[time-nuts] True Position GPSDP + Rb X72

[KA2WEU at aol.com]

Meaning home=home ?  just kidding. ,long staying constant 
 
73 de Ulrich 
 
 
In a message dated 9/24/2017 8:45:35 A.M. Eastern Daylight Time,  
magnus at rubidium.dyndns.org writes:

Hi,

On 09/24/2017 02:30 PM, Bob kb8tq wrote:
>  Hi
> 
> 
>> On Sep 23, 2017, at 9:39 PM, Hal Murray  <hmurray at megapathdsl.net> wrote:
>>
>>
>>  kb8tq at n1k.org said:
>>> If the main use is feeding test gear (and  not direct synthesis) an Rb 
may do
>>> pretty well. Most  instruments assume a dirty reference signal and 
clean it
>>> up  internally.
>>
>> What's the bandwidth on the typical  cleanup PLL?  How well does that 
match
>> the noise from a  Rb?
> 
> It’s like any other PLL with noise involved. You look at  the noise of 
the Rb, the
> noise of the particular cleanup oscillator,  and your system 
requirements. In some
> cases that comes out to a few  seconds. For Time Nut grade with a really 
good
> OCXO you are at some  pretty long numbers.
> 
> If the Rb starts at 2x10^-11 at 1 second  and goes down by square root 
tau: At
> 100 seconds you are at 2x10^12.  Still not as good as a really good OCXO. 
At
> 10,000 seconds you might  get to 2x10^-13 (but probably will not). Your 
OCXO
> likely will climb  out of the “parts in 10^-13” range before 10,000 
seconds.
> 
>  Lots of fun.

Once up on a time, you could order the OSA cesiums width  different 
oscillators, essentially to buy into different balances between  
oscillator cost and performance. The time constant is adapter with  
regards to oscillator type, as the trade off shifts.

I can't recall  any other cesium or rubidium that did this, but HP 
upgraded oscillators at  one point for this reason  too.

Cheers,
Magnus
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