Hi Tom, If I understand you right, the only thing I need from the adev program is the OADEV values and those are the new ADEV? Here's the plot for the past 24 hours using "0" for bins. It takes a few seconds to run, doesn't it?
Thanks for the ideas on what to measure. I'm going to replace the EFC divider with low temp coeff resistors and do a software bug fix, and hopefully that will be the end of fiddling with this thing and I'll be able to get some really long runs in. http://www.evoria.net/AE6RV/GPSstd_PLL/Plots/ADEV.2.6.png thanks for all the help, Bob >________________________________ > From: Tom Van Baak <[email protected]> >To: Discussion of precise time and frequency measurement <[email protected]> >Sent: Thursday, February 6, 2014 5:13 PM >Subject: Re: [time-nuts] Rb as source for ADEV? > > >Hi Bob, > >Short-term measurements like that do a good job using a OCXO and TIC to reveal >TIC and GPS resolution limits. It's a useful exercise, but it usually doesn't >tell you anything about the OCXO itself. > >Long-term measurements like that do a superb job using GPS to measure the >long-term stability and frequency drift rate of the OCXO (or Rb). This, >because for intervals of days to weeks to months you can't beat GPS as an >inexpensive ultimate time/frequency standard. And for those long intervals, >the TIC resolution is usually more than enough. > >Just collect the raw phase data and raw DAC data. In a few weeks you'll be >able to make some really nice plots. > >Also consider freezing the DAC for a week (unlocked) and compare that data >with your locked data. You can then make plots that look like: >http://leapsecond.com/pages/gpsdo/ > >On Rb -- since you're now a time nut, do not let the Rb warm up at all -- the >data get you the first hour or first day will be just as interesting as the >data you collect the next month. > >On ADEV -- I know the source code calls them adev and oadev, but you should >just call it ADEV. No one uses the old back-to-back formula anymore; the >overlapping formula is the default. And then plot using the "all" or "many" >tau method I mentioned. > >/tvb > >----- Original Message ----- >From: "Bob Stewart" <[email protected]> >To: "Discussion of precise time and frequency measurement" <[email protected]> >Sent: Thursday, February 06, 2014 2:23 PM >Subject: [time-nuts] Rb as source for ADEV? > > >I'm getting a little more familiar with ADEV and OADEV now. With a little help >from Tom, I've put together gnuplot scripts and his software to get a decent >plot. But, as some time-nuts have pointed out, my measurements are of one part >of my system being compared to another. Would I learn anything useful by >hooking my Rb standard up to my 5335A and comparing that to the OCXO? How long >should I let the Rb heat up before starting the test? I'm a bit uncertain >about the result of comparing a stable clock of questionable accuracy to an >accurate clock of questionable stability. Hopefully I said that right. > >thanks, > >Bob - AE6RV > > > >_______________________________________________ >time-nuts mailing list -- [email protected] >To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts >and follow the instructions there. > > > _______________________________________________ time-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts and follow the instructions there.
