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DIRECTV Satellite Discussion D-14 @99W

Discussion in 'DIRECTV General Discussion' started by Sixto, Jun 17, 2010.

  1. Jun 20, 2013 #721 of 3078
    James Long

    James Long Ready for Uplink! Staff Member Super Moderator DBSTalk Club

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    If you make a mistake they can bring it back into the shop. It is a little harder to get a satellite back it a problem is found after it is launched. The owners just have to live with the error and look to the next satellite.
     
  2. Jun 20, 2013 #722 of 3078
    bobnielsen

    bobnielsen Éminence grise

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    I don't know what percentage of Directv customers are constrained by OTARD (I'm certainly not), but also I haven't seen anything that suggests a larger dish would be required. It should not be too hard to construct a feedhorn with sufficient bandwidth to cover both KA-hi and BSS bands and adding a diplexer to the feed assembly to separate the bands would seem to be quite doable (FWIW, I do have experience in the technology involved).
     
  3. Jun 21, 2013 #723 of 3078
    HoTat2

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    Yes, as we're only talking about 1 additional GHz from 17.3-20.2 GHz instead of present 18.3-20.2 GHz. How hard can that be to engineer?

    Assuming of course that the current feedhorn dimensions are not already sufficient.


    Again, much agreed;

    Then once separated say a simple scheme to convert the RDBS band down to some point above 2150 MHz on the 99/101 trunk lines 1 and 2 for RB-1 and the 103/110/119; 103/119 lines 3 and 4 for the future RB-2 seems most doable.
     
  4. Jun 21, 2013 #724 of 3078
    SPACEMAKER

    SPACEMAKER Freethinker

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    Is there a launch schedule?
     
  5. Jun 21, 2013 #725 of 3078
    HoTat2

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    Not much released beyond the official FCC filings ...

    http://www.dbstalk.com/topic/170004-directv-satellite-discussion-d14-up-next/?p=3147380

    Addendum: Well ... here's a brief mention of D14's launch expectancy from the Arianespace Launch Schedule for 2014 on the nasaspaceflight.com site harsh referenced earlier;

    Which I assume means a launch "early" in 2014, aboard an Ariane 5 ECA (French lettering for "Cryotechnic Main Stage") rocket. From "Kourou," in French Guiana at ELA-3 (French lettering for Ariane Launch Area 3).
     
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  6. Jun 21, 2013 #726 of 3078
    LameLefty

    LameLefty I used to be a rocket scientist

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    Re the timeline - it doesn't take 4 years to assemble a satellite presuming you have all the parts in hand, on the cleanroom floor, at the time you start building, and presuming you take the absolute minimum time to verify and test and certify each production step along the way. However none of those presumptions is accurate. I would bet a good deal of money that "manufacturing start date" is a milestone that matters about as much as "laying the keel" on a battleship (e.g., "not very much.") Weld the first two members of the bus spaceframe and you've "started manufacturing."

    As for comparison with your subs, I'm pretty sure your employer has a much bigger budget to work with, along with the attendant logistical supply chain infrastructure, than does any satellite manufacturer these days (LMSC may have had comparable resources to work with back in the day during the heyday of the GAMBIT, HEXAGON, and Keyhole programs). Furthermore, your boats get sea trials and periodic refits and port time - once a comsat goes up, that's it. It's gotta work right, the first time and pretty much every time, for 15 years, without servicing, physical upgrades, repairs, refits or replenishment of consumables, 22,300 miles from "port."
     
  7. Jun 23, 2013 #727 of 3078
    harsh

    harsh Beware the Attack Basset

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    If they can't come up with an LNB that will do both Ku and RDBS simultaneously, it seems obvious that two separate LNBs would be required. DIRECTV has patented a setup for Ka and Ku but it depends entirely on the band separation of the signals that won't be available with DIRECTV 14.

    Do you have any theories on a solution?

    The radio wave physics governing this haven't changed recently.
     
  8. Jun 23, 2013 #728 of 3078
    HoTat2

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    What's wrong with my post #723 as well as bobnielson's comments in post #722 as very feasible solutions for a single Ka/Ku/RDBS LNB?
     
  9. Jun 23, 2013 #729 of 3078
    James Long

    James Long Ready for Uplink! Staff Member Super Moderator DBSTalk Club

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    Wow ... if only someone would come up with a design where two LNBs could share the same feedhorn. That would be amazing. Imagine what it would have been like to have C and Ku band reception on a BUD using the same feedhorn 25 years ago. Imaging what it would be like to have two band reception in the same LNB assembly on a DISH "Plus" dish (used to receive 119 and 118.7 on the same OTARD compliant antenna). Or the current Ka / Ku DirecTV LNBs on OTARD compliant antennas? Combining LNBs is standard practice in 2013.

    Sorry, but I do not share your fear uncertainty and doubt. Especially when it comes to comments such as you made about a dish receiving RDBS not being OTARD compliant. It is time to back your claim with facts - not speculation.

    What about RDBS and needing a different LNB would make the dish not be a "OTARD compliant antenna"?

    Hint: A larger LNB does not stop an antenna from being OTARD compliant.
     
  10. Jun 23, 2013 #730 of 3078
    P Smith

    P Smith Mr. FixAnything

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    James, I have the combo C and Ku Chapparel LNBF :) it's has common feedhorn ;)
     
  11. Jun 23, 2013 #731 of 3078
    HoTat2

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    And like I said, you're only talking about .6-1 GHz away from the lower edge of the Ka-lo band.

    For that matter, the current Ka band feedhorn dimensions on the Slimlines are likely sufficient to receive the RDBS band..
     
  12. Jun 24, 2013 #732 of 3078
    harsh

    harsh Beware the Attack Basset

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    And the difference in wavelength between C and Ku is?

    The good book says C-band is about three times the wavelength of Ku. The wavelength for Ku is about 23.6mm versus something short of 75mm for C-band. Now comparing Ku at 23.6mm and RDBS at 17.4mm, those aren't nearly as diverse.

    Multiple frequency designs typically depend on a decisive difference in wavelength. Those antennae are getting pretty near in size.
     
  13. Jun 24, 2013 #733 of 3078
    HoTat2

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    Well harsh

    As an example in Latin America DIRECTV is presently deploying a new dual band LNB to their subscribers that can receive a new 10.95-11.2 GHz band which is only 250 MHz lower than their usual 11.450-12.2 GHz one. And the two bands are apparently separated and directed in their received gigahertz range to two different receiver circuits. One with a 10.5 GHz L.O. and the other with a 13.1 GHz L.O.

    So with the RDBS band at 600-1000 MHz below the Ka-lo band, it should be well within the state of the art to design such frequency separation circuits for the somewhat higher 17/18 GHz frequency range. .
     
  14. Jun 24, 2013 #734 of 3078
    LameLefty

    LameLefty I used to be a rocket scientist

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    Here is a good summary of the entirety of the last few pages (specifically the "contributions" of one person in particular who routinely dogs the Directv threads):

    "A little information is a dangerous thing."

    Fortunately, real spacecraft and RF engineers generally know what they're doing these days. A few minutes with Google and Wikipedia doesn't make up for the fundamental lack of education. Fortunately, there are some folks who DO know this stuff in very great detail who are willing to keep the thread informative and factual.
     
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  15. Jun 24, 2013 #735 of 3078
    James Long

    James Long Ready for Uplink! Staff Member Super Moderator DBSTalk Club

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    DISH 118.7 and 119 are adjacent Ku bands. Same LNBF package.

    118.0W TP1 11.71475 R - 118.0W TP32 12.18525 L
    119.0W TP1 12.22400 R - 119.0W TP21 12.51560 R

    Typically those in the industry can figure these things out. RDBS isn't that far away.
     
  16. Jun 26, 2013 #736 of 3078
    Diana C

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    A couple of random comments:

    On the timeline question...the majority of the delay is waiting for the launch vehicle...it makes little sense to build and then store the satellite. So construction is timed so that testing is complete when they are ready to ship to the launch pad for vehicle integration.

    On RDBS, why assume that the plan is Ka, RDBS and Ku? Why not substitute RDBS for legacy Ku? You could eliminate all the SD duplicates on 101, leaving room for some additional HD. That way, Ku becomes the legacy system for SD viewers, and Ka/RDBS is the HD viewer only platform. This would also only require a LNB swap, which could be done at any pace they desire.
     
  17. Jun 26, 2013 #737 of 3078
    HoTat2

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    Could you rephrase this?

    I don't understand the suggestion here ...

    EDIT: Never mind, After meditating on this, I understand now. An interesting idea;

    Develop a duel 99/103 Ka/RDBS LNB and only mirror SD channels from 101 which have no HD versions on Ka over to the RDBS band on satellites at 99 or 103 to create a predominately "HD viewer" service.

    You would need to supply an EPG and SI data stream over the RDBS band on either of those slots as well. and since RDBS only uses CONUS beam transponders, any markets with spot-beamed SD locals on 101 or 119 without HD versions would be lost, but that should be comparatively few nowadays.
     
  18. Jun 27, 2013 #738 of 3078
    harsh

    harsh Beware the Attack Basset

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    Those frequencies are probably be close enough to be picked up on the same antenna.
     
  19. Jun 27, 2013 #739 of 3078
    harsh

    harsh Beware the Attack Basset

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    Because there are still a lot of unsuitable dishes out there? Transitioning to RDBS would almost certainly require conversion of the entire ODU (including the mounting plate) as opposed to just the LNB assembly as you suggest.

    RDBS probably suffers similar aiming sensitivities as Ka when applied to mobile users.
     
  20. Jun 27, 2013 #740 of 3078
    harsh

    harsh Beware the Attack Basset

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    And when are these folks going to demonstrate their willingness?
     

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