# RS Corrected and RS Uncorrected Stat on THD Diagnostic Screen



## JANNINO (Oct 28, 2004)

Does anyone know how to decipher the statistics on this screen? 

I'm having a pixelation issue on one of my THDs and in a post I saw on the Verizon Fios TV forum I was told that if the RS Corrected number is 0, then there is a problem with the Verizon signal coming in. If this number is increasing with with the pixelation, then the Tivo is causing the problem.

Can anyone provide a little more information on what the meaning of these statistics are??


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## GoHokies! (Sep 21, 2005)

Do you have a link for what you're talking about? I'd love to read up on it.

Also, (and this is only a suggestion) you may want to limit the discussions of your problems to one thread to make it easier to follow the discussions, rather than have multiple threads discussing different facets of the same problem.


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## SCSIRAID (Feb 2, 2003)

JANNINO said:


> Does anyone know how to decipher the statistics on this screen?
> 
> I'm having a pixelation issue on one of my THDs and in a post I saw on the Verizon Fios TV forum I was told that if the RS Corrected number is 0, then there is a problem with the Verizon signal coming in. If this number is increasing with with the pixelation, then the Tivo is causing the problem.
> 
> Can anyone provide a little more information on what the meaning of these statistics are??


RS stands for Reed-Solomon. They invented a mathmatical coding method which is capable of correcting errors in a bitstream. Their methods are incorporated in many digital data transmission schemes. In digital TV, its called FEC or Forward Error Correction.

The RS Corrected value tells you how many times the FEC algorithm had to be used to correct an error since the channel was tuned. The RS Uncorrected value tells you how may times the error exceeded the capability for FEC to correct it. If you are seeing RS Uncorrected values of 0 then all is good. Its normal for RS Corrected to increment but the lower the rate the better. The SNR value is also very important. QAM is designed around an SNR of 34db however YMMV. There are many factors driving overall digital transmission error rate.


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## SCSIRAID (Feb 2, 2003)

Here is an article

http://www.home.agilent.com/upload/cmc_upload/All/6C06MPEGPAPER2.pdf

http://electronicdesign.com/Articles/Index.cfm?AD=1&ArticleID=4648


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## SCSIRAID (Feb 2, 2003)

JANNINO said:


> Does anyone know how to decipher the statistics on this screen?
> 
> I'm having a pixelation issue on one of my THDs and in a post I saw on the Verizon Fios TV forum I was told that if the RS Corrected number is 0, then there is a problem with the Verizon signal coming in. If this number is increasing with with the pixelation, then the Tivo is causing the problem.
> 
> Can anyone provide a little more information on what the meaning of these statistics are??


Re-reading your post... my earlier post didnt fully answer your question.

If your RS Uncorrected value is holding at 0 and you are seeing video problems such as pixelations, then the problem is either bad data in the stream coming from the original provider (i.e. Discovery HD, TNT etc) or the Tivo is corrupting the stream somehow.

If you RS Uncorrected value is incrementing more than say 1 or 2 per hour then you most likely have a 'signal' problem.... too much, too little, too noisy, ingress, etc etc.


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## JANNINO (Oct 28, 2004)

SCSIRAID

I definately am seeing the RS Uncorrect value changing alot, almost by the second which probably means I have a bad signal coming in from Verizon. 

Thanks - now the problem I face is trying to fix that signal and replacing the coax would be difficult at best.


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## JANNINO (Oct 28, 2004)

GoHokies!

I put two separate posts so as to not ask too many questions on one post. I also am very interested in the RS values which SCSIRAID gave a great explanation for.


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## SCSIRAID (Feb 2, 2003)

JANNINO said:


> SCSIRAID
> 
> I definately am seeing the RS Uncorrect value changing alot, almost by the second which probably means I have a bad signal coming in from Verizon.
> 
> Thanks - now the problem I face is trying to fix that signal and replacing the coax would be difficult at best.


Couple questions....

1) Who is your provider? Fios? Cable?
2) Can you describe how your signal distributed... i.e. exactly what is between the source (ont or cable entring the house) and the Tivo


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## AbMagFab (Feb 5, 2001)

See multiple other threads on this issue.

For FIOS, a possible fix (it worked for me and a couple others) is to attenuate your signal down to 31/32 SNR (no more than that). Your signal strength will drop to 60/70, but that's okay.

I was getting severe pixelation within a few minutes before, and now that I've attenuated my signal down, it's been fixed for a week.

Now, I only see the RS numbers go up at the beginning of a show, which appears to be when it's changing channels, and only for a brief second or less. So on the diag screen now, I see a couple thousand corrected, and a few hundred uncorrected, but it doesn't go up after the initial channel change.

Try attentuating your signal down on one of the THD's and see if the problem goes away. I had to attenuate -11db to get to 31/32 SNR. At 33 SNR, I was still seeing the pixelation/macroblocking, so I needed to get down to 31/32.


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## JANNINO (Oct 28, 2004)

SCSIRAID

I have Verizon Fios TV. The line comes into the house from the ONT to an 8 way splitter (not sure if there is an interim stop in the house). Then there is a home run shot to every TV/router in the house (i.e. 5 TVs, and 1 PC). The coax cable to the TV having the issue is RG6 quad shielded and I installed it 4 years ago (i.e. I don't believe the issue is the cable itself).

AbMagFab

Where can you get these "attentuators" from? Radio Shack perhaps? It looks liek they come in different ranges. From what I've read, I should try to attentuate down 5-7 dbs from my 36-38 range to 31 db.


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## mazman (Nov 13, 2002)

JANNINO said:


> SCSIRAID
> 
> I definately am seeing the RS Uncorrect value changing alot, almost by the second which probably means I have a bad signal coming in from Verizon.
> 
> Thanks - now the problem I face is trying to fix that signal and replacing the coax would be difficult at best.


Is the RS Uncorrected changing on both tuners? I had an issue with only one of the tuners. After spending much time & effort trying to get a better signal, TiVo RMA'd the box for me and now things are fine.


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## SCSIRAID (Feb 2, 2003)

JANNINO said:


> SCSIRAID
> 
> I have Verizon Fios TV. The line comes into the house from the ONT to an 8 way splitter (not sure if there is an interim stop in the house). Then there is a home run shot to every TV/router in the house (i.e. 5 TVs, and 1 PC). The coax cable to the TV having the issue is RG6 quad shielded and I installed it 4 years ago (i.e. I don't believe the issue is the cable itself).
> 
> ...


Those are different 'db's'. The attenuators reduce the signal strength which should in turn reduce the SNR. Not a 1:1 relationship. The Tivo doesnt provide actual signal strength measurements (in dbmv).

Hey AMF... I recall that Fios has a hot signal but cant remember whether its +10 or +20 dbmv.... do you remember? The 8 way will drop 11db which still is very hot if the ont output is +20. Probably want an extra 10 over that. What did you end up with?


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## SCSIRAID (Feb 2, 2003)

JANNINO said:


> SCSIRAID
> 
> I have Verizon Fios TV. The line comes into the house from the ONT to an 8 way splitter (not sure if there is an interim stop in the house). Then there is a home run shot to every TV/router in the house (i.e. 5 TVs, and 1 PC). The coax cable to the TV having the issue is RG6 quad shielded and I installed it 4 years ago (i.e. I don't believe the issue is the cable itself).
> 
> ...


http://cgi.ebay.com/Brand-New-3db-A...ryZ73384QQssPageNameZWDVWQQrdZ1QQcmdZViewItem


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## litkaj (Jun 5, 2007)

SCSIRAID said:


> I recall that Fios has a hot signal but cant remember whether its +10 or +20 dbmv.... do you remember? The 8 way will drop 11db which still is very hot if the ont output is +20. Probably want an extra 10 over that. What did you end up with?


It depends on which ONT you have. I believe the older 610 was +20 or +25 and the newer 612 is supposed to be about +10.


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## SCSIRAID (Feb 2, 2003)

litkaj said:


> It depends on which ONT you have. I believe the older 610 was +20 or +25 and the newer 612 is supposed to be about +10.


+10 with an 8 way should be right on what is typically good... -1dbm.

However, +20 or +25 with an 8 way would still be hot hot hot..... too hot... by about 10 db.


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## bkdtv (Jan 9, 2003)

litkaj said:


> It depends on which ONT you have. I believe the older 610 was +20 or +25 and the newer 612 is supposed to be about +10.


The 610 and the 612 are the most widely deployed FiOS ONTs, but there are a few other less commonly deployed models, each with varying levels of output. That's one of the reasons this issue affects some customers and not others in the same local area.

FiOS customers with some ONT installations may require one or two attenuators to get a pixelization-free signal on their Tivo, while others may require none at all.


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## JANNINO (Oct 28, 2004)

AMF

Can you put on more than one attenuator to get to the level you desire (i.e. can you put a 3db and a 6 db to get 9db in total)?


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## hooper (Sep 22, 2007)

Jannino has a moca setup, which I believe assumes a 612 ONT, no? If so the signal is at +10 before the splitter and around zero after the 8-way.

Either way, it is worth having VZ out to measure the signal. Ask the tech for some attenuators even if the signal is OK. They are good to have for troubelshooting.


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## JANNINO (Oct 28, 2004)

What would be the ideal signal strength as measured by:

1) the Verizon tech?
2) the Tivo diagnostic screen?

My tivos are running around 36 to 38 dB as measured by the diagonstic screen but it appears that from prior responses I should be no lower than 31 db as measured by the diagnostic screen.


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## SCSIRAID (Feb 2, 2003)

JANNINO said:


> What would be the ideal signal strength as measured by:
> 
> 1) the Verizon tech?
> 2) the Tivo diagnostic screen?
> ...


The 36-38 is NOT a signal strength.... its a Signal to Noise Ratio. Tivo doesnt provide an actual 'measurement' but more of a 'merit figure' for signal strength.

'Ideal' signal strength is probably around 0dbmv but from what I have learned about Fios... it defies 'ideals'.

As to SNR, conventional thinking is that QAM 256 should be in the 34-35 db range. However, that doesnt seem to hold for Fios as evidenced by quite a few folks that have bad results at that level (due to reasons unknown).


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## SCSIRAID (Feb 2, 2003)

JANNINO said:


> AMF
> 
> Can you put on more than one attenuator to get to the level you desire (i.e. can you put a 3db and a 6 db to get 9db in total)?


Im not AMF.... but attenuators are additive... stack em up and add the values together.


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## keenanSR (Oct 13, 2004)

This is an interesting discussion. I've been trying to figure out the cause of some occasional pixelation with my S3. Originally I had signal strength readings in the 90's, and in fact, for some of the digital cable channels are still around that figure, but my local HD stations have gone from the 90's down to low 80's even dropping into the 70's.

After reading about the RS numbers above I checked mine.

On Tuner 2 I'm getting a fluctuating strength reading of 77-81 with an RS uncorrected number of 280 with a corrected number in the 5 million range. A SNR of 33

On Tuner 1 I'm getting a strength reading of 81 with an RS uncorrected of 0 and a corrected of 22. SNR is 33.

Based on the above I think a call to the cable company(Comcast) is in order as it looks like the signal quality is a bit too weak to drive both tuners adequately.

Any thoughts, or input?

Thanks.

<edit>

Changing channels to reset the numbers shows that one channel in particular seems to have a real problem, within 1 minute of tune, it's already at 150000 corrected errors - problem with the cable company, or a problem with the station's signal..?? This particular station is where I get most of the pixelation issues, although I do get them on the others as well.


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## SCSIRAID (Feb 2, 2003)

keenanSR said:


> This is an interesting discussion. I've been trying to figure out the cause of some occasional pixelation with my S3. Originally I had signal strength readings in the 90's, and in fact, for some of the digital cable channels are still around that figure, but my local HD stations have gone from the 90's down to low 80's even dropping into the 70's.
> 
> After reading about the RS numbers above I checked mine.
> 
> ...


Yup... sounds like the cableco could do some optimizing and improve your situation. Signal strength below 80 will quite likely be a problem. The 90's would be much better. Can you describe your wiring between where the cable enters the house and the Tivo? Splitters can easily cause the problems you describe. Poor quality cables and loose fittings can also cause it. You might try unhooking your coax cables and reconnecting them making sure to snug them up good.

For that 280 uncorrected number... how long were you tuned to that channel. There is a tune time in the diagnostic menu too. Its the rate of uncorrected that is really important.


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## keenanSR (Oct 13, 2004)

SCSIRAID said:


> Yup... sounds like the cableco could do some optimizing and improve your situation. Signal strength below 80 will quite likely be a problem. The 90's would be much better. Can you describe your wiring between where the cable enters the house and the Tivo? Splitters can easily cause the problems you describe. Poor quality cables and loose fittings can also cause it. You might try unhooking your coax cables and reconnecting them making sure to snug them up good.
> 
> For that 280 uncorrected number... how long were you tuned to that channel. There is a tune time in the diagnostic menu too. Its the rate of uncorrected that is really important.


I'm not sure how long it was tuned to that channel for the 280 number. I recorded on that channel from 9-11pm and I checked the diagnostic screen at around 12am so I'm guessing it was around 3 hrs, although that tuner may have been tuned to the channel prior to 9pm. I'll check today and time it to see what the numbers read.

The line in from the pole is a straight shot with possibly 1 joiner at the roof and then it's fed through a grounding block. From there it feeds a 1GHz splitter with one output to a Moto cable amp that feeds an HDHR digital PC tuner and an un-amped feed straight to the S3. The lines within the house are all cut to length professionally terminated. I have not done a visual inspection on the line from the grounding block back to the pole yet, but baring more rain that is something I will do today.

I tried feeding the S3 an amplified signal but it seems to make no difference and in fact decreases the signal strength. The decrease is consistent with my testing this about a year ago when I first got the S3, an amplified signal actually made the signal quality worse with lower strength readings.

I also eliminated the splitter as a test and it makes no difference, the signal strength remains consistent with the current low 80's. When first tuning the channel I can see the number start off high, say an 86-87 very briefly, but then it settles very quickly back down to the very low 80's.

As I noted, last Sept, my readings were in the low to mid 90's, and although I've been through a few software revisions with the S3 I don't believe those revisions would cause any change in the tuner signal strength readings, and in fact, I did not have the pixelation problem back then either. This has been developing over the past few months so my assumption is that something has changed at the cable end as I believe my end has remained static.

Comcast has been upgrading my area to a 1GHz system over the past few months, but I don't believe there has been any "switchover" yet on any lines/equipment that may have caused this. There has been no visible change in the channel lineup and/or announcement from Comcast that the switch to 1GHz from 550MHz has been done. The actual "change" is supposed to happen in Dec.

I'll post some timed readings later today. Meanwhile I'm going to call Comcast. My worry there is that they may test the line and say it's fine based on how well their equipment(STBs) works with the current signal, hopefully they will agree there is a problem.


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## keenanSR (Oct 13, 2004)

Okay, ran a 1 hour test and got the following readings.

For the CBS station,

Uncorrected - 0
Corrected - 11

For the NBC station,

Uncorrected - 286
Corrected - 4558107

Current readings for ABC, 4276 secs since tune start,

Uncorrected - 1433
Corrected - 141404

For NBC again, 987 secs since tune start,

Uncorrected - 39
Corrected - 5163280

S3 never was tuned to the FOX station tonight. It seems to me I definitely have a signal problem. Comcast will be here in the AM...


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## SCSIRAID (Feb 2, 2003)

keenanSR said:


> Okay, ran a 1 hour test and got the following readings.
> 
> For the CBS station,
> 
> ...


Yup.... signal problem or bad tuner.


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## keenanSR (Oct 13, 2004)

SCSIRAID said:


> Yup.... signal problem or bad tuner.


Could a tuner just go bad? That would seem like a longshot to me but I guess it's possible, the S3 has been flawless since last Sept other than this recent signal problem.


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## keenanSR (Oct 13, 2004)

Well, Comcast has been and gone and they say the signal looks good, but, he said he was going to have their in-house "TiVo whiz kid" come out on Sunday. Today's guy was complaining about CableCARDs and TiVo from the minute he got here.


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## SCSIRAID (Feb 2, 2003)

keenanSR said:


> Could a tuner just go bad? That would seem like a longshot to me but I guess it's possible, the S3 has been flawless since last Sept other than this recent signal problem.


Its possible but its more likely that its a signal problem in my opinion. You could change channels until you get the problem ones on the 'other' tuner and check the numbers there. If they are similar on both tuners then you have eliminated the tuner as a problem.


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## keenanSR (Oct 13, 2004)

SCSIRAID said:


> Its possible but its more likely that its a signal problem in my opinion. You could change channels until you get the problem ones on the 'other' tuner and check the numbers there. If they are similar on both tuners then you have eliminated the tuner as a problem.


Yes, I've been playing around with that right now.

Another indicator to me that it's a signal problem is that the recordings made from an HDHR networked tuner also exhibit some signal anomalies, while they don't manifest in exactly the same way - a pixiedust like artifact on the S3 shows up as just a brief flash on the HDHR recording, which could be due to different software encoding/decoding on the PC side - is does seem to prove that the signal is in question.


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## bkdtv (Jan 9, 2003)

keenanSR said:


> Could a tuner just go bad? That would seem like a longshot to me but I guess it's possible, the S3 has been flawless since last Sept other than this recent signal problem.


I doubt it. These are pieces of silicon. They usually either work from the start or are defective and don't work [reliably] at all.


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## keenanSR (Oct 13, 2004)

bkdtv said:


> I doubt it. These are pieces of silicon. They usually either work from the start or are defective and don't work [reliably] at all.


That's my take on it as well, it either works from the getgo or it doesn't work right at all. I've considered that one of the CCs may have gone bad, but then again, they're just a piece of silicon as well and in fact shouldn't have any impact on signal quality/level anyways.

Well, hopefully the "TiVo whiz-kid" will show up Sunday and have some ideas.


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## gthassell (Apr 22, 2003)

I've also been having severe pixelation on only one of my two tuners in the TiVo HD. While I have split the cable coming in, my S3 is perfect (same split point) and one of the two tuners on my TiVoHD is fine. The other is, well, unwatchable.

Signal strength hops all over everywhere, but only on the 2nd tuner. (68 to 93 is a typical series of jumps in a 30 second period on the same channel).

First pics show the first tuner (Tuner 0), 


















and the last pic shows the second tuner (Tuner 1).










For tuner 1, I have uncorrected RS @ about 44 million and corrected RS at about 330 million.

Ugh.


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## keenanSR (Oct 13, 2004)

I haven't received a call from Comcast today on whether their "TiVo whiz kid" is going to show up or not. Haven't noticed any problems yet today, but I've spent most of my time with Sunday Ticket. Great Minn/Dallas game.  

If he doesn't show I'll be calling back in the AM.


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## SCSIRAID (Feb 2, 2003)

gthassell said:


> I've also been having severe pixelation on only one of my two tuners in the TiVo HD. While I have split the cable coming in, my S3 is perfect (same split point) and one of the two tuners on my TiVoHD is fine. The other is, well, unwatchable.
> 
> Signal strength hops all over everywhere, but only on the 2nd tuner.  (68 to 93 is a typical series of jumps in a 30 second period on the same channel).
> 
> ...


Since your signal strength indicates 100... my recommendation would be to attenuate the signal until the 'good' tuner indicates 90's and see if that helps. You might be overloading the tuner. You could add an additional 2 way splitter to knock it down 3.5db.


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## hooper (Sep 22, 2007)

gthassell said:


> I've also been having severe pixelation on only one of my two tuners in the TiVo HD. While I have split the cable coming in, my S3 is perfect (same split point) and one of the two tuners on my TiVoHD is fine. The other is, well, unwatchable.
> 
> Signal strength hops all over everywhere, but only on the 2nd tuner. (68 to 93 is a typical series of jumps in a 30 second period on the same channel).
> 
> ...


 I had the same issue. Tivo sent me a new box and it works fine. Must have been a manufacturing issue on some boxes.


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## keenanSR (Oct 13, 2004)

hooper said:


> I had the same issue. Tivo sent me a new box and it works fine. Must have been a manufacturing issue on some boxes.


How long had you had the S3 before it starting reflecting this behavior? I've had mine for over 13 mos and probably started to notice the issue after about 10-11 mos of use.


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## hooper (Sep 22, 2007)

keenanSR said:


> How long had you had the S3 before it starting reflecting this behavior? I've had mine for over 13 mos and probably started to notice the issue after about 10-11 mos of use.


 I had mine less than a month. It was probably like this from the beginning. Only affected a handful of channels, but was 100% reproducable on those channels. Note however that this seems to only be a Tivo HD issue from what I have gathered.


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## winter (Jan 28, 2002)

gthassell said:


> I've also been having severe pixelation on only one of my two tuners in the TiVo HD. While I have split the cable coming in, my S3 is perfect (same split point) and one of the two tuners on my TiVoHD is fine. The other is, well, unwatchable.
> 
> Signal strength hops all over everywhere, but only on the 2nd tuner. (68 to 93 is a typical series of jumps in a 30 second period on the same channel).


Me too - same situation.

First tuner (tuner 0) is fine all stations, second tuner (tuner 1) has severe pixelation and wildly varying signal strength on certain stations (always the same stations). I'm using FIOS w/ 2 Motorola cable, TivoHD.

Currently on 9.1 waiting to see if 9.2 fixes the problem.


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## AbMagFab (Feb 5, 2001)

For FIOS:
- Fix seems to be to attenuate the signal so that your SNR is down to 31/32 (no more than that). Even though your signal strength drops to the 60's, it's okay.

For Comcast:
- Fix is usually to get a good signal amplifier/cleaner, like the Viewsonics 8x.

In any case, the same symptoms can result from too hot (FIOS), and too weak/dirty (Comcast) a signal.


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## hooper (Sep 22, 2007)

winter said:


> Me too - same situation.
> 
> First tuner (tuner 0) is fine all stations, second tuner (tuner 1) has severe pixelation and wildly varying signal strength on certain stations (always the same stations). I'm using FIOS w/ 2 Motorola cable, TivoHD.
> 
> Currently on 9.1 waiting to see if 9.2 fixes the problem.


 I thought it was the software (9.1) as well. However got the new box, took the old Hard drive and ran a clear and delete and starting using it in the new box. No issues at all.

When I finally got to 2nd level CS at Tivo, my explanation along with are you sure it only happens on tuner 1 issued an RMA almost immediately. Clearly they have had quite a few issue with this.

EVEN before I did the clear and delete everything, I was was able to watch live TV and noticed the problem wasn't showing itself on the new box.

Fios user w/ 2 moto CC's.


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## winter (Jan 28, 2002)

hooper said:


> I thought it was the software (9.1) as well. However got the new box, took the old Hard drive and ran a clear and delete and starting using it in the new box. No issues at all.
> 
> When I finally got to 2nd level CS at Tivo, my explanation along with are you sure it only happens on tuner 1 issued an RMA almost immediately. Clearly they have had quite a few issue with this.
> 
> ...


Thanks. I'll try attenuators and 9.2 and if its no better then I probably try to RMA it.

I'm using an upgraded (internal) hard drive, I don't know if that will cause me problems if I try to request a swap.


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## SCSIRAID (Feb 2, 2003)

winter said:


> Thanks. I'll try attenuators and 9.2 and if its no better then I probably try to RMA it.
> 
> I'm using an upgraded (internal) hard drive, I don't know if that will cause me problems if I try to request a swap.


Id switch the drive back to the stock and let it call home a couple times before requesting the RMA.


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## JANNINO (Oct 28, 2004)

OK - I had the Verizon tech out this Saturday. Here's what we found.

I have a 611 ONT which outputs at +17dB into an 8-way splitter which takes off 12.5dB leaving +4.5dB going out of the splitter. We tested the video signal into one of the TVs and found some errors in the video stream (there should be none). We traced that problem to the 8-way splitter. So we replaced it which eliminated the video errors.

We then tested the signal into the Tivos (I have 4 THDs) and the output was +3.2dB on 3 of them and 0dB on the fourth (the one with the longest distance from the 8-way splitter. I called Tivo HD support and they recommend the signal output at +3dB. 

We tested mulitple Tivo units with both tuners on local HD channels. Most of the Tivo units had pixelation issues on both channels, some only on one channel (i could not get the Tivos to have the same channel on both tuners). However, when I change one of the channels to a non-HD local channel and one on the HD local channel, the HD local sometimes came in fine with no RS uncorrected errors. I then "switched" the channels on each tuner, with one on the local HD channel and the other on the non-local HD channel. The same thing result occurred (locaL HD channel came in fine).

BTW - One of my THD has been upgraded to 9.2 and the same problem still persists. I had tuner 1 on local HD Fox channel and tuner 2 on local HD ABC channel. Both pixelated. Yesterday, I have one tuner to local non HD and the other tuner to local HD FOX (watched the Giants game) and no pixelation occured.

I am still at a loss. I believe the issue is not Verizon related as the signal is coming in clean with no video errors and at the Tivo signal spec (+3.0dB). Unless there is an issue with some of the Cable Cards (which I do not believe is the problem) I have to surmise the issue is Tivo related.

Anyone have any thoughts on this?? I also thought the issue might be bad tuners on the THDs but I have 4 of them and all exhibit the same behavior so I think its very unlikely the tuners are bad on all 4.


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## SCSIRAID (Feb 2, 2003)

JANNINO said:


> OK - I had the Verizon tech out this Saturday. Here's what we found.
> 
> I have a 611 ONT which outputs at +17dB into an 8-way splitter which takes off 12.5dB leaving +4.5dB going out of the splitter. We tested the video signal into one of the TVs and found some errors in the video stream (there should be none). We traced that problem to the 8-way splitter. So we replaced it which eliminated the video errors.
> 
> ...


What does the Tivo indicate as signal strength and SNR on good and 'bad' tuners?


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## AbMagFab (Feb 5, 2001)

JANNINO said:


> AbMagFab
> 
> Where can you get these "attentuators" from? Radio Shack perhaps? It looks liek they come in different ranges. From what I've read, I should try to attentuate down 5-7 dbs from my 36-38 range to 31 db.


I got mine from www smarthome com, here:
http://www.smarthome.com/_/nav.aspx?Ntt=attenuator&pp=24

I bought 10 -3db, 10 -6db, and a couple -10db just for the heck of it. So far, I've put a -10db on the THD's, and -3db's on the S3's (although they didn't really need it, I decided to tone it down anyway).


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## AbMagFab (Feb 5, 2001)

JANNINO said:


> OK - I had the Verizon tech out this Saturday. Here's what we found.
> 
> I have a 611 ONT which outputs at +17dB into an 8-way splitter which takes off 12.5dB leaving +4.5dB going out of the splitter. We tested the video signal into one of the TVs and found some errors in the video stream (there should be none). We traced that problem to the 8-way splitter. So we replaced it which eliminated the video errors.
> 
> ...


Again, the magic number wih FIOS seems to be around SNR, not signal strength. What is your SNR overall, and on the problem channels? If you attenuate it down so the SNR is 31/32, I'll bet your problems go away. Ignore the signal strength (which will drop to the 60's).

(This has already worked for at least 3 people, so you might want to give it a try.)


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## JANNINO (Oct 28, 2004)

Just to give some specs:

My provider is Verizon Fios in northern NJ. I have 2 motorola S-CableCARDS in each THD.

I currently have one of my THD on a local HD ABC station using TUNER 2.
- Signal strength varies all over the place (mostly in the 75-100% range but at times drops does to 46%). 
- SNR also varies but mostly between 32-35dB but sometimes drops to 29dB. 
- There are RS uncorrected values of 58000 in a 3 minute time frame. 
- Clearly there is a ton of pixelation.

While TUNER 2 is on the local HD station, TUNER 1 is on a non HD channel
- Signal strength is steady at 100%.
- SNR steady at 37dB.
- RS Uncorrected value is 0 in a 4 hour time frame
- No pixelation occurring at all.



Now I am going to "switch" the channels on tuner 1 and 2.

TUNER 1 is on local HD channel (same as used above: 807)
- Signal strength vaies between 31-34dB
- SNR all over the place from 81-93% with drops to 46%
- RS Uncorrected value is now 35500 with a 3 minute time frame

TUNER 2 is on non HD channel
-Signal strength is 100%
-SNR is 37dB
- RS Uncorrected value is 245 in a 3 minute time frame
- No apparant picxelation even with the 245 RS Uncorrected value which has remained the same for the last minute.


I have no clue what is going on.

As you can see from above, I can switch tuners but for some reason the local HD channels come in with pixelation evern when I switch tuners. 

Can this somehow be a signal issue with Verizon with only the local HD channels or could this perhaps be a Tivo issue?

My next move will be to try and attenuate the signal, but I briefly tried this before and the pixelation got worse.

I am open to any suggestion at this point.


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## SCSIRAID (Feb 2, 2003)

JANNINO said:


> Just to give some specs:
> 
> My provider is Verizon Fios in northern NJ. I have 2 motorola S-CableCARDS in each THD.
> 
> ...


With signal strength at 100% you could be overloading the tuner. Note that different tuners may have slightly different characteristics. My recommendation is the same as AMF's..... attenuate!  I would start with 6db and see what happens. If you dont have attenuators, try inserting a 4way splitter at the tivo. That will take it down 7db.

It may not make 'sense' but it has been shown to work.... so what do you have to lose.....


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## Joybob (Oct 2, 2007)

SCSIRAID said:


> With signal strength at 100% you could be overloading the tuner. Note that different tuners may have slightly different characteristics. My recommendation is the same as AMF's..... attenuate!  I would start with 6db and see what happens. If you dont have attenuators, try inserting a 4way splitter at the tivo. That will take it down 7db.
> 
> It may not make 'sense' but it has been shown to work.... so what do you have to lose.....


Isn't he saying that he gets pixelation independent of tuner and that it seems to be connected to sporadic signal loss?


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## SCSIRAID (Feb 2, 2003)

Joybob said:


> Isn't he saying that he gets pixelation independent of tuner and that it seems to be connected to sporadic signal loss?


Yes.. its not tuner specific.. and seems to be channel specific. My point is that with signal strength at 100% you may be close to an overload situation. Several folks have reported with FIOS that their similar issue was solved by signal strength reduction with a corrosponding drop in SNR (however contrary to conventional wisdom). In Jannino's case, channel 803 is driving both of his tuners nuts. With the SR Uncorrected numbers he is posting... it 'aint sporadic... its constant. He has nothing to lose and everything to gain by trying attenuation. His reported 37db SNR is something few ever report... its quite exceptional/high. That doesnt mean its wrong... but it is suspicious. Conventional wisdom would say its GREAT... but it 'aint working for Jannino. When conventional wisdom fails.... start thinking unconventionally


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## JANNINO (Oct 28, 2004)

I did attempt to attenuate one of the THDs before the Verizon tech arrived. However, as I started at -3dB and went down to -6dB, -8dB, -10db, the pixelation got worse. However, I did this before we discovered the video errors in the Verizon signal. I will try to attenuate when I get home later today and will report the results.


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