SNR levels

Discussion in 'TiVo Premiere DVRs' started by Dr_Diablo, Feb 17, 2012.

  1. Dr_Diablo

    Dr_Diablo Dr_Diablo

    916
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    Nov 23, 2003
    Midwest

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    Yesterday while on the phone with a Tivo Techie she notived that the SNR level was too high.... 37db...

    While Brighthouse was at my home to address the issues of loss of signals, over 60% channels are dropped, they claim that if the SNR drops any lower it will affect the broadband response... currently at 60 mb downstream...

    The Tivo tech suggested a filter bge plced inline with my cable but the BH folks refused to do so....

    Any suggestions on how to get that SNR nearer to 30db or lower?
     
  2. ghuido

    ghuido New Member

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    May 8, 2007
    Most people report that an SNR Level of 36 is the sweet spot so 37 causing trouble seems to be an odd excuse.

    Take a look at this thread. You can buy some Atteneators to lower your SNR.

    http://www.tivocommunity.com/tivo-vb/showthread.php?t=483157

    What is your Channel Signal Strength at ? Usually in the 80-90% range is the sweet spot. On old TIVO HD 100% used to cause Hot signal problems.

    HAven't heard the same issue with the TIVO Premiere.

    My elite hasn't shown any problems on 36 SNR on Comcast.
     
  3. joblo

    joblo Member

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    Jun 5, 2002
    SNR, which stands for signal-to-noise ratio, cannot be "too high".

    The very idea is nonsensical.
     
  4. MeInDallas

    MeInDallas Member

    924
    4
    Jul 31, 2011
    Dallas, Texas
    Tell the people at Tivo this. They seem to be stuck on this when having signal issues with the Elite.

    "Oh the SNR is too high, get some attentuators and bring it down some and the issues should go away"

    I cant tell you how many times I heard that one :rolleyes:
     
  5. drewdog

    drewdog Member

    64
    1
    Feb 3, 2007

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    What they said, this is nonsense on so many levels. I've been on the phone with tivo (as a technician myself) arguing about this so many times. Attenuating the signal to correct these problems is like taking your car in for an oil change because it needs new tires.
     
  6. turbobozz

    turbobozz New Member

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    Sep 21, 2006
    MD/VA
    I'd guess the TiVo tech was misapplying the SNR info from FiOS issues to your Brighthouse issues.

    Read the first post of this thread...
    http://www.tivocommunity.com/tivo-vb/showthread.php?t=375011

    I've only ever heard of "SNR too high" being an indicator of FiOS ONT's putting out too strong of a signal.
    It was a severely common problem with FiOS and TiVo (and I'm sure both have it well documented internally).
    It might be a problem with other providers, but I haven't particularly noticed a slew of complaints from others.

    The general consensus from backseat drivers here and on other forums was that SNR was merely the indicator of a problem, not the actual cause.
    The actual cause was said to be that the signal was "too hot".
    I'm assuming that means the amplitude of the modulated signal was too high and caused clipping/range/fringe problems with the ADC in the TiVo.
     
  7. gteague

    gteague golftango

    528
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    Apr 1, 2007
    dfw (euless)
    +1+

    in every area i'm familiar with, that's my opinion as well. the number goes up if the difference between the signal (the good stuff) and the noise (the bad stuff) increases. this is generally regarded as a good thing (at least, in the radio world) as shown by this diagram:

    [​IMG]

    here is a snippet from a cable modem troubleshooting page. notice that there are no caveats regarding snr above 30db, the opposite, in fact:

    Downstream SNR: should be 30 dB or higher: the higher the better. As the SNR decreases below 30 dB, performance will steadily decrease, and errors will increase. The cable modem might stop working properly if the SNR drops below 23.5 dB.​

    but the tivo support page seems to indicate that their equipment has problems above a maximum snr, for example, with a qam 256 channel (whatever the heck that is):

    QAM 256
    Minimum SNR 29 dB
    Maximum SNR 35 dB​
    A higher SNR reading means that the video signal is stronger relative to the noise level on the line. ​

    why anyone would even design (or could design, for that matter!) a receiver that even has a maximum snr limit (note that having a maximum signal level limit is very common indeed, but signal level is not snr, as i hope i've conveyed here) is beyond my comprehension and i've been in radio communications for over 40 years, but i will admit to knowing next-to-nothing about cable tv, (as opposed to coax cable, which i do know a little about) as evidence by my nearly 3-month ordeal to get the elite working with a cable card--right now i like very little indeed about cable tv.

    [later note]: when i was researching this post, i came across the following:


    a signal level of -53 dBm measured near an access point and typical noise level of -90 dBm yields a SNR of 37 dB, a healthy value for wireless LANs.

    yes, you read right. this guy <http://www.wireless-nets.com/resources/tutorials/define_SNR_values.html> is saying that 37db is a good snr for a wireless network. how can it be possible that a tivo only has 37db snr through a coax cable? to have that much loss, the distances involved (cable run) must be astronomical.

    /guy (73 de kg5vt)
     
  8. drewdog

    drewdog Member

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    Feb 3, 2007
    I'm sure that this has been discussed in other threads and I don't really feel the need to get too technical. But, The whole thing frustrates me so much.

    In regards to ANY of your cable providers: The Tivo is NO different than any of their own provided digital equipment. It is a digital receiver. In my system we have standards that are required to deliver quality service. RX/TX power, Minimum MER and BER, etc. The list goes on and on. We're a QAM 256 cable system, which means that our digital video is more "fussy" than data.

    I say all this to make one point, If they can make a digital box work in your house, they can make a Tivo work. The cable card needs the RX and the tuning adapter needs the TX.

    I'm over simplifying things, but I think that these cable technicians freak out when they see a Tivo, like its from another planet. Now, finding someone to make the cable card work properly with the billing system. That is a problem that I experience quite often.

    With regard to SNR. If you have high speed data or voip, and you have real SNR problems, I promise you will experience issues with your phone and internet before you see it on your Tivo.

    Sorry if this has all been said before, or if some of you savvy forum members don't like the details I left out, but I woke up on the wrong side of the bed and felt like ranting.
     
  9. turbobozz

    turbobozz New Member

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    Sep 21, 2006
    MD/VA
    Drew, you are not paying attention...
    "SNR too high" is a simplified indicator of a specific problem... that some low level TiVo techs are probably picking up and applying incorrectly.
    The root of "SNR too high" was essentially that the TiVo was having problems handling the direct and/or indirect effects of the RF signal being boosted too strongly.
    Damping the RF signal is a relatively cheap/easy solution to test whether or not the problem really is with a too strong signal.
     
  10. aaronwt

    aaronwt UHD Addict

    23,573
    1,244
    Jan 31, 2002
    Northern...
    Yes, my SNR is typically 37 or 38 since my ONT on FiOS was replaced. No issues.
     
  11. drewdog

    drewdog Member

    64
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    Feb 3, 2007
    Here's a real life example of Tivo running with this in an incorrect way. I once had issues, which ultimately ended up being a cable card problem, where Tivo was telling me to attenuate the incoming signal due to "high snr". However, the input digital signal in db was around -3 to -6. Attenuating that signal the extent that Tivo was requesting would have CAUSED an rf problem. The "tech" on the phone insisted this would fix it. I tried to explain to him that if I knock it down any more than it is, that we'd have no signal at all, but he wasn't having it. Boosting the power (rx) of the cable doesn't have the effect on snr that Tivo seems to think it does. I'd really like to know what started this whole thing in the first place. I agree with Turbo that someone is incorrectly applying this. I just wish I knew what the legit problem was.
     
  12. compnurd

    compnurd Well-Known Member

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    Oct 6, 2011
    i am at 37 also... no issues
     
  13. BHNtechXpert

    BHNtechXpert New Member

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    Nov 7, 2011
    I apologize for any confusing information you have been given. My name is Gary and I work for Bright House Networks. Please PM me here or contact me directly via email : BHNtechXpert@mybrighthouse.com and we'll get this resolved.
     
  14. gteague

    gteague golftango

    528
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    Apr 1, 2007
    dfw (euless)
    wow! time-warner take note!

    oh, i forgot, you only sell the internet, you don't actually use it ...

    /guy
     
  15. Dr_Diablo

    Dr_Diablo Dr_Diablo

    916
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    Nov 23, 2003
    Midwest
    Bought an Atenuator at Amason, droped the SNR to 34 DB, yet still having problems with the recorded rograms either failure to record or will start to record then stop or even swictch recordings to another channel..

    In the past 40 days have replaced 3 TA an 4 cable cards, had the card re-paired to no avil...

    The source signal will funtion for a few days then will begin to lose channels 800 then the lower ones in the 700 range..

    These issues began once the TA was introduced two yrs ago.
     
  16. Soapm

    Soapm Active Member

    1,668
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    May 9, 2007
    Aurora, CO
    If it were true digital SNR wouldn't come into play since all you'd be receiving are 1 and 0. What we get is a frequency multiplexed haugpauge squeezed into a bandwidth container that can vary with simple things like what length the cable was cut. How temperamental is that???

    I really hoped fiber would be true digital but by the time it gets to your set it's back to the haugpauge. The day will come when they all get together and give us true digital so things like SNR won't matter. Come on day...
     
  17. brian1269

    brian1269 Member

    106
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    Jul 24, 2003
    Kingsport, TN
    My new Premier Elite was not recording a few shows. In the history, it said the signal was not available, or something like that. I called TiVo support and the guy had me go to the diagnostics screen and told me the SNR levels (36-37) were too high. I am also gets thousands of RS corrected and uncorrected errors. Had Charter come out and they said all the levels were good, going into the tuning adapter, coming out of it, etc. Not sure what to do now. Sometimes it can't tune channels on the first try, sometimes it takes 10 seconds or so.
     
  18. CoxInPHX

    CoxInPHX COX Communications

    2,475
    67
    Jan 14, 2011
    Phoenix, AZ
    Cisco or Motorola TA?

    SNR levels (36-37) is not the issue, they are not too high.

    Problem is either the Tuning Adapter or Signals are too low.
    Did the Charter tech tell you what your signals actually are?
    It would be good to know what the levels are in dBmV. The only way to find this out is with a meter or a Cable Co STB Diagnostic Menu.

    What range does the TiVo Signal Meter say they are?
    Signal strength of 80-100 is ideal, less than 80 on an Elite could be an issue.
     
  19. MC Hammer

    MC Hammer New Member

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    Jul 28, 2011
    My SNR is 40dB on all 3 of my boxes and I have no issues whatsoever.
     
  20. WVZR1

    WVZR1 Active Member

    995
    142
    Jul 30, 2008
    The WV...
    I've got a "home-run" drop to each of my TiVos and to each of the televisions at the same locations. With a Premiere I can record two and watch a third "live" if I like and the Elite is of course four and a live. My drops are each done with a 2 way "tap" to control signal. Each "home-run" is pretty much equal length and when I had 2 Premiers I had signal strengths of 90+ (higher 90's) on most. I never paid attention to the SNR at the time. I used the SNR at the cable-modem connected directly to the Comcast drop for calculations when doing my calculations for the "tap". The cable-modem is done from 1 leg of a "tap" and the home-runs are from a powered amplifier on the other leg of that tap. The rest of the outlets in the house are from a splitter on another leg of the amplifier. No STB's or TiVo's at those.

    Presently the Elite is 35dB and the Premiere is 36dB and the cable-modem is also at 36dB. Signal strength on the Elite 85+ the Premier 90+ (in similar broadcast frequencies). I've never had issues with dropouts.

    Home-runs with "taps" are likely over-kill but splitters "suck"! Splitters and poor cable choices I'd guess are responsible for more problems than most would think!

    I don't use the tuning adapters that Comcast introduced last summer/fall. Is this SNR signal issue something that is limited to only those using tuning adapters or all of us?
     

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