# High SNR & Missing Recordings



## shortcut3d (Sep 1, 2013)

Apparently my signal is hot from Comcast. SNR was 43-45 across all the tuners. However, my previous Ceton InfiniTV6 ETH did not report the signal so strong. I replaced the 4-way with an 8-way and the SNR only dropped to 39-41 across all tuners with strength still at 100%.

Why do I care? The picture quality is great and channels seem to tune reasonably fast. But there was a missed recording yesterday evening due to not available. Once I noticed it was missed, I manually tuned the channel and it came up right away. There were no conflicts and overlap protection is on. The only thing I can think of is the high SNR.


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## AdamNJ (Aug 22, 2013)

why would a high SNR cause a recording not to work/channel not to tune?

Isn't a higher SNR better then a low one?


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## rifleman69 (Jan 6, 2005)

Not if it's too "hot". Put an antennuator on the line and see if it brings the SNR levels down and cause less problems. Your SNR levels should be closer to 35.


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## code0 (Sep 7, 2013)

My signal was too hot - the Roamio was reporting 35dB (seemed to be the max) and having major macroblocking issues.

Chained a couple of splitters together to get it down a bit, and everything was happy. Ended up having Mediacom come back and supply the attenuator since it was a new cable install (previously was cable modem only).

Since the attenuator was added (10dB in my case), SNR has been 30-33ish, and everything has been great.


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## shortcut3d (Sep 1, 2013)

I guess I'm looking for confirmation that high SNR was the cause of the Not Available message for the missed recording.


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## shortcut3d (Sep 1, 2013)

I reduced my hot signal using an 8-way splitter.

I continue to get random Not Available messages for missed recordings. Is there anything I can do to troubleshoot? History really doesn't seem to help. 

All six tuners are constantly buffering when I flip through them using live TV. If I notice the Not Available message for a recording, I can immediately tune to that channel.

The annoying thing is there is no warning about the not available recording.


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## HarperVision (May 14, 2007)

shortcut3d said:


> Is there anything I can do to troubleshoot? .


Yes, put your Ceton back in and dump the beta Roamio! Why did you get rid of your PC Ceton solution if I may ask?

PS - After re-reading what I wrote, I thought we could combine "beta" and "Roamio" and just call it the "Boatio", as in a new accessory for boats like a boat anchor because that's about as useless as it is in reliability with tuning and recording everything you want. Or maybe "Reamio" because that's what your a$$ feels like after shelling out all that cash for this thing. The TV ad jingle could be......."Ream Me?.....Ohhhhh"


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## kbmb (Jun 22, 2004)

I have Comcast and initially had a hot signal (solid 100's and SNRs in the 43-45 range). What's weird is with those I didn't have any issues.

Anyway....I did chain some splitters together (until my attenuators arrive) to bring the signal down. In cases like these I think the signal level is more important. Like most people say....I high SNR in itself isn't bad....it's when it's a indication that the signal is too hot that the hot signal causes problems.

Anyway.....I took -7dB off the signal to get some of the channels to be less than 100 for signal level. Again, wasn't having issues before and don't see issues now (I just like to tinker  ) I still have channels hitting 100 and a 40 SNR, but will keep it around this and see if anything bad happens.

Problem I have is Comcast messed with channel signals recently....so some channels....like Food Network have a lower signal so if I knock my signal down too much...that channel goes too low.

-Kevin


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## shortcut3d (Sep 1, 2013)

HarperVision said:


> Yes, put your Ceton back in and dump the beta Roamio! Why did you get rid of your PC Ceton solution if I may ask?
> 
> PS - After re-reading what I wrote, I thought we could combine "beta" and "Roamio" and just call it the "Boatio", as in a new accessory for boats like a boat anchor because that's about as useless as it is in reliability with tuning and recording everything you want. Or maybe "Reamio" because that's what your a$$ feels like after shelling out all that cash for this thing. The TV ad jingle could be......."Ream Me?.....Ohhhhh"


The Ceton InfiniTV6 ETH was no where near as stable or reliable as the TiVo Roamio Plus. Channel changes are faster with the Roamio Plus. No pixelation with the Roamio Plus. Don't get me started with PQ issues of the Echo. TiVo is hands down a better solution.

How can I figure out the root cause of a missed recording? I also noticed that My Shows indicates the show is initially recording. Not sure when it stops and disappears. There's not even a partial recording remaining.


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## skid71 (Mar 20, 2013)

Do you have to use a Tuning Adapter? Although I don't have to use one, I have read posts that indicate a TA could cause issues.


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## HarperVision (May 14, 2007)

shortcut3d said:


> The Ceton InfiniTV6 ETH was no where near as stable or reliable as the TiVo Roamio Plus. Channel changes are faster with the Roamio Plus. No pixelation with the Roamio Plus. Don't get me started with PQ issues of the Echo. TiVo is hands down a better solution.
> 
> How can I figure out the root cause of a missed recording? I also noticed that My Shows indicates the show is initially recording. Not sure when it stops and disappears. There's not even a partial recording remaining.


Have you tried the HDHR Prime or the Ceton 6 tuner internal PCI-e card, or just the ETH? Don't get me started on that pos echo either!


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## shortcut3d (Sep 1, 2013)

skid71 said:


> Do you have to use a Tuning Adapter? Although I don't have to use one, I have read posts that indicate a TA could cause issues.


No Tuning Adapter. I agree the behavior is similar to TA issues, which makes it so strange.



HarperVision said:


> Have you tried the HDHR Prime or the Ceton 6 tuner internal PCI-e card, or just the ETH? Don't get me started on that pos echo either!


I had several HDHR Primes and they had really stable firmware late 2012 / early 2013. The channel changes were faster than the InfiniTV and no pixelation. The setup was not bad when I was using Xbox 360 extenders, forced into by 29/59 frame rate bug in WMC. Xbox 360s are power hungry, relatively noisy and have limited IR, so they aren't ideal.

Overall, I'm much happier with TiVo, but need to figure out this missed recording issue. The lack of warning and log information is frustrating.


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## HarperVision (May 14, 2007)

shortcut3d said:


> No Tuning Adapter. I agree the behavior is similar to TA issues, which makes it so strange.
> 
> I had several HDHR Primes and they had really stable firmware late 2012 / early 2013. The channel changes were faster than the InfiniTV and no pixelation. The setup was not bad when I was using Xbox 360 extenders, forced into by 29/59 frame rate bug in WMC. Xbox 360s are power hungry, relatively noisy and have limited IR, so they aren't ideal.
> 
> Overall, I'm much happier with TiVo, but need to figure out this missed recording issue. The lack of warning and log information is frustrating.


Which like I said in the other threads, points to a TiVo issue and NOT the TA, especially since you don't even use one!


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## kbmb (Jun 22, 2004)

shortcut3d said:


> How can I figure out the root cause of a missed recording? I also noticed that My Shows indicates the show is initially recording. Not sure when it stops and disappears. There's not even a partial recording remaining.


After the 8 way splitter....what are your signal levels like and SNR?

-Kevin


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## k2ue (May 9, 2002)

AdamNJ said:


> why would a high SNR cause a recording not to work/channel not to tune?
> 
> Isn't a higher SNR better then a low one?


Good point, it depends how the "SNR" number is derived for presentation -- if it was *true* SNR then reception should be good with any reasonably high number, but not all conveniently implemented measures are accurate for very high SNR. However when the Signal Strength indicator is pegged at 100 it suggests the signal strength is exceeding the design range, and since there is an amplitude component in the signal, there is a risk of limiting, which would produce damaged symbols. It would be wiser to adjust the signal strength so it did not exceed 99 in the strongest case.


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## shortcut3d (Sep 1, 2013)

kbmb said:


> After the 8 way splitter....what are your signal levels like and SNR?
> 
> -Kevin


Lowest I can get with my current set of splitters is 39 max on the current 8-way splitter. What I've notice is not all splitters are created equally. One splitter causes pixelation with the Tivo (no surprise as it did the same with the InfiniTV6 ETH), but cable modem speeds are high beyond spec.


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## kbmb (Jun 22, 2004)

shortcut3d said:


> Lowest I can get with my current set of splitters is 39 max on the current 8-way splitter. What I've notice is not all splitters are created equally. One splitter causes pixelation with the Tivo (no surprise as it did the same with the InfiniTV6 ETH), but cable modem speeds are high beyond spec.


But what are your signal levels like? Can you get any of the tuners to drop below 100?

I have a hot Comcast signal to mine. All mine would be pegged at 100 and 43-46 SNR. Although I wasn't having any tuning issues....I decided to play around to get the signal levels down. Because Tivo doesn't show you above 100, it's tough to tell how much you need.

I put two splitters basically dropping 10.5dB from the line. With that I get some channels to go into the upper 90's. A lot will still be 100 but the SNR will drop a bit. I figure as long as some are under 100, then overall the signal should be ok.

I order some attenuators to replace the splitters.....waiting for them to arrive tomorrow.

-Kevin


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## shortcut3d (Sep 1, 2013)

kbmb said:


> But what are your signal levels like? Can you get any of the tuners to drop below 100?
> 
> I have a hot Comcast signal to mine. All mine would be pegged at 100 and 43-46 SNR. Although I wasn't having any tuning issues....I decided to play around to get the signal levels down. Because Tivo doesn't show you above 100, it's tough to tell how much you need.
> 
> ...


The SNR dropped a bit, but the signal has never fallen below 100 and appears to be pegged.


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## kbmb (Jun 22, 2004)

shortcut3d said:


> The SNR dropped a bit, but the signal has never fallen below 100 and appears to be pegged.


Wow.....I think an 8-way is an -11.5dB loss correct? That's a very hot signal then. Do you have an amp anywhere?

I'd get another splitter if you have one, maybe a 2-way for a -3.5dB loss....and see when you start to finally see the levels go below 100. Chain multiples together if you have to. That's basically what I did to finally get -10.5 to see the levels drop from 100. Then after you find the number, order an attenuator that will give you that amount.

I just ordered these:
http://www.smarthome.com/7800/Signal-Strength-Attenuator-Pads-Mix-Bag/p.aspx

I'll be starting with probably a -10 to see how that goes.

-Kevin


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## kbmb (Jun 22, 2004)

Replaced my splitter-monster with a 10dB attenuator today. So far signal levels are usually at 100. Some stations will dip into 98-99.

I do have higher SNR numbers (39-43). But honestly.....I would have a hard time believing a high SNR itself is bad if I know that the signal isn't too hot. I "think" I know this because I have some channels dipping below 100.

Plus from Tivos page they say this:



> NOTE: If your signal strength is at 100 and the video looks fine, this is not an error. The signal strength meter sets 100 as a safe threshold. If the signal is at this threshold or a bit beyond, your picture quality should be excellent. If the signal strength is well beyond the threshold, it will still register as 100, but you might experience poor picture quality, as some DVR components cycle in and out of "protect" mode to prevent damage.


Clearly that means that you can have a signal over 100.....just not TOO hot.

I really wish Tivo would show a true signal level. Seems it would help solve so many issues if they allowed people to understand the true signal level and not guess.

Would also like to know what _"some DVR components cycle in and out of "protect" mode to prevent damage"_ means. What does the Tivo do when it cycles things off? Is that where you can get the signal not found error?

What's really weird in my splitter setup was......almost all channels were in the upper 90's. However, this afternoon A&E dipped to 67. No idea what Comcast is doing to some channels around here.....but I think I'd rather be a bit hot than too low.

-Kevin


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## Goober96 (Jun 28, 2005)

What is the consensus on what are good numbers? Is a signal strength of 80 too low?


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## kbmb (Jun 22, 2004)

Goober96 said:


> What is the consensus on what are good numbers? Is a signal strength of 80 too low?


According to Tivo, 80-99 is the recommended, with 50-53 the minimum:
http://support.tivo.com/app/answers/detail/a_id/150

Although I saw signal level of 67 result in complete pixelation.

-Kevin


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## shortcut3d (Sep 1, 2013)

No AMP. I may order a couple attenuators.


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## astrohip (Jan 7, 2003)

Just to be clear... I have the occasional missing recording (3 so far). All due to "Signal not available". And I have on occasion flipped thru the channels and found one not tuned in.

DVR Diagnostics on my Pro show all tuners, almost any channel, coming in around SNR 42-43dB, with signal strength of 100 all the time. Comcast/Houston, no TA.

So I'm too hot?

And the secret sauce seems to be buy some attenuators and drop my SNR to ~35dB?

Thanks in advance.


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## kbmb (Jun 22, 2004)

astrohip said:


> Just to be clear... I have the occasional missing recording (3 so far). All due to "Signal not available". And I have on occasion flipped thru the channels and found one not tuned in.
> 
> DVR Diagnostics on my Pro show all tuners, almost any channel, coming in around SNR 42-43dB, with signal strength of 100 all the time. Comcast/Houston, no TA.
> 
> ...


Personally I would look LESS at the SNR and more at the signal. If you can drop the signal so that at least one channel hits 99 (even if it's for a few seconds).....then why worry about the SNR?

Tivo even states on their page that you can have a signal that is "a bit beyond" the 100 and you should have excellent picture quality. Can't image that if you were to get the signal to be right around 100.....even with a high SNR that Tivo would cause the signal to go out. If so that's crazy.

Problem is Tivo doesn't show beyond 100.....so it's a guessing game to get to under or at 100. I finally went with a 6dB attenuator and most all my channels are solidly at 100. However, I know (or am guessing) that I'm not far above because I have some channels hitting 97-99 at times.

Even with this I have SNR numbers from 37-43dB. So far no issues.

What's interesting is.....my old TivoHD never had a problem, and I was pumping the full signal into it.....no attenuation.

-Kevin


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## HarperVision (May 14, 2007)

kbmb said:


> Personally I would look LESS at the SNR and more at the signal. If you can drop the signal so that at least one channel hits 99 (even if it's for a few seconds).....then why worry about the SNR?
> 
> Tivo even states on their page that you can have a signal that is "a bit beyond" the 100 and you should have excellent picture quality. Can't image that if you were to get the signal to be right around 100.....even with a high SNR that Tivo would cause the signal to go out. If so that's crazy.
> 
> ...


If that's what you think then you don't understand how it all works. SNR means "signal to noise ratio" so no matter how high your signal level may be, if the "ratio" of noise to said signal is high enough past the threshold of what the equipment is designed for, then you're screwed, plain and simple. Inversely you can have a low level signal (70 something maybe) but a great signal to noise ratio and get a great picture tuned in.

When I was in broadcast TV we spent a hell of a lot more time suppressing noise and harmonics of the signal by tuning the cavity and transmission lines with line flatteners and network analyzers than we did worrying about our power output and what it looked like on our power meters and spectrum analyzers. Increase the power, it just increases the noise, whereas decreasing noise had a better net effect.

You're most likely seeing a side benefit from lowering the signal power input due to the higher signal creating things like more rf reflections, vswr, anomalies of any not so perfect connections, etc. which in turn naturally improves [edit] the snr.


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## kbmb (Jun 22, 2004)

HarperVision said:


> If that's what you think then you don't understand how it all works. SNR means "signal to noise ratio" so no matter how high your signal level may be, if the "ratio" of noise to said signal is high enough past the threshold of what the equipment is designed for, then you're screwed, plain and simple. Inversely you can have a low level signal (70 something maybe) but a great signal to noise ratio and get a great picture tuned in.
> 
> When I was in broadcast TV we spent a hell of a lot more time suppressing noise and harmonics of the signal by tuning the cavity and transmission lines with line flatteners and network analyzers than we did worrying about our power output and what it looked like on our power meters and spectrum analyzers. Increase the power, it just increases the noise, whereas decreasing noise had a better net effect.
> 
> You're most likely seeing a side benefit from lowering the signal power input due to the higher signal creating things like more rf reflections, vswr, anomalies of any not so perfect connections, etc. which in turn naturally lowers the snr.


Yup...then I don't have a clue.

Please enlighten me.....if I have a signal on my Tivo of 99-100, what is a good SNR?

-Kevin


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## shortcut3d (Sep 1, 2013)

OMG... These missed recordings need to stop. Revenge was not record because it was not available and shows up as a conflict. Only two other shows were recording and I have a Plus. Not to mention it started recording then suddenly disappeared.


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## HarperVision (May 14, 2007)

kbmb said:


> Yup...then I don't have a clue.
> 
> Please enlighten me.....if I have a signal on my Tivo of 99-100, what is a good SNR?
> 
> -Kevin


A good snr for TiVo is apparently 29-35db for QAM256. Technically a higher signal to noise ratio should always be better as long as it doesn't overload other parts of the circuit, and my guess is that's how TiVo designed it as well.


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## moyekj (Jan 24, 2006)

FYI, signal levels are 100 for me on most channels with SNR in the range of 39-42 dB and so far I have not had any missed recordings (after several weeks). So while that may not be in TiVo's defined good range it still works for me. I think the other key specs that need attention are RS corrected/uncorrected errors. I get very low counts on those which is a good sign. If you see high numbers there then it's likely you will see macroblocking on occasion due to dropped bits for RS uncorrected errors and it's a sign of tuning difficulty. These signal and SNR numbers are quite significantly higher than I recall with my Elite, Premiere and S3 units. I did on occasion have Elite fail to tune any/all channels requiring a reboot to fix. Have not had that issue even once yet with my Roamio Pro.


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## andyf (Feb 23, 2000)

astrohip said:


> Just to be clear... I have the occasional missing recording (3 so far). All due to "Signal not available". And I have on occasion flipped thru the channels and found one not tuned in.
> 
> DVR Diagnostics on my Pro show all tuners, almost any channel, coming in around SNR 42-43dB, with signal strength of 100 all the time. Comcast/Houston, no TA.
> 
> ...


We're on the same cable system. I put a 10db attenuator inline and it didn't make a difference. Put a 16db attenuator in and the levels dropped down but it killed my MoCa connection so I'm back at 10db.

I missed 3 recordings last Monday with the 10db attenuator, Hostages, Blacklist and Castle. fortunately Hostage and The Blacklist re-aired Saturday and I saw Castle on Xfinity Online. Haven't seen a No Signal since the update came down. (.2?)

Also Comcast is doing some weird stutters from time to time. Pretty sure it's Comcast because I see it on my other TiVos too.


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## shortcut3d (Sep 1, 2013)

I did the update last week and still got the same missed recording for Revenge last night. Again, it started recording and showed up in My Shows with a red circle, then disappeared at some point while watching another recording. The History says Not Available and is sorted under Conflicts. Only three other shows recorded at that time block.

I disabled Tivo Suggestions as that's all I can think of at this point. This may be related to the 30 sec skip bug / no buffer bug, but I'm not getting the full symptoms.


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## kbmb (Jun 22, 2004)

I'm not sure if Tivo's SNR numbers are correct. I also have what Tivo would probably call a hot signal....signal 100 and SNR numbers of 40-43.

I had to troubleshoot something so I brought my Comcast Motorola box downstairs and plugged in into the line used by Tivo. The Moto box showed 37.5 dB SNR.

Wonder if Tivo boosts the signal internally?

*To the OP:* I think the Not Available is now a known bug with back to back recordings:
http://www.tivocommunity.com/tivo-vb/showthread.php?t=509715

I too am like you, high signal and SNR.....great picture quality.

-Kevin


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