Audio/Video choppiness

Discussion in 'TiVo Help Center' started by Stuxnet, Mar 11, 2011.

  1. Stuxnet

    Stuxnet Alien Infidel

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    Feb 8, 2011

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    What causes choppiness in both audio and video. I get periodic breakup on one channel more than others. There's no visible tiling, just rapid stop/go jerkiness easily seen on the news headline crawl line at the bottom of the screen.

    I just recently upgraded the HDD and its pre-install diagnostics all passed. Notably, the former drive had the same effect with the same channel.

    Thanks in advance.
     
  2. Swisher

    Swisher New Member

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    New York,...
    Could be an indication of a weak incoming signal - common with over-the-air, but less so with cable. You can check signal strength on both tuners in the set-up menu.
     
  3. dlfl

    dlfl Cranky old novice

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    What model TiVo?

    If a Series 3 or 4, tune the bad channel and look in DVR Diagnostics. What are the signal strength, SNR and RS Error counts?
     
  4. Stuxnet

    Stuxnet Alien Infidel

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    It's a Premiere...
    Signal Strength 61, SNR 32.
    The only "RS" values I see are:
    RS Uncorrected: 0
    RS Corrected: 27
     
  5. dlfl

    dlfl Cranky old novice

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    All your numbers are within TiVo's acceptable ranges. See this TiVo support page for details:

    http://support.tivo.com/app/answers/detail/a_id/150

    However the strength is below the recommended range. Compare the readings to other channels that don't have problems.
     
  6. Stuxnet

    Stuxnet Alien Infidel

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    Thanks for the link reference. I hadn't seen that before. I'll scan the other channels and see if their signal strength is comparable. I also have a signal booster I can try if I can't get a response from the cable company.
     
  7. gastrof

    gastrof Hubcaps r in fashion

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    Assuming the signal strength uses "100" as "best", there's no way "61" should be called "acceptable".

    With an OTA dgital tuner, anything in the low 70s starts being unacceptable, in my experience.

    Can't see why cable would be any different.
     
  8. dlfl

    dlfl Cranky old novice

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    Yes, if you look at the TiVo support page linked in my previous post, the wording is as follows:
    Thus "acceptable" is not the right word. In my experience on cable signals on a TiVo HD you really need 70 or better.
     
  9. Stuxnet

    Stuxnet Alien Infidel

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    I scanned my channels and the lower band (digitized analog channels) run 48-50; the digital, including HD, channels run 56-61.

    I slapped on a line "booster" and the HD stations popped up to 85-90. If this were your system would you bug the cable company (Charter), or just leave the signal booster running? Do you know what the line spec is for cable suppliers?

    FWIW, mt Tuning Adaptor statis for SNR says "good".
     
  10. dlfl

    dlfl Cranky old novice

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    What splitters do you have from where the cable enters your location?
    If you have no splitter or just one splitter (frequently located in a box on your exterior wall), your signal should be stronger than what you report and I would complain to the cable co. If you have additional splitters, you may need an amp or "booster". One issue with any amp, booster, or even splitters is how much they attenuate the reverse OOB (out of band) control signal that goes back from your TA into the system for SDV request purposes. This is only an issue if you have a TA. Do you?
     
  11. Stuxnet

    Stuxnet Alien Infidel

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    There is a primary splitter where the cable comes up to the house. From there it splits (one splitter) with several runs to various rooms. The run supplying the TiVo terminates at a wall connection, which is connected to a cable to the TA (so, yes I have a TA for SDV programming).

    I had planned to run the TA cable through a surge protector, but now that sounds less desirable.
     
  12. dlfl

    dlfl Cranky old novice

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    Try running the cable directly into your TiVo, i.e., bypassing the TA temporarily and see what signal strengths you get. This will check if the TA is attenuating the signal too much. Cisco TA's actually boost the signal a dB or 2 while Motorola TA's attenuate 1 or 2 dB. If the signal strengths go way up by bypassing the TA, the TA, or the short cable between TA and TiVo, is defective.

    Otherwise I'd say either the signal delivered to your location is weak or the TiVo is giving false readings (i.e., is defective).

    Go into Tuning Adapter Diagnostics and go to the second page of the first section (Status I think it is). Get the dBmV values for FDC, RDC and Tuner and post here. Preferably do this w and w/o the booster in place if not too inconvenient. FDC should be between -7 and 7 and is the OOB (TA communication) signal coming in to your TA. RDC is should be between 40 and 50 and is the strength of the OOB signal going back from your TA. Too high a value here means there is too much attenuation (e.g., in a splitter or booster) and your TA has to increase the signal to overcome it.
     
  13. unitron

    unitron Well-Known Member

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    Are you sure the problem isn't in the signal before it ever gets to your house, much less into your TiVo? Maybe even before it gets to your cable co?

    For example, the other day my mom was playing back the CBS soaps on her S2 DT and had a similar problem, but the problem was also present on the VCR recording of the same shows she kept on doing post-TiVo acquisition as a backup, so either the problem was introduced when TWC took the feed from WNCT and made it analog 9, or was introduced in WNCT's signal chain, or it got screwed up somewhere in the network-satellite-local affiliate uplink downlink path, or CBS the network screwed it up before they uplinked it to the satellite.

    Or maybe Proctor and Gamble gave 'em a bad tape/file to begin with.
     
  14. Stuxnet

    Stuxnet Alien Infidel

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    With the TA removed, my upper channels (HD) run significantly higher (80-85) with one or two channels as low as 75.

    After I reinserted the TA, signal strength going to the PT dropped to 65-70 (not as bad as my previous report). Could this "improvement might be a "time of day" issues as it's 8:30am now.

    I tried to pull up the TA (MTR-700) values you mentioned... the only dBmV value I found was for the "upstream modem"...
    REQ LEVEL: 045 dBmv
    ACTUAL LEVEL: 046 dBmv

    I beginning to wonder if unitron's remark about a faulty channel might be the cause. I can't say it's not happening on other channels, but I have't observed it yet... Interestingly, I only noticed one channel drop out of my lineup with the TA removed, so I may try a week of viewing with the TA disabled.
     
  15. dlfl

    dlfl Cranky old novice

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    Any problem that affects only one channel does cast suspicion on the channel signal itself.

    However the insertion loss of your TA (apparently it's a Motorola) seems too high to me. Sometimes the short cable between the TA and TiVo is bad, or it may be the TA itself. The numbers I told you to look for apply to the Cisco TA although I think the ones you posted are what Cisco calls the RDC and would be acceptable for that.

    Were your numbers with the booster in place? If so, your incoming signal strength is too low and the cable co should be asked to check it.
     
  16. Stuxnet

    Stuxnet Alien Infidel

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    Feb 8, 2011
    No booster. In the past the booster brings the signal out of the TA up to 85-90.

    I'm going to ask the family be attentive to audio breakup on alternate channels and hit "record" when that occurs so I can check it out. Thanks for your input.
     

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