[time-nuts] V standards

[WarrenS]

Bruce 

Does this mean that by "using carrier phase disciplining techniques"  
One could get two orders less noise than  is shown 
on the SRS page#3  graph http://www.thinksrs.com/downloads/PDFs/Catalog/PRS10c.pdf

Is this also better than you get when using the 1PPS correction sawtooth?
Do you know of a posted plot that shows the noise you get using the Carrier phase techniques?

Do please understand that my questions about using pots etc, 
are to get a better understand about what is going on, 
Not suggestions on how to make one.

Thanks,
WarrenS
************************

WarrenS wrote:
>> Bruce Wrote: 
>> "Sometimes its cheaper and more convenient to build  a high 
>> resolution DAC than use a pot and a conventional DAC. ...
>>     
>
> Very true, And don't forget also more fun, more challenging, and more better!
> which all very import  requirements in this field, maybe more so than performance.
>
> Assuming  100 to 1000 seconds are the typical max tracking times 
> practical in the standard GPSDO's due to temperature changes, 
> initial aging, etc  as stated by Ulrich in the posting  
> http://www.febo.com/pipermail/time-nuts/2008-December/034823.html 
> and IF IE-10 is the best you get from the GPS signal in these same 
> time averages as stated on Page #3 of  
> http://www.thinksrs.com/downloads/PDFs/Catalog/PRS10c.pdf
>
> Doesn't this imply that a Dac with more than about 12 bits becomes 
> an overkill at 100 seconds tracking when using a 1E-7 turning range OSC, 
> and around 18 bits for the same Osc when tracking at 1000 Sec? 
>
> WarrenS
> **********************
>   
Warren

In principle, but this precludes such improvements as correcting for
ambient temperature variations in software etc., without upgrading the
DAC resolution.
Also (as many have discovered) when one is testing various oscillators
of unknown performance its very convenient to have somewhat more EFC DAC
resolution than 12bits or even 14bits.
it is also useful to have a relatively stable low noise reference for
the high resolution DAC.

Also a low resolution DAC precludes (or at least makes more difficult)
using carrier phase disciplining techniques which can have around 2
orders less noise than PPS tracking GPSDOs.
A relatively inexpensive 20 bit DAC can make such experimentation much
easier.


Bruce