MoCA & OTA basics

Discussion in 'TiVo Help Center' started by puffdaddy, Jan 30, 2021.

  1. puffdaddy

    puffdaddy Member

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    Right now, I have the OTA and MoCA signals physically separated (i.e., the antenna signal to goes directly to the bolt's coax and the bolt connects via Ethernet to the network); however, I'm thinking about mixing the OTA and MoCA together. This would allow me to connect the bolt exclusively via coax (and not consume an Ethernet drop) and also provide OTA signal to all drops (allowing for TVs without mini's to at least watch live tv).

    I understand it's best to put a PoE filter where the OTA connects in (to prevent my MoCA network from "leaking" back out through the Antenna), but I don't understand how the splitters affect the OTA and MoCA signals (other than vaguely knowing that each split incurs a ~3dB loss).

    My RG6 cabling was originally
    ONT -> 2-way split -> 6-way split -> six outlets
    _______________ \-> 6-way split -> six outlets

    I don't need the ONT in the mix anymore, as I've got the Internet going over Ethernet from the ONT to my router and because I no longer have cablecards.

    I feel like I should put the incoming OTA coax at the "top" of the tree (where the ONT was connected), but what happens if I were to connect the OTA at one of the outlets at the "bottom" of the tree (to the output of one of the 6-way splits? Does the OTA signal percolate through to the other splits and also back up to the "upper" layers? If so, does the signal also experience a 3db loss in the other direction?

    Additionally, W.R.T. PoE filters, I think I only need one PoE filter (if attached) to directly to the incoming antenna coax, correct? I don't need to worry about the signal radiating out from the wall outlets, correct? And if I were to be extra paranoid about such leakage, an 75ohm F-type cap (either on the output, or directly on the 6-way switches) will prevent any emanations, correct?
     
    Last edited: Jan 30, 2021
  2. ThAbtO

    ThAbtO TiVoholic by the bay TCF Club

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    The OTA does not have MoCa capability so you would need to split the coax to the antenna input and a MoCa adapter.
     
  3. snerd

    snerd Well-Known Member

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    This has a prayer of working, if the signal from the antenna is strong enough. When using only passive splitters, it is best to attach the PoE filter to the input of the topmost splitter, and attach the coax from the antenna to the input of the PoE filter. A typical 2-way splitter has 3.5dB loss, while a typical 6-way splitter has a loss of 11dB. So, the total loss from the top of the tree to any of the 12 outputs will be 14.5dB, which means that the power feeding into the input of the 2-way splitter is reduced by a factor of about 28 when exiting any of the 12 outputs. Whether this will work or not using passive splitters will depend on how good the OTA antenna is, and how long the coax is between the antenna and the input of the top splitter.

    That is very unlikely to work. The signal loss is the same going either way through a splitter, but a splitter is designed to give good port isolation, especially at OTA frequencies, so that very little signal power transfers between ports. MoCA splitters are specially designed to have less isolation at MoCA frequencies so that MoCA signals can "port hop", but a well designed MoCA splitter should still have good port isolation at OTA frequencies. If you feed the OTA signal into an output port with the intention of having it pass to another output port, the signal will have to pass through the splitters twice for an overall loss of 29dB. Your chance of success is much better feeding the OTA to the input of the top splitter. This scheme will only work if the topmost port is left open (or capped with another PoE filter) so that OTA frequencies will be reflected back down through the tree.

    Yes you only need one PoE filter. Best practice is to cap unused ports at the wall plate, and to cap unused splitter outputs. If you have several unused splitter outputs, it is better to use smaller splitters so that the total number of splitter outputs matches the number of rooms with coax ports.

    Which TiVo are you using? Many TiVo OTA models have no built-in MoCA capability.
     
    krkaufman likes this.
  4. krkaufman

    krkaufman TDL shepherd

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    The OP has a BOLT that was apparently doing CableCARD until recently...
    ... so it's hopefully a 4-tuner BOLT capable of both CableCARD or OTA tuning ... and, consequently, equipped w/ a built-in MoCA bridge. (i.e. rather than the MoCA-less "BOLT OTA" model, or a 6-tuner BOLT incapable of tuning OTA)
     
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  5. krkaufman

    krkaufman TDL shepherd

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    One way to avoid the 12-way losses of your as-is setup, as detailed by @snerd, would be to determine which of your TVs lack Mini's, and then connect the coax outlets for those TVs via the same splitter (hoping it's 6 or fewer) and feed the antenna signal only to/through this splitter.

    Alternatively, if you just want the OTA sent to all 12 coax outlets, just for flexibility (i.e. in case a TV were relocated, or if a Mini is broken), but find the antenna strength lacking, you can look into amplification of the antenna signal.
     
  6. puffdaddy

    puffdaddy Member

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    Thanks much. I'm using a bolt (my "OTA" shorthand for the Antenna signal, over the air, confused things), so it's capable of MoCA.

    What you write about the splitters makes sense.
     
  7. Feb 1, 2021 #7 of 10
    myklbear

    myklbear Member

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    I want to reinforce a couple of things that Puff Daddy said. It is very important to cap any open ports with a 75 ohm cap. Also using quality cable and minimizing the number of splitters is very important as the drop across each split leg is 3.5 dB. You must have a terrific OTA signal to drop that much as in your current system. Also remember that different frequencies require increasing amount of power as you go up to get the same signal which is why RF amplifiers have a trim to compensate for that.
    On a question that I have relating to this, I just got an OTA Roameo and on most channels I'm showing 72 to 80. I have a giant Yagi with a 50 to 60 foot run with no splitters but unsure of some of the cable quality. I do have a good picture but my question is if this is nominally enough signal or like a non OTA is it better being closer to 100?
    My cable Roameo had all of its channels signal pegged at 100 so I started putting pads in to get it 85 to 95 and ended up putting 16 dB in line. I reported this to the cable company, CV, who for 6 weeks has chosen to do nothing about it.

    Sent from my Pixel 3 XL using Tapatalk
     
  8. Feb 1, 2021 #8 of 10
    ThAbtO

    ThAbtO TiVoholic by the bay TCF Club

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    At best, you will only yield as high as 72% on the signal strength. If you are using Wifi, that is a different entry line.
     
  9. Feb 1, 2021 #9 of 10
    snerd

    snerd Well-Known Member

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    That is the signal strength after AGC (automatic gain control) has adjusted the level. Those are good numbers for OTA tuners. You'll only see higher numbers for cable tuners. The SNR is more significant, but TiVo likes to spew bogus nonsense about SNR. As long as you're getting good picture quality, you're signals are fine.
     
    krkaufman likes this.
  10. myklbear

    myklbear Member

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    Reassuring confirmation, thanks.

    Sent from my Pixel 3 XL using Tapatalk
     
    snerd and krkaufman like this.

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