I thought I could just re-enter the numbers from the last survey I did. But either something is wrong or I'm missing something (betting on the latter). I can't seem to enable TRAIM. I thought I had it setup just like previously, but under WinCore12 it simply won't turn it on. So, I'm just letting it do a survey again, I guess. IOW, I dunno.
And I have a question about MATH functions on the 5335A, if you don't mind. (I'm an HP newbie.) Is there away to use Ratio A/B and have it give a greater resolution than a whole number, perhaps by having it average over multiple B ticks? I think I figured out how to enter an Offset, but I just get the ratio in single digits which doesn't really give me anything. Bob >________________________________ > From: Bob Camp <li...@rtty.us> >To: Discussion of precise time and frequency measurement <time-nuts@febo.com> >Sent: Friday, August 16, 2013 7:26 PM >Subject: Re: [time-nuts] My GPSDO project: OCXO Thermal Oscillation? > > >Hi > >Also remember - you need to do a survey on the UT+ and put it into position >hold / timing mode. If you don't you can add a bit more to your error budget. > >Bob > >On Aug 16, 2013, at 7:58 PM, Bob Stewart <b...@evoria.net> wrote: > >> I'll figure out something. I'm thinking of icing down my DDS device to put >> it at a known temperature so I can do drift comparisons. If not that, >> there'll be something else I can try. >> >> On another note: I thought I had destroyed everything when I swapped the UT+ >> back into the GPSDO. Fortunately it was just that the UT+ needed to be >> reset, and I had destroyed a USB-TTL adapter and not my new little Adafruit. >> I'm going to have to figure out exactly what command sequence needs to be >> sent to the UT+ to get the comms working again and write a short program to >> do it. For some reason the WinCore12 program wasn't able to bring it up. >> >> Bob >> >> >> >> >> >>> ________________________________ >>> From: Angus <not.ag...@btinternet.com> >>> To: Discussion of precise time and frequency measurement >>> <time-nuts@febo.com> >>> Sent: Friday, August 16, 2013 6:14 PM >>> Subject: Re: [time-nuts] My GPSDO project: OCXO Thermal Oscillation? >>> >>> >>> Hi, >>> >>> To be able to test GPSDO's (and GPS in general) was one of the main reasons >>> that I made a temp controlled chassis for an LPRO and gave it air pressure >>> compensation. That was good for tau's of hundreds to tens of thousands of >>> seconds, and even longer with drift compensation. Add in a clean-up >>> oscillator if desired, and you have a pretty good reference. >>> >>> Incidentally, I tested 2 FEI5680A's, a Temex LPFRS and 3 LPRO's in this >>> type of setup, but only the LPRO's allowed the air pressure effects to be >>> almost completely cancelled out. For some reason the others did not react >>> to fluctuating air pressure as predictably. >>> >>> Angus. >>> >>> From: "Bob Camp" >>> To: "Discussion of precise time and frequency measurement" >>> Sent: August 16, 2013 7:45 PM >>> Subject: Re: [time-nuts] My GPSDO project: OCXO Thermal Oscillation? >>> >>> Hi >>> >>> With the 5335 you have a measurement with dead time. That makes things a >>> bit hard to figure out. A much better way to go is to feed a pair of 1 pps >>> signals into the 5335 and measure their time difference. Unless they are >>> quite close, you can go for a while with no ambiguity to the reading. The >>> effective resolution increases linearly with the time length of the >>> observation. There also are a number of very nice programs that will let >>> you collect the data from the 5335 via GPIB. >>> >>> Assuming your 5335 works like mine does it's got about a 1 ns resolution at >>> 1 second. It'll give you 1 ppb at a 1 second gate and 1 ppt at a 1,000 >>> second gate. By the time it gets to 1,000 seconds the internal counters >>> have overflowed and the reading is a bit messed up. >>> >>> Without some sort of accurate reference, there's really no way to know for >>> sure what's going on with a GPSDO. One solution is to build two or three of >>> them and watch them fight with each other. Another solution is to pick up a >>> Hydrogen Maser. It's always a "what's in your wallet" sort of decision. >>> >>> Bob >>> >>> On Aug 16, 2013, at 2:26 PM, Bob Stewart wrote: >>> >>>> Hi again Bob, >>>> >>>> D'oh, I think I totally misunderstood your figures in my first response. >>>> The .16ppb is not the frequency accuracy of my GPSDO. It's the amount >>>> that I'm moving the OCXO during a 5 minute timeframe, which is something >>>> else entirely. Like I said I do not have a known good oscillator to >>>> compare to. However, I have a DDS oscillator I made some time ago, and it >>>> seems to be pretty stable if I let it be. So, what I've done is to hook >>>> the GPSDO to the clock input of my 5335A. I've then adjusted the DDS so >>>> that it reads near 10.000000 MHz, and watched it over a round-trip 5 >>>> minute period several times with a large enough gate that I get 8 decimal >>>> points on the counter. I don't see any relationship between the few >>>> milli-Hz movement the counter shows and the changes to the DAC. During >>>> several runs last night, I saw less than 30 mHz of movement, which, if >>>> true, would be 3E-9, or 3ppb, right? Or would that be +/- 1.5ppb? >>>> >>>> Bob >>>> >>>> >>>> >>>> >>>> >>>>> ________________________________ >>>>> From: Bob Camp >>>>> To: Discussion of precise time and frequency measurement >>>>> Sent: Friday, August 16, 2013 10:47 AM >>>>> Subject: Re: [time-nuts] My GPSDO project: OCXO Thermal Oscillation? >>>>> >>>>> >>>>> Hi >>>>> >>>>> Ok, let's try some math and see if I can do it without blinking this >>>>> time…. >>>>> >>>>> +/-4 Hz for 6 volts is 0.66 Hz / V >>>>> output is 10 MHz so 1 Hz is 0.1 ppm >>>>> your OCXO is running at 0.066 ppm / V >>>>> That's also 66 ppb / V >>>>> >>>>> 0.02 V at 66 ppb / V is 0.0132 ppb or 13.2 ppt >>>>> >>>>> The UT+ has a sawtooth output that's about 45 ns >>>>> That's 45 ppb at one second >>>>> >>>>> 5 minutes is 300 seconds >>>>> >>>>> so 45 / 300 = 0.15 ppb or 150 ppt >>>>> >>>>> If it's the later clone version it might be about 1/2 of that. >>>>> >>>>> Are you doing sawtooth correction? >>>>> >>>>> Bob >>>>> >>>>> On Aug 16, 2013, at 11:09 AM, Bob Stewart wrote: >>>>> >>>>>> I'm converting the code for the VE2ZAZ FLL to a PLL. I'm seeing the >>>>>> phase correction change the EFC up and down about .02V to .03V over a >>>>>> period of 5 minutes or so (it varies). The full range on the OCXO is >>>>>> about +/- 4Hz varied by 0 to +6V, so at least this is a tiny value. I >>>>>> feel pretty confident with my code at this point. I'm using a Trimble >>>>>> 34310-T OCXO for which I've been able to find almost no information. >>>>>> Could this oscillating phase correction be some sort of thermal >>>>>> oscillation? I've tried two separate 34310s and both act more or less >>>>>> the same. My GPS device is normally a UT+, but I just now swapped in an >>>>>> "Adafruit Ultimate GPS Breakout" to the same effect. Is this good, bad, >>>>>> or indifferent for a GPSDO? I started this project not knowing what to >>>>>> expect, and I still don't. Experienced help, speculation, or even just >>>>>> kind words at this point would be appreciated! =) I don't have a known >>>>>> good/stable reference to compare >>>> this >>>>>> to. >>>>>> >>>>>> Bob - AE6RV >>>>>> _______________________________________________ >>>>>> time-nuts mailing 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. > > > _______________________________________________ time-nuts mailing list -- time-nuts@febo.com To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
