Many data errors after about 15 minutes, restarting stops the errors

Sébastien Aubry

Hello,

I have some signal noise problems using an USB DVB-T tuner AVerMedia AVerTV Volar hd2 (seen as Afatech AF9033 in TVHeadend).
When I plug the antenna cable on my Sony TV, everything works fine. The signal information page gives a "Pre Viterbi" of about 2e-4.

On the computer (HTPC), I sometimes have a lot of Transport Errors and Continuity Errors. The signal is usually very good, but several times per hour, it gets totally scrambled. When this is the case, stopping the playback and starting it again solves the problem, which is weird.

For instance, at this moment, the program I am recording has >100000 errors.
The PER (Packet Error Ratio) is about 0.06, the SNR 31.5 dB and the signal strength -34 dB.

At some other moments, everything works fine.

I use LibreElec 9.2.3 with TvHeadend 4.3-1896 (nightly build).

I have tried :
* to enable/disble the LNA (low noise amplifier) in TvHeadend
* to enable/disble "Force old status" in TvHeadend
* to enable/disable the latest drivers in LibreElec
* to play with the 167KHz offsets
* to replace my cables, amplifier, HTPC
* to disable the hardware descrambling in the "CAs" tab
but it did not improve this problem.

Below are a few screenshots: in 3 of them everything works fine, but in the last one, the image is noisy:

!yesterday.png! A session

!old_status.png! Force old status

!today.png! Another session

!noise.jpg! Signal noise example

I also add a attachment:log.txt of a buggy session:

* I start the streaming from the TVH web interface at 09:12:06
* It works fine until 09:30:22 (18 minutes later) when I encounter the first continuity errors
* I stop it after a lot of errors (~10000) at 09:53:39 and start it again immediately
* then it works fine during at least 21 minutes, at 10:15, though before stopping it, there were errors every minute
* I restart it at 10:45, after thousands of errors
* Again, it works fine until 15 minutes

Do you see anything I could try in order to understand why I get this high noise ?

Should I buy another USB tuner?

Thanks

Note: this was also posted on the "LibreElec forum"

[edit] Below are all the tests run in this topic:

|_.Start time |_.Hardware |_.OS |_.Kernel |_.TV tuner|_.DVB Module |_.PVR |_.Amplifier ? |_.Amplifier level |_.Cables |_.Duration (s) |_.Poor signal count (s) |_.UCB (uncorrected blocks) |_.First UCB at (s) |
| %{color:red}20/07/20 10:25% | HTPC | LibreElec 9.2.3 | 5.1.16 | AVerMedia AVerTV Volar hd2 | dvb_usb_af9035 5.1.16 | TVHeadend | yes | 50% | pink+blue | 1000 | 21 | 1743 | 375 |
| %{color:green}20/07/20 10:49% | HTPC | LibreElec 9.2.3 | 5.1.16 | AVerMedia AVerTV Volar hd2 | dvb_usb_af9035 5.1.16 | TVHeadend | yes | 50% | pink+blue | 1000 | 0 | 0 | |
| %{color:red}20/07/20 11:10% | HTPC | LibreElec 9.2.3 | 5.1.16 | AVerMedia AVerTV Volar hd2 | dvb_usb_af9035 5.1.16 | TVHeadend | yes | 50% | pink+blue | 1200 | 149 | 181119 | 155 |
| %{color:green}22/07/20 01:34% | HTPC | LibreElec 9.2.3 | 5.1.16 | AVerMedia AVerTV Volar hd2 | dvb_usb_af9035 5.1.16 | TVHeadend | yes | 50% | pink+blue | 1200 | 0 | 0 | |
| %{color:red}22/07/20 08:04% | HTPC | LibreElec 9.2.3 | 5.1.16 | AVerMedia AVerTV Volar hd2 | dvb_usb_af9035 5.1.16 | TVHeadend | yes | 50% | pink+blue | 1800 | 4 | 296 | 0 |
| %{color:red}22/07/20 08:39% | HTPC | LibreElec 9.2.3 | 5.1.16 | AVerMedia AVerTV Volar hd2 | dvb_usb_af9035 5.1.16 | TVHeadend | yes | 50% | pink+blue | 2000 | 151 | 259485 | 1320 |
| %{color:green}22/07/20 09:47% |Laptop |Linux Mint 19.3 |5.4.0-42 | AVerMedia AVerTV Volar hd2 |dvb_usb_af9035 5.4.0-42 | TVHeadend | yes | 50% | pink+blue | 2000 | 0 | 0 | |
| %{color:green}22/07/20 10:35% | Laptop | Linux Mint 19.3 | 5.4.0-42 | AVerMedia AVerTV Volar hd2 | dvb_usb_af9035 5.4.0-42 | TVHeadend | yes | 50% | pink+blue | 2100 | 0 | 0 | |
| %{color:green}22/07/20 11:15% | Laptop | Linux Mint 19.3 | 5.4.0-42 | AVerMedia AVerTV Volar hd2 | dvb_usb_af9035 5.4.0-42 | TVHeadend | yes | 50% | pink+blue | 2400 | 0 | 0 | |
| %{color:green}22/07/20 11:58% | Laptop | Linux Mint 19.3 | 5.4.0-42 | AVerMedia AVerTV Volar hd2 | dvb_usb_af9035 5.4.0-42 | TVHeadend | yes | 50% | pink+blue | 2500 | 0 | 0 | |
| %{color:red}22/07/20 13:24% |HTPC |LibreElec 9.2.3 |5.1.16 | AVerMedia AVerTV Volar hd2 |dvb_usb_af9035 5.1.16 | TVHeadend | yes | 50% | pink+blue | 2500 | 117 | 109520 | 1170 |
| %{color:red}22/07/20 15:16% | HTPC | LibreElec 9.2.3 | 5.1.16 | AVerMedia AVerTV Volar hd2 | dvb_usb_af9035 5.1.16 |VDR | yes | 50% | pink+blue | 2500 | 133 | 165932 | 1230 |
| %{color:green}23/07/20 00:07% |Laptop |Linux Mint 19.3 |5.0.0-32 | AVerMedia AVerTV Volar hd2 |dvb_usb_af9035 5.0.0-32 | TVHeadend | yes | 50% | pink+blue | 21000 | 0 | 0 | |
| %{color:green}24/07/20 12:10% |HTPC |OpenELEC 8.0.4 |4.9.30 | AVerMedia AVerTV Volar hd2 |dvb_usb_af9035 4.9.30 |VDR | yes | 50% | pink+blue | 13800 | 0 | 0 | |
| %{color:green}24/07/20 16:47% | HTPC |LibreElec 9.2.3 |5.1.16 |Hauppauge WinTV-dualHD |em28xx 5.1.16 |TVHeadend | yes | 50% | pink+green | 2500 | 0 | 0 | |
| %{color:red}06/08/20 17:52% | HTPC |LibreELEC-Generic.x86_64-9.80-nightly-20200804-a26fe97 |5.7.6 |AVerMedia AVerTV Volar hd2 |dvb_usb_af9035 5.7.6 | TVHeadend | yes | 50% | pink+blue | 2500 | 93 | 58448 | 1208 |

Saen Acro

What is hardware running TVH?

Sébastien Aubry

This is a recent HTPC:
* AMD Ryzen 3 3200G - 4GHz/6Mo/AM4 CPU
* MSI B450M-A PRO MAX - B450/AM4/DDR4/mATX motherboard
* Ballistix BL8G30C15U4B (8GB DDR4 3000 PC24000) OEM RAM

Saen Acro

Try disable embedded sound card (guess realtek )

Sébastien Aubry

Hi,

I went into the BIOS and disabled "HD Audio Controller" (in a screen similar to "this one"

Unfortunately, this did not solve the continuity errors:

!tvh_20200715.png!

attachment:log_20200715.txt . Do not pay attention to the "no input source available", tonight I had 3 (automatically) scheduled recording for only one tuner.

Thanks

Sébastien Aubry

Hello,

I just ran the following tests:
* installing VDR PVR backend + frontend under LibreElec: it seems like I do not get these errors, even after a long playback (I could not find any log or web interface, so I just noticed that visually).
* reverted TVH to the "stable" version (4.2.8-36) under LibreElec 9.2.3: but the same errors occurred after ~30 minutes playback.

Sébastien Aubry

Attached is a low level attachment:debug_sample.txt: 10000 lines for less than 1 minute, but still a lot of continuity errors.

Saen Acro

do you try to use


femon
dvb-fe-tool

to monitor status

I have same tuner used for weeks no problem.

As I read you have signal ampliffier can you reduce power level.

Sébastien Aubry

Hello,

Thank you very much for your help.

I just ran:

femon -H -a1 >

attachment:femon1.txt

Then I lowered the amplifier UHF level to the middle position (it was at about 2/3).

femon -H -a1 >

attachment:femon2.txt

@dvb-fe-tool -a1 --femon -v@: saved to attachment:dvb-fe-tool.txt

Sébastien Aubry

I let it run a bit longer, and apparently the TVHeadend errors are synchronized with "Poor Quality" lines in dvb-de-tool:

Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 30.98dB UCB= 56158707 postBER= 674x10^-9 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.03dB UCB= 56158707 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.15dB UCB= 56158707 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.13dB UCB= 56158707 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.19dB UCB= 56158707 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.07dB UCB= 56158707 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 30.95dB UCB= 56158707 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -38.00dBm C/N= 31.03dB UCB= 56158707 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.03dB UCB= 56158707 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.18dB UCB= 56158707 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.13dB UCB= 56158707 postBER= 0 PER= 0
%{color:red}@Lock (0x1f) Quality= Poor Signal= -37.00dBm C/N= 31.36dB UCB= 56158751 postBER= 93.1x10^-6 PER= 2.20x10^-3@%
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.14dB UCB= 56158773 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.27dB UCB= 56158773 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.17dB UCB= 56158773 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.27dB UCB= 56158773 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.02dB UCB= 56158773 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.38dB UCB= 56158773 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.17dB UCB= 56158773 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -38.00dBm C/N= 30.96dB UCB= 56158773 postBER= 0 PER= 0
Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.25dB UCB= 56158773 postBER= 0 PER= 0

Lock (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.06dB UCB= 56158773 postBER= 0 PER= 0

and after a long time:


Lock   (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.02dB UCB= 56159233 postBER= 0 PER= 0
Lock   (0x1f) Quality= Good Signal= -37.00dBm C/N= 30.92dB UCB= 56159233 postBER= 0 PER= 0
Lock   (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.10dB UCB= 56159233 postBER= 0 PER= 0
Lock   (0x1f) Quality= Good Signal= -37.00dBm C/N= 30.92dB UCB= 56159233 postBER= 0 PER= 0
Lock   (0x1f) Quality= Good Signal= -37.00dBm C/N= 31.07dB UCB= 56159233 postBER= 0 PER= 0
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 30.80dB UCB= 56159317 postBER= 110x10^-6 PER= 2.80x10^-3
Lock   (0x1f) Quality= Good Signal= -37.00dBm C/N= 30.81dB UCB= 56159317 postBER= 0 PER= 0
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 29.83dB UCB= 56161117 postBER= 2.42x10^-3 PER= 60.0x10^-3
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 30.86dB UCB= 56161954 postBER= 318x10^-6 PER= 7.90x10^-3
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 29.70dB UCB= 56162677 postBER= 961x10^-6 PER= 24.1x10^-3
Lock   (0x1f) Quality= Good Signal= -38.00dBm C/N= 31.01dB UCB= 56162677 postBER= 0 PER= 0
Lock   (0x1f) Quality= Poor Signal= -38.00dBm C/N= 29.39dB UCB= 56164210 postBER= 2.07x10^-3 PER= 51.1x10^-3
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 29.99dB UCB= 56166370 postBER= 2.87x10^-3 PER= 72.0x10^-3
Viterbi(0x07) Quality= Poor Signal= -37.00dBm C/N= 31.02dB UCB= 56166699 postBER= 666x10^-6 PER= 16.5x10^-3
Got parameters for DVBT:
FREQUENCY = 522000000
MODULATION = QAM/64
BANDWIDTH_HZ = 8000000
INVERSION = OFF
CODE_RATE_HP = 3/4
CODE_RATE_LP = 1/2
GUARD_INTERVAL = 1/8
TRANSMISSION_MODE = 8K
HIERARCHY = NONE
DELIVERY_SYSTEM = DVBT
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 29.11dB UCB= 56169384 postBER= 3.31x10^-3 PER= 82.7x10^-3
Lock   (0x1f) Quality= Poor Signal= -38.00dBm C/N= 29.28dB UCB= 56171100 postBER= 2.30x10^-3 PER= 57.2x10^-3
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 29.26dB UCB= 56173713 postBER= 2.55x10^-3 PER= 63.4x10^-3
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 28.99dB UCB= 56175735 postBER= 2.72x10^-3 PER= 67.4x10^-3
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 29.11dB UCB= 56177631 postBER= 2.53x10^-3 PER= 63.2x10^-3
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 29.27dB UCB= 56180366 postBER= 2.76x10^-3 PER= 68.9x10^-3
Viterbi(0x07) Quality= Poor Signal= -37.00dBm C/N= 29.32dB UCB= 56181678 postBER= 2.63x10^-3 PER= 65.6x10^-3
Got parameters for DVBT:
FREQUENCY = 522000000
MODULATION = QAM/64
BANDWIDTH_HZ = 8000000
INVERSION = OFF
CODE_RATE_HP = 3/4
CODE_RATE_LP = 1/2
GUARD_INTERVAL = 1/8
TRANSMISSION_MODE = 8K
HIERARCHY = NONE
DELIVERY_SYSTEM = DVBT
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 29.55dB UCB= 56183487 postBER= 2.42x10^-3 PER= 60.3x10^-3
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 29.20dB UCB= 56186533 postBER= 2.98x10^-3 PER= 74.6x10^-3
Lock   (0x1f) Quality= Poor Signal= -38.00dBm C/N= 29.41dB UCB= 56188246 postBER= 2.30x10^-3 PER= 57.1x10^-3
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 29.16dB UCB= 56190289 postBER= 2.74x10^-3 PER= 68.1x10^-3
Lock   (0x1f) Quality= Poor Signal= -37.00dBm C/N= 29.16dB UCB= 56193137 postBER= 2.97x10^-3 PER= 74.3x10^-3

Saen Acro

You have all timeUCB Un Corrected Bits

compare mine



# dvb-fe-tool --femon -v -a1
Device Afatech AF9033 (DVB-T) (/dev/dvb/adapter1/frontend0) capabilities:
     CAN_FEC_1_2
     CAN_FEC_2_3
     CAN_FEC_3_4
     CAN_FEC_5_6
     CAN_FEC_7_8
     CAN_FEC_AUTO
     CAN_GUARD_INTERVAL_AUTO
     CAN_HIERARCHY_AUTO
     CAN_INVERSION_AUTO
     CAN_MUTE_TS
     CAN_QAM_16
     CAN_QAM_64
     CAN_QAM_AUTO
     CAN_QPSK
     CAN_RECOVER
     CAN_TRANSMISSION_MODE_AUTO
DVB API Version 5.11, Current v5 delivery system: DVBT
Supported delivery system:
    [DVBT]
Got parameters for DVBT:
FREQUENCY = 626000000
MODULATION = QAM/64
BANDWIDTH_HZ = 8000000
INVERSION = AUTO
CODE_RATE_HP = 2/3
CODE_RATE_LP = 1/2
GUARD_INTERVAL = 1/4
TRANSMISSION_MODE = 8K
HIERARCHY = NONE
DELIVERY_SYSTEM = DVBT
Lock   (0x1f) Signal= 59,01% C/N= 0,00% UCB= 0 postBER= 0
Lock   (0x1f) Signal= 59,22% C/N= 0,00% UCB= 0 postBER= 0
Lock   (0x1f) Signal= 59,23% C/N= 0,00% UCB= 0 postBER= 0
Lock   (0x1f) Signal= 59,15% C/N= 0,00% UCB= 0 postBER= 0
Lock   (0x1f) Signal= 59,28% C/N= 0,00% UCB= 0 postBER= 0
Lock   (0x1f) Signal= 58,76% C/N= 0,00% UCB= 0 postBER= 0
Lock   (0x1f) Signal= 59,13% C/N= 0,00% UCB= 0 postBER= 0
Lock   (0x1f) Signal= 59,08% C/N= 0,00% UCB= 0 postBER= 0
Lock   (0x1f) Signal= 59,08% C/N= 0,00% UCB= 0 postBER= 0
Lock   (0x1f) Signal= 59,12% C/N= 0,00% UCB= 0 postBER= 0
Lock   (0x1f) Signal= 59,01% C/N= 0,00% UCB= 0 postBER= 0
Lock   (0x1f) Signal= 58,94% C/N= 0,00% UCB= 0 postBER= 0

You have signal problem, not software or hardware problem.

Sébastien Aubry

Hello,
I am going to check that, but since it is a collective installation, I hope that the problem is on my side: it will be difficult to correct it since it works for my neighbours and even on my TV with the same antenna cable.
A few things still make me doubt:
* The "poor signal" messages only occur after ~20 minutes, and go away if I restart the tuning.
* The same channel works fine on my TV either with the same antenna cable, or with another cable from the same amplifier even when the signal is poor on the PC.
* It used to work fine on my previous setup with an Hauppauge WinTV Nova-T-500 PCI card (but I do not have any PCI slot on my new motherboard!)
Don't you think it might also be an USB tuner or driver or OS or cable problem? I am going to test all that.
All my tests were performed on the most "difficult" multiplex, for which the signal is the weakest.

For example, here is what it gives on a "stronger" multiplex: attachment:dvb-fe-tool-594MHz.txt . No UCB, but still some postBER. The C/N switches between 28 and 67 dB...

I plan to run these tests:
* check with other cables (with and without amplifier)
* VDR PVR + dvb-fe-tool (to see if it is TVH related)
* Another laptop under Linux Mint with the same tuner
* Buy another TV tuner
Thanks again

Saen Acro

I my case i use antena with come with tuner.
Transmiter is 20km away and no problems except havy raining and thunder storms.

Sébastien Aubry

Good to know, thanks. Here I am in an old building with big walls, and the reception is supposed to be good, so I still want to investigate.

Flole

If you can turn down the amplifier even more try that, if you go in with a too strong signal there will be distortions. So amplifiers are not always good, if the signal is too strong it's like someone shouting in your ear: It hurts and you won't understand anything.

Saen Acro

Sébastien Aubry wrote:

> Good to know, thanks. Here I am in an old building with big walls, and the reception is supposed to be good, so I still want to investigate.

Are you shure that there is no other amplifier, before yours in building, after master antenna?
<<

Sébastien Aubry

Yes, there may be one. Mine is an indoor amplifier, I am not sure that it is necessary, I have bought it because I thought it might improve the signal. I will try with a direct cable between the PC and the plug, without the amplifier.
Thanks

Saen Acro

Sébastien Aubry wrote:
> Yes, there may be one. Mine is an indoor amplifier, I am not sure that it is necessary, I have bought it because I thought it might improve the signal. I will try with a direct cable between the PC and the plug, without the amplifier.

> Thanks

My guessing someone not pointed antenna good put amplifier boost it to max and there was "acceptable signal" and he leave it.
But antenna can move from wind snow birds etc.
Without spectral analyser cannot be done correct measurement.
<<

Brent McArthur

Why don’t you try a different Linux distribution to LibreELEC with all the same hardware and signal/cables? Rules out the OS and may save you buying new hardware.

We have the same manufacture USB tuner and appear to have the same issue here: https://tvheadend.org/d/7298-too-many-data-errors-on-pi-4-libreelec-kodi-tvheadend-addon?r=42110#message-42110

The Linux distro switch worked for me. I’ve had zero failed recordings since ditching LibreELEC.

Sébastien Aubry

Brent McArthur wrote:
> Why don’t you try a different Linux distribution to LibreELEC with all the same hardware and signal/cables? Rules out the OS and may save you buying new hardware.
>
> We have the same manufacture USB tuner and appear to have the same issue here: https://tvheadend.org/d/7298-too-many-data-errors-on-pi-4-libreelec-kodi-tvheadend-addon?r=42110#message-42110 >

> The Linux distro switch worked for me. I’ve had zero failed recordings since ditching LibreELEC.

Hello,
I have tried to begin the tests with your advice: I installed TVHeadend on an old laptop under Linux Mint and moved the same tuner/cable to this PC.
I used the command:

dvb-fe-tool --femon -v -c 2500 -a0 2>&1 | awk '{ print strftime("%Y-%m-%d %H:%M:%S"), $0; fflush(); }' | tee log.txt

in order to timestamp each line and to get the error output in the log file.

So far, it seems to me that this would be a software or hardware problem:

[edit] see table in the first post

I can provide the log or any details if you want to have a look.
Thank you all for your help.