[time-nuts] Is Timelab with a Prologix-Eth and a PM6680 - working ?

cfo xnews3 at luna.dyndns.dk
Tue Jul 3 17:38:38 UTC 2012


On Tue, 03 Jul 2012 19:08:56 +0200, Azelio Boriani wrote:

> Yes, you can ask here about these things. Anyway, the best is to use the
> TBolt as a reference (not necessarily on the external ref of the
> counter) and test another oscillator or GPSDO. For example: feed the
> TBolt PPS to A, the GPSDO_under_test PPS to B and measure the stability
> of the time interval using TIME A-B. Ideally it should be a constant
> value (even if not exactly 0, but constant). The phase data (the time
> interval errors) can be collected and an Allan deviation computed. 

Azelio , first ... Thanx for walking me through this.

I'll try the above later on.
But what you're saying is that when used as a TIC A->B , i don't need the 
TBolt on ext-ref ? , or do i need the TBolt on both Ext-Ref & on Chan-A ?

If i don't use the TBolt on Ext-Ref , won't i get hit by having a Std-Osc 
installed ? 

I have a GPS Antenna-Splitter , another TBolt (just need to assemble the 
PSU) , and also a X72 Rubi & a few FEI-5680's.

So i could try those when i'm a bit more familiar with the Counter & 
program. 


>
>The default sampling time is 200mS
>
Ahhh ... Thanx now i know why my 1hr Trace Duration was so fast.
I assumed that Timelab would set the sampling interval written in Timelab 
via GPIB. But i'll just select 1sec manually.



> So, to try your setup (TBolt on EXT REF and A): first inform the TimeLab
> that you have 1 second frequency samples, then set the sampling time to
> 1 second (use FUNCTION button on the PM6680) and retry collecting
> data.In this case the predicted uncertainty is 0.005 (5E-10) and sholud
> average out to 5E-13 in 1000 seconds taking into consideratin that the
> full 12 digit resolution is available at the PM6680 GPIB (that is, the
> GPIB has more digits than the display can show, see page 11-18 of the
> manual).
> 

I will try this now , and i assume i should then select Frequency in the 
Data Type - In TimeLab , as i don't use A->B measurements .. Or ?


I'll also dig into - How to calculate measurement errors , as you 
describe above.


Regards
CFO - Tnut-Beginner







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