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Re: [Cbor] [dtn] [EXTERNAL] Re: [EXT] Re: LTC timescale (Re: Question regarding RFC 9171 - How to incorporate "Coordinated Lunar Time")

Jorge Amodio <jmamodio@gmail.com> Sat, 13 April 2024 12:29 UTC

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From: Jorge Amodio <jmamodio@gmail.com>
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Date: Sat, 13 Apr 2024 07:28:26 -0500
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Cc: "Rieber, Richard R (US 347R)" <richard.r.rieber@jpl.nasa.gov>, sburleig.sb@gmail.com, "EXTERNAL-Sipos, Brian J (US 9300-Affiliate)" <brian.sipos@jhuapl.edu>, John Dowdell <john.dowdell.ietf@gmail.com>, DTN WG <dtn@ietf.org>, cbor@ietf.org
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To: Carsten Bormann <cabo@tzi.org>
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Subject: Re: [Cbor] [dtn] [EXTERNAL] Re: [EXT] Re: LTC timescale (Re: Question regarding RFC 9171 - How to incorporate "Coordinated Lunar Time")
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Once again clock != time.

Another reference about atomic clocks on satellites
https://www.nasa.gov/missions/tech-demonstration/deep-space-atomic-clock/what-is-an-atomic-clock/

We need to make clear, the difference between the precision required for navigation and what we need for comms and networking.

While they both are part of LNIS, PNT is way off the interest and mandate for this DTN WG.

Regards
-Jorge

> On Apr 13, 2024, at 01:14, Carsten Bormann <cabo@tzi.org> wrote:
> 
> On 12. Apr 2024, at 19:34, Jorge Amodio <jmamodio@gmail.com> wrote:
>> 
>> Just one quick comment, I'm not buying 100% that spacecraft's internal clocks will have to run exclusively on LTC, that is a very "localized" concept.
> 
> Wikipedia tells me that the on-board clocks of the GPS satellites are faster than TAI (and thus GPS time) by 38 microseconds per day [1].  This is in the same ballpark as the ~ 58.7 µs/d that are widely reported for the moon surface (and thus LTC?) [2].  Clearly, we know how to manage these rate differences.
> 
> Grüße, Carsten
> 
> 
> [1]: https://en.wikipedia.org/wiki/Satellite_navigation
> [2]: https://en.wikipedia.org/wiki/Coordinated_Lunar_Time

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