[time-nuts] Measuring phase with an HP 3456A?

Magnus Danielson magnus at rubidium.dyndns.org
Sat Oct 1 15:52:58 EDT 2016


Bob,

Just try it. Compare it and see how the initial noise slope behaves and 
compare it to other measurements.

Similar phase-measurement setups have been used in historic context.

What ends up being the best method for you is a combination of what 
tools you have available and dare to bring into use.

I haven't tried this approach thought.

One if the key elements to make it work well would be if you can trigger 
the measurements so you know what time-base you have. If your 
observations is at 1.2 s or 1.8 s rather than something more common you 
need to know, and best way is to steer it from a good source.

Cheers,
Magnus

On 10/01/2016 08:32 PM, Bob Stewart wrote:
> I've been spending a small amount of my time looking into making a sort of hybrid DMTD with a pair of DBMs up front feeding the stereo input to a sound card.  So, I got the 100KHz LPF back from Oshpark and hooked it up to my scope for verification - an obvious step.  Then I hooked it up to my 3456A just for grins.  (The two DBM inputs are 10MHz outputs from two different GPSDOs).  So, as I watch this, I think the obvious question: can this measure phase angle better than the 5370A?  I guess I need to send it through a full 100ns of phase change to get a calibration value.  So, who's been down this road and what did you discover?
> Bob
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