What is reverse band?

Discussion in 'DIRECTV Support Forum' started by manowell, Nov 7, 2018.

  1. manowell

    manowell Topic Starter Member
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    My installer at the house told me that the LNB needed to be switched out from a SWM to a RB SWM when I got a Genie and a 4K mini.

    -- later --

    I'm working on a tripod dish for an RV I'm picking up soon, and ordered new hardware for that from Solid Signal. Instead of the "DIRECTV Slimline Single Wire SWM Triple Satellite LNB (SL3-SWM)" that I ordered:
    [​IMG]

    I received the 3D2RBLNB:

    [​IMG]

    Didn't really notice this until I was playing with the aiming meter and the rig on the tripod last night, was frustrated with lower signal levels than I'm used to, and saw the AIM meter had detected (correctly, it seems) Reverse Band.

    If I'm not doing 4K, do I care? Harder to align? This will be a dish aligned as we move, so easier to align the faster and better. Any power differences?
     
  2. texasbrit

    texasbrit SatelliteGuys Pro
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    Nothing is using reverse band at the moment. It's believed to be reserved for future 4K programming. It makes no difference for alignment since it comes from one of the existing satellites.
     
  3. slice1900

    slice1900 SatelliteGuys Pro

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    Other than the goofy name it got saddled with, you can think of it as a third Ka band similar to the existing 'Ka lo' (99cb/103cb) and 'Ka hi' (99ca/103ca)

    Directv applied for the license for it a decade ago, thinking it would be used for 3D. Of course 3D never happened, so they decided to use it for 4K. Whether 4K happens remains to be seen, given that there are still no full time channels on the horizon. But if we ever start seeing a bunch of 4K channels, Directv is ready.
     
  4. manowell

    manowell Topic Starter Member
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    Got it. Got RB LNB aligned, there are four transponders on 99rb that show a signal......
     
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  5. slice1900

    slice1900 SatelliteGuys Pro

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    I think that's still all they have active. They aren't broadcasting anything at all yet (other than maybe some internal testing with AT&T employees) since there are no 4K channels out there for them to carry, but Directv is ready and has been for a while now.
     
  6. goaliebob99

    goaliebob99 SatelliteGuys Master
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    International programming may land up on Reverse Band as well. Sooner than you think.
     
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  7. texasbrit

    texasbrit SatelliteGuys Pro
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    As slice says, they are active but not broadcasting anything.
     
  8. slice1900

    slice1900 SatelliteGuys Pro

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    I doubt it. They'd need to upgrade EVERY international customer to a reverse band dish to make that happen, whereas if they put it on 99/103 Ka or 101 all the customers who have been installed in the past five years with a non-reverse band Slimline paired with their international dish would be fine. They will have tons of spare bandwidth once they drop MPEG2 SD, they don't need to make things harder for them in terms of required upgrades by putting internationals on reverse band.
     
  9. raoul5788

    raoul5788 Studebaker driver
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    How many international customers are there?
     
  10. slice1900

    slice1900 SatelliteGuys Pro

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    I really have no idea, and don't think Directv has ever shared that information. Anecdotally, people in the LA area have posted they see the international dishes all over.

    Even if they only had to upgrade 100K customers, that's still millions of dollars they'd spend to be able to move the international channels to reverse band. Given that they will free up nearly 32 transponders on 101 when they drop MPEG2 SD (I say "nearly 32" because MPEG2 SD only channels on 101 will become MPEG4 SD only) so they will hardly need the room. Converted to MPEG4 SD, the channels on 95* would fit in three transponders so it isn't exactly gonna use a lot of bandwidth.

    If they were going to convert them to reverse band, the time to do that would have been two years ago - mirror them not replace. Then all the installs they did for international customers in the meantime that installed two dishes and an external SWM could have installed a simple reverse band dish. That would have saved them millions I imagine, but maybe they weren't ready to begin broadcasts over reverse band back then.

    I speculated at the time they'd do this, but obviously they didn't. Even then, I figured one they dropped the 95* satellite they'd probably move them back to Ka, to avoid the need to upgrade all the rest.
     
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  11. nelson61

    nelson61 SatelliteGuys Pro
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    You will not find "reverse band" in the FCC federal code defintions.

    The FCC name is 17/24 GHz BSS.


    Sent from my SM-G955U1 using the SatelliteGuys app!
     
  12. Claude Greiner

    Claude Greiner SatelliteGuys Master
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    Not very many.

    But having the Italian Packages and Tv Japan is taking a significant number of customers from Dish.

    I could see Directv moving Italian as they can’t keep up with the demand for international dishes.

    If Directv could now get a decent Arabic and Hindu Package they could really hurt dish networks international base.
     
  13. Claude Greiner

    Claude Greiner SatelliteGuys Master
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    Bye, yeah the signal on the reverse band is about 10 points lower then a regular SWM.

    But regardless both point the save
     
  14. slice1900

    slice1900 SatelliteGuys Pro

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    There's no particular reason why it should have lower signal quality, Directv is authorized for the same power level as Ka and Ku. Either they are broadcasting reverse band at a lower power level for some reason, or there is something in the design of the reverse band LNB that causes it be received with a lower SNR.

    That's perhaps possible because the "simple" way to do it would be to widen the 99/103 feedhorns to enable it to catch a lower frequency signal, split the received signal for each polarity, and use an image filter with the existing 18.05 GHz LO. That would output reverse band inverted from 350 - 750 MHz.

    However, due to the proximity of the 99/103 feedhorns and the 101 feedhorn there probably wasn't room to widen them, so the reception ability at the lower frequency range of reverse band vs Ka may be slightly compromised. I would expect to see slightly higher readings (like a few points, nothing big) on transponders 17/18 vs 1/2 if that's the case. Maybe not on every LNB, but if we got a couple dozen and averaged them together that's the pattern you'd expect if this is the case.
     
  15. Claude Greiner

    Claude Greiner SatelliteGuys Master
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    A true test would be to have both dishes side by side with and without a reverse band and see how much a difference rain fade makes during a storm.
     
  16. slice1900

    slice1900 SatelliteGuys Pro

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    Why? You already have that information from the signal strength screen. The number on that screen is not signal "strength", it is a quality measure directly calculated from the SNR of the received signal. Rain fade reduces your SNR, and when it falls below the minimum signal margin for the modulation used (reflected with a reported "signal strength" of about 20 for CONUS Ka, or about 44 for Ku) it no longer has sufficient error correction information to be able to recover the signal, so it shows '0'.

    If during clear weather the reverse band dish shows a '95' on a given transponder and a non-reverse band dish shows '97' on the same transponder, rain fade will affect the reverse band dish first. However, the difference between 95 and 97 is so small you'd be hard pressed to notice a difference even in a side by side test.
     

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