[time-nuts] NTP stratum 0

[Bill Janssen]

Magnus Danielson wrote:

>From: "Rob Kimberley" <time.bandit at btinternet.com>
>Subject: Re: [time-nuts] NTP stratum 0
>Date: Sat, 14 Jan 2006 18:48:16 -0000
>Message-ID: <!&!AAAAAAAAAAAYAAAAAAAAAOYAZyOzV8ERq+LmT45ypI7CgAAAEAAAAAzy/YBW0+RBmivoTTPkkh0BAAAAAA==@btinternet.com>
>
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>>The Stratum numbers in the Telecom Sync industry and those used in NTP
>>hierarchy are different beasts.
>>    
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>I agree, they are completely different beasts.
>
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>>In Telecom Sync, Stratum 1, 2, 3 et al are internationally defined levels of
>>frequency accuracy.
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>
>Um, no. They are nationally specified in the USA. You find them in ANSI T1.101.
>For their international variants you have to go to ETSI EN 300 462 series, as
>well as the ITU-T Rec. G.810 to G.813. Neither the ETSI or ITU-T standards uses
>Stratum indications, instead they use designations such as PRC, SSU and SEC.
>
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Yes the T1.101 is a USA standard, but when it was finalized there was 
international contributions and every
attempt was made to harmonize the international standards and the USA 
T1.101. I was active in the T1X3
meetings.

Bill K7NOM

>>In NTP Stratum 1 merely means the top of the hierarchical pyramid with
>>Stratum 2, 3 etc below it.
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>Indeed. It is really just a reference chain length from whatever the reference
>is, which may anything form a Ceasium-beam with coordinated time to an
>undiciplined XO.
>
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>>Stratum 0 has been used in discussions I have seen from people at Datum
>>and TrueTime to represent a GPS/NTP reference, but realistically I believe
>>that it should be labelled as Stratum 1.
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>Indeed.
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>>Would  humbly suggest you take a look at www.ntp.org for more information.
>>    
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>Also, the references from earlier this thread adds up. The RFC 1305 is as such
>a very interesting article.
>
>Cheers,
>Magnus
>
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