[ntp:questions] Local Time NTP Server

Jakob Bohm jb-usenet at wisemo.com.invalid
Mon Aug 24 15:46:17 UTC 2020


On 2020-08-24 16:07, William Unruh wrote:
> On 2020-08-24, Jakob Bohm <jb-usenet at wisemo.com.invalid> wrote:
>> On 2020-08-24 12:51, Beth Connell wrote:
>>> Hi,
>>> I'm struggling to find any information on where the free NTP servers are geographically based. In particular, I'm wondering where Facebook, Google, Microsoft, etc are based within the UK. Just for curiousity, I'm wondering how this affects any interference to my location.
>>>
>>> Thanks
>>>
>>
>> All NTP time is GMT (now named UTC, after HM government dropped the
>> ball).  The only geographic factor is the "ping time" to the time
>> server, the servers that are the most distant (longest ping) are the
>> GPS and Galileo satellites, that are hundreds or thousands of km from
>> the receiver, and use their own (non-NTP) protocols to correct for the
>> delay.
> 
> It was renamed because UTC has nothing to do with Greenwich. For
> historical reasons, the time at Greenwich is the same as UTC.
> (Note that the prime meridian now runs through a garbage can in a park
> just south of the Thames rive in London and not along the line marked
> on the ground in Greenwich. No idea why you believe the govt dropped the
> ball. Because the location of Greenwich moves (plate techtonics) it
> would introduce inaccuracies into the definition of time if it were tied
> to Greenwich. Also, you cannot ping the sattelites.

I used "ping time" as the popular name of the round trip time (as 
actually measured by NTP implementations), and thus as a somewhat
vague reference to the equivalant satellite-to-ground time delay.

As for the reference to HM Government, there was a rumor, many years 
ago, that the budgets cuts caused the relevant time management job to 
revert to the IERS in Paris, thus loosing Britain the honor of having 
the time standard refer to the British victory at the Meridian
conference.

If the Greenwich observatory had still been in full operation, the
scientists running it would probably have applied the necessary
corrections for the ground shifting under their instruments,
rather than having the hole place demolished in favor of a symbolic
line on the ground.  They would also probably have become the time
setting command center for the Galileo satellites that replaced their
daily dropping of an actual ball to signal exact meridian noon to
ships setting their navigation chronometers.



>>
>> Another problem is if the NTP server is one of those that deliberately
>> return slightly wrong time before and after each leap second to "smooth
>> out" the leap, some of the companies you mention reportedly do that.
>>
>>
>> Enjoy
>>
>> Jakob


Enjoy

Jakob
-- 
Jakob Bohm, CIO, Partner, WiseMo A/S.  https://www.wisemo.com
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