[time-nuts] wifi with time sync

Bob Camp kb8tq at n1k.org
Fri Jan 13 16:17:19 EST 2017


It just so happens that I’m trying to track down an issue with my WiFi as
I type this. My *guess* is that there is a dropout going on. The only easy
way I can see to get a round trip time with a high data rate is to run ping. 
It’s the only tool that gives me something that is fast enough to spot issues.
Is it perfect? certainly not. Is it an upper bound that is also likely the limit
for things like NTP - in my experience it sure is. That of course assumes 
the gizmo that sends the pings back does so quickly and consistently. I’ve
spent enough time testing that side of it that I’m quite sure it’s true in this case.


> On Jan 13, 2017, at 4:07 PM, John Hawkinson <jhawk at MIT.EDU> wrote:
> Bob Camp <kb8tq at n1k.org> wrote on Fri, 13 Jan 2017
> at 15:35:19 -0500 in <ADCE3C3B-A84F-4F78-93B0-824F5A9B4EFC at n1k.org>:
>> What standard protocol would you recommend I run from the command
>> line on my computer to get a quick estimate of the timing lag and
>> variablilty on my particular WiFi connection?
> Bob: I hope you read the whole of my message, rather than just the
> short upper part you quoted. I said "I'm not aware of a tool that does
> this today" -- I don't think there is a good answer.
> ==> There isn't one. <==
> You can certainly use ping to get a gross upper bound. But rememnber
> it's a gross upper bound, and the underlying technology can do much
> better. As Chris said, ntp will do a good job telling you the delay
> between two hosts (that are running ntp and talking to each other)
> by sending a lot of samples and averaging over time.
> But what is your application here? You haven't made it clear.  Ping is
> not representative of what you could get with a wifi using a new
> technology, which was what was how this thread started, and so the
> context some of the anwers (esp. mine) are in. Ping is representative
> of other things, though.
> --jhawk at mit.edu
>  John Hawkinson
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