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D10 Satellite TECH THREAD - HD Testing Schedule / Press Releases / Location

Discussion in 'DIRECTV General Discussion' started by Sixto, Jul 6, 2007.

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  1. Sep 8, 2007 #1921 of 2718
    donshan

    donshan Godfather

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    Jun 18, 2007
    Good observation John about Celestrak use of "epoch date"! :)

    I also did some reading through the details on celestrak.com and "epoch date" is the correct terminology and the time fraction after "eppoch date begins at 00:00:00 UTC. This clears up the confusion of "epoch" day" vs "Julian day" in my post above.

    Celestrak also specifically states that "epoch time format" the day number changes at midnight and not at noon as with Julian Day used for centuries in astronomical time calculations:

    http://celestrak.com/columns/v04n03/#FAQ02

    Thus I believe it is NASA that has mislabeled their explanation of how to read TLE data on their web page by calling this a "Julian Day Fraction":

    http://spaceflight.nasa.gov/realdata/sightings/SSapplications/Post/JavaSSOP/SSOP_Help/tle_def.html



    Whoever prepared this explanation has everything correct and even their example of how to convert the decimal day fraction to h , m, s is correct. They should have used "epoch day fraction" instead of Julian Day fraction which changes day numbers at 12:00:00 UTC.


    Quote from NASA page which is not correct terminology:

    This is a surprising error for NASA which has plenty of of people who know better, but apparently not the person who prepared the web page graphic.:nono2:

    Edit comment: This orbital stuff is hard enough for a beginner like me to try to learn without having NASA mislabel their explanation!:mad:

    BTW astronomers use this Julian Day number system since almost all data is taken at night. Thus dating an observation takes place on a single "Julian day" number and does not divide the data into two different day numbers by changing day numbers at midnight, however it still leads to confusion in time zones far away from Greenwich where midnight UT may be in the daytime locally.
     
  2. Sep 8, 2007 #1922 of 2718
    mlcdorgan

    mlcdorgan Godfather

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    OK, get it now,
    Thanks All
     
  3. Sep 8, 2007 #1923 of 2718
    SParker

    SParker Active Member

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    So its in its final location or its still heading there? I'm confused!
     
  4. Sep 8, 2007 #1924 of 2718
    litzdog911

    litzdog911 Well-Known Member

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    Still at it's testing location. Not much movement yet towards its final location.
     
  5. Sep 8, 2007 #1925 of 2718
    bakers12

    bakers12 ΔS > 0

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    Sorry about that old info. I gotta quit trying to make sense at 5 a.m.
     
  6. Sep 8, 2007 #1926 of 2718
    Ken984

    Ken984 Active Member

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    Bossier...
    Irs not NEW but it is still current as far as we know.
     
  7. Sep 8, 2007 #1927 of 2718
    MrDad0330

    MrDad0330 Godfather

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    They sure are taking their sweet time moving D10 from 102.6 to 102.775. They are just making us suffer or is there a problem...???
     
  8. Sep 8, 2007 #1928 of 2718
    Ken984

    Ken984 Active Member

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    Bossier...
    Its just for their amusement :), takes a while to make sure all of this is gonna work right, its close, and could be even closer by now, we haven't had a new tle since early yesterday. Either nothing has changed since then or Norad has taken the weekend off.
     
  9. Sep 9, 2007 #1929 of 2718
    EaglePC

    EaglePC Icon

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    Apr 14, 2007
    think its time to worry

    this is now a longer project

    even D* was way ahead of schedule
     
  10. Sep 9, 2007 #1930 of 2718
    Ken984

    Ken984 Active Member

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    Bossier...
    No reason to worry yet, nothing has happened bad. The target is still ahead of us...we all wanted it earlier but D* NEVER said it would be active by now.
     
  11. Sep 9, 2007 #1931 of 2718
    gslater

    gslater Gone to the Dogs

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    Just itching for a new TLE here. It's been over a day and a half now since the last one. At this rate D10 could be halfway to it's permanent location before we even know it's moving. Of course it could still be just sitting there mocking us as well!
     
  12. Sep 9, 2007 #1932 of 2718
    PoitNarf

    PoitNarf New Member

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    Or they could move it half way and then park it there for a few more days :lol:
     
  13. Sep 9, 2007 #1933 of 2718
    john18

    john18 Active Member

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    I though the idea was to move it as few times as possible to save fuel.
     
  14. Sep 9, 2007 #1934 of 2718
    Guitar Hero

    Guitar Hero Godfather

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    They haven't moved it at all. Maybe they don't need to.
     
  15. Sep 9, 2007 #1935 of 2718
    mobandit

    mobandit Hall Of Fame

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    Well, it isn't in it's final position...so it will need to be moved at least once.

    I used to be stationed at Naval Space Command (now defunct) and we didn't update TLE's unless there were changes or "expected" changes on anything except manned missions. NSC was the primary backup to US Space Command for tracking orbiting objects, USSC was who sent the information to NORAD.
     
  16. Sep 9, 2007 #1936 of 2718
    msuspartan

    msuspartan Mentor

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    Jul 11, 2006
    Just a thought - but they may not be moving it yet because of other considerations than technical. They may need to coordinate going live with their PR schedule and perhaps contract dates with content providers that were tied to the original timeline. That may be critical for some providers who are working a tight schedule to go HD. They know we are watching and if they move it ahead of their total schedule we would be on their case if they did not light it up.
     
  17. Sep 9, 2007 #1937 of 2718
    loudo

    loudo Well-Known Member

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    I am sure they want to do as much testing as possible before moving it to it's final position. I remember when they first fired up the MPG4 locals and local RSNs on the channel 90 area, everyone was complaining about pixelation and picture breakups, that with time got cleaned up. I am sure they will try to avoid those problems again.
     
  18. Sep 9, 2007 #1938 of 2718
    oakwcj

    oakwcj Lower Echelon

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    True, but they did say that they were ahead of schedule and would be ready to drift on or about September 1:

    "In its application for the July 23 STA, DIRECTV indicated that it would commence
    drifting on or about September 12, 2007, and that the relocation would be complete on or about
    September 15, 2007. However, DIRECTV is ahead of this schedule and will be ready to
    commence moving DIRECTV 10 to 102.775° W.L. on or about September 1. "

    That didn't happen. Unless it began drifting after the last TeaLEaf [aka "TLE"], it will at best beat the original schedule by no more than a few days. I'm not going to try to guess the cause for this apparent delay, but it's undeniable that the move did not begin on or about September 1.
     
  19. Sep 9, 2007 #1939 of 2718
    mika911

    mika911 Godfather

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    Yep. Good information to remind ourselves about. Just think, if it wasn't for the ahead of schedule permission stuff we'd still consider ourselves on target and getting set for the move.

    Lets hope it does start moving the 12th, or even a day or two early.

    At this point though, time is moving on, so hopefully we won't have to wait that much longer. Hope that sounded right. I just mean at this point if they can be on the original time schedule, we don't have long to wait, since the month is already along.
     
  20. Sep 9, 2007 #1940 of 2718
    tpm1999

    tpm1999 Legend

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    Makes one wonder what Directv really wanted with the FCC "waiver". Getting the new orbital spot? or getting the sattelite up and running quicker than stated? Its now farely obvious that the channels wont go live early, but they have a high probability of getting the 102.775 spot for good.

    hmmm... directv setup the letter as a "good news/bad news" type....
     
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