[Sea-time] Existing Time Management BoF charter & supporting material

[Pitts, Robert L. (MSFC-HP27)[HOSC SERVICES CONTRACT]]

Jon and Peter,

I think you are hitting on the areas that I am most concerned with to include overall distribution and time domains in specific theatres of operation.

Lee

From: SEA-TIME <sea-time-bounces at mailman.ccsds.org> On Behalf Of Shames, Peter M (312B)
Sent: Tuesday, November 06, 2018 12:16 PM
To: Hamkins, Jon (JPL-3320)[Jet Propulsion Laboratory] <jon.hamkins at jpl.nasa.gov>; sea-time at mailman.ccsds.org
Subject: Re: [Sea-time] Existing Time Management BoF charter & supporting material

Hi Jon,

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.

Do the rest of you agree?

Thanks, Peter


From: Jon Hamkins <Jon.Hamkins at jpl.caltech.edu>
Date: Tuesday, November 6, 2018 at 8:34 AM
To: Peter Shames <Peter.M.Shames at jpl.nasa.gov>, "sea-time at mailman.ccsds.org" <sea-time at mailman.ccsds.org>
Subject: Re: [Sea-time] Existing Time Management BoF charter & supporting material

Thanks, Peter.

The IOAG Service Catalog requests the following standards be developed:

• Clock Correlation Procedures [CC] - Magenta Book
• Time Transfer [TT] - Blue Book
• Time Synchronization [TS] - Blue Book

Do we all agree that these are still the appropriate books and colors to
be working toward?  Do we need to update our goals?  Thoughts?

On a separate topic, I have been thinking about what we discussed in
Berlin.  We mentioned time correlation and time synchronization as two
motivations for the work.  As we discussed, time correlation is
determining the offset between two clocks, and time synchronization is
setting two clocks so that they match.  The difference between these
concepts is quite small -- a time synchronized clock output is simply
the time correlated clock output time plus the value of the offset.  In
other words, after time correlation, a time offset is determined.
Whether this offset is used to explicitly synchronize a clock or is
simply added to the clock output each time it is read is an
implementation detail.  For this reason, I recommend that going forward,
we consider time correlation and time synchronization to be
fundamentally the same concept, with the same time correlation standard
governing them.

      ----Jon
On 11/5/2018 5:21 PM, Shames, Peter M (312B) wrote:
Dear Time BoF,
Attached is the current draft of the Time WG Charter and also the IOAG
Service catalog #2.  See pgs 26-27, section 4.5, to see what it is that
the IOAG has requested.  There is also an existing set of materials
relating to this topic that Ed Greenberg developed.
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