[time-nuts] Re: Poor's man NTP

[Bob kb8tq]

Hi

If you are talking about a “rest of the company” sort of thing, 
it probably needs to be looked at carefully. Far better to not do
it than to do it and get in a tangle. 

The NTP “server” is only one part of the error equation, even on
a local network. It may not be the largest contributor to the total
error “as delivered”. If you really are after 1 ms “for sure / all the 
time" to a bunch of clients …. look at PTP.

A proper NTP setup will include at least three independent, accurate,
stable, reliable local servers.Since even numbers get voting processes 
confused and even reliable stuff does break from time to time, five 
independent servers is a good target to aim for. 

Again, better to not do it than to get started and find it’s a project
that can’t be properly implemented. 

Bob

> On Dec 19, 2021, at 4:21 AM, giuseppe at marullo.it wrote:
> 
> Hi Perry,
>> For log purposes, if you're down at the 2ms level you're probably utterly
> fine.
> Sure, 2ms still good IF it is 2ms. 
> 
> Provided I was expecting way less than 1ms, if ntpstat is reliable I could
> stop here.
> 
> One example, ms logs have 1ms "resolution" (short version, please bear with
> me), not sure about accuracy and events may be logged out of order so no big
> deal, 2ms is still plenty of precision.
> 
>> Note that there really isn't anything wrong with wanting to do better for
> its own sake, but from an engineering requirements point of view, you've
> already succeeded.
> Thanks, of course asking here is to improve but what is puzzling me is the
> 2ms value. Is it the actual accuracy?
> Here it is another command output(ntptime):
> 
> ntp_gettime() returns code 0 (OK)
>  time e56974e6.38dfefc0  Sun, Dec 19 2021 10:07:50.222, (.222167714),
>  maximum error 6000 us, estimated error 0 us, TAI offset 37
> ntp_adjtime() returns code 0 (OK)
>  modes 0x0 (),
>  offset 0.347 us, frequency -12.253 ppm, interval 1 s,
>  maximum error 6000 us, estimated error 0 us,
>  status 0x2001 (PLL,NANO),
>  time constant 3, precision 0.001 us, tolerance 500 ppm,
> 
> I don't see 2ms accuracy, it seems better(0.347 us?).
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