[time-nuts] Extended length Phase Noise Measurements with TimeLab

John Ackermann N8UR jra at febo.com
Fri May 3 14:31:00 EDT 2013

Hi Tom --

Are you talking about capture time limits, or minimum tau?  I've never 
encountered any capture time limits in TimeLab and have done out to 30 days.

However, one thing I have noticed with the 5120A ethernet using my own 
capture software is that the data flow will sometimes stop for several 
seconds and then restart.  You don't actually lose any samples, but the 
client software can suffer a TCP timeout.  I got around this by setting 
the timeout in my software (using Perl's libtelnet module under Linux) 
to something like 30 seconds.  That solved the issue for me.

I've never seen the TCP timeout affect TimeLab; I don't know what kind 
of time limit John has coded but it seems to be long enough.

Re the 5120A itself erroring out, it does complain if either the 
frequency or the amplitude change too much during the measurement. 
Unfortunately, I don't know of a way to disable that.

On 5/3/2013 2:21 PM, Tom Knox wrote:
> Recently I was looking at a co-workers Lab View measurements taken with a 5120A. She is studying vibration on Phase Noise. I asked how Lab View compared to TimeLab and she said in many ways she prefers TimeLab but ran into a problem. The research she is currently conducting requires collecting data in extremely long measurement periods beyond the TimeLab limits. Is she missing something? If not is measurement length an easy fix? One other problem during her project was related to the 5120A, occasionally the vibration must hit a resonance and the 5120A stops measurement saying measurement  parameters were exceeded. It would be nice to be able to adjust or disable that feature. Thanks in advance for your ideas.
> Thomas Knox
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