High Demodulation Errors

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teamfox201

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High Demodulation Errors

#1

Post by teamfox201 » Wed Mar 04, 2015 2:53 am

hello!

I have the InfiniTV ETH 6 and I keep getting subscription errors or SDV 1 so I find myself rebooting the tuner, STA1520 and HTPC about every 2-4 days. I submitted the logs to Ceton and they came back saying they see "serious high demodulation errors on your coax line" and to get Time Warner Cable out here. They have been out twice since I installed the system but their support guys cant seem to every find anything wrong (go figure).

Is there any kind of equipment or tricks of the trade from anyone that may know how to troubleshoot RF issues on how to locate whatever is causing this interference or what device on my network may be causing this issue?

If I have to call TWC again, I feel like I will waste another day waiting for them only to freak out when they get here because of the setup and then tell me nothing is wrong .

Any help is appreciated.

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Crash2009

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#2

Post by Crash2009 » Wed Mar 04, 2015 5:05 am

Might as well start by seeing what your signals really are. Get yourself a copy of AllCetonSignals.zip There are a few different versions, one for the 4 tuner and another for the 6 tuner. Post your results using the Code button.

allcetonsignals.zip can be located here at TGB by using the search window.

Here is one version, just to get you started. http://www.thegreenbutton.tv/forums/vie ... 423#p73423

You can do a signal survey of your building using your AllCetonSignals, your tuner, and a long section of coax.

This is the way they originally hooked me up. I was screwed from the start.

0.0 dBmV is the best. The farther away you are from 0.0 dBmV the closer you get to this........
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JohnW248

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#3

Post by JohnW248 » Wed Mar 04, 2015 5:36 pm

Review your RF installation.... It is usually best to run your drop to a two way splitter (TWC gave me mine for free) and then one lead to the TA and one to the tuner. The output from the TA should be terminated with a 75ohm coax terminator.

Then check your signal levels either with the test file or any number of other methods, the easiest is to open the web gui page and look at each tuner and its temp and signal level.

The TA issue could be related if your problem is intrusion into your drop, that's something that the TWC guys should be able to find on any cable they hook their equipment to and your can eliminate any unused cables, etc. The TA requires a couple of signal to work, one is the DAVIC at 74.5 MHz which is the OOB frequency and the other is a channel (which changes) which carries the channel map data. There needs to be both up and down connections to the TA so if its behind anything else like an amp, it has to allow upstream connections.

From the Web Gui you can select the tuning adapter and then right click on the diagnostic link and open in a new tab. If you open RF statistics you'll get a run down of the TAs connections and signal levels:

CURRENT FDC
Freq: 74.500 MHz
DAVIC: Connected
Status: Locked
Level: 5 dBmV
Seconds: 1477657
Corr Bytes: 358
Uncor Blks: 539
Errs Avg/Inst: 0 / 0
Total Bytes: 3700299980
S/N: 29 dB
CURRENT QAM
Freq: 597.000 MHz
Tuning Mode: QAM-256
Status: Locked
Level: 6 dBmV
S/N: 39 dB
Seconds: 232553
Corr Bytes: 15
Uncor Blks: 0
Errs Avg/Inst: 0 / 0
EQ Gain: 1.0
CURRENT RDC
Freq: 15.000 MHz
Power: 52 dBmV
Delay: 644 uSec
Retrans: 0

Here you see the downsteam DAVIC at 74.5, the data channel at 597 and the upstream at 15 MHZ

One other thing to check is that your problem is on the coax to the tuner and not on the network from the tuner to your host.

One suggestion, when you want a service call start with the National CableCARD service desk and let them write the work order in hopes you get a Tech with the right tools and knowledge to check the things that might be at issue. A phone call for regular service does not guarantee that you'll get a cableCARD guy with a truck.

kd6icz

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#4

Post by kd6icz » Wed Mar 04, 2015 6:30 pm

Did TWC in your area just recently convert to all digital?

JohnW248

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#5

Post by JohnW248 » Wed Mar 04, 2015 8:44 pm

I think it was in October 2014, after several delays. They also increased broadband to a max of 300mhz. To do that, they claimed they had to remove all NTSC channels and we got a new line-up as well. Area Los Angeles, LA County North, headend Chatsworth CA

kd6icz

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#6

Post by kd6icz » Thu Mar 05, 2015 7:34 pm

Ok. Go into the tuner Web interface and find out what the frequency is your having issues with. If it lands on one of the 70 or so channels that were previously NTSC the issue could be TWC.

In my area (Fullerton) they switched back in September and about a week after I started having demod issue on certain channels. It was driving me crazy! After about a week of ripping out my hair and thinking my Ceton took a dump something caught my eye. The channel I was having trouble with was on 85MHz.... I realized that was analog channel 6 and put the math together.

What was happening was TWC was migrating channels into the newly freed up spectrum and the new QAM modulators they were installing weren't being properly calibrated. I quickly hooked up my spectrum analyzer to my cable and noticed a little tiny carrier popping up in the middle of the "barts head". This is bad to a sensitive reciever! Quadrature Amplitude Modulation (key words Amplitude Modulation) must NOT have a carrier present or the reciever won't be able to properly tune in and lock up on the signal. What was worse was my Motorola STB I had in the same room was not affected by this. It had a much more tollarent tuner.

It took Ceton to use their internal contacts to get it resolved. But once they got involved the issue went away in 48 hours!

TeddyR

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#7

Post by TeddyR » Fri Mar 06, 2015 1:32 am

Here in Glendale/Burbank CA when Charter went all digital the issue for many had been in locations that had undocumented filters that were meant to block the non internet traffic for the users that had the internet only options previously. One person I know had 3 filters on their line and when they decided to get regular cable the installer found 2 of the 3 filters. The third was causing similar issues mentioned above since it was only meant to block certain "analog" stations so depending on where the SDV placed the frequency for the requested channel the channel would intermittently drop out.
Time is on my side.

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Crash2009

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#8

Post by Crash2009 » Fri May 01, 2015 10:13 am

teamfox201 wrote:hello!

I have the InfiniTV ETH 6 and I keep getting subscription errors or SDV 1 so I find myself rebooting the tuner, STA1520 and HTPC about every 2-4 days. I submitted the logs to Ceton and they came back saying they see "serious high demodulation errors on your coax line" and to get Time Warner Cable out here. They have been out twice since I installed the system but their support guys cant seem to every find anything wrong (go figure).

Is there any kind of equipment or tricks of the trade from anyone that may know how to troubleshoot RF issues on how to locate whatever is causing this interference or what device on my network may be causing this issue?

If I have to call TWC again, I feel like I will waste another day waiting for them only to freak out when they get here because of the setup and then tell me nothing is wrong .

Any help is appreciated.
You might be getting MoCA interference from the neighbors, or from within. POE prevents that.

Better late than never.....http://www.thegreenbutton.tv/forums/vie ... 949#p88949

ptown02

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#9

Post by ptown02 » Tue Jul 07, 2015 3:32 pm

kd6icz wrote:Ok. Go into the tuner Web interface and find out what the frequency is your having issues with. If it lands on one of the 70 or so channels that were previously NTSC the issue could be TWC.

In my area (Fullerton) they switched back in September and about a week after I started having demod issue on certain channels. It was driving me crazy! After about a week of ripping out my hair and thinking my Ceton took a dump something caught my eye. The channel I was having trouble with was on 85MHz.... I realized that was analog channel 6 and put the math together.

What was happening was TWC was migrating channels into the newly freed up spectrum and the new QAM modulators they were installing weren't being properly calibrated. I quickly hooked up my spectrum analyzer to my cable and noticed a little tiny carrier popping up in the middle of the "barts head". This is bad to a sensitive reciever! Quadrature Amplitude Modulation (key words Amplitude Modulation) must NOT have a carrier present or the reciever won't be able to properly tune in and lock up on the signal. What was worse was my Motorola STB I had in the same room was not affected by this. It had a much more tollarent tuner.

It took Ceton to use their internal contacts to get it resolved. But once they got involved the issue went away in 48 hours!
Hi,

I'm in the DFW area and I've had a whole slew of issues crop up after TWC did the digital roll out in early June. First, the CableCARD could not get an OOB lock, therefore it could not be validated and start receiving encrypted channels. After that issue was resolved, I started getting macroblocking and eventually lockups when tuned to certain channels. If I change the channel (up or down) and then back to the problem channel the feed resumes and everything is fine for 15 to 30 minutes before the same symptoms show up again.

I haven't hooked up the spectrum analyzer yet, but wouldn't be opposed to taking one home from work and checking it out... Have your issues with TWC been resolved? What was the final solution?

-Ptown02

kd6icz

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#10

Post by kd6icz » Wed Jul 08, 2015 3:35 pm

Yes they have. Once I got Ceton involved they went through their channels and within 48 hours the issue disappeared. All the DAC technician needs to do is properly calibrate the modulator for the new frequency. Most likely their is a carrier that needs to be "nulled".

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#11

Post by ptown02 » Wed Jul 08, 2015 6:14 pm

I'm having a heck of a time getting TWC to come out an analyze the signal. I also sent this link to Ceton and they act like they haven't read it because they do not acknowledge it. Do you happen to have the Ceton ticket number? I could reference it in my response to Ceton so they would have something to go on...

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Crash2009

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#12

Post by Crash2009 » Sat Jul 11, 2015 8:22 pm

ptown02 wrote:I'm having a heck of a time getting TWC to come out an analyze the signal. I also sent this link to Ceton and they act like they haven't read it because they do not acknowledge it. Do you happen to have the Ceton ticket number? I could reference it in my response to Ceton so they would have something to go on...
You don't need TWC to analyze your signal until after you prove it's no good for yourself. Run allcetonsignals.zip and use your tuner as your analyzer. 0.0 dbmv is the best. + or - 12.0 dbmv is still within the tuners spec. + or - 18 equals no picture.

Sometimes, simply moving the tuners supply line 2 or 3 splitters upstream will result in an improved signal. Each 3 way costs you 3.5 dbmv. Do the math, three 3way splitters puts you at -10.5, if your main in is -2.0 dbmv, (and that's not too bad), that puts your signal at -12.5 dbmv. I've been there, the tv is not worth watching.

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#13

Post by ptown02 » Thu Jul 16, 2015 9:06 pm

Crash2009 wrote:
ptown02 wrote:I'm having a heck of a time getting TWC to come out an analyze the signal. I also sent this link to Ceton and they act like they haven't read it because they do not acknowledge it. Do you happen to have the Ceton ticket number? I could reference it in my response to Ceton so they would have something to go on...
You don't need TWC to analyze your signal until after you prove it's no good for yourself. Run allcetonsignals.zip and use your tuner as your analyzer. 0.0 dbmv is the best. + or - 12.0 dbmv is still within the tuners spec. + or - 18 equals no picture.

Sometimes, simply moving the tuners supply line 2 or 3 splitters upstream will result in an improved signal. Each 3 way costs you 3.5 dbmv. Do the math, three 3way splitters puts you at -10.5, if your main in is -2.0 dbmv, (and that's not too bad), that puts your signal at -12.5 dbmv. I've been there, the tv is not worth watching.
The signal level is fine, it's the signal quality that is poor.

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Crash2009

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#14

Post by Crash2009 » Fri Jul 17, 2015 4:29 am

ptown02 wrote:The signal level is fine, it's the signal quality that is poor.
Are you talking about the SNR?

Why don't you run allcetonsignals.zip and post the results?

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#15

Post by ptown02 » Fri Jul 17, 2015 4:45 am

Crash2009 wrote:
ptown02 wrote:The signal level is fine, it's the signal quality that is poor.
Are you talking about the SNR?

Why don't you run allcetonsignals.zip and post the results?
AllCetonSignals.zip only shows the received signal level in dBmV. I'm getting demodulation errors on the 231MHz channel only. The signal level is around 0dBmV and the SNR starts at 39dB and slowly drifts to 32dB. While it slowly drops, the pixelation/macroblocking becomes worse and worse until WMC pops up the "Weak TV Signal" screen. If you go to the ceton tuner web page you can see that the tuner is tuned to channel 1200 (in this case) with a signal level of 0dBmV with an SNR of ~32dB. This whole process takes anywhere from 5 to 60 minutes. I've disconnected the MoCA network, the cable modem, the tuning adapter and nothing seems to help.

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#16

Post by Crash2009 » Fri Jul 17, 2015 1:01 pm

Could we see a simple sketch of your network ('s) topology? Please show all:

TA's, Tuners, Splitters.

MoCa transmitters, receivers, POE's.

Ethernet Nic's, Switches, Routers, Modem.

HTPC's, Extenders, etc.

A simple sketch on paper will suffice, take a picture or scan, and the upload attachment button is:

HERE
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Crash2009

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#17

Post by Crash2009 » Fri Jul 17, 2015 1:54 pm

I think I remember John W writing about specific frequency that drifted. I'll get back to you on that.

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#18

Post by Crash2009 » Fri Jul 17, 2015 6:24 pm

I found one of the posts that sound like you describe. Some of the troubleshooting steps involve eliminate RF interference as a possibility. Using distance between components and tinfoil. http://www.thegreenbutton.tv/forums/vie ... 669#p87669 Not sure if they found a solution other that "dead tuner". You might have to ask Tzr, click on his name and send an IM.

Try searching "frequency" or "SNR"

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#19

Post by ptown02 » Mon Jul 20, 2015 2:14 pm

Hey, I read through the thread you linked. They did not find a solution and it is EXACTLY the same issue as I'm seeing. I've turned off everything attached to the coax network in my house and terminated all open ends with 75 ohm loads. I've had better luck working on 2 MW radars operating at +100kV and had better luck. Ceton has replaced the InfiniTV tuner and the problem persists. Ceton has officially engaged TWC to help resolve the issue as it seems to be provider centric.

I'm in the exact same scenario that kd6icz described up above with the TWC digital roll out in his area. Everything was working great and now it doesn't. I've done everything except take the spectrum analyzer in from work and hook it up to the cable drop. I'm not above that, but REALLY don't feel like it...

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#20

Post by Crash2009 » Tue Jul 21, 2015 1:19 am

You're welcome. you got what you asked for and that was to get ceton on on board and now they're putting pressure on TWC for a solution.
xx
FYI KD6 has developed mb/ps problems recently resulting in a teardown. Any similarity with yours?

http://www.thegreenbutton.tv/forums/vie ... f=7&t=8926

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