[time-nuts] Re: CTI OSC5A2B02 OXCO testing

[john.haine]

Or use a picPET and feed the ocxo output to the ref input and the 1pps pulse from a GPS into the pulse input.  I've done this with a pp07 to check my CTI ocxo frequency.Sent from my Galaxy
-------- Original message --------From: "Forrest Christian (List Account) via time-nuts" <time-nuts at lists.febo.com> Date: 03/06/2023  07:43  (GMT+00:00) To: Discussion of precise time and frequency measurement <time-nuts at lists.febo.com> Cc: Reginald Beardsley <pulaskite at yahoo.com>, "Forrest Christian (List Account)" <lists at packetflux.com> Subject: [time-nuts] Re: CTI OSC5A2B02 OXCO testing The way I would approach it as a beginner is with a 10mhz to 1hz picdiv anda timestamping counter like a tapr ticc.  Both ofFeed the ticc's reference clock with your 10mhz reference.   Then run the10mhz out of the ocxo into the picdiv which will result in 1hz output. Then run this 1hz into one of the ticc channels.That way you'll get a high accuracy timestamp of each 10,000,000th pulse. If they are exactly 1 second apart you're right on 10mhz.   This laststatement is oversimplified and ignores all sorts of potential errors suchas accuracy of the clock source and other sources of measurement noise butis good enough to get you started down the time nuts path.Note that by logging each timestamp you can then feed that into timelab oranother other similar tool and get some detailed statistical analysis ofthe ocxo over various time periods.One other method which may use hardware you already have is to feed your 10mhz reference clock into one channel on a 2 or more channel oscilloscopeand the ocxo output into the second channel.   Trigger off of the firstchannel and watch how much the signal on the second channel drifts.  Ifthey are both on the same frequency there will be no relative drift.   Ifthey are different they will drift and the rate will increase the furtherapart they are.   There is math you can do to determine how off if you cantime how long it takes a single cycle to drift.  Note that it doesn't takemuch of a difference for this method to not be usable as you quickly getdrift rates which exceed what a human can interpret on the screen.Note that all of the above is just to get you started.   Like I impliedthere is a lot of details I left out or oversimplified, but that should getyou started.On Fri, Jun 2, 2023, 9:55 PM Reginald Beardsley via time-nuts <time-nuts at lists.febo.com> wrote:> Hi,>> I've tried to avoid time-nutting for a long time, but I have lost the> battle.>> I bought 10 bare CTI modules on ebay for $2.93 each which I wish to test> over a long period of time.  I can set up 2-4 GHz SMA relay switching,> GPSDO reference etc.  Question is, what to read the frequency with.  My> 5386A with a GPSDO isn't precise enough.>> I don't know anything about it yet, but nanoPFA  FW on a nanoVNA  H4 looks> attractive.  Are there other instruments/methods to consider?  I have a> crazy mid 90's lab, so a bit more is not an issue other than where to put> it.>> All I'm looking for is a pebble tossed in the right direction.  Current> plan is an LM399 reference with emitter followers driving Vref on the> OXCOs, very stiff PSU and a fairly stable temperature.>> Thanks,> Reg> _______________________________________________> time-nuts mailing list -- time-nuts at lists.febo.com> To unsubscribe send an email to time-nuts-leave at lists.febo.com_______________________________________________time-nuts mailing list -- time-nuts at lists.febo.comTo unsubscribe send an email to time-nuts-leave at lists.febo.com