[time-nuts] TimeLab and the Adev plot

[Azelio Boriani]

>In the second sentence, I make the point that when you take two sample values, at various taus, you really do not
>average them but rather make their time stability contribution (trigger jitter and resolution) less important relative to
>the tau between them. This is by itself not an averaging effect.
Agreed that it is not an averaging effect, then taking two samples at
various tau is, for example, taking samples at 2 seconds instead of 1
second or using two samples for the actual tau under consideration?

On Mon, Feb 3, 2014 at 11:28 PM, Magnus Danielson
<magnus at rubidium.dyndns.org> wrote:
> On 03/02/14 01:19, Azelio Boriani wrote:
>>
>> Magnus, please, can you elaborate this:
>> > A common mistake is to assume you can average it out, but that gives you
>> > a different measure which does not
>> > represent the ADEV values you are comparing with. The time between
>> > samples will scale down the relative impact of
>> > the time-noise, but not really average it.
>> That is, have I to increase the time between samples or take samples
>> and average them? For example, go from samples every second to samples
>> every 2 seconds or average two samples every second to obtain a sample
>> every 2 seconds. The last method will (apparently) increase the
>> resolution...
>
>
> What I am saying in the first sentence is that taking the average of samples
> does not give you improved limit, but just add filtering which makes low-tau
> ADEV values which is biased to look better than the real ADEV for that
> measurement is.
>
> In the second sentence, I make the point that when you take two sample
> values, at various taus, you really do not average them but rather make
> their time stability contribution (trigger jitter and resolution) less
> important relative to the tau between them. This is by itself not an
> averaging effect.
>
> Cheers,
> Magnus
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