[time-nuts] Re: problem with Trimble Mini-T

[John Ackermann N8UR]

I measured a Thunderbolt using both TinyPFA and a TimePod and got the 
attached ADEV plots.  From one second out, they're virtually 
indistinguishable.  I was very impressed!

It may be a while before I am able to publish results, but in 
September/October I did a very long data collection run using four 
TinyPFAs measuring different GPS/GPSDO sources at a 10 Hz rate over a 
total of 42 days.  The TinyPFAs ran flawlessly over that period writing 
to a laptop over USB.  Again, very impressive.

John
----

On 11/7/23 12:25, Erik Kaashoek via time-nuts wrote:
> Magnus,
> I know both John Ackermann and Bob did extensive measurements with the 
> tinyPFA and compared it to other phase measurement tools.
> Erik.
> 
> On 7-11-2023 16:53, Magnus Danielson via time-nuts wrote:
>> Hi Erik,
>>
>> OK, that makes sense. That's fine. Thanks for the clarification!
>>
>> I have yet to setup and test tinyPFA. Will be interesting to compare 
>> it to other measurement solutions.
>>
>> Cheers,
>> Magnus
>>
>> On 2023-11-07 07:29, Erik Kaashoek via time-nuts wrote:
>>> Hi Magnus
>>> The ADEV was a separate measurement using the 10MHz output of the 
>>> Mini-T against my most stable DOCXO using a tinyPFA
>>> Erik.
>>>
>>> On 6-11-2023 20:12, Magnus Danielson via time-nuts wrote:
>>>> Hi Erik,
>>>>
>>>> Really happy to hear you got hold of the issue, and happy that my 
>>>> little suggestions got you in the right track quick enough.
>>>>
>>>> With ADEV, do you mean the Lady Heather self-reports or that of a 
>>>> separate reference measurement?
>>>>
>>>> Cheers,
>>>> Magnus
>>>>
>>>> On 2023-11-06 16:47, Erik Kaashoek via time-nuts wrote:
>>>>> Hi Magnus,
>>>>> Thanks for telling me to check everything.
>>>>> I turned out to be leakage from another 10MHz source with an output 
>>>>> coax running close to the coax from the reference.
>>>>> To ensure the PLL worked correctly I first validated in open loop 
>>>>> mode the control range of the DAC, which turned out to have 10MHz 
>>>>> correctly centered in the middle of the DAC range.
>>>>> Then I enabled the PLL and after about 10 minutes the PLL was 
>>>>> stable and within 1e-10 of a Rubidium reference.
>>>>> The 0.1s ADEV without PLL active is just below 0.8e-11. With PLL 
>>>>> active the 01. - 100 s ADEV is at about 3e-11 which is good enough 
>>>>> for me. The active PLL ADEV can be further improved by making the 
>>>>> loop time constant longer if needed (it is now at 100s)
>>>>> Erik.
>>>>>
>>>>>
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