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Do high SNR levels on Verizon FiOS affect Roamio Picture Quality

Discussion in 'TiVo Roamio DVRs' started by leepoffaith, May 4, 2014.

  1. kbmb

    kbmb Active Member

    1,286
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    Jun 22, 2004
    NH
    I'm similar to you......tend to find that running 100% with 41-43dB gives me a perfect picture and no corrections. Ran my TivoHD on the same line that way for 8 years.

    The problem with Tivo's reading is you have no idea if what you are running is the equivalent to 103% or 123%. Like you said....is hot really not "hot". Seems to me a perfect signal would be right on 100%.

    This notion that Tivo always wants you to attenuate to get down to something less than 100% seems absurd to me. Doesn't mean I'm right.....just sounds absurd. Wish my parents were ok with me attenuating my grades years ago ;-)

    If they would just also show an actual signal level, then I think a lot of this would be solved.

    However, if you are a user and showing 100% and are having the cutouts, pixelation, signal loss.....then yeah, I'm guessing your signal is TOO hot. But again, Tivo has to guess just as much as we do since they don't show an actual number!

    -Kevin
     
  2. kbmb

    kbmb Active Member

    1,286
    13
    Jun 22, 2004
    NH
    That's interesting and the first I've heard that. So you think it's better to split the signal (terminating unused ports) than simply applying a traditional attenuator?

    -Kevin
     
  3. leepoffaith

    leepoffaith Member

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    Apr 21, 2014
    Tampa, FL
    Thank you for all the feedback! Everyone on this Tivo forum is so helpful. I've decided that, for the time being, I'm going to keep it as is. 98% of my channels are crystal clear (better then the fios box was in my opinion). I was able to watch a Cinamax movie last night without an issue as well. I had this problem once before about 2-3 years ago with the standard FiOS boxes and they had to end up replacing the ONT box. I have the ONT on the outside of my home and I believe the Florida sun really takes it's toll on it.

    I am going to be purchasing a coaxial compression tool, coaxial stripper/cutter and a bunch of compression fittings so I can replace all my connections in my OnQ box (where all my cable lines come in to). Right now they are the old school small connection where you just crimp the end. I will also be cutting an appropriate length cord to use with the Roamio because I realized that I am using too long of a cord and it is bending in a weird way.

    If after getting the cords all set I still have the issue I will look into purchasing a 6 db attenuator.
     
  4. nooneuknow

    nooneuknow TiVo User Since 2007

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    Feb 5, 2011
    Cox Cable...
    From another thread: http://www.tivocommunity.com/tivo-vb/showthread.php?p=10097616#post10097616

     
  5. nooneuknow

    nooneuknow TiVo User Since 2007

    3,554
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    Feb 5, 2011
    Cox Cable...
    Based on my own experience: Yes, absolutely.

    It's also worth noting that the local Cox techs are prohibited from using attenuators. All attenuation must be done using splitters, and simply terminating any unused (extra) ports. Any attenuators found while out on a truck-roll, must be removed.

    I had no issues with attenuators before Cox went to 1GHz, and then the spectrum became too wide mange equally/properly with them. While the attenuators they had been using were 1GHz rated, the problems with the difference in high and low frequencies, and how much the same attenuators would change the signal, pretty much required using splitters.

    I don't know if you've ever opened up a modern MSO-grade splitter, but I have, and there's a lot more to a splitter than most probably think. They really should be called "distribution and isolation devices", as "splitting" paints a crude picture, compared to what's really going on. I've seen many post things about how they think splitters work, and many of them are very wrong.

    What's fun is to peel the metal back off a cheap splitter like "Gemeni" brand, and then do the same with one that came from your cable company. It's hard to believe those junk ones ever worked for anything.

    Splitters will always do a better job (even if only by a marginal amount, in some cases) of keeping the attenuation more equal across all frequencies. It's more work to do, that way. But, IMHO, well worth the effort. I doubt Cox would prohibit using basic attenuators, unless there was a need to. Attenuators are cheap and easy to quickly install. Between parts and labor costs, I'm sure the splitter-only rules have to be worth it, or they simply wouldn't go that route.
     
  6. ustavio

    ustavio New Member

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    Oct 19, 2013
    I've had various experiences with and without attenuators and splitters. I have a TiVoHD and a Roamio Pro. Until recently, I had two Verizon Fios Set Top Boxes and ran the HD and Pro side by side with the STBs via splitter.

    With the Pro, I found that when my SNR (at 100%) was 40-42db, the Fios STB was giving me a reading of 35-37db. The TiVoHD gave me an almost compatible SNR at 37-38db. Both TiVos and STBs were using high quality Regal/Antronix splitters with 3.5db loss on each split. Without splitters, the Pro gives 40-44db and the HD still gives 37-38db. With both the Pro and HD I experienced zero RS uncorrected and uncorrected before and after splitter use. The only way I've been able to get Signal Strength below 100% is to use multiple splitters and/or attenuators. Using 6-12db Holland, I can get into TiVo's preferred zone and drop SNR on the Pro to under 40db and the HD to 30ish, depending. Individual channels can range the gamut of higher and lower. However, I find a RS corrected and uncorrected errors occur frequently and more importantly, I get audio and/or video pixilation issues and other glitches I did not have before.

    I ditched the Fios STBs to embrace the pure TiVo experience (okay, really to save money) so I no longer have the ability to compare SNR values but with all the experimentation (splitters, attenuators, splitters with attenuators, splitters daisy chained with splitters, splitters daisy chained with splitters plus attenuators) and with all the resulting various Signal Strength and SNR values on both the Pro and HD, I have found that using nothing gives me the best picture and audio quality.With unadulterated out of the wall Coax, I get on the Pro, 40-43db pegged at 100% (depending on channel) and on the HD I get 37-38db pegged at 100%. I also get zero RS corrected and uncorrected. On the HD i get very occasional RS changes when I leave one channel tuned in all the time (my wife likes HGT V), but they also seem to occur when Fios does a channel lineup change, or there is a Service Connection or a Fios line hiccup. The only reason I know this occurs is because the OCD part of me checks every now and again. More importantly, if the RS corrected or uncorrected has changed, it is not "changing" in front of me. Almost always, these will go away with a VCM connection. Rarely, if it is on a channel that has been locked for weeks on end, just changing the channel back and forth dispatches the errors. Regardless, the picture/audio quality remains solid.

    I agree that splitters do a better job than attenuators at bringing values into TiVos preferred range. But the preferred range (Signal Strength >75 <100) (SNR >32 <36) is difficult if not impossible to achieve on all channels, all the time whether using splitter(s) or attenuators(s) or a combination of the two. While I might get it on channel A, on channel B I would get a SS of 53 and SNR of 24. Pixilation and various glitches were quite plentiful. Especially when changing between channels with "approved" values and those that fell outside them. Recorded shows were hit and miss, many were just unwatchable.

    If one throws into this mix, an issue on Fios' end or a specific channel having a seizure or ESPN experiencing live transmission problems (of which they sometimes neglect to inform the viewer until after said viewer has had a seizure), it is sometimes near impossible to determine if audio/video quality issues are internal or external or both.

    I've been fiddling around with this stuff for years now. It was even more of a nightmare with TWC their tuning adapter and the platform issues they inherited from Adelphia.

    So far I haven't burned out any tuners (knock on wood) but I have fried my brain over signal strength/SNR values. As of today, my cranky old TiVoHD and spiffy Roamio Pro seem to function best with no splitters or attenuators, a signal strength pegged at 100% (on all channels) and an SNR that runs 40-43db on the Pro and 37-38db on the HD. I can, however, fully understand and appreciate, given the multiple variables involved, why folks have different experiences with different Cable/ISP systems and set ups.
     
  7. kbmb

    kbmb Active Member

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    Jun 22, 2004
    NH
    I have had a very similar experience to yours. When I first got my Plus, noticed the 100% signal and 41-43dB. I brought my Comcast DVR down and plugged it into that same connection and it displayed the SNR in the 37-38dB.

    I noticed my Basic is more in the 37dB range, but that's on a longer cable run. I guess one of these days I should bring the basic down and see the difference between that and the Plus on the same run.

    -Kevin
     
  8. kbmb

    kbmb Active Member

    1,286
    13
    Jun 22, 2004
    NH
    So I thought I'd actually do this experiment this morning because I was curious.

    My setup is Comcast. I have a single cable run from the pole to the basement of our house. Inside the house it's split with a 3-way splitter:

    -7dB: to the cable modem on the 1st floor (about a 10' run)
    -7dB: to the Roamio Plus on the 1st floor (about a 25' run)
    -3.5dB: to the Roamio Basic on the 2nd floor (about a 60' run)

    With this setup:

    The Roamio Plus is consistently at 100% signal and 41-43dB SNR. Have had no issue with this.

    The Roamio Basic has a signal of 92-95% and ~37dB SNR

    So what I decided to do this morning was swap them to see what would happen with the signal levels. Well, I was half expecting that the levels would swap and stay at the location.....but they didn't. The levels followed the Tivo, so moving the Plus upstairs on the longer run, it had the exact same signal levels as downstairs, and the Basic on the shorter run downstairs had the same as when it was upstairs.

    No doubt the Plus/Pro have to boost the signal to get the 6 streams....but it's looking like that signal is really boosted compared to the Basic.

    -Kevin
     
  9. nooneuknow

    nooneuknow TiVo User Since 2007

    3,554
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    Feb 5, 2011
    Cox Cable...
    I keep forgetting the 6-tuner model (Plus/Pro) discussions tend to lead down this path...

    Now I seem to recall some folks very unhappy with the amplification being always-on, and TiVo blaming the source signal for damaging things, etc.

    Good move swapping things around. That made sense.

    I also tend to use my Tuner Adapter readings to see a true, non-TiVo, reading, and you should see a lower SNR value on the TA (being a true SNR, not TiVo calculated). This is only valid if using a two-way split, with equal-length cables, to the TA and TiVo, without any attenuators in-line, after that split.

    I'm also now recalling some TiVo advice that involves pulling the coax, then checking the reading to make sure they go to zero/null values. TiVo considers any other result to be a TiVo fault condition.

    I kept talking about the other threads that predate this one. Yet, I didn't go back and pour over them again, where I'd have spotted some reminders on the Plus/Pro differences.
     
  10. kbmb

    kbmb Active Member

    1,286
    13
    Jun 22, 2004
    NH
    Don't have a tuning adapter, so can't use that as a measurement....wish I had one of those tools the cables guys have. Back in my TivoHD days, we were having issues that we thought were signal related.....the Comcast guy came out and saw that all signal levels were fine (turned out to be some issue on Comcast's side). And like I said before....before we got the Basic, we had the Comcast DVR and I hooked that up to the same line as the Plus and it read lower SNR numbers.


    Just because I love testing these things, I went and pulled the coax on both my Tivos:

    Roamio Plus coax plugged in:
    Signal: 100%
    SNR: ~41dB
    OOB SNR: ~35dB

    Roamio Plus coax UNplugged:
    Signal: -
    SNR: ~17db (although saw one jump to 29dB)
    OOB SNR: ~3-4dB

    ------

    Roamio Basic coax plugged in:
    Signal: 92-95%
    SNR: ~37dB
    OOB SNR: ~400dB (not sure why the Basic shows this number)

    Roamio Basic coax UNplugged:
    Signal: -
    SNR: ~9-15db
    OOB SNR: ~44-47dB

    -Kevin
     
  11. nooneuknow

    nooneuknow TiVo User Since 2007

    3,554
    0
    Feb 5, 2011
    Cox Cable...
    I'm going to have to defer analysis of these results to somebody who remembers what thread this was covered in.

    Either I don't know the "secret" to searching TCF, or I just suck at it...

    The truth is out there. ...somewhere...

    Next time I have the opportunity to check mine, I will. I'll probably stick a terminator on the input to eliminate any stray RF that might get in (although, this was not a specified prerequisite in the thread I'm recalling).
     
  12. kbmb

    kbmb Active Member

    1,286
    13
    Jun 22, 2004
    NH
    Maybe this is the thread you were thinking of:
    http://www.tivocommunity.com/tivo-vb/showthread.php?t=514853

    Based on 1 person saying Tivo said it was defective and they got it RMA'd....although I'm not sure I would trust much of what Tivo support says. These days they generally tend to be mostly clueless.

    I notice back then I also pulled the coax on my Tivos and reported the numbers.....although see numbers are a little off because I had an old setup.

    Would be curious to see others if they have a SNR when the cable is pulled. Again....I'm not having issues so not sure what the difference is.


    -Kevin
     
  13. triftraf

    triftraf New Member

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    Jan 26, 2006
    I was one of the people that had their Roamio Pro's RMA'd. The new Roamio actually showed even higher SNR and ended up requiring MORE attenuation/splitters to get the signal strength and SNR low enough. It seemed more sensitive to the problem than the first one. The first one ran beautifully for a week before issues started showing up - whereas the new one did all sorts of weird stuff (lagging, losing signal, rebooting and not starting up, etc) without attenuating...

    Both units (the RMA'd one and the new one) show SNR when the cable is disconnected... And thus I don't believe the first unit needed to be RMA'd...
     
  14. nooneuknow

    nooneuknow TiVo User Since 2007

    3,554
    0
    Feb 5, 2011
    Cox Cable...
    That's not the one I was thinking of. I also wouldn't consider a one-off report from one person to be reliable enough to base an opinion on that I'd repeat.

    Until I spot what else I've seen again, or somebody else finds it, I'm kind of dead-in-the-water on any meaning of the "disconnected cable test".

    I swear there was a thread where the test resulted in a few people getting RMAs. I'd be hesitant to RMA one of my own, unless I was certain it needed to be replaced. I'm not feeling to confident that this "test" proves much.

    I'll still report back when I get a chance to try it on my 3 base Roamios. I'll be doing:

    1. Base reading, for each tuner.
    2. Pulled coax cable readings.
    3. Readings with terminator on input.
    4. Readings after a reboot.

    I'd add 5. Readings w/o cablecard inserted. But, they are hard to get to on base models.
     

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