Comcast - What Signal is Best Signal Level

[rlawson4]

I have comcast and of course am having cable card problems. I have 2 Tivo HD's and one is working well (finally). The other doesn't seem to want to work with the cable cards. I don't know if the signal is too low or high. I am having a tech (ha ha ha) come out Saturday to measure the signal (sorry for not knowing the correct terminology). So, if anyone can provide me the best signal and the terminology to use with the tech (ha ha ha), I would appreciate it.

[pauljb55]

I get about 62% and mine works fine.
You can use the HD Tivo to determine your signal strength

[rlawson4]

I cannot use the HD to get signal level because the cable cards in that box will not pair. They paired fine in my other box. They are going to measure it with their meters. I need db level ect from their end to check it. What is the best and optiminal signal from their point of view.

[jrm01]

The signal as measured by the TiVo is not what he will want to see. He should be putting a device on the line at the TiVo connection point to measure the signal. It should be somewhere between -10 to +13 dBmV. Hopefully he can measure SNR also, which should be 32-35.

[rlawson4]

The signal as measured by the TiVo is not what he will want to see. He should be putting a device on the line at the TiVo connection point to measure the signal. It should be somewhere between -10 to +13 dBmV. Hopefully he can measure SNR also, which should be 32-35.

Thanks. That is what I needed to know. It is weird why one Tivo works fine with the cable cards and no matter how many cards are brought out, the second tivo does not. I can get basic cable out of that outlet, and I even swapped out a new Tivo box to make sure. Now, I am really thinking something is up with the outlet, even though it works for basic cable. Any further ideas or thoughts are welcome.

[jrm01]

Thanks. That is what I needed to know. It is weird why one Tivo works fine with the cable cards and no matter how many cards are brought out, the second tivo does not. I can get basic cable out of that outlet, and I even swapped out a new Tivo box to make sure. Now, I am really thinking something is up with the outlet, even though it works for basic cable. Any further ideas or thoughts are welcome.

I was just checking a few other posts, and some people recommend that for the TiVo the signal strength should be a little tighter than I suggested: Signal -10 to +10 and SNR of 31-32.

[rlawson4]

Thanks again. This forum is great. You would not know a brand name or place to get an ATTENUATOR?

[jrm01]

Thanks again. This forum is great. You would not know a brand name or place to get an ATTENUATOR?

An attenuator would only be needed if the signal is too strong. For this I usually just add a splitter (capping the unused leg) to attenuate the signal.

If you need something more exact try this: http://www.smarthome.com/7800.html


The usual problem is too weak a signal requiring an amplifier. Comcast can put one at the entry point if all outlets need it, or you can get an amplified splitter for $15-20.

[rlawson4]

Thanks a bunch. I will report back Saturday when they measure the signal.

[rlawson4]

I had Comcast out today and my signal was too strong. I was get +14 - + 19 on some stations. He put a splitter on the outlet and brought it down to +4. The new S-Card he brought out paired and is working. Unfortunately, he only brought one. So, I have one working tuner. Progress but not success until I get another card. He work order clearly stated to bring 2 S-Card or 1 M. He brought 1 S-Card. In fairness, at least he knew how to decrease signal level without messing everything else up. I will say that getting the Tivo HD to work has been like throwing more money away at a casino in order to win back what was lost. What I mean is that had I known the amount of time necessary to get this to work (countless calls to Comcast, 4 truck roles, 4 trips to their office, numerous conversations with so called supervisors, I would have never bought the Tivo. It is sad to say that I persisted because I had already wasted so much time and energy, and it is still not over.

[CrispyCritter]

I had Comcast out today and my signal was too strong. I was get +14 - + 19 on some stations. He put a splitter on the outlet and brought it down to +4. The new S-Card he brought out paired and is working. Unfortunately, he only brought one. So, I have one working tuner. Progress but not success until I get another card. He work order clearly stated to bring 2 S-Card or 1 M. He brought 1 S-Card. In fairness, at least he knew how to decrease signal level without messing everything else up. I will say that getting the Tivo HD to work has been like throwing more money away at a casino in order to win back what was lost. What I mean is that had I known the amount of time necessary to get this to work (countless calls to Comcast, 4 truck roles, 4 trips to their office, numerous conversations with so called supervisors, I would have never bought the Tivo. It is sad to say that I persisted because I had already wasted so much time and energy, and it is still not over.So in other words, because Comcast has been totally incompetent, you feel you should have gone with a Comcast DVR from the beginning????

Hang in there; it sounds like you're almost there!

[rlawson4]

So in other words, because Comcast has been totally incompetent, you feel you should have gone with a Comcast DVR from the beginning????

Hang in there; it sounds like you're almost there!

You are right, and I am almost there. Their DVR sucks. That is why I bought the Tivo. I just cannot believe how much time I have spent on this thing. It has been completely unproductive time. Time is money.

[morac]

I was just checking a few other posts, and some people recommend that for the TiVo the signal strength should be a little tighter than I suggested: Signal -10 to +10 and SNR of 31-32.
While those signal levels sound about right, I would recommend a higher SNR. A SNR of 31 might be good for FIOS, but I have Comcast and my picture craps out if my SNR drops below 32. Currently my SNR is around 35 or 36 on most channels and they work fine. The only channel I really have issues with is NBC-HD, but since the OTA channel also has problems, it's not the cable signal.

[yunlin12]

If you have a cable modem, in my area, if you open a web browser to 192.168.100.1, you see a modem status page, and there usually is a link to signal or something like that, and the modem usually reports the signal strength in dBmV, and SNR. Be sure to look for the inbound values, not the outbound one. My modem shows -12dBmV and 32dB SNR, and it's on the same splitter as my S3, which is pretty happy with the cable signal.

Edit: at the same time my Tivo S3 is reporting 35dB SNR. So maybe the way the cable modem and the Tivo measures SNR are different

[dubluv]

You are right, and I am almost there. Their DVR sucks. That is why I bought the Tivo. I just cannot believe how much time I have spent on this thing. It has been completely unproductive time. Time is money.

while i feel your frustration, as pointed out it should be pointed at your provider, not tivo. the tivoHD is a fine device, and as i watch the prices drop weekly, i'm thinking of adding another. (249 at costco) you should be alot happier once you're using all of the features that us tivo users have enjoyed up to now. the ability to use multiroom viewing, downloading movies from amazon.com, etc etc etc. hang in there kid.:up:

[rlawson4]

while i feel your frustration, as pointed out it should be pointed at your provider, not tivo. the tivoHD is a fine device, and as i watch the prices drop weekly, i'm thinking of adding another. (249 at costco) you should be alot happier once you're using all of the features that us tivo users have enjoyed up to now. the ability to use multiroom viewing, downloading movies from amazon.com, etc etc etc. hang in there kid.:up:

I totally agree. My issue is with Comcast. They have done everything they could do to make this difficult. That being said, Tivo is not without any fault. They should have a cable card concierge. A # that we can call where they deal with the cable company once the cable company screws up. A service that Tivo provides that can access inside numbers at the cable companies. Tivo is not without blame. They already knows that these issues exist. Comcast is 90% to blame. Tivo should be helping more.

[lrhorer]

The signal as measured by the TiVo is not what he will want to see. He should be putting a device on the line at the TiVo connection point to measure the signal. It should be somewhere between -10 to +13 dBmV. Hopefully he can measure SNR also, which should be 32-35.

+13 dBmV!!!! I think not, especially on a digital stream. If his subscriber tap comes right off the line extender and he has a very short subscriber drop with only 1 outlet and no high speed internet, then the very highest frequency analog channels might be +13dBmV or even more, but certainly every channel is not going to be that high. Conversely, if he subscriber tap is at the very end of the line, then channel 2 might be +13dBmV, but the rest of the channels are certainly going to be lower. What's more, since most CATV companies run their digital streams 10dB or more lower than analog streams, the levels on the digital channels should be much, much lower than +13 dB, and may be quite reasonably a little lower than -10. The S/N on analog channels should be better than 52dB, and the S/N on the digitals will probably be in the high 30s or 40s. Any higher than that and distortion is going to be a severe problem. Distortion is a much, much bigger problem for digital streams than low levels or low S/N.

[lrhorer]

An attenuator would only be needed if the signal is too strong. For this I usually just add a splitter (capping the unused leg) to attenuate the signal.
I'm not sure what you mean by "capping" the port. If you mean terminating the port with a 75 ohm terminator, then this will work, but it's a kludge, and it results in a lot of cable clutter. Since small form factor (smaller than an AA battery) attenuators can be gotten for under $2 plus shipping, and since they come in much more flexible values than just 3.5dB (2-way), 7dB (4-way), or 11dB (8-way), there's really not much reason to go with the splitter kludge, at least not long term.


The usual problem is too weak a signal requiring an amplifier.
No, it isn't. CATV engineers take great care to make sure the signal delivered to every home in the CATV distribution is optimal for the average user, which for most systems is specified to be 2 receivers and a 30 meter subscriber drop. This results in perfectly usable signal levels on up to 4 receivers for 95% of all homes. If the subscriber's house meets these criteria and the signal levels are out of bounds, then the CTV system is out of balance and the solution is for the CATV technician to properly balance the amplifiers or replace any defective devices in the system. Adding attenuation or amplification will-nilly is just covering up for the CATV provider's problems and is very likely to result in future problems when the problem is fixed or gets worse.

Note that because of the way the CATV plant is spec'ed, some customers may indeed suffer levels which are too high, especially if they are very close to the subscriber tap (I've seen houses less than 3 meters from the tap) and only have 1 outlet with no broadband internet. Others maybe a long way from the subscriber tap, with very long house drops and multiple outlets. In this case, an amp may be indicated. My house, for example, is over 120 meters from the subscriber tap, and I have 9 receiver drops plus broadband, so the CATV company installed an amp. In my case, it's the proper thing to do, because even with plant levels perfectly up to engineering spec, the signal levels are little low at the high end of the spectrum for good analog reception.

The moral of the story is this: if you are having problems, have the CATV company verify and if necessary balance the levels at the output of the line amplifier (not just the subscriber tap) feeding your house. Then have them verify levels behind your receiver(s) and if necessary replace any bad passive devices or cables in the signal path. At that point if the signal levels are still out of range, then and only then is an inline attenuator or amplifier in order. At the very least there is no reason for the subscriber to bear costs for fixing the CATV company's problem.

[lrhorer]

I had Comcast out today and my signal was too strong. I was get +14 - + 19 on some stations. He put a splitter on the outlet and brought it down to +4.
He should be fired. Indeed, when I was working for the CATV company, if one of our technicians had done this, I would have pushed for his supervisor to fire him, or at the very least write him up. A signal level of +19 dBmV on any channel at the back of the receiver is almost surely way, way beyond spec, even for a neighborhood where drop levels were deliberately engineered to be high. I would occasionally do this if the area boasted many very large estates. It was a more economical solution than putting house amplifiers in every home when the minimum subscriber drop length was 200 meters or more, but even the highest output tap in this situation would barely see +19dBmV on the very highest channel right out of the line extender. Taps further down the line would see much lower levels on the highest channel, and after passing through even just 20 meters of RG-6, the signal level on the highest channel should be way, way down from +19dBmV. The tech was just being lazy. He should have checked the levels at the line extender (or fiber node as the case may be). In many CATV companies, this means calling out a maintenance technician, because many companies make the service technician responsible only back to the subscriber tap.

No matter what the situation, the tech should not have attenuated the signal with a splitter. Every CATV company keeps a large stock of attenuators.

What I mean is that had I known the amount of time necessary to get this to work (countless calls to Comcast, 4 truck roles, 4 trips to their office, numerous conversations with so called supervisors,
Well, it wasn't necessary, any more than dealing with a telemarketer is necessary, just a sad fact of life. Neither TiVo nor you are responsible for the CATV company's incompetence. 'Just like it wasn't TiVo's fault that after my last CableCard install the CATV company decided to start double-billing me for my broadband access. When I called in to raise all Hell, they not only wanted to refuse to refund my money, they wanted to refuse to remove the double billing. 'Frustrating, yes. 'Incompetent, yes. 'Completely unacceptable, yes, but hardly TiVo's fault.

I would have never bought the Tivo. It is sad to say that I persisted because I had already wasted so much time and energy, and it is still not over.
That's like blaming Porsche because your local shade-tree mechanic doesn't know how to fix a 911. Things are getting better in general, but I can guarantee you TiVo or not, there is a high likelihood any service issues with the CATV company are going to result in a painful experience. Since moving to my current house in 2000, I have had 4 major issues with broadband internet service and 3 while I had a leased Scientific Atlanta 8300 DVR. Each instance took more than a week and multiple phone calls and service appointments to resolve, and that was with equipment owned and operated by the CATV company themselves. In my case, I generally have it better than most subscribers, because I used to be an engineer for the local CATV company (prior to their purchase by Time Warner), and I not only know many of the supervisors and engineers still at the company, but being an engineer there is no way they can feed me a line of B.S. A couple have tried, but I set them straight in a big hurry. It helps if you read up very carefully on the technology and get a good understanding of it before having someone look under the hood. This applies to more than just CATV or DVRs, by the way. It applies to that Porsche or your Laptop, as well.

[HiDefGator]

That's like blaming Porsche because your local shade-tree mechanic doesn't know how to fix a 911.

Since there's no Porsche dealer nearby to help with the problem, it would be reasonable for him to question the logic in owning such a high priced troublesome toy in the first place.

[rlawson4]

He should be fired. Indeed, when I was working for the CATV company, if one of our technicians had done this, I would have pushed for his supervisor to fire him, or at the very least write him up. A signal level of +19 dBmV on any channel at the back of the receiver is almost surely way, way beyond spec, even for a neighborhood where drop levels were deliberately engineered to be high. I would occasionally do this if the area boasted many very large estates. It was a more economical solution than putting house amplifiers in every home when the minimum subscriber drop length was 200 meters or more, but even the highest output tap in this situation would barely see +19dBmV on the very highest channel right out of the line extender. Taps further down the line would see much lower levels on the highest channel, and after passing through even just 20 meters of RG-6, the signal level on the highest channel should be way, way down from +19dBmV. The tech was just being lazy. He should have checked the levels at the line extender (or fiber node as the case may be). In many CATV companies, this means calling out a maintenance technician, because many companies make the service technician responsible only back to the subscriber tap.

No matter what the situation, the tech should not have attenuated the signal with a splitter. Every CATV company keeps a large stock of attenuators.


Well, it wasn't necessary, any more than dealing with a telemarketer is necessary, just a sad fact of life. Neither TiVo nor you are responsible for the CATV company's incompetence. 'Just like it wasn't TiVo's fault that after my last CableCard install the CATV company decided to start double-billing me for my broadband access. When I called in to raise all Hell, they not only wanted to refuse to refund my money, they wanted to refuse to remove the double billing. 'Frustrating, yes. 'Incompetent, yes. 'Completely unacceptable, yes, but hardly TiVo's fault.


That's like blaming Porsche because your local shade-tree mechanic doesn't know how to fix a 911. Things are getting better in general, but I can guarantee you TiVo or not, there is a high likelihood any service issues with the CATV company are going to result in a painful experience. Since moving to my current house in 2000, I have had 4 major issues with broadband internet service and 3 while I had a leased Scientific Atlanta 8300 DVR. Each instance took more than a week and multiple phone calls and service appointments to resolve, and that was with equipment owned and operated by the CATV company themselves. In my case, I generally have it better than most subscribers, because I used to be an engineer for the local CATV company (prior to their purchase by Time Warner), and I not only know many of the supervisors and engineers still at the company, but being an engineer there is no way they can feed me a line of B.S. A couple have tried, but I set them straight in a big hurry. It helps if you read up very carefully on the technology and get a good understanding of it before having someone look under the hood. This applies to more than just CATV or DVRs, by the way. It applies to that Porsche or your Laptop, as well.

What you are saying proves my point. How am I supposed to know that the "fix" the cable guy did was not the right thing to do. So, when I have problems later, I know now. Do I need an electrical Engineering Degree to runs this thing? I do not expect that the products I buy have so many potential problems, and it is not as if I wasn't prepared for some issues. I could never recommend the Tivo to anyone at this point, regardless of fault. I can just imagine buying this for my 64 year-old parents. So, I do not disagree with your technical assessment. In fact, it sounds as if you know exactly what you are talking about. The problem is that a simple country lawyer like me cannot be expected to know all that I have had to learn to get this thing to work. It is not as if I am a complete idiot, but I never expected that I had to be trained on my to get the right digital signal into my house.

[morac]

What you are saying proves my point. How am I supposed to know that the "fix" the cable guy did was not the right thing to do. So, when I have problems later, I know now. Do I need an electrical Engineering Degree to runs this thing?
No, but it helps. :)

Things should be as simple as inserting the cableCARD, having it provisioned and that's it, but the problem is the S3/HD seems a lot more sensitive to line issues than the box provided by the cable company. I've had Comcast techs tell me cableCARDs technology is just flaky, but since the tuners are what tune the signal I'd have to say it's more TiVos fault in that case. Granted it's also the cable providers fault for rushing out services that, in many areas, the lines were never designed to handle. In my area, they are slowly replacing all the cable lines equipment because it is old and prone to failure, but that doesn't stop them from offering digital TV, phone and Internet service even though it fails periodically (at least 2 or 3 times a year, usually more). My area isn't even the worst area in the system.

By the way from talking to the techs who come out to the house, I doubt many of them have an EE degree. Most of them seem to just have enough on the job training to try and diagnose issue (by reading their meter) without actually have any background knowledge.

The line techs are a different story, but there is no way for the public to interact with them.