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Re: [gpsd-dev] [PATCH] Clarifications needed for the time-service HOWTO

From: Beat Bolli
Subject: Re: [gpsd-dev] [PATCH] Clarifications needed for the time-service HOWTO
Date: Mon, 21 Oct 2013 22:13:18 +0200
User-agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.7; rv:24.0) Gecko/20100101 Thunderbird/24.0.1

On 21.10.13 19:34, Eric S. Raymond wrote:
> Other experts, feel free to chime in.
> Gary E. Miller <address@hidden>:
>>> Is it really true that most public NTP servers are Stratum 2, or
>>> are there more layers in normal use?
>> Maybe most, but you'll see a lof of 1 and 3's.
> I've been doing research. Revised text near the end of first section:
>      You will hear time service people speak of "Stratum 0" (the reference
>      clocks) "Stratum 1" (NTP servers directly connected to reference
>      clocks over a path with known and compensated-for latency)
>      "Stratum 2" (publicly accessible servers that get time from Stratum 1
>      over a network link.) Stratum 3 chimers redistribute time from Stratum
>      2, and so forth. There are defined higher strata up to 15, but
>      you will probably never see a public chimer higher than Stratum 3.
>      Ordinary client computers are normally configured to get time from one
>      or more Stratum 2 (or less commonly Stratum 3) servers. With GPSD and
>      a suitable GPS, you can easily condition your clock to higher
>      accuracy than typical Stratum 2; with a little effort you can do
>      better than public Stratum 1 servers.
> If this is misstating the facts in any way - for example, if Stratum 3
> and up servers are more common than we are implying here - someone
> please speak up.
>>> More generally: what can I discover about the quality of the chimers
>>> I listen to?
>> Just compare several. 
> "Just compare several".  How delightfully vague!  What I need to
> document for the HOWTO is *how to do this*.  Concrete procedure.
> (1) What reporting tool do I run?  
> (2) Where among the numbers it will display for each chimer is
> the figure of merit I should be paying attention to? 
> (3) What do reasonable values of that figure look like?  What
> do weird outliers look like?
> It would be illuminating if you replied with a transcript of how
> the report looks on your system and pointed out which numbers are
> the significant ones.  If you can include a contrasting report 
> from a system with bad chimers, please do.

Let me try this one (see the attachment).

mail: echo '<address@hidden>' | tr -d '[A-S]'
pgp: 0x506A903A; 49D5 794A EA77 F907 764F  D89E 304B 93CF 506A 903A
icbm: 47.0452 N, 7.2715 E

"It takes love over gold, and mind over matter" -- Dire Straits

Attachment: tuning.diff
Description: Text document

Attachment: signature.asc
Description: OpenPGP digital signature

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