[time-nuts] Best counter setting for ADEV?

[Azelio Boriani]

OK, and then what about measurements beyond 1000 sec (for the same DUT's
ADEV in the 1E-13's) taken with a 500pS counter and a 50pS counter? Nice to
hear that there is exactly no difference, just use average...

On Thu, Oct 4, 2012 at 2:34 PM, Adrian <rfnuts at arcor.de> wrote:

> Azelio,
>
> as an example, with a 53131A you have an output 'granularity' of +/- 500
> ps.
> No matter how much averaging happens inside the counter, if the least
> significant digit is 500 ps, then the (ADEV) measurement limit is always
> 5E-10 at 1 sec as I posted in the initial post to this thread. This is not
> the accuracy of the counter, it's simply the available display and output
> string resolution.
> At 10 sec., the ADEV limit of the same counter is 5E-11 etc. etc. finally
> getting limited by the reference source and other effects.
> If the DUT's ADEV is in the 1E-13's, any measurement values below 1000
> sec. are void and represent just the measurement limit of the +/- 500ps
> counter.
>
> Now I'm waiting to receive 'glasses' for my 53131A that are in transit :)
>
> Adrian
>
>
> Azelio Boriani schrieb:
>
>> Taking 10 samples from a 1nS counter leads you to a 100pS resolution but
>> the noise at best (if it is really random) is reduced by SQRT(10). So, as
>> already pointed out here, there is no real substitute for lower noise,
>> higher resolution measurements.
>>
>> On Thu, Oct 4, 2012 at 3:01 AM, Bob Camp <lists at rtty.us> wrote:
>>
>>  Hi
>>>
>>> A 1 ns resolution TI counter will do the measuring part just fine.
>>> Hitting
>>> the number, is where it gets a bit crazy. A *good* GPSDO might get near
>>> that.
>>>
>>> Bob
>>>
>>> On Oct 3, 2012, at 8:56 PM, Kevin Rosenberg <kevin at rosenberg.net> wrote:
>>>
>>>  On Oct 3, 2012, at 6:52 PM, Kevin Rosenberg <kevin at rosenberg.net>
>>>> wrote:
>>>>
>>>>> Nice plot! Yes, I'd have trouble measuring 10E-14 at 10E5 seconds.
>>>>>
>>>> Sorry, 1E-14 at 1E5.
>>>>
>>>>
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