Hi Have you tried it with the latest firmware update?
I’ve never seen the problem here. Bob > On Apr 14, 2020, at 1:05 PM, Taka Kamiya via time-nuts > <[email protected]> wrote: > > Bob, Tobias, et al > > TICC (TAPR) isn't problem free either. It has a tendency to get TimeLab > confused on data from port A and port B. The data stream has identifier on > them but TimeLab discards it. Then it expects A and B comes alternately. I > communicated with both developers but for time being, the solution is to > record the data and inspect. > > --------------------------------------- > (Mr.) Taka Kamiya > KB4EMF / ex JF2DKG > > > On Tuesday, April 14, 2020, 7:48:34 AM EDT, Bob kb8tq <[email protected]> > wrote: > > Hi > > If the phase slips are “well behaved” they can be handled. The problem > with a dual channel setup is that they are often not well behaved. The > period is 100 ns so a frequency drift of 1 ppb will put you in trouble in > under 2 minutes. > > The only real answer is to do it properly and time tag the two outputs. > Any other approach will get you yelling and screaming at the test set. > Playing with two counters and not time tagging is in the “yelling and > screaming” category as well. > > Get a TAPPR TICC if you really want to do a DMTD. > > Of course you *could* just use a single mixer. That works fine with the > counter you already have. It will give you an A to B test just like a > DMTD. The only limitation is the need to tune at least one of the oscillators > in each pair. > > There is no requirement that you tune only one. If both are tunable, > you could tune one to the high end of its range and the other to the low end. > With most OCXO’s, there is plenty of tune range. > > Bob > >> On Apr 14, 2020, at 2:23 AM, Tobias Pluess <[email protected]> wrote: >> >> Hey Bob >> >> ok now I see your point! you talk about the phase spillovers. Timelab and >> also Stable32 can correct for them, so it shouldn't be a problem, right? >> >> But I agree, if you cannot correct for the spillovers it becomes even more >> difficult. >> >> >> Tobias >> >> On Tue., 14 Apr. 2020, 01:38 Bob kb8tq, <[email protected]> wrote: >> >>> Hi >>> >>> The gotcha with using a conventional counter (as opposed to a time tagger) >>> is that you never know when things are going to “slip” past each other. >>> When they >>> do you get a major burp in your data. Bill’s setup is running a time >>> tagger …. >>> >>> ( = It runs an internal time count, each edge gets “labeled” with a >>> precise time >>> stamp that is good to nanoseconds or picoseconds. A Time Interval Counter >>> simply measures the time between edges. That sounds like the same thing, >>> but >>> it’s not quite ….) >>> >>> >>>> On Apr 13, 2020, at 6:11 PM, Tobias Pluess <[email protected]> wrote: >>>> >>>> Hi Bob >>>> >>>> Riley suggests to use a single TIC >>>> >>>> http://wriley.com/A%20Small%20DMTD%20System.pdf >>>> >>>> when you look at the block diagram Fig. 4, you can see that one TIC >>> allows >>>> to compare two oscillators. >>>> I don't know exactly how, though :-) >>> >>> The gotcha with using a conventional counter (as opposed to a time tagger) >>> is that you never know when things are going to “slip” past each other. >>> When they >>> do you get a major burp in your data. Bill’s setup is running a time >>> tagger …. >>> >>>> >>>> OK and I see your point on the 8663. I will try to use another reference! >>>> I definitely didn't keep mine on for a long time. I didn't use the signal >>>> generator for a while now, so it was unplugged for a few months. I assume >>>> that's far from optimal for the 10811's stability. >>> >>> Best approach is to mount your reference off on it’s own and just power >>> it. That way >>> you don’t wear out all the guts of a fancy piece of gear. >>> >>> Bob >>> >>>> >>>> >>>> Tobias >>>> >>>> >>>> >>>> On Mon., 13 Apr. 2020, 23:53 Bob kb8tq, <[email protected]> wrote: >>>> >>>>> Hi >>>>> >>>>>> On Apr 13, 2020, at 5:06 PM, Tobias Pluess <[email protected]> wrote: >>>>>> >>>>>> Hi Bob >>>>>> awesome, thanks! of course it is 1e6, not 1e7, I got a mistake :-) >>>>>> >>>>>> Maybe I have some good OpAmps for this purpose in my box. I will try >>> it! >>>>> of >>>>> >>>>> You need something that is quiet (like the OP-37) and has a pretty good >>>>> slew >>>>> rate. Past that, there are a lot of candidates. The TI OPA-228 family is >>>>> one. >>>>> >>>>>> course I saw that my setup was not ideal as there was a bit of noise on >>>>> the >>>>>> signals which I guess does lead to some jitter in the trigger circuit >>> and >>>>>> therefore decreases my measurement noise floor. >>>>> >>>>> Typically a good limiter takes you from 3 or 4 digits up to 6 or 7 good >>>>> digits. >>>>> Net result is a measurement that’s good in the vicinity of parts in >>> 10^-13 >>>>> >>>>>> >>>>>> Can you say something about how it would be done using a TIC? >>>>>> I don't have two identically good counters, but the HP 5335A could be >>>>> used >>>>>> as TIC, couldn't it. >>>>> >>>>> The standard way of doing the test is to run two counters / two TIC/s / >>>>> two whatever’s. >>>>> I know of no practical way to do it with a single 5335. >>>>> >>>>>> >>>>>> And the offset source I used is not directly the HP 10811, but the HP >>>>> 8663A >>>>>> Signal generator internally uses a 10811 as reference source. But I >>>>> didn't >>>>>> wait for days for it to warm up properly. (Should I?) >>>>> >>>>> The 8663 synthesizer adds a *lot* of crud to the 10811. Regardless of >>> how >>>>> you >>>>> use the 10811, it needs to be on for a while. How long very much depends >>>>> on >>>>> just how long it’s been off. Best to keep it on all the time. >>>>> >>>>>> >>>>>>> Fun !!! >>>>>> Yea, of course! :-) >>>>>> I already implemented the ADEV, MDEV and TDEV calculations in Matlab by >>>>>> myself. I use TimeLab to see what numbers I should expect, and then I >>>>> want >>>>>> to compute it all myself in Matlab because I want to see how it >>> actually >>>>>> works. ;-) >>>>> >>>>> Be careful any time you code this stuff for the first time. It’s >>> amazingly >>>>> easy >>>>> ( = I’ve done it ….) to make minor errors. That’s in no way to suggest >>> that >>>>> you should not code it up yourself. I generally do it in Excel or in C. >>>>> >>>>> Bob >>>>> >>>>>> >>>>>> >>>>>> Best >>>>>> Tobias >>>>>> >>>>>> >>>>>> >>>>>> On Mon, Apr 13, 2020 at 10:50 PM Bob kb8tq <[email protected]> wrote: >>>>>> >>>>>>> Hi >>>>>>> >>>>>>> Ok, first the math: >>>>>>> >>>>>>> If your offset oscillator is 10 Hz high at 10 MHz, you have a: >>>>>>> >>>>>>> 10,000,000 / 10 = 1,000,000 : 1 multiplier in front of the DMTD >>>>>>> >>>>>>> You get to add a 6 to what Time Lab shows you. >>>>>>> >>>>>>> If you are getting an ADEV at 1 second of 1x10^-4 then that multiplier >>>>>>> gets you to 1x10^-10 >>>>>>> >>>>>>> So, what’s going on? >>>>>>> >>>>>>> You can’t feed the mixer outputs straight into a counter. The counter >>>>>>> front >>>>>>> end does not handle LF audio sine waves very well. You need to do an >>>>>>> op-amp based limiter. A pair of OP-37’s in each leg ( or something >>>>>>> similar) >>>>>>> should do the trick. >>>>>>> >>>>>>> Second, the offset source needs to be pretty good. A 10811 tuned high >>>>> with >>>>>>> both the mechanical trim and the EFC is a pretty good choice to start >>>>> out. >>>>>>> >>>>>>> If you only have one counter, simply ignore the second channel. You >>> are >>>>> now >>>>>>> running a single mixer. It still works as a comparison between the >>>>> offset >>>>>>> oscillator >>>>>>> and your DUT. >>>>>>> >>>>>>> If you want to do it properly as a DMTD, then you set up two counters. >>>>> One >>>>>>> to measure mixer A and the other to measure mixer B. Set them both up >>>>> to >>>>>>> measure frequency. Time tag the data files so you know which reading >>>>>>> matches up with which. >>>>>>> >>>>>>> Fun !!! >>>>>>> >>>>>>> Bob >>>>>>> >>>>>>>> On Apr 13, 2020, at 3:18 PM, Tobias Pluess <[email protected]> wrote: >>>>>>>> >>>>>>>> Hi again Bob >>>>>>>> >>>>>>>> I tried to do some measurements with a DMTD! >>>>>>>> In my junk box I found a little PCB from earlier experiments on that >>>>>>> topic, >>>>>>>> with a power splitter and two SRA-3H mixers, it was even already >>> wired >>>>>>> for >>>>>>>> the DMTD configuration. So I gave it a try! >>>>>>>> As "transfer oscillator" I used my HP 8663A signal generator, and set >>>>> it >>>>>>>> high in frequency by 10 Hz. To the two mixers, I connected the two >>>>> 10MHz >>>>>>>> signals and at the mixer outputs, I put a little lowpass filter with >>>>>>> 100Hz >>>>>>>> corner frequency. >>>>>>>> The output signals from the two SRA-3 mixers are almost 0.5Vpp, so I >>>>>>> tried >>>>>>>> to feed them directly into the HP 5335A TIC and used the TI mode to >>>>>>> measure >>>>>>>> the delay between the two signals. >>>>>>>> This gives 10 readings/sec, which I try to process with TimeLab. >>>>>>>> It does give some interesting graphs, but I don't know yet how to >>>>>>> correctly >>>>>>>> set up TimeLab for this kind of measurement. I.e. now, I get an ADEV >>> in >>>>>>> the >>>>>>>> order of 1e-4 (at tau=1sec) to 1e-5 (at tau=500sec). So does that >>> mean >>>>> I >>>>>>>> simply need to multiply this with 1e-7 to get the *real* ADEV at >>> 10MHz? >>>>>>>> this would mean that my real ADEV is in the range of 1e-11 to 1e-12, >>>>>>> which >>>>>>>> is indeed my target value, BUT I expect that things are not that >>>>> simple. >>>>>>>> (i.e. what if I didn't set the transfer oscillator high by +10Hz but >>>>> only >>>>>>>> by 9.9Hz for example). >>>>>>>> Can you give some hints on that? >>>>>>>> Of course I also did the noise floor test (i.e. I fed the 10MHz >>> signal >>>>>>> into >>>>>>>> a power splitter and connected the two outputs to my DMTD with two >>>>>>>> different lenghts of cables. This gave results starting at 1e-4 going >>>>>>> down >>>>>>>> to 1e-7, maybe it would have gone even lower but I measured only for >>> a >>>>>>>> couple of minutes.) >>>>>>>> >>>>>>>> Can you give some hints on that? >>>>>>>> >>>>>>>> Best >>>>>>>> Tobias >>>>>>>> HB9FSX >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> >>>>>>>> On Fri, Apr 3, 2020 at 1:45 PM Bob kb8tq <[email protected]> wrote: >>>>>>>>> >>>>>>>>>> Hi >>>>>>>>>> >>>>>>>>>> The quick way to do this is with a single mixer. Take something >>> like >>>>> an >>>>>>>>>> old >>>>>>>>>> 10811 and use the coarse tune to set it high in frequency by 5 to >>> 10 >>>>>>> Hz. >>>>>>>>>> >>>>>>>>>> Then feed it into an RPD-1 mixer and pull out the 5 to 10 Hz audio >>>>>>> tone. >>>>>>>>>> That tone is the *difference* between the 10811 and your device >>> under >>>>>>>>>> test. >>>>>>>>>> If the DUT moves 1 Hz, the audio tone changes by 1 Hz. >>>>>>>>>> >>>>>>>>>> If you measured the 10 MHz on the DUT, that 1 Hz would be a very >>>>> small >>>>>>>>>> shift >>>>>>>>>> ( 0.1 ppm ). At 10 Hz it’s a 10% change. You have “amplified” the >>>>>>> change >>>>>>>>>> in frequency by the ratio of 10 MHz to 10 Hz ( so a million X >>>>> increase >>>>>>> ). >>>>>>>>>> >>>>>>>>>> *IF* you could tack that on to the ADEV plot of your 5335 ( no, >>> it’s >>>>>>> not >>>>>>>>>> that >>>>>>>>>> simple) your 7x10^-10 at 1 second would become more 7x10^-16 at 1 >>>>>>>>>> second. >>>>>>>>>> >>>>>>>>>> The reason its not quite that simple is that the input circuit on >>> the >>>>>>>>>> counter >>>>>>>>>> really does not handle a 10 Hz audio tone as well as it handles a >>> 10 >>>>>>> MHz >>>>>>>>>> RF signal. Instead of getting 9 digits a second, you probably will >>>>> get >>>>>>>>>> three >>>>>>>>>> *good* digits a second and another 6 digits of noise. >>>>>>>>>> >>>>>>>>>> The good news is that an op amp used as a preamp ( to get you up to >>>>>>> maybe >>>>>>>>>> 32 V p-p rather than a volt or so) and another op amp or three as >>>>>>>>>> limiters will >>>>>>>>>> get you up around 6 or 7 good digits. Toss in a cap or two as a >>> high >>>>>>> pass >>>>>>>>>> and low pass filter ( DC offsets can be a problem ….) and you have >>> a >>>>>>>>>> working >>>>>>>>>> device that gets into the parts in 10^-13 with your 5335. >>>>>>>>>> >>>>>>>>>> It all can be done with point to point wiring. No need for a PCB >>>>>>> layout. >>>>>>>>>> Be >>>>>>>>>> careful that the +/- 18V supplies to the op amp *both* go on and >>> off >>>>> at >>>>>>>>>> the >>>>>>>>>> same time …. >>>>>>>>>> >>>>>>>>>> Bob >>>>>>>>>> >>>>>>>>> >>>>>>>> _______________________________________________ >>>>>>>> time-nuts mailing list -- [email protected] >>>>>>>> To unsubscribe, go to >>>>>>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>>>>>>> and follow the instructions there. >>>>>>> >>>>>>> >>>>>>> _______________________________________________ >>>>>>> time-nuts mailing list -- [email protected] >>>>>>> To unsubscribe, go to >>>>>>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>>>>>> and follow the instructions there. >>>>>>> >>>>>> _______________________________________________ >>>>>> time-nuts mailing list -- [email protected] >>>>>> To unsubscribe, go to >>>>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>>>>> and follow the instructions there. >>>>> >>>>> >>>>> _______________________________________________ >>>>> time-nuts mailing list -- [email protected] >>>>> To unsubscribe, go to >>>>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>>>> and follow the instructions there. >>>>> >>>> _______________________________________________ >>>> time-nuts mailing list -- [email protected] >>>> To unsubscribe, go to >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>>> and follow the instructions there. >>> >>> >>> _______________________________________________ >>> time-nuts mailing list -- [email protected] >>> To unsubscribe, go to >>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >>> and follow the instructions there. >>> >> _______________________________________________ >> time-nuts mailing list -- [email protected] >> To unsubscribe, go to >> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com >> and follow the instructions there. > > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. > > _______________________________________________ > time-nuts mailing list -- [email protected] > To unsubscribe, go to > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com > and follow the instructions there. _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com and follow the instructions there.
