[time-nuts] wifi with time sync

John Hawkinson jhawk at MIT.EDU
Sat Jan 14 10:53:53 EST 2017


This has nothing to do with time-nuts, can it stop please?

[ I don't know what forum to send you to for "weird wifi problems"; there
is probably no good one, because it is a very common consumer problem :( ]

NTP was mentioned because you (Bob Camp) had not defined the problem
very well, and asked some questions that it can solve. It will not
help spot an instanteous failure; it will help characterize the delay
of your network, and do so over fairly long time averages.

It seems pretty clear that nobody knows much about the protocol discussed
at CES, and probably most people have stopped reading this thread because
it is discussing something else entirely (...).
So we can probably just stop there.

However: I do not think your use of the word "overlay" is one that makes sense.
Typically things that are overlays increase overhead rather than reduce it.
Similarly, buffering causes delays which reduce the ability to get precise
timing, they do not help it. So while we can't say with much certainty
what a "magic protocol" is, it is surely not "giant buffers."

I tried to engage with you off-list and give you some pointers on this, but
that does not seem to be working. Consumer wifi driver problems are manifestly
inappropriate for this list, and trying to do both at once leads to gross
confusion :( I know this is my personal opinion and I don't speak with any
authority.

--jhawk at mit.edu
  John Hawkinson


Bob Camp <kb8tq at n1k.org> wrote on Sat, 14 Jan 2017
at 10:46:16 -0500 in <3EE57DEE-3D6E-438B-9D1F-C2BC216C6925 at n1k.org>:

> Ok, what I see is that every few hours, I get a “rogue delay” on a
> single ping. How would NTP help me spot a single transit with a 250
> ms round trip and identify the time it occured? Keep in mind that
> NTP is going to throttle back to a very low level of “chat” quite
> quickly…..
> 
> While this *is* getting far more into my WiFi (which I had no real
> intention of doing) it does apply to timing and running audio over
> WiFi as well. The basic transport as it runs up through the various
> layers is *not* very good time wise. There is indeed a real need for
> some sort of overlay to take care of that issue. I’d still love to
> know if this magic protocol is simply giant buffers and some sort of
> tagging or if they do something more interesting.


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