[MOIMS-NAV-EXEC] FW: Request for CCSDS Navigation Standards Normative Annex Registry: Time Systems

Thu Sep 20 21:56:54 UTC 2018

Dear Nav WG (especially Dan Oltrogge, Dave Vallado, and Fran Martinez, who had worked on the most recent version of the Time Systems material):

Some comments on the attached material just submitted to SANA, to which I introduced one change that we can discuss at the Fall Meetings if there is disagreement with my action (#1 immediately below). I also have a question (#2) about correspondence between the existing annexes and the new registry.

1. I removed the entry for "GPSZ". The description took almost a full page of the table in the document, and had much more detail than any of the other Time Systems. I first wanted to shorten it, but supply a reference that contains the detail. Several Google searches later, there was nothing that showed up in the first page of results (so it didn't appear to be very commonly cited). After a few more searches, I found https://www.gps.gov/technical/ps/1995-SPS-signal-specification.pdf , which contains the detail. However, I later found on https://www.gps.gov/technical/ps/ that this document has been twice superseded, and neither of those documents refer to the GPSZ or "Z count" or anything, implying that it's more or less obsolete, or at least no longer commonly utilized, which suggested to me we don't need it in the SANA. The GPS.gov page states regarding the most current version of the document: "This document defines the levels of performance the U.S. government makes available to users of the GPS Standard Positioning Service, also known as the civilian GPS service. The Office of the Secretary of Defense issues the document on behalf of the U.S. government. Earlier versions were referred to as "signal specifications" instead of performance standards. The 4th Edition of the GPS SPS Performance Standard, dated Sep 2008, is currently in effect and supersedes all prior versions. Prior versions are provided here for historical reference purposes. These documents are no longer in effect."

2. I compared the table to the Time Systems annexes in the current versions of ADM, ODM, PRM, and TDM. I am guilty of not paying close attention as the material was being compiled, but we do have a few entries left out of the new SANA registry compared to the document annexes. Specifically, GMST, MET, and MRT are not listed. I can understand leaving MET and MRT out because they require an ICD (as is indicated in the notes in the existing annexes), on the other hand, SCLK is in the table and also requires an ICD. I'm not sure why GMST is left out of the registry but it's in the annex for all of ADM, ODM, PRM, and TDM. 

Anyway, we will no doubt have some tweaks we will request of the SANA team going forward, and they have usually been very prompt about making smallish changes once a given registry has been set up on their website.

Regards,
David

On 9/20/18, 2:29 PM, "MOIMS-NAV-EXEC on behalf of Berry, David S (3920)" <moims-nav-exec-bounces at mailman.ccsds.org on behalf of David.S.Berry at jpl.nasa.gov> wrote:

    Hello SANA...

    Attached is revised material that the CCSDS Navigation WG would like to register with the SANA in the Time Systems registry (currently a beta at https://beta.sanaregistry.org/r/time_systems ). In his email of 13-Sep-2018, Julien Bernard indicated that it would be possible to promote this registry into the most recently deployed version of the SANA website.

    For now I propose to leave the "References" column of the registry empty; we are compiling references and will provide the specific info later (but per Peter Shames' preferences we will not request that files be stored on the SANA registry).

    Once this registry is updated with the revised material, we will be able to start modifying our standards documents to remove annexes that currently contain this material, and refer customers to the SANA for values for the associated keywords. 

    The Working Group is still completing the detail for the remaining sub-registries we have previously discussed with you, and will provide them as we complete them.

    Please advise if you have any questions, and thanks very much for your support!

    Regards,
    David Berry
    Chair, CCSDS Navigation WG

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