First Drawing

Discussion in 'DIRECTV - Coax Networking (private)' started by Tom Robertson, May 31, 2009.

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  1. 69hokie

    69hokie Icon

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    Hmmm...69hokie Broadcasting Corporation....nahhh, don't need FCC vans in the area or neighbors complaining about interference!!!:scratchin
     
  2. dave29

    dave29 New Member

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    They would be:confused:, :lol:
     
  3. Tom Robertson

    Tom Robertson Lifetime Achiever DBSTalk Club

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    Somehow true MoCA manages to work with OTA, so I should think we "might" be able to work here too.

    Cheers,
    Tom
     
  4. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Can you be more specific?
    CATV MoCA is 1100 +/- 25 MHz, which:
    1) is out of the OTA band,
    2) doesn't go to an antenna, but "merely" backfeeds to the CATV system.
     
  5. Tom Robertson

    Tom Robertson Lifetime Achiever DBSTalk Club

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    I'm thinking MoCA isn't just for CATV, but any coax network including OTA.
     
  6. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Yes, "BUT" 1100 MHz, isn't an issue like 850 MHz is going to be.
    The "new" free channels from the crossover are for others to use the 800+ MHz band.
     
  7. Tom Robertson

    Tom Robertson Lifetime Achiever DBSTalk Club

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    MoCA is designed for use in terrestrial, catv, dbs, and telco environments. In other words, "ask the MoCA people how they managed it". :)

    I guess they worked something out.
     
  8. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    They don't connect an 850 MHz, 49-54 dBmV signal to an antenna with ~ 20 dB gain, which would have an ERP of ~ 100 miliwatts, in an environment where there would be things like cell phones using this band.
    "That's how to manage it", and why DirecTV may have chosen NOT to support diplexing for over a year now with SWM.
     
  9. 66stang351

    66stang351 New Member

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    Or, they just hoped that nobody would notice....
     
  10. Tom Robertson

    Tom Robertson Lifetime Achiever DBSTalk Club

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    You have me quite confused. Where does it say they don't hook MoCA up that way? Everything I read says they can hook MoCA to terrestrial coax nets.

    Cheers,
    Tom
     
  11. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Please post/send me "what you're reading".

    If the MoCA 1075-1125 MHz is connected to a CATV or OTA, it's out of band with most low power devices. Cable & "phone service" are going to end up in fiber [dead end], and aren't going to be using the 850 MHz, as this would conflict with their band usage.
    "Seems like" DirecTV is the [only] first user of the MoCA 850 MHz.
     
  12. Tom Robertson

    Tom Robertson Lifetime Achiever DBSTalk Club

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  13. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    You must have another doc, since [after going over all 22 slides twice] there is no mention of any frequencies, one line that has "terrestrial", and done of the pictures show an OTA antenna.
    The 1100 MHz, is what [as I've tried to explain] works with "terrestrial", because: 1) it's out of band, & 2) UHF antennas are going to have their gain drop way off "up there".
    "This doc" is to promote MoCA, and does a good job, BUT lacks the "nuts & bolts". Give me an engineering doc, and then we'll get an idea of the what & how.
    I'm only left with "my knowledge" of RF/Microwaves, and what does happen and not the "how they get around this [and this and..]".
    "These Boys" aren't stupid/dumb, but at the saem time, [so far] not that forthcoming with the specs.
     
  14. David Ortiz

    David Ortiz Save the Clock Tower!!

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    Certainly not technical, but from the FAQ
     
  15. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    "Meat":

    The MoCA standard is specifically designed to go backward through splitters (insertion) and go from splitter output to output (isolation). All outlets in a house can be reached from each other by a single isolation jump and a number of insertion jumps. Each isolation jump has an attenuation of 25dB and each insertion jump attenuates approximately 3dB. MoCA has a dynamic range in excess of 55dB while supporting 135Mbps throughput. Therefore, MoCA can work effectively through a significant number of splitters.

    Can adjacent dwellings hear/interfere with a MoCA network?

    Drop cables and multitaps isolate coax between homes. Multitaps give varying amounts of isolation between tap ports that vary with frequency, and can be insufficient to fully isolate homes in the 860 - 2000 MHz band. Multitaps come in 2, 4 and 8 tap versions, the majority being 2 and 4 tap multitaps. Coax can support reliable 100 Mbps in a 50 Mhz bandwidth or less, enabling more than 8 channels/homes to exist independently above 850 Mhz.
    If necessary, physically isolating homes on coax requires that simple 850 MHz low pass filters be installed between the multitap and the POE. Since there are more channels supported than shared homes on a multitap, each home can be operated on its own frequency, eliminating the need for physical isolation filters until the neighborhood is heavily penetrated with multiple channels per home, and usage rates indicate more channels than are available within the total bandwidth. Thus, in combination with encryption, coax supports private independent networks that are not degraded by neighboring homes.

    Every bit of this is for the 1075-1125 MHz CATV system.
     
  16. David Ortiz

    David Ortiz Save the Clock Tower!!

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    This PDF is certainly more technical. I found it while searching for info about POE filters.
     
  17. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Yes/no, it does go into the "how MoCA" signal works [for bit rates/distance], but not too strong on the "simply" RF end. [and again no OTA antenna anywhere]. Now "all we need is" some of those 850 MHz low pass filters for the OTA legs, and "we're set".
     
  18. dave29

    dave29 New Member

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    The PDF is a pretty good read, but like you said, no OTA anywhere.

    The "low pass filter" seems like a good solution.
     
  19. veryoldschool

    veryoldschool Lifetime Achiever Staff Member Super Moderator DBSTalk Club

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    Sure, and "just ask your local Radio Shack" for one. :lol:
    The 850 was for the CATV system. You would want one that started [well stopped] at 700 MHz.
     
  20. dave29

    dave29 New Member

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    Maybe Moca will make them for us:sure:
     
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