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FIOS TV pixellation fix - attenuate to SNR 31

Discussion in 'TiVo Series3 HDTV DVRs' started by AbMagFab, Nov 19, 2007.

  1. webin

    webin New Member

    307
    0
    Feb 13, 2008
    Hillsboro,...
    Yep... I do notice a difference when I put a little attenuation on the line. Most of my pixellation comes on 801 (Local Fox) and 803 (Local CW). Without attenuation, they are usually bearable, but occasionally completely unwatchable. With 8dB attenuation, they are always watchable, with only occasional mild pixellation.... but 802 (ABC) will sometimes lose it's signal completely. In the last couple days (while trying to test), I've actually not seen very much pixellation at all, and currently don't have any attenuators on.

    Go figure... as soon as I want to test a theory (moca interference), it gets better on its own. I'm sure it's just a temporary clear area and pixellation will return eventually.
     
  2. hmm52

    hmm52 New Member

    405
    0
    Feb 25, 2008
    Lower...
    I ran a basic test to find effect of Verizon filter on tiling/pixelation through my S3. Without attenuators it has been medium to heavy on the local HDs this morning and evening. I've seen worse. Both test series were with no attenuation, VZ STB powered up, and channels tuned for 45-70 minutes. RS Uncorrected values are at per hour rate and rounded to nearest thousand.

    (first series)--filter installed at splitter input. Actiontec coax disconnected

    507MHz... ch816... 743k RS Unc
    525MHz... ch812... 605k RS Unc
    525MHz... ch817... 714k RS Unc
    519MHz... ch813... 450k RS Unc

    (second series)--filter removed from splitter. Actiontec coax connected

    525MHz... ch817... 742k RS Unc
    519MHz... ch813... 516k RS Unc

    No tiling was observed on scan of other channels which have previously tiled - with and w/o filter. Tests were obviously limited but the filter doesn't look like a factor to me, not in pixelation. I'll leave it off to see if anything else crops up. 11db is doing the job at the moment.
     
  3. richsadams

    richsadams Active Member

    8,893
    2
    Jan 4, 2003
    Good info. Thanks! :up:
     
  4. webin

    webin New Member

    307
    0
    Feb 13, 2008
    Hillsboro,...
    I was really looking forward to testing the moca theories tonight, but I can't get the dang thing to be anything other than perfect!
     
  5. hmm52

    hmm52 New Member

    405
    0
    Feb 25, 2008
    Lower...
    Verizon is cooperating with my tests. Most of the locals are still coming in at over 10,000 RS Uncorrected errors per minute. I ran 3 more series, all with 11db attenuators at S3 input. The second of these failed because of a freeze/reboot, and was redone. RS Unc values and rates were checked only at beginnings and ends of tests, and found to be over 10,000/minute each time; end of last test was highest, 11,330 - without attenuation. Duration was over 9 hours for both series. RS Uncorrected at per hour rate. (not in thousands)

    (3rd series)--filter removed 11db attenuation Actiontec coaxed

    513 MHz... ch811... 25,056 RS Unc

    (4th series)--filter installed 11db attenuation Actiontec coaxed

    513 MHz... ch811........ 689 RS Unc

    I'll rerun the tests for obvious reasons.

    EDIT--- I'm wrapping up the tests because the quality of the VZ feed has shown itself to be too uneven. The final series were run this morning for an hour each. RS Uncorrected errors were very different when checked at end of each test for 15 minutes - attenuators removed.

    (5th series)-- filter installed 11db atten. router coac connected

    513 MHz... ch 811..... 5 RSU/hour....... With atten. removed - 1222 RSU/min.

    (6th series)-- filter removed 11 db atten. router coax connected

    513 MHz... ch 811..... 1 RSU/hour....... With atten. removed - 8667 RSU/min.

    ------- Anybody who wants to try my VZ filter in their setup is welcome to do that. Send me a PM. I don't think it diminishes pixelation in my configuration and use. Immediate and consistent results are what I'm looking for. Found with attenuation. Not found with the low pass filter.
     
  6. jpulver

    jpulver New Member

    14
    0
    Mar 27, 2007
    My Tivo HD worked fine with Comcast for a long time. Then my Tivo HD worked fine with Verizon FIOS for two months after I replaced Comcast with Verizon in January 2008. (Twelve hours for installation; an installer who had never seen a Tivo; great consternation.) By March, severe pixelation began on certain HD channels (the worst have been high-def CBS, ABC, NBC).

    Verizon techs came and went more times than I can count. They were clueless. Most recently a tech tried everything he could think of (yet again) and then, as another tech had done before, he decided to swap out the cable cards. Big problem, however: He had never installed cable cards in a Tivo before. I was without service for two or three days while Verizon tried to figure out how they had screwed up my account. My account did not show that I am entitled to cable cards, so the cards wouldn't activate.

    I called Tivo more than once, too, trying to get some help. The Tivo folks seemed to know less than Verizon, and certainly less than I had learned on this forum and elsewhere. Finally, a couple of days ago, I called Tivo and this time insisted on talking with someone who was familar with the pixelation problem involving Verizon FIOS and Tivo HD.

    Here's what I was told this time: It's imperative that Verizon install a "low-pass filter" at the ONT, and that the signal then be attenuated at the cable outlet closest to the Tivo HD. To fine-tune, I was told to attach attenuators to the cable until the diagnostics page (Tivo Central/Messages & Settings/Account & System Information/Diagnostics) shows a signal strength below 95 and an SNR no higher than 30-35. I was told I could reduce the signal strength to as low as 70-75. I was told to keep adding attenuation until the pixelation stops.

    The Tivo tech asked me to notify Verizon that the preceding procedures and instructions will rectify the problem. For some reason, he said, Tivo was having trouble getting the word spread throughout Verizon. Odd. He emphasized that BOTH the low-pass filter AND the attenuators are needed to eliminate the pixelation.

    I was skeptical, after having worked on this problem for months, but willing to try one more time. The Verizon tech came back, installed a low-pass filter and gave me a bag of attenuators. After adding 12 db of attenuation, I still had some pixelation. But after adding a total of 14 db of attenuation the pixelation finally has gone away. (At least for the past two days; but this time I think it's been stopped for good.)

    On the "bad" channels, my signal strength is now down to 68-75, and SNR down to 30-33. I still get some RS Uncorrected errors, but not nearly as many as before. The large number (millions, sometimes) of RS Uncorrected errors always coincided with the pixelation.

    My concern now is that the HD picture quality has been diminished. I'll keep watching, and if I become certain that the picture quality is not worth it, I'll do what I've been threatening to do for three months: switch back to Comcast and pay the extra $20 a month for fewer channels.

    I hope this post helps others struggling with this frustrating problem.
     
  7. richsadams

    richsadams Active Member

    8,893
    2
    Jan 4, 2003
    That's very good info...thanks for the post. I'll keep it for the day that the VZ folks arrive at our doorstep, hopefully next month.

    You have to wonder what happened between the time FIOS was installed and two months later to mess up your signal. :confused: Others have reported similar issues; worked for months and then all sorts of problems that could only be corrected with attenuation, and now it looks like a filter as well. Then it makes me wonder if things will change again sometime down the road as it appears to have for others posting here that were able to reduce or remove their attenuation to get decent PQ. Hopefully VZ is narrowing things down to a signal that will work for everyone.

    Thanks again! :up:
     
  8. wmcbrine

    wmcbrine Ziphead

    10,369
    22
    Aug 2, 2003
    Eh? Apart from actual errors (which appear as pixellation or dropouts), you can't affect the PQ from a digital signal. It's either there, or it's not. Attenuators cannot make it look worse (other than by causing dropouts).
     
  9. hmm52

    hmm52 New Member

    405
    0
    Feb 25, 2008
    Lower...
    I haven't noticed degradation in PQ with attenuation, as long as you don't push it too far and create pixelation or no tune with weak signals, anywhere in the lneup. Which is your VHO? My feed was perfect for 1st 8 months - VHO8 (Phia.) & local CO; off and on issues since then; very good for 3 month stretch until 2 weeks ago. Summer vacations?

    Since the local HDs are the repeat offenders, I'll finish the Feb '09 antenna setup this weekend. It's better to get the locals reliably that way than receive aggravated calls from my wife, or sit down to recordings destroyed due to complacency. And if it's only the locals. you don't need attenuators with antenna in setup. I expect another rough period when VZ adds the new channels so fasten your seat belts.

    As noted in edit to my previous post, I haven't found reason to believe in the low pass filter as a remedy for pixelation. Anyone who wants to try it for themselves, send me a PM.
     
  10. jpulver

    jpulver New Member

    14
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    Mar 27, 2007
    I hope you're right about attenuation not affecting PQ. I'll keep checking the PQ. Thanks.
     
  11. moyekj

    moyekj Well-Known Member

    11,150
    33
    Jan 23, 2006
    Mission...
    If you eliminate RS uncorrected errors and signal strength is OK then that's as good as it gets.
     
  12. jpulver

    jpulver New Member

    14
    0
    Mar 27, 2007
    My signal strength sometimes drops down to the 60s (with 14 db attenuation and a low-pass filter) but I'm still getting a picture. I still occasionally get a few hundred uncorrected errors (rather than the millions I was getting before the filter and attenuators), but no pixellation now. I think I'm good to go at this point. Finally.

    Oh, and I think I'll soon decide that the picture quality has not been affected. I returned my tv's settings to default, and that seemed to do the trick.
     
  13. bhaas

    bhaas New Member

    174
    0
    Aug 5, 2003
    MD
    Any thoughts from folks why the filter should be installed at the ONT and not in front of the TiVo? There are no active components between the ONT and TiVo that can cause mixing or distortion products among the moca and TV signals- it would occur in the tivo's receiver. It seems, without knowing much about the setup, that the filter should be just upstream from the tivo. Clearly I don't understand something in the moca layout.
     
  14. rifleman69

    rifleman69 Member

    853
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    Jan 6, 2005
    Oregon

    He is right, this isn't analog anymore.
     
  15. rocko

    rocko Cuckoo for TiVo

    1,551
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    Oct 29, 2002
    Northeast...
    Wouldn't installing the low-pass filter at the ONT kill MoCA throughout the network? I guess it's OK if you don't have any STBs running but I imagine it would hose any MoCA dependent hardware. I, like others, am using NIMs to carry my ethernet to far-flung spots in my house.

    Edit: Not to mention the Actiontec - I'm also a Verizon internet subscriber and am not running the ethernet from my ONT with cat 5.

    I ask this in the interest of clarification, since I'm not (fingers crossed) experiencing major uncorrected errors. FYI I do have about 8db of attenuation on my S3 but none on my THD.
     
  16. ah30k

    ah30k Active Member

    2,211
    0
    Jan 8, 2006
    I think the intent would be to install the low-pass just at the TiVo. Installing the low-pass at the ONT would do nothing since all of the MoCA sources would be on the local LAN.
     
  17. rocko

    rocko Cuckoo for TiVo

    1,551
    0
    Oct 29, 2002
    Northeast...
    When I said "throughout the network" I, of course, was referring to the local LAN. My point was that it would kill all MoCA traffic, screwing with VOD and the like.
     
  18. ah30k

    ah30k Active Member

    2,211
    0
    Jan 8, 2006
    A filter only stops signals going through the filter. If the filter is on any one device it would only stop the MoCA on that device. In this case, the filter on the ONT would prevent MoCA from going into the ONT. This neither helps the TiVo or stops the MoCA from working on the LAN. I don't thing the MoCA is used for VOD, just for inter-STB sharing. I am I am having a hard time explaining this in text form, the heat must be getting to me.
     
  19. bhaas

    bhaas New Member

    174
    0
    Aug 5, 2003
    MD
    VoD and guide data, etc are delivered to the ONT via IP transport... the data (1490nm, IIRC) not the television (1550nm) optical path. I am not sure how the STB receives the guide and VoD- dedicated TV band channel and signalling, I imagine
     
  20. hmm52

    hmm52 New Member

    405
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    Feb 25, 2008
    Lower...
    I can't help with the speculation. I would tend to agree that if it's TiVos in particular that are having problems with the MoCA traffic then put the filters just ahead of them.

    The tech who swapped out the ONT & splitter and installed the low pass filter, all in November, is the sharpest cable tech I've met. He is now the "Big Boss" for my general area. He is the only tech who has clipped a meter inside the ONT and read line errors at different frequencies directly from the street feed. This was after he checked everything thoroughly throughout the house. I know. It seems ass backwards but it's the Verizon way. Once he saw the volume of line errors at ONT, he told me it had to be corrected at the street or central office level. Within 36 hours it was.

    He installed the LP Filter at the input side (from ONT) of a 6 way splitter. Included on the output side were 4 cablecard devices, none of them TiVo then, and a basic VZ SD STB. The filter hasn't interfered with VZ STB guide data. I've never used VOD - except what drifted over from neighbors through clearQAM while with Comcast.
     

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