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Tivo HD Pixelation Troubleshooting

Discussion in 'TiVo Series3 HDTV DVRs' started by Chimpware, Aug 3, 2007.

  1. Aug 29, 2007 #201 of 1597
    navman

    navman New Member

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    Aug 10, 2007
    Talked to tivo customer service about pixellation issues on my tivo hd. was told they released a new software a few days ago that should fix the issue for people with SA cards. On asking them as to why I hadnt gotten this software update despite forcing several connections, i was told something to the effect of "it is a rolling release" being tested on limited tivohds and everyone should get it soon. Was I being lied to or is this the truth. The new software according to them was 8.3, which I thought was for TivoHD's older sibling. By the way I talked to Cal, he is a supervisor.
     
  2. Aug 30, 2007 #202 of 1597
    lrhorer

    lrhorer Active Member

    6,924
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    Aug 31, 2003
    San...
    Well, for several reasons, actually. First of all, there is a difference between "can't" and "doesn't". The modem does, the TiVo doesn't. The fact the TiVo designers decided not to incorporate a more fully featured signal measurement system has nothing to do with the fact the modem designers decided in favor of the measurement utility. We could have noses as sensitive as a dog's, but we don't. Willie Shoemaker could have been as big as Ed "Too Tall" Jones, but he wasn't.

    Secondly, Your coffee pot could have a digital temperature readout, and it would not make it cost terribly much more, but it would cost a little bit more and consequently few, if any, coffee pots have built-in digital thermometers. Even though the cost would not be much higher it would be somewhat higher and the extra feature would perhaps be of questionable value in most consumer's minds. Was it a bad decision on the part of the TiVo engineers not to incorporate a more significant signal measurement system? 'Not really. Incorporating it might have been a slightly better decision, but then they would have had to use a different receiver than they did, which could have spelled other troubles of which we are not aware. It's unlikely TiVo makes the receiver. It's almost surely an OEM part delivered to TiVo's assembly plant by the manufacturer. It's possible it was custom engineered to TiVo's specs, but more likely TiVo simply purchased an off-the-shelf module.

    Thirdly, while a poor enough signal level will definitely cause problems for a digital receiver like the TiVo, it is only one of a large number of likely culprits to cause problems on a CATV system, and probably not the most likely, at that, especially for a digital signal.

    No, it went down by 3.5dB, not 3.5dBmV. A Decibel (dB) is a way to compare two signal levels. A dBmV is a specific amount of power. One dBmV is an amount of power equal to .0168 microwatts. A change of 3.5dBmV is a reduction (or increase) of .0298 microwatts, no matter what the original level may have been. A change of -3.5dB is a halving of the original signal, whether it was originally 20dBmV, 0dBmV, or -50dBmV. Inserting a 2-way splitter into an RF line will cause the signal level to drop by .0298 microwatts (+3.5dBmV) if and only if the signal level without the splitter is .0597 microwatts, or +7.0 dBmV. In other words, adding a splitter will change the signal level by -3.5dB, not 3.5dBmV, except in the unique case where the original signal level is +7.0dBmV.

    If the unsplit signal level were +60dBmV, adding the splitter drops the signal level by -3.5dB, or in that case by 5.96 milliwatts, which is a drop of +56.5dBmV. If the unsplit signal level were 0dBmV, adding the splitter will again change the level by -3.5dB from 0 to -3.5dBmV, which is a change of -3.5dBmV.

    Well isn't that the same as the change from +7dBmV to +3.5dBmV? No the change from +7dBmV to +3.5dBmV is +3.5dBmV, or .0298 microwatts, while the change from 0dBmV to -3.5dBmV is -3.5dBmV or 6.7nanowatts - 1/4 as much.

    The change from +3.5dBmV to 0dBmV is 0dBmV. The change from +20 dBmV to +16.5dBmV is +16.5dBmV. The change from +55.5dBmV to +53dBmV is +53dBmV.

    See the pattern?

    A -1dB change frrom +60dbMv to +59dBmV is a change of +53.13dBmV. A +1dB change from +60dBmV to +61dBmV is a change of 54.13dBmV.
     
  3. Aug 30, 2007 #203 of 1597
    richsadams

    richsadams Active Member

    8,893
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    Jan 4, 2003
     
  4. Aug 30, 2007 #204 of 1597
    lrhorer

    lrhorer Active Member

    6,924
    0
    Aug 31, 2003
    San...
    'Not true. The only significant measurement of the quality of a signal is the S/N ratio at the receiver's demodulator. Note several things, however:

    1. The actual noise level includes any deviation from the precise hypothetical waveform produced by the transmitter. There may be a significant difference between this value and the value measured by the device in the receiver. How significant depends on the method used to quantify the measurement and what the actual sources of the noise are. These include noise in the original signal, amplifier noise, thermal noise, distortion components, common mode interference, superhetrodyne noise (generated by the receiver itself), and ingress carriers, among other things.

    2. While it is possible to have a good signal level and still have a poor S/.N, the reverse is not true. One cannot have a good S/N with a problematical signal level. A good S/N doesn't necessarily mean the signal isn't lower or higher than it should be, it just means the difference isn't going to cause trouble, and bringing the signal level closer to optimum values isn't going to help the picture any. Doing so will only have a small effect on the S/N, and above the S/N threshold, increasing the S/N has no noticeable overall effect

    3. In an otherwise perfectly functioning CATV plant, there is a direct relationship between the signal level and the S/N. If the originating signal is effectively perfect and there are no other significant sources of noise (including the receiver itself), then the S/N will increase exactly 1 dB for each dB the signal level is raised at the head-end until 3rd order distortion becomes significant. At that point, increasing the signal by 1 dB will REDUCE the S/N by 2 dB. Similarly, in a hypothetically noise free CATV plant, the only noise is going to be in the receiver itself and raising the signal level 1 dB will raise the S/N 1 dB until the signal reaches the point where thermal and superhetrodyne noise in the receiver are lower than common mode interference, at which point increasing the signal level 1 dB will REDUCE the S/N by 2 dB.

    4. Unlike analog signals, whose perceived quality degrades slowly as the S/N drops, digital signals are either good or bad. The degradation window where the signal goes from being perfect over very long timescales to being completely unrecoverable is quite narrow, sometimes as little as 6dB. It's also quite low compared to analog signals. In order to produce a picture deemed identical to an original "perfect" video when viewed side by side, the S/N ratio needs to be 65dB or higher, yet the video is poor but recognizable even at 20dB. A simple PCM signal can hypothetically be recovered as long as it's S/N is greater than 6dB. In practice, however, even with the best equipment the stream will start to suffer drop-outs any time the S/N drops below about 12dB. HD Video, however, is not PCM. It's QAM. Quadriture modulation significantly increases the bit rate for a given signal bandwidth, but the cost is the S/N must be mich higher in order to prevent lost data. What's worse, the HD stream is highly compressed, so while the loss of a single bit in an uncompressed digital video stream isn't even noticeable, the loss of a single bit in an MPEG stream will likely cause a very noticeable artifact indeed. Even so, QAM receivers can be designed which operate extremely well at S/N ratios of 25 or even 20dB. I'me sure the TiVo receivers are not that good, but I would be very surprised if they required more than 30dB or at most 35dB S/N. Anything above that is just fine, and increasing it won't have any real effect.

    5. Measuring the signal level is not difficult or consequently expensive. All it requires is a tuner and a voltmeter. Since the TiVo already has a tuner, all that would be necessary is to place a voltmeter circuit at the point where the signal leaves the I.F. section before it enters the demodulator. The S/N is a much more difficult parameter to measure accurately, but it can be made less so by making certain assumptions aboout the signal - at the cost of making the measurement more likley to suffer aliasing. That's in large measure where the caveat comes in about the reported S/N being good enough when in fact it is not. If this is the case, and it is due to out of range signal levels, then moving the signal lavels back toward optimum values will indeed resolve quality issues even though the measured S/N may change relatively little.
     
  5. Aug 30, 2007 #205 of 1597
    Dr_Diablo

    Dr_Diablo Dr_Diablo

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    Nov 23, 2003
    Midwest

    That "fix"...b2 was released on the 16th, an failed to solve the problem for those with SA cards, some however with the Motorola cards claim some improvement
     
  6. Aug 30, 2007 #206 of 1597
    mike_camden

    mike_camden New Member

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    Dec 11, 2006
    That's not accurate -- every post on this board that I have seen (with the exception of two) using Motorola cards with the Tivo HD report COMPLETE improvement. In my case pixelation is gone, and I'm very happy with Tivo. For thiose with SA cards, I'm confident that Tivo will be taking care of you based on how well and quickly they fixed the issue for us with Moto cards.
     
  7. Aug 30, 2007 #207 of 1597
    ChrisPA

    ChrisPA New Member

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    Aug 2, 2007
    Bucks...
    To provide a data point, I am still experiencing pixelation problems with my FIOS Motorola CC setup. This is in direct comparison to my Verizon DVR, which I have not seen experience a problem (admittedly I watch on this setup somewhat less often, so it could be that I've missed an occasional problem. With the Tivo, I can almost always flip through the channels at any time to find a channel experiencing pixelation). BTW, my signal strength is virtually always 100% with SNR of 37/38 dB

    Additionally, as I think I mentioned earlier, in the few days prior to switching over to FIOS from Comcast, the Tivo also experienced pixelation problem tuning unencrypted QAM on Comcast's feed (no cable cards).

    Overall things are better with B2 software, but still not perfect. It seems that fewer stations are affected, and the average severity is lessened. But... there are still occasions where a given channels is unwatchable (which channel is not consistentl).
     
  8. Aug 30, 2007 #208 of 1597
    richsadams

    richsadams Active Member

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    Jan 4, 2003
    Ah...I stand corrected! Thanks for the clarification...I either got it wrong from my source, or they have it wrong, which isn't likely. And thanks for the additional detailed info...very good stuff.

    Bringing understanding and solid information to this forum takes a lot of effort and caring; a very positive and appreciated quality. :up:
     
  9. Aug 30, 2007 #209 of 1597
    Phantom Gremlin

    Phantom Gremlin New Member

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    Jun 20, 2002
    Tualatin,...
    I respect your arguments for the TiVo not having a more featured measurement system. But I think the extra info could have been very useful.

    I understand the difference between dB and dBmV.

    I need you to re-read what I originally wrote. I wrote that with a splitter inserted the reading went down by 3.5 dBmV.

    Prior to the splitter the power level meter was reading -6.0 dBmV. After the splitter the power level meter was reading -9.5 dBmV. BTW, though completely irrelevant, right now my power level is reading 5.8 dBmV, with a 35.6 dB S/N. That's with a distribution amp.

    The use of the word reading isn't my choice. It's in the message from the cable modem. The text is:

    Power Level
    5.8 dBmV
    The Downstream Power Level reading is a snapshot taken at the time this page was requested. Please Reload/Refresh this Page for a new reading.


    You were so anxious to exhibit your superior knowledge that you created a straw man to knock down.
     
  10. Aug 30, 2007 #210 of 1597
    Phantom Gremlin

    Phantom Gremlin New Member

    1,555
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    Jun 20, 2002
    Tualatin,...
    Yes I'm frustrated. Mostly because the product has so much potential. It's so close to what I want, and yet not quite there. Still, I'm keeping it.

    As to what the OP might do, I agree that your advice was much better than my bickering.
     
  11. Aug 30, 2007 #211 of 1597
    richsadams

    richsadams Active Member

    8,893
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    Jan 4, 2003
    Frankly I can't wait to switch over to "all HD" equipment. Just wish they'd had the THD earlier...could have bought two plus had some left over for what we paid for the S3. :mad: But that's how it goes.

    Hang in there...I'm positive they'll get it sorted out, they always have. ;)
     
  12. Aug 31, 2007 #212 of 1597
    dadler

    dadler New Member

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    Aug 12, 2007
    Interlaken NJ
    I called Tivo about the pixelation problem and insisted upon an additional month of warranty since I was worried the fix would be coming after my warranty period. While Tivo said "yes", I was concerned that a phone rep. from Tivo could not (or would not) have anyway to send a letter or email confirmin the extension of the warranty. There is no way to communicate to Tivo in writing , in either direction!
     
  13. Aug 31, 2007 #213 of 1597
    richsadams

    richsadams Active Member

    8,893
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    Jan 4, 2003
    Good idea. As long as they gave you a case number you should be okay.

    TiVo
    P.O.Box 2160
    Alviso, CA 95002-2160
     
  14. Aug 31, 2007 #214 of 1597
    Chimpware

    Chimpware New Member

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    Jan 30, 2002
    I had a very similar conversation with Tivo rep. I originally was told by the Rep. that they would also extend the warranty on my equipment for the 30 days as well (I bought mine 2 untis from Circuit City). I was told that they would accept the Tivo HD units and refund my purchase price if the pixelation was not remedied within the additional 30 day period. When I asked for everything in writing I was told it was noted in my case log and the4y could not provide any written confirmation. I was not comfortable and wanted confirmation from a supervisor. When the supervisor got on the line they said there was some confusion and they could extend the trial period for the service, but not the equipment because I purchased it from another company.

    So in the end I have nothing in writing and I hope that having it noted in the case log is enough, although the "misunderstanding" with the CSR has me a bit worried. My plan, if this is not fixed within 30 day period (as I decided to take a chance based on recent post from TivoPony regarding fix for SA Scard users) is to cnacel service and try to sell the Tivo HDs on ebay.
     
  15. Aug 31, 2007 #215 of 1597
    richsadams

    richsadams Active Member

    8,893
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    Jan 4, 2003
    That is concerning. At least keep a log of when you called, what was said and exactly who you talked to each time. Hopefully that would hold up in "TiVo Court".
     
  16. Sep 1, 2007 #216 of 1597
    Brian-1337

    Brian-1337 New Member

    18
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    Aug 19, 2007
    I have a Moto M-Card with my TiVo HD. I have the b2 software. I have the following problems:
    1. Pixelation while watching live TV - I've seen it on digital channels - not sure about analog. Skip-back will reproduce the same pixelation effect - suggesting the pixelation is getting written to the hard drive (though maybe the recorded data itself causes the TiVo to have problems the same way each time?). I even tried saving the live TV to the hard drive & rebooting, but the pixelation still happens in the same spot.
    2. Pixelation while watching recordings (but resolved with a reboot) - I tried to watch a suggested recording of South Park last night but it was unbearable. However, when I unplugged the machine and rebooted, the recording played fine.
    3. Pixelation in the menus - I've seen this happen a few times.
    I'm very concerned. What's going on? Issue #1 seems to suggest there's a problem with my cable signal - but issue #2 & 3 suggest a problem with the TiVo itself.

    I'm glad to hear TiVo is working on a patch for SA Cablecard users, but that (I presume) won't help me, especially with issue #2 & 3. Any suggestions on what to do? If this can't get resolved by my 30 day window, I'll be returning it, unfortunately.

    I'm a first-time TiVo user, and this has been a poor and frustrating experience.
     
  17. Sep 1, 2007 #217 of 1597
    Brian-1337

    Brian-1337 New Member

    18
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    Aug 19, 2007
    Oh, also, I had an issue a few days ago where I couldn't watch a Live TV channel at all. I tried to tune in Last Comic Standing (in digital / HD), and it would show a second or two of video & audio, but then freeze the image and cut out the audio. Any other channel seemed to work all right.

    Rebooting fixed the issue.

    I hope someone can help - this is very frustrating.
     
  18. Sep 1, 2007 #218 of 1597
    jfh3

    jfh3 New Member

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    Apr 15, 2004
    Denver area
    Don't quite understand the logic here - obviously Tivo can't extend the return policy for another company, but I see NO reason why they can't extend the WARRANTY on the box itself, since they are the ones that honor the warranty, not the vendor.
     
  19. Sep 1, 2007 #219 of 1597
    richsadams

    richsadams Active Member

    8,893
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    Jan 4, 2003
    Sorry to hear that you're having such frustrating problems. When you buy a new CE piece of equipment you should expect to have a great out-of-box experience. :( As a long-time TiVo user I’ve run into the odd glitch, but TiVo has always been able to tidy things up pretty quickly. I’m sure they will be able to get these bugs straightened out as well. We’re planning on replacing our S2’s with TiVo HD’s pretty soon…so they’d better! ;)

    I'd say that all of your woes could be attributed to the ongoing signal/cable card/software issues being discussed...except for #3 (and the bit in #2 where rebooting will temporarily clear things up as well as the part about not being able to watch live TV at one point) which is more worrisome. If you're experiencing macroblocking (or any trouble for that matter) with your menus there may be more to it. Those kinds of problems are generally found in a defective or dieing hard drive.

    I would call TiVo support, have them open a case and explain that part of the issue clearly. IMHO it's a good candidate for a replacement.
     
  20. Sep 2, 2007 #220 of 1597
    Brian-1337

    Brian-1337 New Member

    18
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    Aug 19, 2007
    Thanks - I'll give it a shot. I'm skeptical about whether it's hardware related (given that reboots fix much of it) but I'll try talking with them.
     

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