How To Diplex OTA with the AT9 dish & MPEG-4

Discussion in 'DIRECTV Installation/MDU Discussion' started by Cap'n Preshoot, Aug 19, 2006.

  1. Aug 19, 2006 #1 of 323
    Cap'n Preshoot

    Cap'n Preshoot Godfather

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    Before you say it can't be done, yes it can and doing so is easy. Done properly, the signals will not conflict. This has been tested and does work.

    You simply need to relocate the B-Band Convertor (BBC) module to a convenient location (i.e., attic perhaps) and then diplex your OTA signal into the downlead after the BBC module. See? I told you it was easy.

    The instructions that came with your MPEG-4 receiver instruct you to connect your BBC module to the receiver. However, it does not need to be right at the receiver and in fact can be located anywhere in the coax downlead between the AT9 dish and the receiver, or if an external multiswitch is used, anywhere between the output of the multiswitch and the receiver.

    The only important thing to remember is the BBC module must be ahead of your OTA diplexer.

    To keep it straight, here's the correct order of things:
    1) Option 1 no external multiswitch, In the attic, connect the coax coming from the DISH to the INPUT of the BBC module. Connect the OUTPUT of the BBC module to the SAT connector of the Diplexer. Connect the TV/SAT connector of the diplexer to the coax cable that goes downstairs to the receiver. Connect your OTA signal to the TV connector of the diplexer.

    2) Option 2, WITH an external multiswitch Do not tamper with the cables going to the INPUTS of the multiswitch. Use a short coax jumper to connect the INPUT of the BBC module to one of the OUTPUTS of the multiswitch. Connect the OUTPUT of the BBC module to the SAT connector of the Diplexer. Connect the TV/SAT connector of the diplexer to the coax cable that goes to the receiver. Connect your OTA signal to the TV connector of the diplexer.

    Downstairs at the receiver, connect the coax from the attic to the TV/SAT connector of a second diplexer. Connect the SAT connector of the diplexer to the SAT input connector of your receiver. Connect the TV connector of the diplexer to the ANTENNA connector of your receiver.

    Yes, you can use a splitter with your OTA input lead to have enough outputs available to diplex the signal in to the coax downleads. However, you cannot connect your OTA signal to any of the INPUTS of your multiswitch because a Ka/Ku multiswitch does not provide an OTA input connector.

    edit: do not put the BBC module outside. It is not weatherproof.
    edit: this concept only works if your BBC module is separate (external). If it's built-in, like on the HR10-250, you might not be able to use this idea but keep reading - the more we pursue this, the more we're learning
     
  2. Aug 20, 2006 #2 of 323
    Tseren

    Tseren Cool Member

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    This is great to hear. Does the BBC only come with the H20? Is there a solution if I have an HR10 with no extra cables for OTA and an AT9 dish?
     
  3. Aug 20, 2006 #3 of 323
    Cap'n Preshoot

    Cap'n Preshoot Godfather

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    The solution offered is intended for those who have the new AT9 dish along with MPEG-4 capable receivers with external BBC modules.

    I'll admit I'm not familiar with the HR10-250. However, from reading I see that it is MPEG-4 capable but it does not appear to use an external BBC module, (built-in apparently) so unfortunately this idea won't work for the HR10-250 (or any other MPEG-4 capable receivers that do not have the external BBC module.

    actually it might work. This is becoming a work in progress
     
  4. Aug 20, 2006 #4 of 323
    Cap'n Preshoot

    Cap'n Preshoot Godfather

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    The way it works it very simple;

    The Ka LNB at the AT9 Dish downconverts the 20 Ghz Ka band satellite frequencies to the 250~750 Mhz "B band" so they can be sent down the coax to the receiver.

    The B-Band convertor module (BBC) up-converts the 250~750Mhz signals to 1650~2150 Mhz before entering the receiver.

    However, in theory this up-conversion can take place anywhere and does not necessarily need to take place right at the receiver. It can just as easily occur someplace else, like for instance in the attic or someplace where all your cabling comes together in a centralized location.

    Although this idea of moving the BBC module away from the back of the receiver to the attic or someplace else works very well for allowing us to Diplex our OTA signals into the same coax cable, it does not come without some possible penalty.

    The possible penalty would be likely to appear in situations where you have a fairly long coax run as measured from the back of the receiver to the point at which you wind up inserting (or point where you would like to insert) the BBC module and do your OTA signal diplexing. The issue is the attenuation or signal loss at the BBC output frequencies (1650~2150 Mhz).

    When we talk about using RG6 coaxial cable for residential satellite distribution, the generally accepted standard is 7 db of signal loss per 100 feet of cable at 1000 Mhz. (1000 Mhz chosen to represent the approx range of frequencies that the cable will ordinarily be carrying. The range is actually 950~1450). However, at 2150 Mhz this little matter of signal loss is all of a sudden closer to 10 dB per 100 feet. That's a 3 db difference which represents twice as much loss. (it's a logrithmic slide rule math function, for RF signal levels db=10 Log P1/P2).

    The result is the higher frequency signals from the BBC module get attenuated twice as much as the lower frequency signals, so long coax runs between the receiver and the BBC module need to be avoided.

    If you want to try this, my own recommendation would be to keep the coax length between the receiver and BBC module as short as possible and not to exceed 50 feet.

    Use of an inline broadband amplifier module that's rated for 2150 Mhz would boost these signals, but unless it is a special slope or tilt-adjusting amplifier you would still have a 3db difference between the uppermost and lowermost signals at the receiver, just that they would (or should) both be stronger.
     
  5. Aug 20, 2006 #5 of 323
    Cap'n Preshoot

    Cap'n Preshoot Godfather

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    I'd like to hear from someone who has an HR10-250 (or other MPEG-4 HD DVR) with the built-in B Band convertor and who also might have a BBC module lying around to test with (perhaps borrow it from your H20 if you have one of those too.)

    I'd like to find out:

    1) will the built-in B-band convertor in the DVR pass 1650~2150 Mhz signals which have already been converted externally by an external BBC?

    2) will the control signals pass through the receiver and work to also control an external BBC?

    The way to find out the answers would be to attach a BBC to the sat input of your receiver/DVR and see if that input can still receive the Ka band (MPEG-4) signals. If it does, then we might still be able to use an upstream BBC to let us Diplex OTA into the same coax. That would sure be nice.

    Though not listed on their web site, I'm sure if this was possible that Solid Signal would be only too happy to sell them separately.
     
  6. Aug 20, 2006 #6 of 323
    bpayne

    bpayne Legend

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    Your explanation of how BBCs work was about 95% correct- there's only one thing you left out...

    There a 2 different orbital slots for KA and 2 different polarities located at 2 different bands. Currently, 103 and 99 are occupying the 1650-2150 mHz spectrum- commonly referred to as the C-band (it's not literally C-band aka FTA, it's just a shortcut way of saying "the 1650-2150 mHz frequency range carrying half the KA downlink"). :)

    When the last two of the five KA satellites launch- one at 99 and the other at 103, their downlink will be downconverted to the 250-750mHz range, or the B-band, by the LNB. The BBC receives control signals from the box which inturn tells the LNB which polarity of the B-band it wan't to receive for that frequency range only, the LNB or switch sends it down and then the BBC upconverts that 250-750 mHz range to 950-1450 because the box, internally, doesn't recognize 250-750mHz.


    I've tested what you propose and in theory, it should work. The only problem is is that there's no way to know if it will work correctly until DirecTV starts sending down the polarities which will allow us to test it properly. Currently, if someone does not have a BBC connect to the sat input, they will not see any problems or missing channels.
     
  7. Aug 20, 2006 #7 of 323
    D-Bamatech

    D-Bamatech Godfather

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    {Currently, if someone does not have a BBC connect to the sat input, they will not see any problems or missing channels.[/QUOTE]
    -------
    Thank you.. can I get a witness! :rolleyes:

    Now tell me how to allign the At-9 and properly balance the signal to maxium results for multiple sat feeds that arent even there yet. he he..

    There's "some " people here that tell me that i must allign a AT-9 dish to "look" at something that is "for the future" (lol). Not on paper, Not in a lab, But actually standing on Site. Im good but i just cant seem to be able to do that. No meters and no tv screens produce any result no matter what i do (??) (chuckle), so im wondering just how can i do this. Lmao "i can SEE 4 but thats it"
    ( Big D* and feb/March'o6 At-9 mandate revisited= "non functioning DMA boo boo":lol: )
     
  8. Aug 20, 2006 #8 of 323
    Cap'n Preshoot

    Cap'n Preshoot Godfather

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    Thanks. The important thing is at least someone else agrees with me that this should work.
     
  9. Aug 20, 2006 #9 of 323
    Cap'n Preshoot

    Cap'n Preshoot Godfather

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    Bama, ol' buddy, I understand you have a whole lot of pent-up frustrations about the AT9, the HSPs, and maybe some other things, but this thread is about OTA diplexing, not about aligning a dish. Lets everyone please try to confine our remarks in this thread to the topic of Diplexing. Thank you!!!!
     
  10. Aug 20, 2006 #10 of 323
    D-Bamatech

    D-Bamatech Godfather

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    I didnt mention an Install company this time (HSP). I saw it(comment) quite relivent due to the statement concerning the module and nothing "coming down" that even effects it. Like that "other guy" telling me "for future use" .. ya know.. he he.

    Ill leave "yall" alone and just go back to helping these folks then. (chuckle)

    this place IS hilarious @ times though.. ya gotta admit. I laugh all day in here.:lol:
     
  11. Aug 20, 2006 #11 of 323
    boba

    boba Hall Of Fame

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    Bamatech I agree we laugh all day but most of us are laughing at you. Not saying you are right or wrong but you act like a spoiled little child which can be very humourous at times.:lol: :lol: :lol:
     
  12. Aug 20, 2006 #12 of 323
    cbeckner80

    cbeckner80 Godfather

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    Amen; :hurah:
     
  13. Aug 20, 2006 #13 of 323
    D-Bamatech

    D-Bamatech Godfather

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    thank you.. :lol:

    im taking my toys and going home then...
     
  14. Aug 21, 2006 #14 of 323
    greywolf

    greywolf DBSTalk Club Member

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    The HR10-250 is an MPEG2 only DVR. The HR20-700 is the Ka band MPEG4 capable box and its 2 BBCs are external.
     
  15. Aug 21, 2006 #15 of 323
    Budget_HT

    Budget_HT Mentor

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    I don't have an HR20-700 yet, but I have read posts from Earl that say it both ways.

    First he said no external B-Band converter. Later he said there were supposed to be two external B-Band converters and they were missing from his HR20-700 box when he got it.

    I had the impression that the B-Band converters might be temporary or not needed for some new coax solution (hopefully single coax) from DirecTV, but I have no direct information for that assumption.
     
  16. Aug 21, 2006 #16 of 323
    Cap'n Preshoot

    Cap'n Preshoot Godfather

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    The only way to do two receivers (DVR + watch another channel) over one common coax with satellite would be with signal stacking, which can get expensive.

    Offhand I'd say the likelihood of the BBC becoming built-in or otherwise incorporated into the box is probably pretty good.
     
  17. Aug 21, 2006 #17 of 323
    Clint Lamor

    Clint Lamor Hall Of Fame

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    DirecTV has a technology they are going to use called Frequency Translation Module (FTM) this will send all needed signals down a single line to your receiver and your receiver will then use it's internal hardware to sort everything out. If you do a google of it you can find some posts on it. I "THINK" the chip to do this at least in the receiver is made by broadcom. At least I found them talking about it in one of my searches.
     
  18. Aug 21, 2006 #18 of 323
    janzy

    janzy New Member

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    Used Cap'n Preshoot's solution today and it s working great!
     
  19. Aug 22, 2006 #19 of 323
    cadjoe

    cadjoe Cool Member

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    1) I assume that an ATSC signal can be used with the diplexer for this scenario?

    2) I assume that the Ka/Ku Multiswitch can be used with the HR10-250, and same scenario would work as in 2nd JPG?

    3) Is it confirmed that the HR20-700 will have a dual internal BBC, and as above will it pass if already done?

    4) Will the newer 2nd Gen 5 LNB downconvert?

    Picture says a 1000 words, so did I get it right ?

    Thanks,

    CadJoe
     

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  20. Aug 22, 2006 #20 of 323
    Cap'n Preshoot

    Cap'n Preshoot Godfather

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    Can I expect my usual royalty commission check in the mail? ;)

    Glad we were able to help out. Are you using the H20?

    CPS
     

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