[time-nuts] Distributiuon Amlifier Altinex DA1804NT

Attila Kinali attila at kinali.ch
Sun May 31 06:24:12 EDT 2015


On Sat, 30 May 2015 23:11:41 -0400
Vlad <time at patoka.org> wrote:

> Looking to the drift values, the case with T-Bolt has better value, I 
> think. But it has bigger spikes.

That is not 100% clear. If you look at the MV89 vs DATUM frequency difference,
you see that (at least) one of the OCXO is still settling in the first hour.

Looking at the ADEV values, then you can say that the DATUM is more
stable than the T-Bolt up to 1000s. You cannot say much over 1000s
as you have measured only for 8h.

The spikes in the frequency diffrence you have in the T-Bolt case,
might be due to bad antenna position. You are measuring at a precision
level, where i wouldn't trust a GPS based system to stay on frequency
short term (below couple 100s to 1000s)

I am not 100% sure what you want to measure, if it's just the noise
and ADEV performance of your distribution amplifier, then the canonical
way to do this, would be to use one low noise XO and a power splitter,
feed one signal trough the amplifier, and one directly into something
with which you can measure phase.

One way would be the sound card based system i mentioned earlier.
Another would be to build a DMTD like [1] and use a TDC like [2].


			Attila Kinali

[1] "A Small Dual Mixer Time Difference (DMTD) Clock Measuring System",
by W.J. Riley, 2010
http://www.wriley.com/A%20Small%20DMTD%20System.pdf

[2] http://www.ko4bb.com/dokuwiki/doku.php?id=precision_timing:pictic

-- 
< _av500_> phd is easy
< _av500_> getting dsl is hard


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