[time-nuts] Cheap jitter measurements

Bob kb8tq kb8tq at n1k.org
Tue Apr 10 19:22:00 UTC 2018


Hi

> On Apr 10, 2018, at 2:59 PM, Hal Murray <hmurray at megapathdsl.net> wrote:
> 
> 
> kb8tq at n1k.org said:
>> Yes, but looping back to the start of this thread, the intent is to actually
>> measure the jitter directly.  That’s where the whole need for a stamped
>> pulse comes from. To paraphrase the earlier comments, the intent is to get
>> away from a “self reported” result and actually do a direct measurement.  
> 
> I think that should be a reasonable project.
> 
> 1) Write some code to grab the time, send a pulse, grab the time.  Log that.
> 2) Use a time-stamp counter to log the time of the pulse.
> 3) Write the software to merge the two log files.

Provided you can get NTP (and not just the kernel) to time the pulse accurately it 
would work. It’s a bit more cumbersome than a message out of a serial port. 

Bob


> 
> 
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