[time-nuts] EFC info on Trimble 34310-T OXCO

[Bob Camp]

Hi

The only Rb’s I know of that go out to the 24 to 72 hour tau’s are full blown GPSDO Rb’s. 

Bob

On Aug 25, 2014, at 1:53 PM, Dave M <dgminala at mediacombb.net> wrote:

> I found the parameters for the X72's 1PPS input.  The range of Tau is 5 - 10,000 seconds, or about 2 hrs, 45 min.  at the longest setting.  It defaults to 400 seconds. However, mine doesn't have the firmware to enable the 1PPS input, so it really doesn't matter.
> Out of curiosity, does anyone know of any Rb units that can be programmed to a 24 hr (or longer) Tau, either by EFC or 1PPS input?
> 
> Dave M
> 
> 
> Bob Camp wrote:
>> Hi
>> 
>> It is not what is done in the Efratom Rb’s. Their pps input is set up
>> to get things on frequency / on time quickly. The assumption is that
>> you plug it into a pps to get it “right” and then take off on your
>> mission. That takes them into the short (for a Rb) time constant
>> region.
>> 
>> Bob
>> 
>> On Aug 24, 2014, at 5:56 PM, Brooke Clarke <brooke at pacific.net> wrote:
>> 
>>> Hi Bob:
>>> 
>>> I think that's what's done in the SRS PRS10
>>> http://www.prc68.com/I/PRS10.shtml
>>> 
>>> Have Fun,
>>> 
>>> Brooke Clarke
>>> http://www.PRC68.com
>>> http://www.end2partygovernment.com/2012Issues.html
>>> http://www.prc68.com/I/DietNutrition.html
>>> 
>>> Bob Camp wrote:
>>>> Hi
>>>> 
>>>> If you lock an Rb to GPS, you need / want / should do it with a
>>>> *very* long time constant. Numbers in the one day to several days
>>>> range are commonly seen. If you lock it up with a tighter (shorter
>>>> time constant) loop, it will just wander around as it follows the
>>>> GPS input. That’s what would happen if you hook your Rb to your
>>>> Trimble and turn on the disciplining on the Rb. It will
>>>> significantly degrade the stability of the Rb.
>>>> 
>>>> If you have a temperature stable environment (or create one) you
>>>> can get some very good results with an (good) Rb locked to a (good)
>>>> GPS via a proper long time constant setup. It’s not easy, but it
>>>> can be done.
>>>> 
>>>> Bob
> 
> 
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