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<p class="MsoNormal">Hi Jon,<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Good questions. As we have been addressing time synchronization that topic explicitly includes automated means doing this, especially in a multi-mission, networked (DTN), context. I think of it as NTP for DTN. This is a substantially
bigger topic than a simple addition of an offset.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Do the rest of you agree?<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Thanks, Peter<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">Jon Hamkins <Jon.Hamkins@jpl.caltech.edu><br>
<b>Date: </b>Tuesday, November 6, 2018 at 8:34 AM<br>
<b>To: </b>Peter Shames <Peter.M.Shames@jpl.nasa.gov>, "sea-time@mailman.ccsds.org" <sea-time@mailman.ccsds.org><br>
<b>Subject: </b>Re: [Sea-time] Existing Time Management BoF charter & supporting material<o:p></o:p></span></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Thanks, Peter.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">The IOAG Service Catalog requests the following standards be developed:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">• Clock Correlation Procedures [CC] - Magenta Book<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">• Time Transfer [TT] - Blue Book<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">• Time Synchronization [TS] - Blue Book<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Do we all agree that these are still the appropriate books and colors to
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">be working toward? Do we need to update our goals? Thoughts?<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">On a separate topic, I have been thinking about what we discussed in
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Berlin. We mentioned time correlation and time synchronization as two
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">motivations for the work. As we discussed, time correlation is
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">determining the offset between two clocks, and time synchronization is
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">setting two clocks so that they match. The difference between these
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">concepts is quite small -- a time synchronized clock output is simply
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">the time correlated clock output time plus the value of the offset. In
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">other words, after time correlation, a time offset is determined.
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Whether this offset is used to explicitly synchronize a clock or is
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">simply added to the clock output each time it is read is an
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">implementation detail. For this reason, I recommend that going forward,
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">we consider time correlation and time synchronization to be
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">fundamentally the same concept, with the same time correlation standard
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">governing them.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"> ----Jon<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">On 11/5/2018 5:21 PM, Shames, Peter M (312B) wrote:<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Dear Time BoF,<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Attached is the current draft of the Time WG Charter and also the IOAG
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">Service catalog #2. See pgs 26-27, section 4.5, to see what it is that
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">the IOAG has requested. There is also an existing set of materials
<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">relating to this topic that Ed Greenberg developed.<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">_______________________________________________<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in">SEA-TIME mailing list<o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><a href="mailto:SEA-TIME@mailman.ccsds.org">SEA-TIME@mailman.ccsds.org</a><o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><a href="https://mailman.ccsds.org/cgi-bin/mailman/listinfo/sea-time">https://mailman.ccsds.org/cgi-bin/mailman/listinfo/sea-time</a><o:p></o:p></p>
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<p class="MsoNormal" style="margin-left:.5in"><o:p> </o:p></p>
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