Low signal on one frequency

[jziggity]

So here is what I've got, I'm hoping other members here can offer some insight. I am running an InfiniTV PCIe card with temps steady at 45 degrees, so no heat issues.

A couple of months ago, I had an issue where the SNR level dipped way down on just one frequency (57000, which I presume is measured in Mhz?). It dipped as low as 28 for a short time, but by about a day later, it had recovered enough for the two channels assigned to that frequency, NBC HD and FOX HD, to be watchable again. So, I didn't worry about it too much at that time.

Since then this frequency has always had a lower SNR level than all of the rest of my frequencies, but it has been high enough to not be more than an occasional annoyance with only minor picture pixelations and very short sound drop-outs. As of a few days ago, the problem has resurfaced, and this time it has been about 3 days and the problem has not rectified itself.

When it first started several days ago, both channels were unwatchable. There was massive pixelation across the entire screen and extremely choppy to non-existent audio. I have read the Ceton card is much more sensitive to signal levels than other equipment, which I verified by switching my TV to its internal tuner using a coax connection. On the TV's tuner, both channels worked just fine. Granted I don't know for sure what the signal level was on the coax to the TV, since I have no equipment to measure that.

As of right now, SNR levels are still low, hovering around a high 31 to a low 32. The actual signal level on this frequency is about 1.1 dBmV. My coax setup is the drop line from the pole to an 8-way amplified splitter which feeds the rest of the house, including the InfiniTV, a cable/VOIP modem, and 3 TV's. Unused coax runs are capped off at the wall jack with F terminators. All coax is RG6 (not sure about quad shielding though). I am running the latest beta drivers on the InfiniTV card and the latest drivers on my video card.

Since the problem went away and then reappeared without any change in my hardware, and it only affects one frequency, that being the lowest one by far (the next highest frequency is 111000), I am operating under the assumption that this has to be a cable system issue (Time Warner). So, how do I get a hold of someone at the cable company who: 1.) understands the problem, and 2.) can actually do something about it?

I had a tech out during the first instance of this issue. The gruff older guy had zero interest in the problem, didn't hook up any meters or anything, and told me flat out it would be an issue for the engineers to look in to, and they don't even care about it unless the SNR drops to 28 or below. *sigh*

Additionally, I don't have any MoCa devices on my network. All ethernet cables are cat6, running through a gigabit switch and gigabit router. The problem appears the same both directly on the PC and on Xbox extenders, so I'm going to say my network is not the problem. I did read something at some point about using either a high-pass or low-pass filter to see if that would help. At the time when the signal levels were the lowest, I disconnected the coax from my cable modem, and that made no difference, so would the filters even do anything? Is there anything I can do to boost the signal on this frequency without overdriving the rest of them?

I think I have about covered all of the nuances of this. I really feel like it is a cable system issue, but I just don't see them working hard (or at all) to correct or investigate this further. I'm already on their very small minority user list for being a cablecard user and not having any of their boxes. For those that read this far, what do you think? Thanks!

[barnabas1969]

Do you have a Tuning Adapter (aka Tuning Resolver)? If so, how is it connected? Is the InfiniTV connected to the output of the Tuning Adapter?

[jziggity]

Do you have a Tuning Adapter (aka Tuning Resolver)? If so, how is it connected? Is the InfiniTV connected to the output of the Tuning Adapter?

Yes actually, I do. I guess that's the one piece of hardware I forgot to mention. I have the coax from the wall going to the input of the TA, then the output of the TA going to the InfiniTV card. I can try to get a separate coax run directly from the amplified splitter to the InfiniTV card (I will have to buy another cable, I don't think I have one that long on hand). I will try that and advise.

[barnabas1969]

Or, you could just try putting a 2-way splitter before the TA, and don't use the output from the TA. This is easier and cheaper than running a completely new cable from your amp. It may or may not help your problem, but it's worth a try. The "57000" number is 57000 KHz, which is equivalent to 57.000 MHz. That's a pretty low frequency for a channel to be on. It's possible that the return channel (listed as RDC in the Ceton internal web pages) from your TA is interfering with it.

[jziggity]

Oh man, sometimes the easiest solution is the correct one. The problem started up yet again today - massive pixelation and audio drop outs. I started playing around with the coax cables between the wall jack, the TA and the InfiniTV card. As soon as I started messing with the coax cable between the TA and the card, it cleared up. The signal levels didn't change, they were still lower than all of the other channels, but the actual picture and audio immediately cleared up. I wiggled the cable a bit more, and the signal broke up again. I would say problem identified. I replaced that cable, and what do you know, the issue appears to be resolved. *sigh* I wished I would have checked something so obvious much sooner, but I'm glad it appears to be resolved. I'm gonna chalk this up to a bad coax cable.

[barnabas1969]

Loose connectors is another one to check. And... don't use RG-59U cables... nor ones with connectors that you put on yourself, unless you have the really nice compression crimper.

Oh, and as for the cheap cables and bad connectors... don't use them anywhere in the house, because they can pickup interference from the environment and inject it into your coax wiring throughout the house.

[jziggity]

I must have spoken too soon, once again. I thought the issue was resolved, but tonight it is back again, with a vengeance. I have eliminated all possible problems except for the signal itself being provided by TWC. When I noticed the problem was really bad, I directly tuned the 2 major offending channels using the digital tuners built in to my 2 HDTV's. I was surprised to see the same audio/video breakup issues on these TV tuners as well. These tuners are supplied each by their own separate coax runs from my splitter/amplifier, thus eliminating the InfiniTV and the coax cables connected to it altogether. Okay, so it can't be my tuner card. I even tried eliminating my amplifier/splitter by using a coax coupler to connect the incoming drop line from the pole directly to the coax run feeding my TA and InfiniTV card. No joy there either, still the same problem. Okay, so it's not the amplifier.

And since each TV and the InfiniTV card are using their own coax runs, all commercially purchased (no home-made ends), I highly doubt the cables are the problem either. So, that leads me to conclude this MUST be a TWC signal issue. The signal levels themselves are fine, right now as the TV signal is breaking up the SNR is hovering in the high 34's with a signal level of about 1.5. Temps are at about 49. So, the two biggest problem channels also share that same very low frequency of 57Mhz. If I tune to their SD counter parts, which are on a completely different frequency, no problems. Granted it makes my eyes nearly water watching SD, but at least the video and audio are there without any break-ups. So, it can't be the signal the cable company is getting from the networks either.

So, I have a tech visit scheduled for tomorrow morning from the cable guy. This should be really interesting. My solid bet is going to be that the problem will have magically disappeared by the time he gets here tomorrow, so there will be nothing for him to investigate. I'm hoping that's not the case. Even if the problem is still there, I have no idea what the tech would do to resolve the issue.

Here we go again!

[barnabas1969]

Murphy's Law: When a broken appliance is demonstrated for the repairman, it will work perfectly.

[jaimeknapp]

Jziggity,

Your problem sounds substantially the same as mine (clear QAM channels at a base frequency of 723000). I have found mine is not due to a low signal level, but there are signal anomalies that occur at quite irregular intervals. I have witnessed concurrent events in the data stream on the InfiniTV, Hauppage 2250 and Samsung screen internal tuners simultaneously, but not on the local's OTA signals. They appear different, with the Samsung tuners seeming to skip a small number of video frames and losing audio quite briefly while the others display corrupted video lasting perhaps 1-second. Personally, since I have seen these to be much more common at certain times of day, I believe that there is some brief signal injected at the node level causing this. Time Warner service in San Antonio, TX has witnessed this, supposedly elevating it to engineering, with no resolution.

What amplified splitter are you using?

Have you tried connecting the InfiniTV and tuning adapter as directly to your drop as possible, disconnecting all other coax runs?

[jziggity]

Well, no surprises after the tech visit. All signal levels checked out great, which is what I expected. The tech said there had been an outage last night - he wasn't sure exactly where, but thought it might have led to some of the issues that I saw. He said TWC has a regular replacement interval schedule for the amplifiers hanging on their lines strung between the poles, and that should be in progress as well. I would say the issue is between 90-95% improved from what was going on last night. I am still seeing very occasional video blips and just really short audio drop outs every now and then. I have pretty much accepted that this is the baseline standard of what I should expect given my setup.

While the tech was here, I was having problems with some random SDV channels having gone missing. Not all of them, just a few here and there. A call to the TWC cablecard line, the guy sent additional hits to my TA, and after a little while, they all came back. I feel like I have to hold my breath now lest something else go on the fritz!

[jziggity]

Jziggity,

Your problem sounds substantially the same as mine (clear QAM channels at a base frequency of 723000). I have found mine is not due to a low signal level, but there are signal anomalies that occur at quite irregular intervals. I have witnessed concurrent events in the data stream on the InfiniTV, Hauppage 2250 and Samsung screen internal tuners simultaneously, but not on the local's OTA signals. They appear different, with the Samsung tuners seeming to skip a small number of video frames and losing audio quite briefly while the others display corrupted video lasting perhaps 1-second. Personally, since I have seen these to be much more common at certain times of day, I believe that there is some brief signal injected at the node level causing this. Time Warner service in San Antonio, TX has witnessed this, supposedly elevating it to engineering, with no resolution.

What amplified splitter are you using?

Have you tried connecting the InfiniTV and tuning adapter as directly to your drop as possible, disconnecting all other coax runs?

I did eliminate the amplifier during testing by using a coupler to tie directly in to my main drop line from the pole. This is the amplifier I am using: http://www.cabletvamps.com/Products/EDA-FT08300.htm

Based on all of the testing outlined above, and the fact that the audio/video glitches come and go, with absolutely no other change to my hardware and software setup, I have to believe it is strictly a TWC thing (Milwaukee area). Even the tech who stopped out and tested my signal levels said everything looked great internally inside of my house. He acknowledged there are certain "known" channels that have more glitches than others. I believe the only solution would be if/when TWC makes improvements to their distribution network or finds a problem in or around my neighborhood with the wiring somewhere.

Since I have a very non-traditional setup (per TWC, supposedly about 100 or so customers in WI using a cablecard), I'm assuming such repairs and/or troubleshooting will never take place. I'm also assuming this is not an issue for regular cable box users, as I didn't have the problem when I did have a couple of boxes. If this were a problem for regular TWC cable box users, it would be fixed much sooner I presume. I have one contact I can try for the Appleton, WI area who has been extremely helpful in the past, but I'm not all that optimistic.