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MOCA Problem

Discussion in 'TiVo Roamio DVRs' started by mschill, Jun 22, 2014.

  1. mschill

    mschill New Member

    2
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    May 18, 2013
    I just bought a Roamio Pro and want to enable MOCA so I can use a mini in my bedroom. I have a ARRIS TG6862G/CT router from Comcast. I have split my coaxial cable with a RadioShack splitter that can accommodate up to 3 ghz. The coaxial cables from the wall go into my Roamio and my router and an Ethernet cord connects my Roamio to the router.

    When I try to change network connections to enable MOCA I get Error C33. It says "There is a problem with your network settings. The DVR was unable to connect to your MoCA network."

    Does anyone have any suggestions for someone with modest technological abilities but great love of Tivo?

    Thank you!
     
  2. CoxInPHX

    CoxInPHX COX Communications

    2,349
    6
    Jan 14, 2011
    Phoenix, AZ
    The actual model number looks like Arris TG862G/CT (not TG6862G/CT)

    On the Roamio Pro, Under "Change Network Settings" did you select "Use this DVR to create a MoCA Network"

    [​IMG]

    You do not want to choose "Connect using MoCA" on the Roamio Pro.
    =================================================

    * On the Mini you do choose "Connect using MoCA"
     
  3. aaronwt

    aaronwt UHD Addict

    19,154
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    Jan 31, 2002
    Northern...
    No need to have a 3GHz splitter. More noise can be introduced into the line using a splitter that goes up so high. MoCA, in the TiVo, does not use frequencies anywhere near that.
     
  4. tarheelblue32

    tarheelblue32 Active Member

    3,641
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    Jan 12, 2014
    Raleigh, NC
    A 3GHz splitter is probably going to be better than a 1GHz splitter for MoCA.
    I would think that most splitters will have enough shielding to help block most interfering signals.
     
  5. aaronwt

    aaronwt UHD Addict

    19,154
    19
    Jan 31, 2002
    Northern...
    1 Ghz splitters work perfectly fine with the MoCA the TiVos use.

    Sent from my Droid DNA using Forum Runner
     
  6. tarheelblue32

    tarheelblue32 Active Member

    3,641
    2
    Jan 12, 2014
    Raleigh, NC
    I know that most 1 Ghz splitters will work fine with MoCA, but a splitter rated for 1 Ghz isn't guaranteed to pass through higher frequencies, even though it usually will. There could be some 1 Ghz splitters that truly won't pass through higher frequencies that would cause problems for MoCA.
     
  7. nooneuknow

    nooneuknow TiVo User Since 2007

    3,554
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    Feb 5, 2011
    Cox Cable...
    MoCA operates at an extremely higher dBmV (signal power), than your cable signals and is designed specifically to work with 1GHz (and sometimes lower) rated splitters, even though it operates at frequencies exceeding 1GHz.

    The whole idea is to not have to rewire your whole house and not to have to change all the splitters.

    MoCA is designed to "punch-through" (power-through) splitters rated for cable signals at frequencies lower than MoCA operates at. A standard splitter has 130dB of port isolation, stopping signals from passing between the OUT ports. MoCA blasts right past this. That's no small feat.

    Since MoCA is designed to work through 1GHz (and sometimes lower ratings of decent quality) splitters, I'd expect taking the expected rating and increasing it, would have potential to create more problems than it might ever possibly eliminate.

    Most instances of anybody stating that increasing their splitter ratings beyond 1GHz (when starting out with 1GHz) helped or fixed anything, likely was due to the original splitter being junk-grade quality, being defective, being borderline, etc. In reports like this, which I seldom even see, the person generally doesn't even consider trying a new 1GHz splitter. They see people (with good intentions) posting false information (or flawed information), stating that since MoCA exceeds 1Ghz, higher rated splitter are required. Some who read such posts, not knowing any better, unnecessarily spend extra money for ratings that are NOT required . Even worse, this misinformation gets repeated/passed-along, and propagates.

    If I got better results with a higher rated splitter, and had eliminated any doubt about the quality/functionality of the splitter used before, I'd look for the "real" problem, rather than calling it "fixed". There's almost certainly something else hampering the MoCA signal, by making it weaker, and unable to power-through, as it should, when a higher-rated splitter causes any improvement.
     
  8. tarheelblue32

    tarheelblue32 Active Member

    3,641
    2
    Jan 12, 2014
    Raleigh, NC
    I agree with pretty much all of that. 1 GHz splitters should work just fine with MoCA most of the time, but so should 3 Ghz (or 2 GHz or 2.3 Ghz) splitters.
     
  9. L David Matheny

    L David Matheny Active Member

    1,588
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    Jan 29, 2011
    SE Ohio
    So MoCA adapters operate in flamethrower mode even when not overcoming 130dB of port isolation? Are none of them smart enough to dial back the power when it's not needed? Is there no way that this can interfere with other signals, by overload or intermodulation or some other mechanism?
     
  10. nooneuknow

    nooneuknow TiVo User Since 2007

    3,554
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    Feb 5, 2011
    Cox Cable...
    A 2 or 3GHz rated splitter will still have at least 130dB of port isolation between the out ports, if of decent quality. Some true high-end splitters have much higher port isolation. The higher the port isolation, the better, when it comes to your non-MoCA frequencies passing through the splitters. The isolation specs often increase with the rating of the splitter, in many/most cases. It's a selling-point for some splitter suppliers, when you view the specs from a site made for those who buy in bulk. It's not as prominently stated, if it even is, when you look at marketing specs for retail marketing.

    So, MoCA can't just dial-down, because you install splitters rated at higher frequencies, including the whole MoCA band and above. The port isolation is important, and can not be taken out of the picture. At the same time, while the port isolation remains between the out ports (out-out), there is minimal isolation (via inductive coupling) between the in and out ports (in-out/out-in). So, any increase in the rating for regular (non-MoCA) frequencies, could cause the MoCA signals that go between in-out/out-in to pass at a higher dBmV, since it needs virtually no power to pass from in-out/out-in, but still has to power-through the out-out isolation.

    If you follow all that, you might see how installing splitters rated at higher frequencies, could result in an imbalance, with the MoCA actually pushing harder to overcome the out-out isolation, and that higher dBmV going right through in-out/out-in, where there's almost nothing to bring the level down by much. I'm not saying this is going to cause issues with certainty, just that there's a logical theoretical possibility of creating the imbalance I spoke of. So, yes, this imbalance could start causing issues with other things on the coax, if not protected by MoCA PoE filters (internal, or add-on), which completely block MoCA, and reflect it back.

    So, in summation, greater than 1GHz splitter rating for cable + MoCA is usually unnecessary, unless the non-MoCA base frequencies that will be passing through need it exceed 1GHz. Unless we're talking satellite, or some other coax base set of frequencies, I'm not aware of any cable plants using >1GHz. If I was going to recommend a splitter, based on 1GHz somehow not being enough for MoCA (some unusual situation), I'd say to try something like a 1.2GHz one, rather than jump to 2 or 3GHz (which some wrongly assume 2GHz is the minimum, due to MoCA hitting 1650Mhz).

    When it's a forum member saying TiVo users that want to use MoCA require 2 or 3GHz rated splitters, it's usually an honest error, or repeating what they've seen somebody else post. When it's a store, or a hired installer saying so, then it's just a way to make more money off the higher markup on the higher-rated splitters. The real possibility is folks might be getting advice from somebody who doesn't know how MoCA really works, and why base-frequency ratings don't apply in the same ways.

    EDIT/ADD: I have yet to hear of any cable provider, who also uses MoCA for their leased STB/DVR boxes, using greater than 1.2GHz rated splitters. Most use 1GHZ (or 1002Mhz, which is just creative labeling/marketing). My Cox market actually uses the entire 1GHz spectrum of their 1GHz RF network backbone, and uses the retail MoCA band, just like TiVo uses, and they still install 1GHz/1002MHz splitters. Most markets don't even have a 1GHz RF network, allowing them to use the lower bands inside the 1GHz spectral range. Some MoCA systems (non-retail) operate entirely within 1GHz, and not above it. I'm not extremely familiar with those systems.

    EDIT/ADD: Family member having serious medical issue, so proofreading is minimal.
     
  11. aaronwt

    aaronwt UHD Addict

    19,154
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    Jan 31, 2002
    Northern...
    When I switched my 8 way, 1GHz splitter out to an 8 way, 1.2Ghz splitter. It made a difference in the MoCA rates that were reported on the TiVos. Like up to 290mb/s instead of 275mb/s.. but in actual use it made no difference.
     
  12. Lord_Vader

    Lord_Vader New Member

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    Jan 29, 2009

    Thanks.
     

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