing (was GPSDO Alternatives)
Bob Camp li...@rtty.us ha scritto: Hi I believe your second counter (the one that starts on one edge and stops on the other) will have trouble. It is unlikely you will get your 14 ns resolution out of it. Are you thinking to sync logic inside the device or other problems? (not considering defects like bugs or silicon errata). The analog TDC is a fine idea. Cheap, easy, Easy for many, not for me. This is why I like the idea to play with the TAC, I have very little experience with such high speed stuff, it's like going where I've never been, so I'm curious. and requires a few parts that are not built into the micro controller. The simple answer is to use a cheap CPLD (possibly sub $2) for a bunch of this stuff and move on. A possible way to go if I cannot reach meaningful results form the Idea I want to try. Now I dont have pld stuff at hand, I should make a board and buy the parts, or search for devboards, while the micro stuff I have is there, ready to go :) Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] STM32 based thing (was GPSDO Alternatives)
Fabio Eboli fabi...@quipo.it ha scritto: Bob Camp li...@rtty.us ha scritto: The analog TDC is a fine idea. Cheap, easy, Easy for many, not for me. This is why I like the idea to play with the TAC, I have very Here I'm using TAC and TDC for the same meaning... little experience with such high speed stuff, it's like going where I've never been, so I'm curious. Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] STM32 based thing (was GPSDO Alternatives)
Hello Michael! Michael Tharp g...@partiallystapled.com ha scritto: On 12/05/2012 08:03 AM, Fabio Eboli wrote: I'm seriously thinking to attempt a gpsdo. ... The platform I will try to use is the STM32F103 microcontroller Coincidentally, my previous time-nut project was built around the same chip. I built a simple GPSDO using a STM32F103C with a bit of ... Here are the design documents, if you're curious: http://hg.partiallystapled.com/circuits/serafine/raw-file/d75ab09ca163/out/production.PDF Thank you very much, I will study it with interest, it will be very helpul to see what you have done. Can I ask you more details? I didnt's understand how you are using the timers: are you timestamping each pps transistion using the internal clock? Are you using the pll to obtain 72MHz (x9) for the clock? same as many, if not all, other GPSDOs out there. I'm reasonably happy with the hardware as a GPSDO experimentation platform (but not looking to sell anything at this time). Good, to be clear my project will not be commercial in any way, only an amateur attempt, documented as far as my time permits. And my skills are not enough for anything that can be sold in this field :) The current project, as I've mentioned before, is a self-contained GPS-to-NTP server based on STM32F107, which has built-in ethernet but is otherwise very similar to the F103. The finished board won't be This is another advantage of the STM32 (or other manufacturers cortex arm micros), one can easily port the project up to higher specs devices; for example ST sells the stm32F4 discovery for around 20eu that is powered by an stm32F407 that is cortex M4F device full of ram and flash and communication ports, and that support FPU etc, it's a 168MHz device, but I'havent checked it's timers capability. I will stick with the 103 for now, my goals are the basic ones: building a counter and figuring out how to discipline a Rb, the communication/logging/pc support software is really a big work to do and i'm not planning to go there for some time :) Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing 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] STM32 based thing (was GPSDO Alternatives)
Hello, I've written few messages on this mailing list, I'm an absolute beginner on timing science. I've never introduced myself, so this is a sort of introduction... Although this has nothing to do with arduino, reading the post by Chris Albertson about an arduino-based GPSDO, I will share what I'm thinking to do. Now I'm slowly documenting myself, the argument is so vast and over my head that I need time to start understanding, the luck is that this mailing list (their memebers) is... powerful :) I'm seriously thinking to attempt a gpsdo. It's mainly to learn something new. For some reason I collected some Rb oscillators, and I'd like to have a 10MHz absolute reference, so I will try to discipline one of the Rb, and later maybe an OCXO. The project will proceed slowly and there is some probability (small, but not null) that it will be abandoned, because of time problems of the author (could be a paradox?). The platform I will try to use is the STM32F103 microcontroller, the reasons are: - Mainly I have some devboards I used to develop some hw in the past, that now sit unused, and since I've used it in the past I have some experiece with it. - It contains extensive timing hw, it can measure external pulses with internal 72MHz Ck as timebase, downside is the 72MHz is internally generated by a PLL from a lower frequency. - It has two 12bit DAC, and external reference options. - It has good and fast (12bit 1uS) ADC useful if one would try to build a time to amplitude interpolator (is that name right?). - DMA facility to collect measurements without messing with nested interrupts. - At least two RS232 interfaces, easy to interface to a PC. For a beginner probably the learning curve is steeper than an arduino, but I never used arduino, so cannot compare. But for who is not accustomed to program an arm micro, I think it will not be too difficult to try: - devboards are CHEAP (ST and others seem to sell them at less than the IC cost alone) - Programming the flash is easy, the uc contains a bootloader, you only need an usb-to serial adapter - Once developed a working example, one can mod the progam easily, it will be written in C language. - There are free and working toolchains for these devices. For now my plans are rather nebulous, but roughly: - I will start trying to check the jitter of the GPS I will use (hope I receive it soon), with a counter and a PC. - I will start building a time interval counter with the stm32, that will use an external 10MHz as timebase to measure the PPS of the gps, this will make me getting familiar with internal micro timers, they have some million possible configurations. I will try to use the internal PLL clock as a digital interpolator, to try to reach better than 20nS resolution. - start to build some form of simple disciplining... dont know yet how. Fabio. Chris Albertson albertson.ch...@gmail.com ha scritto: With the price of T-Bolts now higher, does it make sense to build your own GPSDO? What is the simplest phase detecter that could work? I think only that, and then a duouble oven crystal from eBay, a GPS and and Arduido. Yes the Aruino is expensive compared to a bare uP chip but using one, I thin you could build a GPSDO without a PCB and the Arduino's USB connection could be usful for power and logging/control. If ther phase detector where simple enough it could be build on a prototype board the fits on top of the Arduino. There are some other designs but because programming a uP and making a PCB seem to be rare skills that job tends to fall on one person. Anyone can program an Arduino and with out need of a PCB the entire design could be puted on a web page and the replicated with common parts. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing 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] Re: MT3339 chipset 10ns jitter?
Hello Jacques, and the List.
Thank you for sharing these docs.
Indeed the PPS specs of the MT3339 are confusing.
Maybe measurement on a living specimen can help?
I have a R-D 1992 counter, and a GPIB interface.
When I will have the GPS I will be able to log
some data on the PC, although I never tried to use
the Racal Counter remotely I will try.
Also I hope somebody can suggest the best way to test
the PPS from the gps using the Racal 1992, I'm not a
time nut, so I could make gross errors.
I was thinking simply to measure and log the PPS
connected to input A with the counter set to
Period A, and 10s integration time to gain
more resolution, all this for some (many?) hours.
Fabio.
Jacques Tiete jacq...@tiete.org ha scritto:
Hello TNutters,
maybe new thread?
you can have a look at two specsheets of the MT3339 chipset on my FTP-site
1) http://nixie.ramdac.be/TNutstuff/MT_IT530_Data_Sheet_rev_1_0.pdf
on page 8 PPS output 100 ms high pulse, rising edge +/-1 μs @
full second GPS epoch... so it states +/-1 μs
2) http://nixie.ramdac.be/TNutstuff/gtop module application note
-a00 _mt3339 series_.pdf
on page 32 The accuracy level of 1PPS for GlobalTop GPS module is
within 100ns (same for majority of MTK GPS modules).
The reference design below can help improving this accuracy to
within 80ns.
but on page 14 1PPS signal is an output pulse signal used for
timing application, its electronic characteristic are listed below:
1PPS signal and its pulse width
with 100ms duration
Low Voltage level: 0~0.4V
High Voltage level: 2.8~3.1V
Duration: 100ms (Firmware
customization for duration is available)
Period: 1s Accuracy
(jitter):10ns
So what shall we believe?
The rest of the PDF's make a good read.
73's
Jacques
Message: 4
Date: Fri, 23 Nov 2012 16:44:27 +0100
From: Jacques Tiete jacq...@tiete.org
To: time-nuts@febo.com time-nuts@febo.com
Subject: Re: [time-nuts] time-nuts Digest, Vol 100, Issue 95
Message-ID: 7c466c42-c05a-46e2-b3c4-793672874...@tiete.org
Content-Type: text/plain; charset=us-ascii
About:
{
Date: Thu, 22 Nov 2012 22:26:24 +0100
From: Fabio Eboli fabi...@quipo.it
To: time-nuts@febo.com
Subject: [time-nuts] MT3339 chipset in Globaltop's FGPMMOPA6H
Message-ID: 2012112624.71854hb9oslin...@webmail.micso.net
Content-Type: text/plain; charset=ISO-8859-1; DelSp=Yes;
format=flowed
Hello, while asking info about the FE5682,
I realized that for another project
(model plane data logging) I will buy
some cheap gps modules built around an
MT3339 chipset.
In my mind somewhere I stored the fact
that in the datasheet of these module
is mentioned the pps output, so I checked
and the manufacturer is claiming that it
has High accuracy 1-PPS timing support
for Timing Applications (10ns jitter)
This is the module I'm talking about:
http://www.mirifica.it/store/gps/342-globaltop-fgpmmopa6h-pa6h.html
http://www.alcom.be/binarydata.aspx?type=doc/GTop-FGPMMOPA6H-Datasheet-V0A.pdf
Has anybody used this chipset or similar for GPSDO?
I have no experience with discipled oscillators
but if there is any hope that the pps out
of these modules is good for the task maybe
it's time for me to start reading more about
the subject.
The final goal will be to check the timing
of the Rb I have around.
Thanks,
Fabio.
}
Hello TNutters,
I did some test with this module from Adafruit
(http://www.adafruit.com/products/746) and it seems not a bad unit.
Tested it together
with my TBolt and the PPS seems quite stable most of the time, I did
not do any logging and math on the result,
just letting the TBolt trigger the scope and apart from the cable
offset I guess 80% of the time the module was
within 10 to 15 ns.
However the specs are not very clear and it is a typical chip for
mobile use in eg. carnav stuff. I also saw some
other specs where the jitter was specified as 100ns. and even one
with a 1 microsec. so I'm a little confused.
As soon as I have some time I plan to connect this module to a
BeagleBone and do some testing for an NTP server
I think the Beagle is better for this than the RaspBerry because of
the real ethernet port.
Greetz,
Jacques Tiete
0499 99 83 78
jacq...@tiete.org
Op 23-nov.-2012 om 00:19 heeft time-nuts-requ...@febo.com het
volgende geschreven
This message was sent using IMP, the Internet Messaging Program.
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Re: [time-nuts] time-nuts Digest, Vol 100, Issue 95
Hello Jacques,
what revision of the module do you have?
On adafruit's page, under Downloads tab
you can see that they use 3 different GPS units:
PA6B for first revision, built around an MT3329
PA6C for the second and PA6H for the third,
both with MT3339 chipset.
Where did you see the different jitter claims?
Globaltop's site has the most recent datasheets,
but you need to sign up and they dont contain much
info anyway:
http://www.gtop-tech.com/en/category/GPS-Antennt-Module/A01_MT3339.html
Fabio.
Jacques Tiete jacq...@tiete.org ha scritto:
About:
{
Date: Thu, 22 Nov 2012 22:26:24 +0100
From: Fabio Eboli fabi...@quipo.it
To: time-nuts@febo.com
Subject: [time-nuts] MT3339 chipset in Globaltop's FGPMMOPA6H
Message-ID: 2012112624.71854hb9oslin...@webmail.micso.net
Content-Type: text/plain; charset=ISO-8859-1; DelSp=Yes;
format=flowed
Hello, while asking info about the FE5682,
I realized that for another project
(model plane data logging) I will buy
some cheap gps modules built around an
MT3339 chipset.
In my mind somewhere I stored the fact
that in the datasheet of these module
is mentioned the pps output, so I checked
and the manufacturer is claiming that it
has High accuracy 1-PPS timing support
for Timing Applications (10ns jitter)
This is the module I'm talking about:
http://www.mirifica.it/store/gps/342-globaltop-fgpmmopa6h-pa6h.html
http://www.alcom.be/binarydata.aspx?type=doc/GTop-FGPMMOPA6H-Datasheet-V0A.pdf
Has anybody used this chipset or similar for GPSDO?
I have no experience with discipled oscillators
but if there is any hope that the pps out
of these modules is good for the task maybe
it's time for me to start reading more about
the subject.
The final goal will be to check the timing
of the Rb I have around.
Thanks,
Fabio.
}
Hello TNutters,
I did some test with this module from Adafruit
(http://www.adafruit.com/products/746) and it seems not a bad unit.
Tested it together
with my TBolt and the PPS seems quite stable most of the time, I did
not do any logging and math on the result,
just letting the TBolt trigger the scope and apart from the cable
offset I guess 80% of the time the module was
within 10 to 15 ns.
However the specs are not very clear and it is a typical chip for
mobile use in eg. carnav stuff. I also saw some
other specs where the jitter was specified as 100ns. and even one
with a 1 microsec. so I'm a little confused.
As soon as I have some time I plan to connect this module to a
BeagleBone and do some testing for an NTP server
I think the Beagle is better for this than the RaspBerry because of
the real ethernet port.
Greetz,
Jacques Tiete
0499 99 83 78
jacq...@tiete.org
Op 23-nov.-2012 om 00:19 heeft time-nuts-requ...@febo.com het
volgende geschreven
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Re: [time-nuts] FE-5682A coming, any info?
Ziggy Bob and paul, I'll open it up and check. I have a pair of lab psu to test the unit and a pair of FE5680 to compare the timing. Thank you all for the useful info. Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing 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] MT3339 chipset in Globaltop's FGPMMOPA6H
Hello, while asking info about the FE5682, I realized that for another project (model plane data logging) I will buy some cheap gps modules built around an MT3339 chipset. In my mind somewhere I stored the fact that in the datasheet of these module is mentioned the pps output, so I checked and the manufacturer is claiming that it has High accuracy 1-PPS timing support for Timing Applications (10ns jitter) This is the module I'm talking about: http://www.mirifica.it/store/gps/342-globaltop-fgpmmopa6h-pa6h.html http://www.alcom.be/binarydata.aspx?type=doc/GTop-FGPMMOPA6H-Datasheet-V0A.pdf Has anybody used this chipset or similar for GPSDO? I have no experience with discipled oscillators but if there is any hope that the pps out of these modules is good for the task maybe it's time for me to start reading more about the subject. The final goal will be to check the timing of the Rb I have around. Thanks, Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@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-5682A coming, any info?
I hope so, the 5680 takes approx 22W on startup, if it is the same on the 5682 that shuld be less than 1/2A Fabio. Hi At 48 volts I would expect the startup to be well below an amp... Bob On Nov 22, 2012, at 12:51 PM, paul swed paulswedb at gmail.com wrote: Good luck and remember that when it starts the current will be much higher then when it runs. As I recall I think 2 amps when warm 750 ma... This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] MT3339 chipset in Globaltop's FGPMMOPA6H
I guess you are right :) Let's put this way: I will try to use that module's pps to try to build a GPSDO, or I'll try to discipline one of the Rb oscillators, once I will have gathered enough reading material. Unless of course somebody tried before and found show stoppers with such modules. Fabio. P.S. Sorry for non-threading mails, probably I'll have the issue sorted with the next messages. In my opinion, you should read about GPSDOs anyway. The availability of a precise PPS or not, should not prevent you from increasing your knowledge. On Thu, Nov 22, 2012 at 10:26 PM, Fabio Eboli FabioEb at quipo.it wrote: Hello, while asking info about the FE5682, This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing 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-5682A coming, any info?
Hello, I have a pair of FE-5682A coming, not that I need them, but I had flat shipping from the seller freakyflickers on ebay fro another item, I was asked 14USD each. I'm a bit confused by the pinout on the datasheet: http://www.ko4bb.com/Manuals/05)_GPS_Timing/FEI/FE-5682A_Datasheet_REVB.pdf The pinout: 1 RF out 2 RF RTN (Chassis GND) 3 DC ISOL RF RTN 4 CHASSIS GND 5 Lamp Volts 6 BITE OUT 7 EXT. C-FIELD V adj. 8 -48V RTN 9 CRYSTAL V MON 10 POWER -48V a) power supply: On the specs it reports Input Voltage Range +19 TO +32Vdc but the pinout reports pins 10 POWER -48V and 8 -48V RTN how is supposed to be powered? b) pins 1 and 2 seem self explanatory, but pin 3 DC ISOL RF RTN what should mean? Should I connetc it to ground (or any reference I have)? c) pins 5 and 9 are monitors for working voltage of lamp and VCXO, am I correct? When I will have the units here I'll open them up and post some pics. Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@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-5682A coming, any info?
Thank you, Peter and Paul. Now I see that the pinout is almost identical to LPRO-101, the only difference are pins 8 and 10 for power supply. That's nice, I like the external C-Field control, and monitor voltage for lamp, they can be useful. I'm not familiar with telco power supplies, I know only that they used 48V with positive to ground. So the supply should be 48V, positive to pin 8 and negative to 10 ? Should I expect the GND to be connected to pin 8? Or it will be floating at middle voltage (hence the 19 to 32V rating), in this case all I need will be a dual 24V psu. Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing 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] About Racal Dana tactile switches
Hello, this is my first message on this list, I've read the recent thread about racal dana's switches, this is the way i've done it: http://imageshack.us/photo/my-images/194/pulsantenuovo1r.jpg/ in this thread more details: http://www.eevblog.com/forum/product-reviews-photos-and-discussion/racal-dana-1992-teardown/msg90950/#msg90950 A little crude but in a pair of hours i swapped all the switches. To obtain the proper tip shape to fit the original caps, i cutted a cross in a 2mm thick little brass plate and fixed it to a soldering iron, found the correct flow temperature of the plastic and the work was simple. The switches are normal 6x6mm tactile, only they tend to bounce sometime. Fabio. This message was sent using IMP, the Internet Messaging Program. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
