Re: [time-nuts] GPSDO Alternatives
Hal Murray wrote: albertson.ch...@gmail.com said: 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. You also need a good D2A to drive the EFC on the osc. A synchronous filter of a suitably level translated (CMOS analog switch plus low noise reference) PWM output should work well. 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. I wouldn't want to power a GPSDO from USB. It will get power cycled every time I need to work on the logging PC. Besides, you only get 2.5 watts. The oven will probably take more than that during warm-up. 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.
Re: [time-nuts] GPSDO Alternatives
Chris There is a low cost solution and I have the input circuit perfect for GPS on a $1 gate array I have boards and am presently using Shera original version. Would like to buy his version 402NE but have not been able to get a response from him. Have repeatedly asked for help on this list for some one to step forward to write the uproc. program. No one. The total material cost would be less than $ 25 PCB included GPS receiver OCXO or RB would be extra. If the FE 5680A with RS232 would be used cost is less than $ 15. There are now PIC's out there that can also do the timing function reducing cost even more but that will take more smarts. Bert Kehren In a message dated 12/4/2012 9:06:26 P.M. Eastern Standard Time, albertson.ch...@gmail.com writes: 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. On Tue, Dec 4, 2012 at 4:01 PM, Bob Camp wrote: > Hi > > I would guess that HP/Agilent/Symmetricom and Trimble made 100X more > GPSDO's than the next five people in the business combined over the 1995 to > 2005 period. > > Bob > > On Dec 4, 2012, at 10:26 AM, paul swed wrote: > > > Al > > I like the truetime products. In general easy to understand and last a > long > > time. > > But there never seemed to be that many. Sure they were used in > broadcasting > > and maybe power. But the others like the 3801 and tbolt were used in > telco > > and mobile apps so there were 10,000s turned out and thats why we get > them > > for cheap. I simply never see the truetime dc60 or gps units around. > Though > > I have my stock of dc468 sat clocks. :-) Working. I hacked a goes sat > > replacement 3-4 years ago. > > That said some of the older gps technology is a bit slippery on exactly > how > > good they are. > > So for perhaps amateur purposes they are totally fine but when you start > > comparing to a Tbolt or 3801 various behaviors apear. > > Odetics GPStars as an example slip cycles on purpose. Its a mode you can > > set and by default is how they are set. > > For what they were intended for they are perfect. But at least 1 X10 > poorer > > then other devices. Its not at all broken. It was a general time piece > for > > radio networks. Give or take 500 ms. > > Regards > > Paul > > WB8TSL > > > > > > On Tue, Dec 4, 2012 at 9:58 AM, Al Wolfe wrote: > > > >> Most of the choices I've seen here mention the Tbolts, 3801, 3805, > etc, > >> but I have never seen anyone mention the TrueTime XL-AK. It advertises > 40 > >> nsec 1 pps. Frequency as 1 x 10-12 per day. I have one and it seems to > work > >> well but have no way to test it against anything else yet. It has four > each > >> 10 MHz sine output that I have been using for house sync for HP3586, > >> HP8924c, PTS160, etc. > >> > >> So how does the TrueTime compare to other GPSDO's? > >> > >> Al, K9SI > >> > >> __**_ > >> 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. > -- 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] Very challenging phase noise measurement, does anyone have an idea??
Hello Time-nuts, I have to do a phase noise measurement and I'm wondering if anyone here has any ideas on that. We have to measure the phase noise of a 125kHz carrier (5Vp-p signal level). The measurement system should have a noise floor that is -164dBc/Hz at a distance of 1kHz to 8kHz away from the carrier. Our current plan is to use 2 of these sources, have one in free running mode and lock the other one to the first one using an XOR gate and then use the output of the XOR gate as an output signal. However, we are wondering if any of you know a better idea. Maybe there is an off-the-shelf piece of equipment that can do that that we could rent. Or maybe we could increase the frequency to a few megahertz using a pll, which means the signal comes into the measurement range of our FSUP phase-noise analyzer. Problem is, the phase detector would then need to have an insanely low noise-floor (in our idea the XOR also has to have this insanely low noise floor as well off course) so does anyone have experience with anything like this? Does anyone know an XOR with these good specs? I don't have a clue what a standard 74lvc1g86 would do. Needless to say the supply of this XOR would have to be ridiculously clean, but I do have a solution for that problem. Any help is greatly appreciated! Best regards, Hans Rosenberg ___ time-nuts mailing list -- time-nuts@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 challenging phase noise measurement, does anyone have an idea??
Hi Just about any of the high speed CMOS parts should work. A 74AC86 is about the earliest part I would trust. Any of the fast logic families that came after that should do equally well. Bob On Dec 5, 2012, at 7:03 AM, Hans Rosenberg wrote: > Hello Time-nuts, > > I have to do a phase noise measurement and I'm wondering if anyone here has > any ideas on that. We have to measure the phase noise of a 125kHz carrier > (5Vp-p signal level). The measurement system should have a noise floor that > is -164dBc/Hz at a distance of 1kHz to 8kHz away from the carrier. > > Our current plan is to use 2 of these sources, have one in free running mode > and lock the other one to the first one using an XOR gate and then use the > output of the XOR gate as an output signal. However, we are wondering if any > of you know a better idea. Maybe there is an off-the-shelf piece of equipment > that can do that that we could rent. Or maybe we could increase the frequency > to a few megahertz using a pll, which means the signal comes into the > measurement range of our FSUP phase-noise analyzer. Problem is, the phase > detector would then need to have an insanely low noise-floor (in our idea the > XOR also has to have this insanely low noise floor as well off course) so > does anyone have experience with anything like this? Does anyone know an XOR > with these good specs? I don't have a clue what a standard 74lvc1g86 would > do. Needless to say the supply of this XOR would have to be ridiculously > clean, but I do have a solution for that problem. > > Any help is greatly appreciated! > > Best regards, > > Hans Rosenberg > ___ > time-nuts mailing 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] PPS offset between GPS receivers
Hi Rather major typo there Should be - 2 us would NOT come as a big surprise. Bob On Dec 4, 2012, at 7:39 PM, Bob Camp wrote: > Hi > > Based on a quick look, the SkyNav does not appear to be a timing specific > part. A 2 us error in a navigation part would come as a big surprise. > > Bob > > > > On Dec 3, 2012, at 11:12 PM, Gabs Ricalde wrote: > >> I'm using a Symmetricom 58534A GPS timing receiver and a GPS board with a >> SkyNav SKG25A1 module driving stratum 1 NTP servers. >> >> On one of the servers, the ppstest output while the 58534A is connected >> looks like: >> source 0 - assert 1354495734.00102 >> source 0 - assert 1354495735.00040 >> >> When I switch the PPS source to the SKG25A1, the ppstest output >> indicates the PPS of that receiver is about 2 us early compared to the >> 58534A: >> source 0 - assert 1354495740.97923 >> source 0 - assert 1354495741.97905 >> >> The setup looks like this: >> 58534A GPS -> 10 m CAT5 cable -> MC3486 RS422 receiver -> GPIO >> active antenna -> 3 m cable -> SKG25A1 GPS -> GPIO >> >> Both receivers were factory reset before the test. >> I'm planning on getting another GPS receiver to check which receiver >> is at fault. Has anyone found timing differences this large with their >> GPS receivers? >> >> ___ >> time-nuts mailing 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] -hp- 5065A battery pack
Hi I have no problem with restoring gear to it's original state. I mostly was wondering just how much time the considered "enough" back when the 5365 was made. There's been a bit of drift in things like that over the years. Sounds like in this case, not as much as in other areas. Bob On Dec 4, 2012, at 8:37 PM, paul swed wrote: > But thats not HP. :-) > I would agree that a external ups would be about the same price and for > some of them you can slightly increase the battery size. There are a lot of > surplus ones out there for a very few dollars. Shippings normally the > bigger cost these days. > Regards > Paul. > > On Tue, Dec 4, 2012 at 7:42 PM, Bob Camp wrote: > >> Hi >> >> So roughly what a simple UPS would give you. >> >> Bob >> >> On Dec 4, 2012, at 7:34 PM, Dan Rae wrote: >> >>> On 12/4/2012 3:51 PM, Bob Camp wrote: Hi How much backup time does that battery pack give you? Bob >>> Bob, it's at least what they claim in the manual for that Option, >> something like fifteen minutes from what I remember. >>> >>> Dan >>> >>> ___ >>> time-nuts mailing 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] GPSDO Alternatives
Hi Does the synchronous filter on the PWM still have a sample and hold in it, or has somebody come up with a different approach? Bob On Dec 5, 2012, at 3:06 AM, Bruce Griffiths wrote: > Hal Murray wrote: >> albertson.ch...@gmail.com said: >> >>> 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. >>> >> You also need a good D2A to drive the EFC on the osc. >> >> >> > A synchronous filter of a suitably level translated (CMOS analog switch plus > low noise reference) PWM output should work well. >>> 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. >>> >> I wouldn't want to power a GPSDO from USB. It will get power cycled every >> time I need to work on the logging PC. Besides, you only get 2.5 watts. The >> oven will probably take more than that during warm-up. >> >> >> > 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.
Re: [time-nuts] GPSDO Alternatives
On 12/5/12 12:06 AM, Bruce Griffiths wrote: Hal Murray wrote: albertson.ch...@gmail.com said: 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. You also need a good D2A to drive the EFC on the osc. A synchronous filter of a suitably level translated (CMOS analog switch plus low noise reference) PWM output should work well. True.. but I think the OP was wanting something that doesn't require designing a circuit and building it. So what you really want is a high performance DAC on a Arduino shield, or, alternately, a high performance DAC on a cheap eval board that you can easily hook up to an Ardino type processor. This is a bit trickier.. Lots of ADC stuff out there, not so much DAC stuff. http://embeddednewbie.blogspot.com/2011/02/review-of-arduino-dac-solutions.html seems to have a number of approaches. Adafruit has a shield with a Microchip MCP4921 12 bit serial dac here's a 16 bit solution http://www.shaduzlabs.com/article-12.html but it's a "build it yourself" solution. If you're not size/mass/power constrained, you might be able to find an inexpensive used programmable power supply. I do this using a Prologix controller driving Agilent E3646 power supplies.. Big, Expensive, etc. but it does work. 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. I wouldn't want to power a GPSDO from USB. It will get power cycled every time I need to work on the logging PC. Besides, you only get 2.5 watts. The oven will probably take more than that during warm-up. 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] 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 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.
Re: [time-nuts] PPS offset between GPS receivers
Hi everyone, As Tom suggested, I redid the test with less than 1 ft. of wire from the PPS output to the GPIO without any logic gates or line receivers. Same result, the SKG25A1 was 2 microseconds ahead of the 58534A. Without any other way of testing, I would probably trust the output of the timing receiver more than the SkyNav module. Anyway the SkyNav board is an inexpensive unit and I wouldn't mind setting an offset in ntpd. I don't have a scope yet, and a low jitter PPS GPIO is the closest thing I have to a TIC. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PTTI 2012, part 2
I couldn't resist and did a little reading. So, the MIT Flea has MOT cells? That would seem to be the deal breaker to me. The rest is "just plumbing". And smoke and mirrors. On Tue, Dec 4, 2012 at 8:23 PM, wrote: > > > > In a message dated 12/4/2012 6:10:36 P.M. Eastern Standard Time, > docdai...@gmail.com writes: > > I will build one right away.. but I didnt see your request. My problem > is > surface mount components (the multipin or no leads)... I am not confident > in that. but I would certainly try. I am not a programmer and also > figure somebody with more soldering skills than those I have picked up > ruining things would be desired. I am always willing to try not to ruin > something. > > Doc > KX0O > > > On Tue, Dec 4, 2012 at 4:25 PM, wrote: > > > Paul > > Frankly I do not think I will live long enough to see a time nut build > a > > fountain Rb. Over the four years I have watched many smoke and mirror > > projects with nothing coming out of is. In German we have a saying: > paper > > is > > patient. We should walk before we run. > > Many members did buy a FE 5680, how many do you think are in operation, > if, > > there would be discussions about its temperature performance. take a > close > > look on page 7 figure 5 of the brochure, I also see it. Personally I > use a > > Shera loop. But that is an overkill and for some to complex since it > > requires direct analog C field control. My real focus is on controlling > > FRK-H, > > M100 and HP 5065. > > What is needed is a coordinated effort to start with temperature > control, a > > simple GPSDO only taking care of aging using RS232 interface an analog > > loop for controlling something like a Morion. Stability and accuracy > > could be > > in the 1 E-12 range, low cost able to be assembled by 90% of list > members, > > but then I proposed it once before looking for some one to develop the > > filter. No response, it is clear that very few are willing or able to > > actually > > build something. > > When Corby wrote about his experience with the dual mixer / counter, > large > > response and we will have a complete documentation set, but when I > asked > > for a few that would be willing to build one right away, I would make > > complete kits, I got one response. Sad, but that is the reality. > > How many FE 5680A door stops do you think are out there? How many > > PICTICII's do you think are in use? > > Bert Kehren Miami. > > > > > > In a message dated 12/4/2012 9:49:29 A.M. Eastern Standard Time, > > paulsw...@gmail.com writes: > > > > Basements the key. So for me bigger is better. Heck if its a rack thats > > ok. > > It gets interesting in what types of components you can use if you are > > willing to go larger. > > Great point on the laser and optics. Funny thing is for small change > you > > can actually get used optics bench components at least at the last MIT > > flea > > I ran across the items. They were snapped up by the way. > > From what I have seen of time-nuttery and Hydrogen masers I am actually > > not > > all that sure its beyond this group. > > Regards > > Paul > > > > On Tue, Dec 4, 2012 at 9:34 AM, Bob Campwrote: > > > > > Hi > > > > > > Indeed, you likely won't get USNO grade with a shoe box sized part. > You > > can > > > get one to work and do quite good ADEV. No, I haven't done it, I'm > just > > > going on what I've been told. The main point being that for a > basement > > > project - smaller is probably lower cost. > > > > > > Bob > > > > > > -Original Message- > > > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] > On > > > Behalf Of Poul-Henning Kamp > > > Sent: Tuesday, December 04, 2012 9:19 AM > > > To: Discussion of precise time and frequency measurement; Bill Dailey > > > Subject: Re: [time-nuts] PTTI 2012, part 2 > > > > > > > > > In message > > > > > > , Bill Dailey writes: > > > > > > >If you look at the papers on portable rubidium fountains > > > >they are significantly bigger than a shoebox (65 cm). > > > > > > Diameter is controlled by dispersion of the launched atoms > (=recovery > > rate) > > > and the layers of shielding. > > > > > > 65cm looked like close to a minimum for USNO grade, amateurs could > > probably > > > make do with less shielding. > > > > > > -- > > > Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 > > > p...@freebsd.org | TCP/IP since RFC 956 > > > FreeBSD committer | BSD since 4.3-tahoe > > > Never attribute to malice what can adequately be explained by > > incompetence. > > > > > > ___ > > > time-nuts mailing list -- time-nuts@febo.com > > > To unsubscribe, go to > > > https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts > > > and follow the instructions there. > > > > > > > > > > > > ___ > > > time-nuts ma
Re: [time-nuts] GPSDO Alternatives
A low noise sample and hold is still required. Bruce Bob Camp wrote: Hi Does the synchronous filter on the PWM still have a sample and hold in it, or has somebody come up with a different approach? Bob On Dec 5, 2012, at 3:06 AM, Bruce Griffiths wrote: Hal Murray wrote: albertson.ch...@gmail.com said: 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. You also need a good D2A to drive the EFC on the osc. A synchronous filter of a suitably level translated (CMOS analog switch plus low noise reference) PWM output should work well. 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. I wouldn't want to power a GPSDO from USB. It will get power cycled every time I need to work on the logging PC. Besides, you only get 2.5 watts. The oven will probably take more than that during warm-up. 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.
Re: [time-nuts] GPSDO Alternatives
Hi If the intent is to come up with something in the same league as the TBolt there are a few other things you will need: 1) Something to compare the two pps signals to within 0.1 ns. 2) A large amount of code on the control processor (there are a multitude of special cases ...) 3) A large amount of code on a PC to monitor it and control it (like Lady Heather) 4) A set of standards to compare it to while you train and debug it 5) The test gear to collect and analyze the comparison and debug data with (you will have many months of data) 6) Some sort of control over the feature list. The complexity of 2-5 will go up significantly each time a nice to have thing is added. Once you get past step one, the rest of that list dwarf's anything like which D/A to use. I'm not at all saying it can't be done. Only that the bulk of the effort starts after you have the hardware. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Jim Lux Sent: Wednesday, December 05, 2012 7:58 AM To: time-nuts@febo.com Subject: Re: [time-nuts] GPSDO Alternatives On 12/5/12 12:06 AM, Bruce Griffiths wrote: > Hal Murray wrote: >> albertson.ch...@gmail.com said: >>> 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. >> You also need a good D2A to drive the EFC on the osc. >> >> > A synchronous filter of a suitably level translated (CMOS analog switch > plus low noise reference) PWM output should work well. True.. but I think the OP was wanting something that doesn't require designing a circuit and building it. So what you really want is a high performance DAC on a Arduino shield, or, alternately, a high performance DAC on a cheap eval board that you can easily hook up to an Ardino type processor. This is a bit trickier.. Lots of ADC stuff out there, not so much DAC stuff. http://embeddednewbie.blogspot.com/2011/02/review-of-arduino-dac-solutions.h tml seems to have a number of approaches. Adafruit has a shield with a Microchip MCP4921 12 bit serial dac here's a 16 bit solution http://www.shaduzlabs.com/article-12.html but it's a "build it yourself" solution. If you're not size/mass/power constrained, you might be able to find an inexpensive used programmable power supply. I do this using a Prologix controller driving Agilent E3646 power supplies.. Big, Expensive, etc. but it does work. >>> 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. >> I wouldn't want to power a GPSDO from USB. It will get power cycled >> every >> time I need to work on the logging PC. Besides, you only get 2.5 >> watts. The >> oven will probably take more than that during warm-up. >> >> > 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.
Re: [time-nuts] GPSDO Alternatives
Hi I was hoping somebody had worked out a way around that. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Bruce Griffiths Sent: Wednesday, December 05, 2012 12:27 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPSDO Alternatives A low noise sample and hold is still required. Bruce Bob Camp wrote: > Hi > > Does the synchronous filter on the PWM still have a sample and hold in it, or has somebody come up with a different approach? > > Bob > > On Dec 5, 2012, at 3:06 AM, Bruce Griffiths wrote: > > >> Hal Murray wrote: >> >>> albertson.ch...@gmail.com said: >>> >>> 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. >>> You also need a good D2A to drive the EFC on the osc. >>> >>> >>> >>> >> A synchronous filter of a suitably level translated (CMOS analog switch plus low noise reference) PWM output should work well. >> 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. >>> I wouldn't want to power a GPSDO from USB. It will get power cycled every >>> time I need to work on the logging PC. Besides, you only get 2.5 watts. The >>> oven will probably take more than that during warm-up. >>> >>> >>> >>> >> 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] GPSDO Alternatives
I wonder if two hardware interrupts on the Arduino itself could not be used for phase locking? There's also an ARM 80 MHz version of the Arduino package that might be applied, admittedly at higher cost... Don Jim Lux > On 12/5/12 12:06 AM, Bruce Griffiths wrote: >> Hal Murray wrote: >>> albertson.ch...@gmail.com said: 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. >>> You also need a good D2A to drive the EFC on the osc. >>> >>> >> A synchronous filter of a suitably level translated (CMOS analog >> switch >> plus low noise reference) PWM output should work well. > > True.. but I think the OP was wanting something that doesn't require > designing a circuit and building it. > > So what you really want is a high performance DAC on a Arduino shield, > or, alternately, a high performance DAC on a cheap eval board that you > can easily hook up to an Ardino type processor. > > This is a bit trickier.. > Lots of ADC stuff out there, not so much DAC stuff. > http://embeddednewbie.blogspot.com/2011/02/review-of-arduino-dac-solutions.html > > seems to have a number of approaches. Adafruit has a shield with a > Microchip MCP4921 12 bit serial dac > > here's a 16 bit solution http://www.shaduzlabs.com/article-12.html but > it's a "build it yourself" solution. > > If you're not size/mass/power constrained, you might be able to find an > inexpensive used programmable power supply. I do this using a Prologix > controller driving Agilent E3646 power supplies.. Big, Expensive, etc. > but it does work. > 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. >>> I wouldn't want to power a GPSDO from USB. It will get power cycled >>> every >>> time I need to work on the logging PC. Besides, you only get 2.5 >>> watts. The >>> oven will probably take more than that during warm-up. >>> >>> >> 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. > -- "Neither the voice of authority nor the weight of reason and argument are as significant as experiment, for thence comes quiet to the mind." De Erroribus Medicorum, R. Bacon, 13th century. "If you don't know what it is, don't poke it." Ghost in the Shell Dr. Don Latham AJ7LL Six Mile Systems LLP 17850 Six Mile Road POB 134 Huson, MT, 59846 VOX 406-626-4304 www.lightningforensics.com www.sixmilesystems.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] Power Grid Time and Frequency
Do you have a link for the nifty site? Date: Tue, 04 Dec 2012 19:22:11 -0800 From: Jim Lux To: time-nuts@febo.com Subject: Re: [time-nuts] Time security musing - attacking the clock itself There's a nifty website out there that shows the instantaneous and integrated phase difference between various places on the pacific coast, so you can see power flow changing. = Simon Engineering is the art of making what you want from what you can get at a profit. ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] PTTI 2012, part 2
On 12/05/2012 03:26 PM, Mark Kahrs wrote: I couldn't resist and did a little reading. So, the MIT Flea has MOT cells? That would seem to be the deal breaker to me. The rest is "just plumbing". And smoke and mirrors. While participating at the NIST T&F seminars, one of the "tours" was in fact a lab in laser-cooling rubidium atoms. It wasn't all that hard with the right tools. We got to tune the lasers :) 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.
Re: [time-nuts] GPSDO Alternatives
Am 05.12.2012 18:31, schrieb Bob Camp: Hi If the intent is to come up with something in the same league as the TBolt there are a few other things you will need: 1) Something to compare the two pps signals to within 0.1 ns Following Ulrich Bangerts suggestions, that a loop time constant should be at about 3 hours (GPS disciplining an OCXO), do I really need that resolution? Ok, the more accurate, the better. But the question is: can I reduce this requirement when using long time constants (1s)? The ratio then is 10E14... Volker ___ time-nuts mailing list -- time-nuts@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 challenging phase noise measurement, does anyone have an idea??
Isn't the FSUP a 110K euros equipment 20Hz-50GHz capable? 125KHz shouldn't be a problem. I had an FSUP for 25 seconds to play with... really impressive but too limited test time to appreciate fully. On Wed, Dec 5, 2012 at 1:14 PM, Bob Camp wrote: > Hi > > Just about any of the high speed CMOS parts should work. A 74AC86 is about > the earliest part I would trust. Any of the fast logic families that came > after that should do equally well. > > Bob > > On Dec 5, 2012, at 7:03 AM, Hans Rosenberg wrote: > > > Hello Time-nuts, > > > > I have to do a phase noise measurement and I'm wondering if anyone here > has any ideas on that. We have to measure the phase noise of a 125kHz > carrier (5Vp-p signal level). The measurement system should have a noise > floor that is -164dBc/Hz at a distance of 1kHz to 8kHz away from the > carrier. > > > > Our current plan is to use 2 of these sources, have one in free running > mode and lock the other one to the first one using an XOR gate and then use > the output of the XOR gate as an output signal. However, we are wondering > if any of you know a better idea. Maybe there is an off-the-shelf piece of > equipment that can do that that we could rent. Or maybe we could increase > the frequency to a few megahertz using a pll, which means the signal comes > into the measurement range of our FSUP phase-noise analyzer. Problem is, > the phase detector would then need to have an insanely low noise-floor (in > our idea the XOR also has to have this insanely low noise floor as well off > course) so does anyone have experience with anything like this? Does anyone > know an XOR with these good specs? I don't have a clue what a standard > 74lvc1g86 would do. Needless to say the supply of this XOR would have to be > ridiculously clean, but I do have a solution for that problem. > > > > Any help is greatly appreciated! > > > > Best regards, > > > > Hans Rosenberg > > ___ > > time-nuts mailing 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] GPSDO Alternatives
Don't forget that an OCXO needs faster than 10K seconds EFC updates, that's why you need resolution first. On Wed, Dec 5, 2012 at 10:24 PM, Volker Esper wrote: > > Am 05.12.2012 18:31, schrieb Bob Camp: > >> Hi >> >> If the intent is to come up with something in the same league as the TBolt >> there are a few other things you will need: >> >> 1) Something to compare the two pps signals to within 0.1 ns >> > > Following Ulrich Bangerts suggestions, that a loop time constant should be > at about 3 hours (GPS disciplining an OCXO), do I really need that > resolution? Ok, the more accurate, the better. But the question is: can I > reduce this requirement when using long time constants (1s)? The ratio > then is 10E14... > > Volker > > > ___ > time-nuts mailing 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 challenging phase noise measurement, does anyone have an idea??
For phase noise the frequency range is 1MHz to 8/26.5/50GHz The spectrum analyzer works from 20Hz to max. Adrian Azelio Boriani schrieb: Isn't the FSUP a 110K euros equipment 20Hz-50GHz capable? 125KHz shouldn't be a problem. I had an FSUP for 25 seconds to play with... really impressive but too limited test time to appreciate fully. On Wed, Dec 5, 2012 at 1:14 PM, Bob Camp wrote: Hi Just about any of the high speed CMOS parts should work. A 74AC86 is about the earliest part I would trust. Any of the fast logic families that came after that should do equally well. Bob On Dec 5, 2012, at 7:03 AM, Hans Rosenberg wrote: Hello Time-nuts, I have to do a phase noise measurement and I'm wondering if anyone here has any ideas on that. We have to measure the phase noise of a 125kHz carrier (5Vp-p signal level). The measurement system should have a noise floor that is -164dBc/Hz at a distance of 1kHz to 8kHz away from the carrier. Our current plan is to use 2 of these sources, have one in free running mode and lock the other one to the first one using an XOR gate and then use the output of the XOR gate as an output signal. However, we are wondering if any of you know a better idea. Maybe there is an off-the-shelf piece of equipment that can do that that we could rent. Or maybe we could increase the frequency to a few megahertz using a pll, which means the signal comes into the measurement range of our FSUP phase-noise analyzer. Problem is, the phase detector would then need to have an insanely low noise-floor (in our idea the XOR also has to have this insanely low noise floor as well off course) so does anyone have experience with anything like this? Does anyone know an XOR with these good specs? I don't have a clue what a standard 74lvc1g86 would do. Needless to say the supply of this XOR would have to be ridiculously clean, but I do have a solution for that problem. Any help is greatly appreciated! Best regards, Hans Rosenberg ___ time-nuts mailing 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] GPSDO Alternatives
Hi The TBolt does a resolution somewhere better than 0.1 ns. It (in some cases) has been shown to hold better than 1 ns stability. That would be hard to do with a low resolution timing setup. Some seem to like 100 seconds as an averaging time, others seem to want something longer. If you have an Rb, you would certainly want something much longer (days). Most modern setups step through a number of different time constants and stop when things get out of hand. The one on the bench in front of me is sitting at 8,000 seconds. A 1.0x10^-12 goal is often tossed around for this sort of stuff. A 1 ns timing accuracy (resolution would need to be better than the accuracy) would get you to that goal in 1,000 seconds. That's in a perfect world. In a noisy world you likely would have to wait a bit longer. TBolt to TBolt comparisons do hit that sort of goal well short of 10,000 seconds (but rarely short of 2,000). This all comes down to a "what is your objective?" sort of thing. You can not simultaneously decide you want to do 10X better than a TBolt, but that an approach that's 10X worse is ok. (Thus my reference to managing the feature list). If you are going to price the design against a $130 (or $200) item, then you should also spec it against the same item. To spec compare it one way and price compare it another way simply isn't being honest. Design is so much fun Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Volker Esper Sent: Wednesday, December 05, 2012 4:25 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] GPSDO Alternatives Am 05.12.2012 18:31, schrieb Bob Camp: > Hi > > If the intent is to come up with something in the same league as the TBolt > there are a few other things you will need: > > 1) Something to compare the two pps signals to within 0.1 ns Following Ulrich Bangerts suggestions, that a loop time constant should be at about 3 hours (GPS disciplining an OCXO), do I really need that resolution? Ok, the more accurate, the better. But the question is: can I reduce this requirement when using long time constants (1s)? The ratio then is 10E14... Volker ___ time-nuts mailing 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 challenging phase noise measurement, does anyone have an idea??
Hi A "3048" style measurement with the carrier suppressed by lock should do pretty well. If the XOR's are out, there are a lot of mixers available that work at 125 KHz. A simple op-amp buffer and a sound card could do what you need to do. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Adrian Sent: Wednesday, December 05, 2012 4:33 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Very challenging phase noise measurement, does anyone have an idea?? For phase noise the frequency range is 1MHz to 8/26.5/50GHz The spectrum analyzer works from 20Hz to max. Adrian Azelio Boriani schrieb: > Isn't the FSUP a 110K euros equipment 20Hz-50GHz capable? 125KHz shouldn't > be a problem. I had an FSUP for 25 seconds to play with... really > impressive but too limited test time to appreciate fully. > > On Wed, Dec 5, 2012 at 1:14 PM, Bob Camp wrote: > >> Hi >> >> Just about any of the high speed CMOS parts should work. A 74AC86 is about >> the earliest part I would trust. Any of the fast logic families that came >> after that should do equally well. >> >> Bob >> >> On Dec 5, 2012, at 7:03 AM, Hans Rosenberg wrote: >> >>> Hello Time-nuts, >>> >>> I have to do a phase noise measurement and I'm wondering if anyone here >> has any ideas on that. We have to measure the phase noise of a 125kHz >> carrier (5Vp-p signal level). The measurement system should have a noise >> floor that is -164dBc/Hz at a distance of 1kHz to 8kHz away from the >> carrier. >>> Our current plan is to use 2 of these sources, have one in free running >> mode and lock the other one to the first one using an XOR gate and then use >> the output of the XOR gate as an output signal. However, we are wondering >> if any of you know a better idea. Maybe there is an off-the-shelf piece of >> equipment that can do that that we could rent. Or maybe we could increase >> the frequency to a few megahertz using a pll, which means the signal comes >> into the measurement range of our FSUP phase-noise analyzer. Problem is, >> the phase detector would then need to have an insanely low noise-floor (in >> our idea the XOR also has to have this insanely low noise floor as well off >> course) so does anyone have experience with anything like this? Does anyone >> know an XOR with these good specs? I don't have a clue what a standard >> 74lvc1g86 would do. Needless to say the supply of this XOR would have to be >> ridiculously clean, but I do have a solution for that problem. >>> Any help is greatly appreciated! >>> >>> Best regards, >>> >>> Hans Rosenberg >>> ___ >>> time-nuts mailing 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] Very challenging phase noise measurement, does anyone have an idea??
Yes, I have taken a look and the FSUP is 1MHz min at the signal analyzer. Timepod? No, 500KHz min... an R&S FAM modulation analyzer? On Wed, Dec 5, 2012 at 10:48 PM, Bob Camp wrote: > Hi > > A "3048" style measurement with the carrier suppressed by lock should do > pretty well. If the XOR's are out, there are a lot of mixers available that > work at 125 KHz. A simple op-amp buffer and a sound card could do what you > need to do. > > Bob > > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of Adrian > Sent: Wednesday, December 05, 2012 4:33 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Very challenging phase noise measurement, does > anyone have an idea?? > > For phase noise the frequency range is 1MHz to 8/26.5/50GHz > The spectrum analyzer works from 20Hz to max. > > Adrian > > > Azelio Boriani schrieb: > > Isn't the FSUP a 110K euros equipment 20Hz-50GHz capable? 125KHz > shouldn't > > be a problem. I had an FSUP for 25 seconds to play with... really > > impressive but too limited test time to appreciate fully. > > > > On Wed, Dec 5, 2012 at 1:14 PM, Bob Camp wrote: > > > >> Hi > >> > >> Just about any of the high speed CMOS parts should work. A 74AC86 is > about > >> the earliest part I would trust. Any of the fast logic families that > came > >> after that should do equally well. > >> > >> Bob > >> > >> On Dec 5, 2012, at 7:03 AM, Hans Rosenberg > wrote: > >> > >>> Hello Time-nuts, > >>> > >>> I have to do a phase noise measurement and I'm wondering if anyone here > >> has any ideas on that. We have to measure the phase noise of a 125kHz > >> carrier (5Vp-p signal level). The measurement system should have a noise > >> floor that is -164dBc/Hz at a distance of 1kHz to 8kHz away from the > >> carrier. > >>> Our current plan is to use 2 of these sources, have one in free running > >> mode and lock the other one to the first one using an XOR gate and then > use > >> the output of the XOR gate as an output signal. However, we are > wondering > >> if any of you know a better idea. Maybe there is an off-the-shelf piece > of > >> equipment that can do that that we could rent. Or maybe we could > increase > >> the frequency to a few megahertz using a pll, which means the signal > comes > >> into the measurement range of our FSUP phase-noise analyzer. Problem is, > >> the phase detector would then need to have an insanely low noise-floor > (in > >> our idea the XOR also has to have this insanely low noise floor as well > off > >> course) so does anyone have experience with anything like this? Does > anyone > >> know an XOR with these good specs? I don't have a clue what a standard > >> 74lvc1g86 would do. Needless to say the supply of this XOR would have to > be > >> ridiculously clean, but I do have a solution for that problem. > >>> Any help is greatly appreciated! > >>> > >>> Best regards, > >>> > >>> Hans Rosenberg > >>> ___ > >>> time-nuts mailing 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] Very challenging phase noise measurement, does anyone have an idea??
Hi The lower limit on the TimePod may not be a hard limit. I believe it's 200 KHz, so maybe double the frequency ... Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Azelio Boriani Sent: Wednesday, December 05, 2012 4:57 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Very challenging phase noise measurement, does anyone have an idea?? Yes, I have taken a look and the FSUP is 1MHz min at the signal analyzer. Timepod? No, 500KHz min... an R&S FAM modulation analyzer? On Wed, Dec 5, 2012 at 10:48 PM, Bob Camp wrote: > Hi > > A "3048" style measurement with the carrier suppressed by lock should do > pretty well. If the XOR's are out, there are a lot of mixers available that > work at 125 KHz. A simple op-amp buffer and a sound card could do what you > need to do. > > Bob > > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On > Behalf Of Adrian > Sent: Wednesday, December 05, 2012 4:33 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Very challenging phase noise measurement, does > anyone have an idea?? > > For phase noise the frequency range is 1MHz to 8/26.5/50GHz > The spectrum analyzer works from 20Hz to max. > > Adrian > > > Azelio Boriani schrieb: > > Isn't the FSUP a 110K euros equipment 20Hz-50GHz capable? 125KHz > shouldn't > > be a problem. I had an FSUP for 25 seconds to play with... really > > impressive but too limited test time to appreciate fully. > > > > On Wed, Dec 5, 2012 at 1:14 PM, Bob Camp wrote: > > > >> Hi > >> > >> Just about any of the high speed CMOS parts should work. A 74AC86 is > about > >> the earliest part I would trust. Any of the fast logic families that > came > >> after that should do equally well. > >> > >> Bob > >> > >> On Dec 5, 2012, at 7:03 AM, Hans Rosenberg > wrote: > >> > >>> Hello Time-nuts, > >>> > >>> I have to do a phase noise measurement and I'm wondering if anyone here > >> has any ideas on that. We have to measure the phase noise of a 125kHz > >> carrier (5Vp-p signal level). The measurement system should have a noise > >> floor that is -164dBc/Hz at a distance of 1kHz to 8kHz away from the > >> carrier. > >>> Our current plan is to use 2 of these sources, have one in free running > >> mode and lock the other one to the first one using an XOR gate and then > use > >> the output of the XOR gate as an output signal. However, we are > wondering > >> if any of you know a better idea. Maybe there is an off-the-shelf piece > of > >> equipment that can do that that we could rent. Or maybe we could > increase > >> the frequency to a few megahertz using a pll, which means the signal > comes > >> into the measurement range of our FSUP phase-noise analyzer. Problem is, > >> the phase detector would then need to have an insanely low noise-floor > (in > >> our idea the XOR also has to have this insanely low noise floor as well > off > >> course) so does anyone have experience with anything like this? Does > anyone > >> know an XOR with these good specs? I don't have a clue what a standard > >> 74lvc1g86 would do. Needless to say the supply of this XOR would have to > be > >> ridiculously clean, but I do have a solution for that problem. > >>> Any help is greatly appreciated! > >>> > >>> Best regards, > >>> > >>> Hans Rosenberg > >>> ___ > >>> time-nuts mailing 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. ___ time-nuts mailing list -- time-nuts@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 challenging phase noise measurement, does anyone have an idea??
>> running >> mode and lock the other one to the first one using an XOR gate and then >> use >> the output of the XOR gate as an output signal. However, we are >> wondering >> if any of you know a better idea. Maybe there is an off-the-shelf piece Nearly any idea is better than the XOR gate you proposed. A simple double balanced diode mixer followed by an LT1028 preamp would easily meet your needs. Rick Karlquist N6RK ___ time-nuts mailing list -- time-nuts@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 challenging phase noise measurement, does anyone have an idea??
running mode and lock the other one to the first one using an XOR gate and then use the output of the XOR gate as an output signal. However, we are wondering if any of you know a better idea. Maybe there is an off-the-shelf piece Nearly any idea is better than the XOR gate you proposed. A simple double balanced diode mixer followed by an LT1028 preamp would easily meet your needs. What about simply mixing two signals in a resistor network, sampling by ADC, and mixing purely in DSP domain on a non-linearity (e.g. f(x)=x^2)? Regards, Marek ___ time-nuts mailing list -- time-nuts@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 challenging phase noise measurement, does anyone have an idea??
This last idea is interesting... could be simulated by Matlab or similar. On Wed, Dec 5, 2012 at 11:34 PM, Marek Peca wrote: > running mode and lock the other one to the first one using an XOR gate and then use the output of the XOR gate as an output signal. However, we are wondering if any of you know a better idea. Maybe there is an off-the-shelf piece >>> >> Nearly any idea is better than the XOR gate you proposed. A simple double >> balanced diode mixer followed by an LT1028 preamp would easily meet your >> needs. >> > > What about simply mixing two signals in a resistor network, sampling by > ADC, and mixing purely in DSP domain on a non-linearity (e.g. f(x)=x^2)? > > Regards, > Marek > > > ___ > time-nuts mailing 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 challenging phase noise measurement, does anyone have an idea??
This last idea is interesting... could be simulated by Matlab or similar. It is known to work in ordinary non-linear transistor-based mixers. It will produce more messy spectrum than double-balanced mixer, however, for this purpose and completely within digital domain, it makes absolutely no harm, in my oppinion. On the other hand, simplicity of two resistors & ADC may help. If in doubt, let the original poster try this and send us the data for analysis. (Mailing-list or personal e-mail(s).) Regards, Marek ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO Alternatives
Good list Bob, many people underestimate what it takes to make a working, commercial GPSDO, especially one that has to perform in volume and beyond a single well taken care of unit in a Ham shack. Once you have taken care of items 1) and 2), the real work begins. This is where our customers get confused some times, they think items 1) and 2) are easy to do, and all that needs to be done to make a working product, and they try themselves. We just had someone try connecting the CSAC to a GPS receiver themselves, and in their setup they spent two months trying to get it to work before they gave up. The GPS behaved such that the CSAC could not lock onto it reliably. This happens quite often because at first sight it looks simple to do, and folks like Shera have come up with solutions that are simple and work well, but don't have any bells or whistles. One item often overlooked for example is that every OCXO during a production run behaves very differently from the OCXO next to it. The retrace time is different. The tempco is different. The EFC sensitivity is specified in large ranges such as 1ppm to 10ppm, one crystal may jump, another may have EFC hysterisis etc, and the software/hardware has to be able to handle all of these variations without requiring every unit to be fine-tuned by hand during production. And then the OCXO will actually change it's behavior over time due to aging and deminishing retrace error as the unit is operated etc. It's surprising that we still find room to make major improvements to our software 5 years after we sold the first Fury, for example we recently added things like leapsecond prediction/compensation without having an almanac loaded yet, with the help of a time-nut we found a very obscure bug in the NXP ARM processor that was supposed to be fixed years ago but wasn't, and we continuously keep improving and fine-tuning our algorithms and adding more commands/features to it. If there is one thing I learned, it is that one is never finished improving the software. That is why we are time-nuts I guess. bye, Said In a message dated 12/5/2012 09:29:14 Pacific Standard Time, li...@rtty.us writes: Hi If the intent is to come up with something in the same league as the TBolt there are a few other things you will need: 1) Something to compare the two pps signals to within 0.1 ns. 2) A large amount of code on the control processor (there are a multitude of special cases ...) 3) A large amount of code on a PC to monitor it and control it (like Lady Heather) 4) A set of standards to compare it to while you train and debug it 5) The test gear to collect and analyze the comparison and debug data with (you will have many months of data) 6) Some sort of control over the feature list. The complexity of 2-5 will go up significantly each time a nice to have thing is added. Once you get past step one, the rest of that list dwarf's anything like which D/A to use. I'm not at all saying it can't be done. Only that the bulk of the effort starts after you have the hardware. Bob ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] Very challenging phase noise measurement, does anyone have an...
Hans, would mixing your 125KHz with a 2.5MHz or 5MHz low noise reference to get it into a range that the analyzer can read work? You could use a system like the Miles timepod phase noise analyzer, a mixer, a 5MHz low-noise reference, and a low-pass filter to make use of the >500KHz lower range of the timepod. You could divide your 5MHz reference by 2 to get 2.5MHz +/-125KHz, with a 2.5MHz carrier being easier to filter out one of the two side-bands with a high/low-pass or notch filter? Maybe the FSUP itself could be used to remove one of the sidebands and the 2,5MHz carrier, and analyzer the remaining side-band? bye, Said In a message dated 12/5/2012 13:27:28 Pacific Standard Time, azelio.bori...@screen.it writes: Isn't the FSUP a 110K euros equipment 20Hz-50GHz capable? 125KHz shouldn't be a problem. I had an FSUP for 25 seconds to play with... really impressive but too limited test time to appreciate fully. On Wed, Dec 5, 2012 at 1:14 PM, Bob Camp wrote: > Hi > > Just about any of the high speed CMOS parts should work. A 74AC86 is about > the earliest part I would trust. Any of the fast logic families that came > after that should do equally well. > > Bob > > On Dec 5, 2012, at 7:03 AM, Hans Rosenberg wrote: > > > Hello Time-nuts, > > > > I have to do a phase noise measurement and I'm wondering if anyone here > has any ideas on that. We have to measure the phase noise of a 125kHz > carrier (5Vp-p signal level). The measurement system should have a noise > floor that is -164dBc/Hz at a distance of 1kHz to 8kHz away from the > carrier. > > > > Our current plan is to use 2 of these sources, have one in free running > mode and lock the other one to the first one using an XOR gate and then use > the output of the XOR gate as an output signal. However, we are wondering > if any of you know a better idea. Maybe there is an off-the-shelf piece of > equipment that can do that that we could rent. Or maybe we could increase > the frequency to a few megahertz using a pll, which means the signal comes > into the measurement range of our FSUP phase-noise analyzer. Problem is, > the phase detector would then need to have an insanely low noise-floor (in > our idea the XOR also has to have this insanely low noise floor as well off > course) so does anyone have experience with anything like this? Does anyone > know an XOR with these good specs? I don't have a clue what a standard > 74lvc1g86 would do. Needless to say the supply of this XOR would have to be > ridiculously clean, but I do have a solution for that problem. > > > > Any help is greatly appreciated! > > > > Best regards, > > > > Hans Rosenberg ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO Alternatives
Over the last two years or so I've put some thought into various home brew alternatives to purchasing a surplus or new GPSDO. The goal for me would be to have a reference source that combined the short to medium term stability of one of my best OCXO's with the long term stability of a GPSDO. The application would be to serve as a house standard for my test gear and a time server. I've envisioned a scheme whereby I'd use an off the shelf time interval counter (probably a surplus HP5370) to continuously compare the OCXO output to the raw 1pps output from a suitable GPS receiver. (This project would likely give me the excuse I've been looking for to purchase a CNS II GPS receiver that I believe are one of the better choices for raw 1pps accuracy.) The counter would be connected to a PC via GPIB. I'd then need to write the necessary code to periodically steer the OCXO via a to be determined digital to analog converter which in turn would then drive the EFC input on the OCXO. Rather than implement a software PLL scheme I'd likely start by simply computing the average drift over each day and then simply adjust the OCXO every day or so but eventually I'd expect to implement a PLL scheme in software.I’m hopeful that at first I could implement this in EZGPIB or something similar. I expect eventually I’d end up coding this in C. The main missing piece in the puzzle for me is a suitable DAC that can commanded by a PC (either by RS 232 or GPIB.) I leave PC's and various pieces of test gear on all the time currently (they help heat my basement lab in the winter) so I'm not worried about dedicating a PC and TIC to this. I'd also need a low noise power supply for the DAC and I suspect the performance of the DAC and the pysical interface between the DAC and the OCXO would be the weakest link in this whole system. After contemplating the time, effort, and expense to complete a project such as this I've settled for now on simply manually adjusting my OCXO's from time to time and if I am concerned about the drift while using once of them as a reference I simply compare the OCXO in question to a GPSDO while carrying out my other measurement. The drift of the OCXO can then be accounted for. In reality I can’t imagine having the time to even properly plan let alone implement something like this until I retire and I suspect I’d be lucky if I matched the performance of my best existing GPSDO. The other alternative that occurs to me is simply connecting a high end OCXO to a Thunderbolt board. Sorry if I come across as overly cynical or pessimistic here (: > Message: 3 > Date: Wed, 05 Dec 2012 22:24:43 +0100 > From: Volker Esper > To: Discussion of precise time and frequency measurement > > Subject: Re: [time-nuts] GPSDO Alternatives > Message-ID: <50bfbb9b.7010...@t-online.de> > Content-Type: text/plain; charset=ISO-8859-1; format=flowed > > > Am 05.12.2012 18:31, schrieb Bob Camp: > > Hi > > > > If the intent is to come up with something in the same > league as the TBolt > > there are a few other things you will need: > > > > 1) Something to compare the two pps signals to within > 0.1 ns > > Following Ulrich Bangerts suggestions, that a loop time > constant should > be at about 3 hours (GPS disciplining an OCXO), do I really > need that > resolution? Ok, the more accurate, the better. But the > question is: can > I reduce this requirement when using long time constants > (1s)? The > ratio then is 10E14... > > Volker > > > > > -- > ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
Re: [time-nuts] GPSDO Alternatives
Hi If you make the leap to - my control processor will be a PC, feature creep is a bit easier: 1) The "email when in trouble" feature 2) Wireless network interface 3) Ethernet network interface 4) HDMI video for that 1080P status display 5) Full keyboard and mouse for data entry 6) 16 TB raid array for log files 7) Parallel port for printed running status log 8) Auto update of firmware That's not saying you don't *also* have another computer as a monitor via client / server sort of stuff. You may grin at some of the above, but I can easily see all of that winding up on somebody's wish list. Bob On Dec 5, 2012, at 6:26 PM, Mark Spencer wrote: > > Over the last two years or so I've put some thought into various home brew > alternatives to purchasing a surplus or new GPSDO. The goal for me would be > to have a reference source that combined the short to medium term stability > of one of my best OCXO's with the long term stability of a GPSDO. > > The application would be to serve as a house standard for my test gear and a > time server. > > I've envisioned a scheme whereby I'd use an off the shelf time interval > counter (probably a surplus HP5370) to continuously compare the OCXO output > to the raw 1pps output from a suitable GPS receiver. (This project would > likely give me the excuse I've been looking for to purchase a CNS II GPS > receiver that I believe are one of the better choices for raw 1pps accuracy.) > The counter would be connected to a PC via GPIB. > I'd then need to write the necessary code to periodically steer the OCXO via > a to be determined digital to analog converter which in turn would then drive > the EFC input on the OCXO. Rather than implement a software PLL scheme I'd > likely start by simply computing the average drift over each day and then > simply adjust the OCXO every day or so but eventually I'd expect to implement > a PLL scheme in software.I’m hopeful that at first I could implement this > in EZGPIB or something similar. I expect eventually I’d end up coding this > in C. > > The main missing piece in the puzzle for me is a suitable DAC that can > commanded by a PC (either by RS 232 or GPIB.) I leave PC's and various > pieces of test gear on all the time currently (they help heat my basement lab > in the winter) so I'm not worried about dedicating a PC and TIC to this. > > I'd also need a low noise power supply for the DAC and I suspect the > performance of the DAC and the pysical interface between the DAC and the OCXO > would be the weakest link in this whole system. > > After contemplating the time, effort, and expense to complete a project such > as this I've settled for now on simply manually adjusting my OCXO's from time > to time and if I am concerned about the drift while using once of them as a > reference I simply compare the OCXO in question to a GPSDO while carrying out > my other measurement. The drift of the OCXO can then be accounted for. > > In reality I can’t imagine having the time to even properly plan let alone > implement something like this until I retire and I suspect I’d be lucky if I > matched the performance of my best existing GPSDO. The other alternative > that occurs to me is simply connecting a high end OCXO to a Thunderbolt > board. > > Sorry if I come across as overly cynical or pessimistic here (: > > >> Message: 3 >> Date: Wed, 05 Dec 2012 22:24:43 +0100 >> From: Volker Esper >> To: Discussion of precise time and frequency measurement >> >> Subject: Re: [time-nuts] GPSDO Alternatives >> Message-ID: <50bfbb9b.7010...@t-online.de> >> Content-Type: text/plain; charset=ISO-8859-1; format=flowed >> >> >> Am 05.12.2012 18:31, schrieb Bob Camp: >>> Hi >>> >>> If the intent is to come up with something in the same >> league as the TBolt >>> there are a few other things you will need: >>> >>> 1) Something to compare the two pps signals to within >> 0.1 ns >> >> Following Ulrich Bangerts suggestions, that a loop time >> constant should >> be at about 3 hours (GPS disciplining an OCXO), do I really >> need that >> resolution? Ok, the more accurate, the better. But the >> question is: can >> I reduce this requirement when using long time constants >> (1s)? The >> ratio then is 10E14... >> >> Volker >> >> >> >> >> -- >> > > ___ > time-nuts mailing 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 challenging phase noise measurement, does anyone have an idea??
You can always use an external mixer / phase detector and the baseband input of a HP 3048A or FSUP. Just to name a few: For low power (+7dBm) you can use a SRA-3 which goes from 25kHz to 200MHz SRA-3MH +13dBm from 25kHz to 200MHz SRA-3H +17dBm from 50kHz to 200MHz For high power signals use a RAY-3. It goes from 70kHz to 200MHz. The IF must be specified from DC, which for the above is the case. Between mixer and baseband input a lowpass filter is required to suppress the sum signal (2x f_input) sufficiently. Adrian Azelio Boriani schrieb: Yes, I have taken a look and the FSUP is 1MHz min at the signal analyzer. Timepod? No, 500KHz min... an R&S FAM modulation analyzer? On Wed, Dec 5, 2012 at 10:48 PM, Bob Camp wrote: Hi A "3048" style measurement with the carrier suppressed by lock should do pretty well. If the XOR's are out, there are a lot of mixers available that work at 125 KHz. A simple op-amp buffer and a sound card could do what you need to do. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On Behalf Of Adrian Sent: Wednesday, December 05, 2012 4:33 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Very challenging phase noise measurement, does anyone have an idea?? For phase noise the frequency range is 1MHz to 8/26.5/50GHz The spectrum analyzer works from 20Hz to max. Adrian Azelio Boriani schrieb: Isn't the FSUP a 110K euros equipment 20Hz-50GHz capable? 125KHz shouldn't be a problem. I had an FSUP for 25 seconds to play with... really impressive but too limited test time to appreciate fully. On Wed, Dec 5, 2012 at 1:14 PM, Bob Camp wrote: Hi Just about any of the high speed CMOS parts should work. A 74AC86 is about the earliest part I would trust. Any of the fast logic families that came after that should do equally well. Bob On Dec 5, 2012, at 7:03 AM, Hans Rosenberg wrote: Hello Time-nuts, I have to do a phase noise measurement and I'm wondering if anyone here has any ideas on that. We have to measure the phase noise of a 125kHz carrier (5Vp-p signal level). The measurement system should have a noise floor that is -164dBc/Hz at a distance of 1kHz to 8kHz away from the carrier. Our current plan is to use 2 of these sources, have one in free running mode and lock the other one to the first one using an XOR gate and then use the output of the XOR gate as an output signal. However, we are wondering if any of you know a better idea. Maybe there is an off-the-shelf piece of equipment that can do that that we could rent. Or maybe we could increase the frequency to a few megahertz using a pll, which means the signal comes into the measurement range of our FSUP phase-noise analyzer. Problem is, the phase detector would then need to have an insanely low noise-floor (in our idea the XOR also has to have this insanely low noise floor as well off course) so does anyone have experience with anything like this? Does anyone know an XOR with these good specs? I don't have a clue what a standard 74lvc1g86 would do. Needless to say the supply of this XOR would have to be ridiculously clean, but I do have a solution for that problem. Any help is greatly appreciated! Best regards, Hans Rosenberg ___ time-nuts mailing 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. ___ time-nuts mailing list -- time-nuts@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 challenging phase noise measurement, does anyone have an idea??
That would be a good way to do it. I wouldn't use an XOR gate or other digital phase detector for this, due to the low slew rate among other things. Instead, you could phase lock two of your sources with a double-balanced mixer, then run the IF through a lowpass filter and a quiet opamp or other LNA. The baseband noise can then be viewed on a spectrum analyzer that goes down to whatever the minimum offset of interest is. The analyzer's noise floor doesn't matter, it just needs to be something that can tune down to the 100 Hz-1 kHz area. An old-school HP 8566 or 8568 is ideal. For calibration details, see the references in the last FAQ entry at http://www.ke5fx.com/gpib/faq.htm , especially HP 11729B-1. Alternatively, I'm not sure where the noise floor of the FSUP is, but if it is otherwise low enough, you could mix the 125 kHz with an ultra-low-noise OCXO and measure one of the resulting sidebands. It might or might not be necessary to filter the other sideband depending on how the FSUP works. You could also build a low-noise 8x active multiplier to get to 1 MHz where the FSUP can see it, as well. This would have the advantage of not requiring a ULN OCXO for mixing, and would also boost the PN by 18 dB for easier measurement on the FSUP. However, you'd need to be careful with the multiplier's residual noise, especially in the first couple of stages. If you need to make these measurements over and over, go with the multiplier or mixer, otherwise I'd use an analog quadrature PLL. -- john Miles Design LLC > -Original Message- > From: time-nuts-boun...@febo.com [mailto:time-nuts- > boun...@febo.com] On Behalf Of Adrian > Sent: Wednesday, December 05, 2012 4:40 PM > To: Discussion of precise time and frequency measurement > Subject: Re: [time-nuts] Very challenging phase noise measurement, does > anyone have an idea?? > > You can always use an external mixer / phase detector and the baseband > input of a HP 3048A or FSUP. > > Just to name a few: > For low power (+7dBm) you can use a SRA-3 which goes from 25kHz to > 200MHz > SRA-3MH +13dBm from 25kHz to 200MHz > SRA-3H +17dBm from 50kHz to 200MHz > For high power signals use a RAY-3. It goes from 70kHz to 200MHz. > The IF must be specified from DC, which for the above is the case. > > Between mixer and baseband input a lowpass filter is required to > suppress the sum signal (2x f_input) sufficiently. > > Adrian > > > Azelio Boriani schrieb: > > Yes, I have taken a look and the FSUP is 1MHz min at the signal analyzer. > > Timepod? No, 500KHz min... an R&S FAM modulation analyzer? > > > > On Wed, Dec 5, 2012 at 10:48 PM, Bob Camp wrote: > > > >> Hi > >> > >> A "3048" style measurement with the carrier suppressed by lock should > do > >> pretty well. If the XOR's are out, there are a lot of mixers available that > >> work at 125 KHz. A simple op-amp buffer and a sound card could do what > you > >> need to do. > >> > >> Bob > >> > >> -Original Message- > >> From: time-nuts-boun...@febo.com [mailto:time-nuts- > boun...@febo.com] On > >> Behalf Of Adrian > >> Sent: Wednesday, December 05, 2012 4:33 PM > >> To: Discussion of precise time and frequency measurement > >> Subject: Re: [time-nuts] Very challenging phase noise measurement, > does > >> anyone have an idea?? > >> > >> For phase noise the frequency range is 1MHz to 8/26.5/50GHz > >> The spectrum analyzer works from 20Hz to max. > >> > >> Adrian > >> > >> > >> Azelio Boriani schrieb: > >>> Isn't the FSUP a 110K euros equipment 20Hz-50GHz capable? 125KHz > >> shouldn't > >>> be a problem. I had an FSUP for 25 seconds to play with... really > >>> impressive but too limited test time to appreciate fully. > >>> > >>> On Wed, Dec 5, 2012 at 1:14 PM, Bob Camp wrote: > >>> > Hi > > Just about any of the high speed CMOS parts should work. A 74AC86 is > >> about > the earliest part I would trust. Any of the fast logic families that > >> came > after that should do equally well. > > Bob > > On Dec 5, 2012, at 7:03 AM, Hans Rosenberg > >> wrote: > > Hello Time-nuts, > > > > I have to do a phase noise measurement and I'm wondering if anyone > here > has any ideas on that. We have to measure the phase noise of a 125kHz > carrier (5Vp-p signal level). The measurement system should have a > noise > floor that is -164dBc/Hz at a distance of 1kHz to 8kHz away from the > carrier. > > Our current plan is to use 2 of these sources, have one in free running > mode and lock the other one to the first one using an XOR gate and > then > >> use > the output of the XOR gate as an output signal. However, we are > >> wondering > if any of you know a better idea. Maybe there is an off-the-shelf piece > >> of > equipment that can do that that we could rent. Or maybe we could > >> increase > the frequency to a few megahertz using a pll, which means the signal > >> comes > into the measureme
Re: [time-nuts] Very challenging phase noise measurement, does anyone have an idea??
Hi You might be surprised by the noise floor of an XOR run at 125 KHz. They are quite good at that low a frequency. Bob On Dec 5, 2012, at 8:24 PM, John Miles wrote: > That would be a good way to do it. I wouldn't use an XOR gate or other > digital phase detector for this, due to the low slew rate among other > things. Instead, you could phase lock two of your sources with a > double-balanced mixer, then run the IF through a lowpass filter and a quiet > opamp or other LNA. The baseband noise can then be viewed on a spectrum > analyzer that goes down to whatever the minimum offset of interest is. The > analyzer's noise floor doesn't matter, it just needs to be something that > can tune down to the 100 Hz-1 kHz area. An old-school HP 8566 or 8568 is > ideal. > > For calibration details, see the references in the last FAQ entry at > http://www.ke5fx.com/gpib/faq.htm , especially HP 11729B-1. > > Alternatively, I'm not sure where the noise floor of the FSUP is, but if it > is otherwise low enough, you could mix the 125 kHz with an ultra-low-noise > OCXO and measure one of the resulting sidebands. It might or might not be > necessary to filter the other sideband depending on how the FSUP works. > > You could also build a low-noise 8x active multiplier to get to 1 MHz where > the FSUP can see it, as well. This would have the advantage of not > requiring a ULN OCXO for mixing, and would also boost the PN by 18 dB for > easier measurement on the FSUP. However, you'd need to be careful with the > multiplier's residual noise, especially in the first couple of stages. > > If you need to make these measurements over and over, go with the multiplier > or mixer, otherwise I'd use an analog quadrature PLL. > > -- john > Miles Design LLC > > >> -Original Message- >> From: time-nuts-boun...@febo.com [mailto:time-nuts- >> boun...@febo.com] On Behalf Of Adrian >> Sent: Wednesday, December 05, 2012 4:40 PM >> To: Discussion of precise time and frequency measurement >> Subject: Re: [time-nuts] Very challenging phase noise measurement, does >> anyone have an idea?? >> >> You can always use an external mixer / phase detector and the baseband >> input of a HP 3048A or FSUP. >> >> Just to name a few: >> For low power (+7dBm) you can use a SRA-3 which goes from 25kHz to >> 200MHz >> SRA-3MH +13dBm from 25kHz to 200MHz >> SRA-3H +17dBm from 50kHz to 200MHz >> For high power signals use a RAY-3. It goes from 70kHz to 200MHz. >> The IF must be specified from DC, which for the above is the case. >> >> Between mixer and baseband input a lowpass filter is required to >> suppress the sum signal (2x f_input) sufficiently. >> >> Adrian >> >> >> Azelio Boriani schrieb: >>> Yes, I have taken a look and the FSUP is 1MHz min at the signal > analyzer. >>> Timepod? No, 500KHz min... an R&S FAM modulation analyzer? >>> >>> On Wed, Dec 5, 2012 at 10:48 PM, Bob Camp wrote: >>> Hi A "3048" style measurement with the carrier suppressed by lock should >> do pretty well. If the XOR's are out, there are a lot of mixers available > that work at 125 KHz. A simple op-amp buffer and a sound card could do what >> you need to do. Bob -Original Message- From: time-nuts-boun...@febo.com [mailto:time-nuts- >> boun...@febo.com] On Behalf Of Adrian Sent: Wednesday, December 05, 2012 4:33 PM To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Very challenging phase noise measurement, >> does anyone have an idea?? For phase noise the frequency range is 1MHz to 8/26.5/50GHz The spectrum analyzer works from 20Hz to max. Adrian Azelio Boriani schrieb: > Isn't the FSUP a 110K euros equipment 20Hz-50GHz capable? 125KHz shouldn't > be a problem. I had an FSUP for 25 seconds to play with... really > impressive but too limited test time to appreciate fully. > > On Wed, Dec 5, 2012 at 1:14 PM, Bob Camp wrote: > >> Hi >> >> Just about any of the high speed CMOS parts should work. A 74AC86 is about >> the earliest part I would trust. Any of the fast logic families that came >> after that should do equally well. >> >> Bob >> >> On Dec 5, 2012, at 7:03 AM, Hans Rosenberg wrote: >>> Hello Time-nuts, >>> >>> I have to do a phase noise measurement and I'm wondering if anyone >> here >> has any ideas on that. We have to measure the phase noise of a 125kHz >> carrier (5Vp-p signal level). The measurement system should have a >> noise >> floor that is -164dBc/Hz at a distance of 1kHz to 8kHz away from the >> carrier. >>> Our current plan is to use 2 of these sources, have one in free > running >> mode and lock the other one to the first one using an XOR gate and >> then use >> the output of the XOR gate as an output signal. However, we are wonde
Re: [time-nuts] Very challenging phase noise measurement, does anyone have an idea??
On 12/5/12 2:45 PM, Marek Peca wrote: This last idea is interesting... could be simulated by Matlab or similar. It is known to work in ordinary non-linear transistor-based mixers. It will produce more messy spectrum than double-balanced mixer, however, for this purpose and completely within digital domain, it makes absolutely no harm, in my oppinion. On the other hand, simplicity of two resistors & ADC may help. for that matter, fit two sinusoids to the two inputs (which will inevitably be at different frequencies, eh?) ___ time-nuts mailing list -- time-nuts@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 challenging phase noise measurement, does anyone have an idea??
Hi Digitizing two signals and winding up 170 db down is maybe a bit more complicated than just going to quadrature and getting rid of the need to do so…. at least for a one off application. Bob On Dec 5, 2012, at 9:00 PM, Jim Lux wrote: > On 12/5/12 2:45 PM, Marek Peca wrote: >>> This last idea is interesting... could be simulated by Matlab or similar. >> >> It is known to work in ordinary non-linear transistor-based mixers. It >> will produce more messy spectrum than double-balanced mixer, however, >> for this purpose and completely within digital domain, it makes >> absolutely no harm, in my oppinion. On the other hand, simplicity of two >> resistors & ADC may help. >> > > for that matter, fit two sinusoids to the two inputs (which will inevitably > be at different frequencies, eh?) > > > ___ > time-nuts mailing 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 challenging phase noise measurement, does anyone have an idea??
Bob Camp wrote: > Hi > > You might be surprised by the noise floor of an XOR run at 125 KHz. They > are quite good at that low a frequency. > > Bob An XOR, unlike a mixer, does not have a null when the phases are in quadrature. This is the fundamental problem with using it as a phase detector. Rick ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
[time-nuts] XOR Mixers
There is a nice XOR mixer in the 9046 PLL chip. Also a dual F/F mixer. Don't use other versions of the 4046. They have detector dead spots. You also have the advantage of being able to use them with signals from about 100 mV to 5V. I haven't used the chip for the purpose mentioned. Simon Date: Wed, 5 Dec 2012 20:48:14 -0500 From: Bob Camp To: Discussion of precise time and frequency measurement Subject: Re: [time-nuts] Very challenging phase noise measurement, does anyone have an idea?? Message-ID: <74167b7c-e58f-4bb8-a78e-ba2a02be5...@rtty.us> Content-Type: text/plain; charset=us-ascii Hi You might be surprised by the noise floor of an XOR run at 125 KHz. They are quite good at that low a frequency. Bob Engineering is the art of making what you want from what you can get at a profit. ___ time-nuts mailing list -- time-nuts@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)
On 12/05/2012 08:03 AM, Fabio Eboli wrote: 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 Coincidentally, my previous time-nut project was built around the same chip. I built a simple GPSDO using a STM32F103C with a bit of support circuitry, using the timer in "input capture" mode to timestamp pulses and act as a coarse time-to-digital converter. I got a simple PLL control algorithm working but haven't yet refined it so it tracks rather poorly. My intent was to adopt some of the self-tuning attributes of NTPns, which I will likely revisit for the next project. Some more details about what was on the board: - A NC7WZ14 CMOS inverter to square up the sine wave from the OCXO, which then feeds... - A PIC12F1501 as a programmable divider, using TVB's picDIV code lightly modified to work on that particular chip - The STM32F103 itself, which compares pulses from the divider to pulses from the GPS receiver and makes adjustments via... - A slow 16-bit DAC constructed from a PWM output on the STM32, a two-pole RC filter, a buffer op-amp, and a third RC pole. This drives the OCXO's frequency control. The PWM is also tweaked over 16 consecutive periods to add 4 more bits of precision, a sort of crude pulse-density modulation. - There's also an op-amp to buffer the 10MHz sine wave for 50 ohm output, and a digital buffer for a 50 ohm PPS output from the divider Here are the design documents, if you're curious: http://hg.partiallystapled.com/circuits/serafine/raw-file/d75ab09ca163/out/production.PDF The precise parts of course are not important, it's just an example of things I chose to get the job done. The general shape of it is the 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). 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 nearly precise enough to compete with a "real" GPSDO as it is based on a small on-board VCTCXO but should shore up the algorithms enough for me to revisit the GPSDO again. -- m. tharp ___ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
