[time-nuts] Some results of PRS10 and Trimble Resolution T

[Ulrich Bangert]

Hallo Said,

the M12+'s pps jitter has a strong frequency component at a repetion
rate of 2 s. This component has a peak to peak value of 2-4 ns and is
almost unseen in the raw pps values. It is, however, clearly to be seen
if you manage to compute the sawtooth corrected pps values.

What you see in the PRS10 output is simply a feedthrough of this
frequency component, even with natural pll time constants of some hours
or so. While i do not own a PRS10 myself, i use exactly the same
software algorithms as the PRS10 including the pre-filter in my GPSDO
(FRK-L or LPRO or FTS-1200 or HP10811 against M12+) and i come to very
close results regardless which local oscillator i use. The bump gets
smaller with higher pll time constants but you will no get rid of it
completely.

For a quick check, remove the M12+ pps and let the PRS10 run on its own,
you should see no bump in this case.

Regards

Ulrich, DF6JB

> -----Ursprüngliche Nachricht-----
> Von: time-nuts-bounces at febo.com 
> [mailto:time-nuts-bounces at febo.com] Im Auftrag von SAIDJACK at aol.com
> Gesendet: Montag, 26. Juni 2006 19:44
> An: time-nuts at febo.com
> Betreff: Re: [time-nuts] Some results of PRS10 and Trimble 
> Resolution T
> 
> 
> Hello Erik,
>  
> I recently measured my PRS10 as well.
>  
> You can see a big hump (about 1.6E-011) at the 2s measurement 
>  intervall.
> 
> While this is within spec, does anyone know why the unit is 
> so noisy at  that 
> particular intervall? Is there a filter setting that would 
> improve  this?
>  
> Could this be power supply injected noise?
>  
> I have set PT to 7, driving the unit with an Motorola M12+.
>  
> I measured the ADEV with the new TSC5120A. Other oscillators 
> I have measure  
> at around 1E-012 at 2s, so it's not a setup problem.
> 
> Thanks,
> Said
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