[time-nuts] GPSDO diurnal variation

Bill Dailey docdailey at gmail.com
Wed Aug 1 01:55:28 EDT 2012


Tom,

I am going to try to find systematic problems.  I just moved to a qs1r from my flex which is what I use to measure,  it seems something just isn't right.  I have never seen variation like this but I haven't ever had another standard so this is new territory for me in several ways.  Will get back with you when I have some things ironed out.

Doc

Sent from my iPad

On Jul 31, 2012, at 5:39 PM, "Tom Van Baak" <tvb at LeapSecond.com> wrote:

> See: http://www.leapsecond.com/pages/tbolt-8d/
> 
> As you can see, the phase stays within 5 or 10 ns during the day. The frequency stays within 5e-11 with 10 second averaging times; 5e-12 with 1000 second averaging times.
> 
> Send me your raw data (off-list) and I'll have a look at it. How sure are you that the 2.5e-11 variation is the GPSDO and not the "precision oscillator", or your comparator?
> 
> /tvb
> 
> ----- Original Message ----- 
> From: "Bill Dailey" <docdailey at gmail.com>
> To: "Time Nuts" <time-nuts at febo.com>
> Sent: Tuesday, July 31, 2012 5:27 PM
> Subject: [time-nuts] GPSDO diurnal variation
> 
> 
>> Does anyone have plots of true frequency variation of their 10 MHz standards over days?  I am trying to see if what I am seeing is typical or if I need to get a better antenna/gpsdo tuning/temp control.  Right now I am on vacation so am capturing data under much warmer than normal temps (ac turned down) and am seeing 250 uHz deviation with a period of about 24 hours (2.5x10-11).  I am trying to look at this in a way that is more intuitive and concrete to me than Allan deviation.  I am using a precision oscillator as the comparator and am removing linear drift (stochastic) in excel.  It seems surprisingly high.
>> 
>> Doc
>> KX0O
> 
> 
> 
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