[gpsd-dev] NTP Pool (was Re: Draft Stratum 1 Microserver HOWTO is up)

[Clark B. Wierda]

On Fri, May 20, 2016 at 1:30 PM, Hal Murray <address@hidden> wrote:

[pool limit of 100 ms]

address@hidden said:
> That's weird.  Why would they have a precision requirement *above* RFC5905's
> "A few tens of milliseconds"?  You'd think they'd want it to be below that.

If you want time in the range of 10s of ms, you need to select the servers you use.  With something like the pool, you are likely to get a server on the other side of the country with associated routing quirks.

I think the goal of the pool project has always been good-enough rather than great accuracy.  100 seems like a reasonable cutoff point to me.  What did you have in mind?

Another consideration is that there is only one monitoring station.

From reading their documentation, they monitor the pool candidates and report on their merit.  The availability of the metrics could be better, but they are trying to ensure a minimum.  Their goal is related to human-scale time.  Also, I think their focus is spreading the load.

BTW, I was getting within 5ms using generic ublox-7 puck (no PPS) on an old laptop. USB PPS (GR-601W) was reliably under 1ms.

Clark