TiVo Community
TiVo Community
TiVo Community
Go Back   TiVo Community > Main TiVo Forums > TiVo Series3 HDTV DVRs
TiVo Community
Reply
Forum Jump
 
Thread Tools
Old 11-19-2007, 12:38 PM   #1
AbMagFab
What happened, TiVo?
 
AbMagFab's Avatar
 
Join Date: Feb 2001
Posts: 3,638
FIOS TV pixellation fix - attenuate to SNR 31

Since I was the first person to post this, and we've since seen this fix nearly everyone who has tried it, I'd like to recommend we sticky this?

Problem: Pixellation with FIOS TV, usually on a fixed set of channels at a time (often one or two frequencies), but the channel "block" can also sometimes move after a while.

Why: Since FIOS TV goes from fiber to coax right at your house, there is virtually no signal loss from the source. This means you can have a signal as hot as 10-15db. While this is "within specifications", it appears that it's too hot for the Tivo (more likely, there are other factors that trigger this issue as well, but it's all related to being such a strong, hot signal).

Symptoms: Other than the obvious pixellation, the most notable objective symptoms are in the Diagnostics screen. Most notably, the "RS Uncorrected" count will skyrocket when on a bad channel. Sometimes it will start at 0 and stay there for a few minutes, but once it gets hit, it just shoots through the roof (like 100's of thousands). RS Corrected will also count up, but that's not really an issue by itself. If you change channels (off the frequency) and then change back, it might stick at 0 for a few minutes, then it will skyrocket again. Sometimes, it's time of day related, where it will be fine at noon, but at 4pm it's skyrocketing again. Often you won't see any problem on the cable box, cable DVR, or TV w/cable card, even at the same time on the same channel.

Potential fix: It seems that the Tivo tuners are more sensitive than the cable box tuners and even TV tuners with cable cards. While SNR by itself, technically, isn't a fix, it's the best indicator for a fix. On the diagnostics screen, you want to look at the SNR number (not the cable card ones, the tuner ones). Usually this will be in the high 30's. For FIOS TV and Tivo HD/S3, the "magic SNR number" appears to be 31. So you want to attenuate your signal down so that the SNR is 31. Even at 32/33, the pixellation will continue. While you will see your signal strength drop, as long as it stays above ~45, you should be fine.

Where to buy: You can buy in-line attentuators from a number of places, just do a google search. They are about $2/each, or less in bulk (10 or more). I suggest you get a mixed bag, like a few each of 10db, 6db, and 3db to give you some flexibility in how much you attenuate the signal at each Tivo.

Installation: Just plug in line, in the coax (they screw in to the coax end). You can do this right before the Tivo (best for testing this fix), or you can do it at the source, and then tweak a little bit at each Tivo (install one more if needed, since cable lengths can cause variable attenuation).

Non-FIOS problems: While this might work for people without FIOS, it's less likely since this is due to too strong a signal. Most pixellation (IMO) other than this are due to any number of factors, including too weak a signal, dirty hubs between you and the CO, and a bad source signal.


That's it. This has fixed a dozen or so people since I've posted it and been tracking it, so I think we can officially say this is a fix for at least a good number of people who have tried it.
__________________
Tivo since '99, DirecTV since '96, Comcast since '06, FiOS TV '07!

Multiple S3s, HDs, HDXLs, Premieres - all looking like relics now
TiVo is on it's way out -
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
!
AbMagFab is offline   Reply With Quote
Old 11-19-2007, 12:59 PM   #2
bkdtv
Registered User
 
Join Date: Jan 2003
Location: DC Metro Area
Posts: 7,902
Repost...

Steps to Fix
  1. Order a pack of attenuators. These screw on to the end of the coax.

    http://www.smarthome.com/7800.html

    Verizon issues these same attenuators to installers, but most do not know to use them for TiVos.

  2. Find a channel with pixelization.

  3. Once you've found a channel with pixelization, open Settings -> System Information -> Diagnostics. With this screen, you can monitor your SNR and number of RS Corrected and RS Uncorrected errors.

    Your goal is to eliminate the RS Uncorrected errors and the fluctuation in the SNR. A few occasional RS Corrected errors are fine; it is the RS Uncorrected Errors that indicate pixelization.

  4. Disconnect the coax cable from the TiVo.

    Note the process of disconnecting and reconnecting the coax will result in a lot of RS Uncorrected and RS Corrected errors, but don't worry about that. Only worry about errors that increment after the cable is firmly connected.

  5. Most seem to require -10dB to -16dB of new attenuation. A few require as much as -20dB. I would start with -20dB and work your way down.

    Screw one -20dB attenuator onto the end of the coax cable. Then reconnect the coax back to the TiVo.

  6. Is the problem fixed? Wait 60 seconds. Have the RS Uncorrected errors stopped incrementing on the Diagnostics screen?

  7. If not, or you aren't getting a picture, disconnect the coax again and repeat using one -10dB attenuator and one -6dB attenuator.

    Is the problem fixed? Wait 60 seconds. Have the RS Uncorrected errors stopped incrementing on the Diagnostics screen?

  8. If not, disconnect the coax again and repeat using one -10dB attenuator and one -2dB attenuator.

    Is the problem fixed? Wait 60 seconds. Have the RS Uncorrected errors stopped incrementing on the Diagnostics screen?

  9. If not, disconnect the coax again and repeat using a single -10dB attenuator.

    Is the problem fixed? Wait 60 seconds. Have the RS Uncorrected errors stopped incrementing on the Diagnostics screen?

  10. If not, disconnect the coax again and repeat using a single -6dB attenuator.

  11. By now, the problem should be fixed.

You may want to check a random channel in each QAM block to confirm the problem is eliminated on all channels. I would suggest you test the channels below:
  • one local SD channel (ex: NBC)
  • one local HD channel (ex: CBS-HD)
  • one national SD channel (ex: USA)
  • one national HD channel in the lower QAM block (ex: FOOD-HD or HGTV)
  • one national HD channel in the QAM block (ex: MHD or SHO-HD).
If you ever see stutter on the Tivo that is not accompanied by RS Uncorrected errors on the Diagnostics screen, that can be fixed with a Settings -> Reboot. I've had the studder issue occur twice since July and a reboot fixed it each time. This issue should be eliminated completely with the next Tivo software update.

Last edited by bkdtv : 12-16-2007 at 06:35 AM.
bkdtv is offline   Reply With Quote
Old 12-05-2007, 11:41 PM   #3
JonHB
Registered User
 
Join Date: Aug 2007
Posts: 69
Add me to the list of people that have fixed this problem by using an attenuator.

I came home tonight and turned on the TV and the channel currently on (KTLADT/805) was severely pixelated. Ahh, perfect opportunity to work on this. Good thing I ordered those attenuators a couple of weeks ago!

I put on a -10 dB and it brought my signal to -31dB. RS uncorrected stopped dead in its tracks! Whoo hoo!!

Follow the instructions given in the first 2 posts of this thread and you will fix your problem completely.

Thank you AbMagFab & bkdtv for documenting this so well.
JonHB is offline   Reply With Quote
Old 12-06-2007, 01:57 PM   #4
litkaj
Registered User
 
Join Date: Jun 2007
Location: Exton, PA
Posts: 257
You've got to be careful with this as it's very possible when working top-down that you've fixed a few channels and broken others. Make sure that you check one channel from each frequency.
__________________
Jason Litka

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
litkaj is offline   Reply With Quote
Old 12-06-2007, 02:03 PM   #5
rlawson4
Registered User
 
Join Date: Nov 2007
Location: Atlanta, Georgia
Posts: 25
Where do you buy and ATTENUATOR? Do you have a model # so I can see if Amazon has one.
rlawson4 is offline   Reply With Quote
Old 12-06-2007, 02:46 PM   #6
bkdtv
Registered User
 
Join Date: Jan 2003
Location: DC Metro Area
Posts: 7,902
Quote:
Originally Posted by rlawson4 View Post
Where do you buy and ATTENUATOR? Do you have a model # so I can see if Amazon has one.
Instructions and order details are in the second post.

http://www.smarthome.com/7800.html
bkdtv is offline   Reply With Quote
Old 12-06-2007, 02:47 PM   #7
rlawson4
Registered User
 
Join Date: Nov 2007
Location: Atlanta, Georgia
Posts: 25
Thank. Much appreciated.
rlawson4 is offline   Reply With Quote
Old 12-07-2007, 09:04 AM   #8
joysbox
Happy Happy Joy Joy
 
Join Date: Jun 2003
Location: Leesburg, VA
Posts: 157
grrr, want to try this, but I only have problems in PLAYBACK mode, I haven't seen any pixilation in live tv. I only really get to see tv about 2 hours a day at best. Any suggestions?
j
__________________
joysbox!
series 2 80 hr lifetime
series 2 DT 80 hr lifetime
series 2 80 hr Humax DTR-800 monthly
Series 3 cable card with lifetime

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
joysbox is offline   Reply With Quote
Old 12-07-2007, 03:10 PM   #9
richsadams
Registered User
 
Join Date: Jan 2003
Posts: 8,853
Nice work AbMagFab and bkdtv. FIOS is coming to our neighborhood soon (buh-bye Comcast). Hopefully things will be fine, but your info will be a good addition to my toolbox in case something comes up.
richsadams is offline   Reply With Quote
Old 12-07-2007, 03:39 PM   #10
yunlin12
Tivonation Citizen
 
yunlin12's Avatar
 
Join Date: Mar 2003
Location: San Jose, CA
Posts: 1,221
Not sure if it applies for FiOS, but is there a signal strength indicator anywhere in your system? I'm on Comcast with hidh speed internet, and if I go to http://192.168.100.1/, I can see a web page served by the cable modem reporting these statistics. Mine says about 34 SNR, and an inbound signal strength of 12dBmV. My electrical engineer gut feeling is that both the signal strength and the SNR need to be tuned correctly to make the receiver work right. I think of the signal strength as a DC signal, and SNR as the AC signal. But without knowing the industry definition for these measurements, it's hard to say what's best.

Here's a link to AVS post about using cable modem to see signal strength info:
http://www.avsforum.com/avs-vb/showt...7#post12405367
__________________
ReplayTV 3000 (RIP)
Hughes HDVR2 DTivo (adopted by friend)
Tivo S2 Dual Tuner (Craiglisted)
Tivo S3 750GB (decommissioned)
Tivo HD 750GB (adopted by parents)
Tivo Premiere
Tivo Premiere XL
yunlin12 is offline   Reply With Quote
Old 12-07-2007, 03:50 PM   #11
bkdtv
Registered User
 
Join Date: Jan 2003
Location: DC Metro Area
Posts: 7,902
The TiVo or Motorola DVR is the only signal strength indicator.

Verizon FiOS does not use modems. Fiber connects to the box on the side of your house (or in your basement), and from there you have ethernet output.
bkdtv is offline   Reply With Quote
Old 12-08-2007, 11:04 PM   #12
evlg
Registered User
 
Join Date: Jun 2002
Location: Dallas, TX
Posts: 24
Quote:
Originally Posted by litkaj View Post
You've got to be careful with this as it's very possible when working top-down that you've fixed a few channels and broken others. Make sure that you check one channel from each frequency.
How do I know which channels are on a frequency? How many frequencies do I have? Do I just have to try every single channel on the TiVo?
evlg is offline   Reply With Quote
Old 12-08-2007, 11:29 PM   #13
bkdtv
Registered User
 
Join Date: Jan 2003
Location: DC Metro Area
Posts: 7,902
Quote:
Originally Posted by evlg View Post
How do I know which channels are on a frequency? How many frequencies do I have? Do I just have to try every single channel on the TiVo?
The channels are grouped together as follows:

National SD channels
Local SD channels
Local HD channels
National HD channels - low (ex: Food HD, HGTV)
National HD channels - high (ex: MHD, SHO-HD)

You can check a few channels from each group.
bkdtv is offline   Reply With Quote
Old 12-09-2007, 08:03 AM   #14
AbMagFab
What happened, TiVo?
 
AbMagFab's Avatar
 
Join Date: Feb 2001
Posts: 3,638
Quote:
Originally Posted by bkdtv View Post
The channels are grouped together as follows:

National SD channels
Local SD channels
Local HD channels
National HD channels - low (ex: Food HD, HGTV)
National HD channels - high (ex: MHD, SHO-HD)

You can check a few channels from each group.
Not really. The channels are grouped about 10 per frequency (SD) and 2 per frequency (HD).

You can see the frequency of the channel on each card on the diagnostics screen.
__________________
Tivo since '99, DirecTV since '96, Comcast since '06, FiOS TV '07!

Multiple S3s, HDs, HDXLs, Premieres - all looking like relics now
TiVo is on it's way out -
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
!
AbMagFab is offline   Reply With Quote
Old 12-09-2007, 08:04 AM   #15
AbMagFab
What happened, TiVo?
 
AbMagFab's Avatar
 
Join Date: Feb 2001
Posts: 3,638
Quote:
Originally Posted by litkaj View Post
You've got to be careful with this as it's very possible when working top-down that you've fixed a few channels and broken others. Make sure that you check one channel from each frequency.
No you don't. I wish you "theory" folks would stay in your own threads.

If this appears to fix the problem for you (as described quite dramatically by people in this thread), then it's fixed. The problem doesn't move around because of the attenuation.

Stop spreading FUD, please.
__________________
Tivo since '99, DirecTV since '96, Comcast since '06, FiOS TV '07!

Multiple S3s, HDs, HDXLs, Premieres - all looking like relics now
TiVo is on it's way out -
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
!
AbMagFab is offline   Reply With Quote
Old 12-09-2007, 08:05 AM   #16
AbMagFab
What happened, TiVo?
 
AbMagFab's Avatar
 
Join Date: Feb 2001
Posts: 3,638
Quote:
Originally Posted by evlg View Post
How do I know which channels are on a frequency? How many frequencies do I have? Do I just have to try every single channel on the TiVo?
It doesn't matter. If you don't notice the problem anymore, it's fixed.
__________________
Tivo since '99, DirecTV since '96, Comcast since '06, FiOS TV '07!

Multiple S3s, HDs, HDXLs, Premieres - all looking like relics now
TiVo is on it's way out -
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
!
AbMagFab is offline   Reply With Quote
Old 12-09-2007, 12:32 PM   #17
bkdtv
Registered User
 
Join Date: Jan 2003
Location: DC Metro Area
Posts: 7,902
Quote:
Originally Posted by AbMagFab View Post
Not really. The channels are grouped about 10 per frequency (SD) and 2 per frequency (HD).

You can see the frequency of the channel on each card on the diagnostics screen.
I think you misinterpreted my comment. There isn't likely to be much difference between two adjacent QAM channels, so my suggestion was to check a handful of channels from different blocks. Verizon groups channels in QAM blocks as I indicated above.

If you were going to check one channel from each block after installing an attenuator, you might check for pixelization (or RS Uncorrected errors) on USA, your local NBC (SD), your local CBS (HD), FOOD-HD, and SHOHD or MHD.
bkdtv is offline   Reply With Quote
Old 12-10-2007, 10:45 PM   #18
jmr50
Registered User
 
Join Date: Dec 2003
Posts: 46
In spite of flushing $50 on AbMagFab's last suggestion for macroblocking problems (the ill-advised just-amp-it idea), I decided to give this one a try, because some of the measurements I'd collected suggested we were overdriving the TiVo. And, thankfully, it actually does seem to have helped the problem - 16dB of attenuation has worked great for 2 weeks now, and still going strong, with no side effects on any channels. If you're sitting on the fence, I can give a resoundingly positive vote. And, it was a cheap fix, too.
jmr50 is offline   Reply With Quote
Old 12-10-2007, 11:50 PM   #19
AbMagFab
What happened, TiVo?
 
AbMagFab's Avatar
 
Join Date: Feb 2001
Posts: 3,638
Quote:
Originally Posted by jmr50 View Post
In spite of flushing $50 on AbMagFab's last suggestion for macroblocking problems (the ill-advised just-amp-it idea), I decided to give this one a try, because some of the measurements I'd collected suggested we were overdriving the TiVo. And, thankfully, it actually does seem to have helped the problem - 16dB of attenuation has worked great for 2 weeks now, and still going strong, with no side effects on any channels. If you're sitting on the fence, I can give a resoundingly positive vote. And, it was a cheap fix, too.
Nice to see you just throw money at problems without thinking. Glad to help.

Did you consider doing some problem solving yourself? Naw, that's too gosh darn complicated for you country-folk.

For what it's worth - amping is a solution for some problems, and attenuation is a solution for other problems. Amazing!
__________________
Tivo since '99, DirecTV since '96, Comcast since '06, FiOS TV '07!

Multiple S3s, HDs, HDXLs, Premieres - all looking like relics now
TiVo is on it's way out -
To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
!
AbMagFab is offline   Reply With Quote
Old 12-11-2007, 11:05 AM   #20
FiosUser
Registered User
 
Join Date: Nov 2007
Posts: 100
I have fixed my Fios + Tivo Series 3 pixelation problem this way.

I added two 3 and one 8 attenuators to the back of my Tivo. Problem solved. (I had pixelation on TNT and TBS).
FiosUser is offline   Reply With Quote
Old 12-11-2007, 11:24 AM   #21
dgbretz
Registered User
 
Join Date: Jun 2007
Posts: 17
Does it make any sense to have pixelation without any RS Uncorrected Errors? I have seen pixelation and then checked the diagnostics and not seen any errors.

I plan to try the attenuators to get to the 'right' SNR anyways but would like to understand why I don't see errors reported.
dgbretz is offline   Reply With Quote
Old 12-11-2007, 09:16 PM   #22
litkaj
Registered User
 
Join Date: Jun 2007
Location: Exton, PA
Posts: 257
Quote:
Originally Posted by AbMagFab View Post
No you don't. I wish you "theory" folks would stay in your own threads.

If this appears to fix the problem for you (as described quite dramatically by people in this thread), then it's fixed. The problem doesn't move around because of the attenuation.

Stop spreading FUD, please.
Yes, you do. It's not "theory" and it's certainly not FUD. The original problem is not moving; the new problem is occurring because certain channels are now too weak to tune properly. I know this can happen as it happened to me two months ago.

I started getting some breakups and pixelation on 459MHz through 477MHz (digital versions of 1-49 and all of the Music Choice channels). When running a cable directly to the ONT didn't help I figured the signal might have been too strong.

I broke out the collection of attenuators I had the install tech leave me when the CableCARDs were first "installed" and went to work. 459-477 cleared up with anywhere between 15-20dB of attenuation. However, at anything more than 17dB the channels in the low 700's started flaking out. I backed off to -16dB and now everything is fine.
__________________
Jason Litka

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
litkaj is offline   Reply With Quote
Old 12-24-2007, 01:10 PM   #23
sflippen
Registered User
 
Join Date: Mar 2003
Location: Newport News, VA
Posts: 6
Worked for me!


I just began having severe pixelation problems three months after installation. I was not aware of this suggestion on the forum. I thought that based on a varying signal strength (TiVo-provided) from 70-90% and sometimes all the way to 0 (lost lock), I was looking at a bad cable or a problem with incoming signal. The VZ HD STB worked fine, which was mildly frustrating when reporting the problem.
I insisted it was not a "TiVo" problem and requested a tech dispatch to check signal levels. She was proud to show me the results which were, "Excellent"!
Fortunately, there was a video SME, Sean, at the VZ Hampton FSC that was aware of the issue and advised to install the attenuator. The problem is solved!
sflippen is offline   Reply With Quote
Old 12-26-2007, 11:03 PM   #24
vfrjim
Registered User
 
Join Date: Dec 2007
Posts: 28
Thanks for the fix, I had an adjustable Attenuator from Radio Shack hanging around, I attached it and adjusted it till it said 31 db(down from 38 db) and no more pixelization on my Tivo with Fios.
vfrjim is offline   Reply With Quote
Old 12-27-2007, 01:45 AM   #25
richsadams
Registered User
 
Join Date: Jan 2003
Posts: 8,853
Quote:
Originally Posted by vfrjim View Post
Thanks for the fix, I had an adjustable Attenuator from Radio Shack hanging around, I attached it and adjusted it till it said 31 db(down from 38 db) and no more pixelization on my Tivo with Fios.
Thanks for the update and welcome to the forum.

I don't have any real macroblocking problems, but I have one of these and wondered if it is the same thing you're using JIC.


richsadams is offline   Reply With Quote
Old 12-27-2007, 07:20 PM   #26
vfrjim
Registered User
 
Join Date: Dec 2007
Posts: 28
Quote:
Originally Posted by richsadams View Post
Thanks for the update and welcome to the forum.

I don't have any real macroblocking problems, but I have one of these and wondered if it is the same thing you're using JIC.

looks like it but mine is black in color
vfrjim is offline   Reply With Quote
Old 12-29-2007, 11:26 AM   #27
litkaj
Registered User
 
Join Date: Jun 2007
Location: Exton, PA
Posts: 257
I've been looking for one of those for a while. Anyone know where to get one? Radio Shack doesn't sell them any more.
__________________
Jason Litka

To view links or images in signatures your post count must be 10 or greater. You currently have 0 posts.
litkaj is offline   Reply With Quote
Old 12-29-2007, 11:49 AM   #28
richsadams
Registered User
 
Join Date: Jan 2003
Posts: 8,853
Quote:
Originally Posted by litkaj View Post
I've been looking for one of those for a while. Anyone know where to get one? Radio Shack doesn't sell them any more.
When the OP mentioned the device it reminded me that I had something like it that I actually purchased years ago to address a red-push issue I had with a Mitsubishi RP TV I used to have. (It didn't really help.) For whatever reason I kept it in my box of electronic "stuff".

I don't have FIOS () but I do have a very strong signal (35db - 37db) from Comcast and get some macroblocking on a couple of HD channels (NBC in particular). I thought about attenuating the incoming signal to see if it would make any difference and vfrjim's post peaked my interest.

I doubt that this little device will help much...it's pretty cheaply made and not very precise. I suspect that usng dedicated attenuators as others have suggested is the way to go but it might give me an indication if making some adjustments will work. I'll report back once I've given it a try.

I thought that RS might still be selling them based on a similar post from a few months ago.
richsadams is offline   Reply With Quote
Old 12-29-2007, 04:24 PM   #29
bizzy
Registered User
 
Join Date: Jan 2004
Location: San Francisco, CA
Posts: 707
Wow, I thought I was probably the last person in the world using a mitsu rptv

Are you still waiting for your "Promise" Module?
bizzy is offline   Reply With Quote
Old 12-29-2007, 10:22 PM   #30
richsadams
Registered User
 
Join Date: Jan 2003
Posts: 8,853
Quote:
Originally Posted by bizzy View Post
Wow, I thought I was probably the last person in the world using a mitsu rptv

Are you still waiting for your "Promise" Module?
Ha! Good one! I just wish I had kept it now...it was "HD Ready" after all.
richsadams is offline   Reply With Quote
Reply
Forum Jump




Thread Tools


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Advertisements

TiVo Community
Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
vBulletin Skins by: Relivo Media

(C) 2013 Magenium Solutions - All Rights Reserved. No information may be posted elsewhere without written permission.
TiVoŽ is a registered trademark of TiVo Inc. This site is not owned or operated by TiVo Inc.
All times are GMT -5. The time now is 10:02 PM.
OUR NETWORK: MyOpenRouter | TechLore | SansaCommunity | RoboCommunity | MediaSmart Home | Explore3DTV | Dijit Community | DVR Playground |