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Linux drivers - bad signal level / quality

Linux drivers - bad signal level / quality

Postby andersh » Fri Dec 04, 2015 1:58 am

I've been using this card with MediaPortal in Windows for a while and it's been working fine.

Recently I've been testing TVHeadend and Linux, using the same machine and card, just dual booting operating systems. Using Ubuntu 15.10 server.

uname -a:
Linux slemmehtpc 4.2.0-19-generic #23-Ubuntu SMP Wed Nov 11 11:39:30 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux

What I notice is that the signal quality seems to be less under Linux, causing slight problems and some continuity errors.

Under Windows using MediaPortal I see both signal level and quality around 95, while under Linux I see signal levels at 83-85 and SNR at 55-58. See attached screenshots.

Both systems are using the latest drivers from your download site - and I'm using DVB-C.

Any suggestions on how to improve the Linux driver quality?
Attachments
lspci.out.gz
(1.81 KiB) Downloaded 352 times
tvh_nrk1.png
mp_nrk1.png
andersh
 
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Re: Linux drivers - bad signal level / quality

Postby cody » Mon Dec 14, 2015 5:42 am

the signal level in Linux is closer to the real one, not the one in Windows. in fact no signal statistics in percentage can be real, because the hardware measures that in dB and dBm and there is no such thing as dB and dBm to percentage conversion. that is also why you see those different levels - because in each os those dB and dBm values are converted to percentage with different "fake" calculation, but the initial dB and dBm retuened by the hardware are the same - you can be sure in that as your signal is the same.

on the other question about the continuity errors - do those increase over time in Linux? what i see is few such errors on your screenshot and that usually happens at the beginning when you switch to the mux - because there are data buffer from the old tune, here you can read:

viewtopic.php?f=168&t=9484&sid=29b42da94354043dc4b9a525775f30f5#p33882

how to tell tvheadend to make sure skip enough bytes after tune to new mux is made.
cody
 
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Re: Linux drivers - bad signal level / quality

Postby andersh » Tue Dec 15, 2015 4:29 am

Thanks for the clarification on signal levels.

The continuity errors seem to appear at random intervals while watching TV.

Typical result from a 20 minutes session watching a single channel:

Dec 14 21:05:12 slemmehtpc tvheadend[18476]: subscription: 01D2: "10.0.0.109 [ kodi | Kodi Media Center ]" unsubscribing from "TV2 HD", hostname="10.0.0.109", username="kodi", username="Kodi Media Center"
Dec 14 21:05:12 slemmehtpc tvheadend[18476]: capmt: tvheadend: Removing CAPMT Server from service "TV2 HD" on adapter 3
Dec 14 21:09:20 slemmehtpc tvheadend[18476]: TS: GET/256MHz/NRK1 HD: H264 @ #512 Continuity counter error (total 1)
Dec 14 21:09:20 slemmehtpc tvheadend[18476]: TS: GET/256MHz/NRK1 HD: MPEG2AUDIO @ #640 Continuity counter error (total 1)
Dec 14 21:09:20 slemmehtpc tvheadend[18476]: TS: GET/256MHz/NRK1 HD: TELETEXT @ #576 Continuity counter error (total 1)
Dec 14 21:09:20 slemmehtpc tvheadend[18476]: TS: GET/256MHz/NRK1 HD: AC3 @ #641 Continuity counter error (total 1)
Dec 14 21:10:41 slemmehtpc tvheadend[18476]: TS: GET/256MHz/NRK1 HD: H264 @ #512 Continuity counter error (total 5)
Dec 14 21:10:41 slemmehtpc tvheadend[18476]: TS: GET/256MHz/NRK1 HD: TELETEXT @ #576 Continuity counter error (total 5)
Dec 14 21:10:41 slemmehtpc tvheadend[18476]: TS: GET/256MHz/NRK1 HD: AC3 @ #641 Continuity counter error (total 5)
Dec 14 21:10:41 slemmehtpc tvheadend[18476]: TS: GET/256MHz/NRK1 HD: MPEG2AUDIO @ #640 Continuity counter error (total 5)
Dec 14 21:10:41 slemmehtpc tvheadend[18476]: TS: GET/256MHz/NRK1 HD: DVBSUB @ #601 Continuity counter error (total 1)
Dec 14 21:17:01 slemmehtpc CRON[29713]: (root) CMD ( cd / && run-parts --report /etc/cron.hourly)
Dec 14 21:25:17 slemmehtpc tvheadend[18476]: TS: GET/256MHz/NRK1 HD: H264 @ #512 Continuity counter error (total 7)
Dec 14 21:25:17 slemmehtpc tvheadend[18476]: TS: GET/256MHz/NRK1 HD: AC3 @ #641 Continuity counter error (total 7)
Dec 14 21:25:17 slemmehtpc tvheadend[18476]: TS: GET/256MHz/NRK1 HD: TELETEXT @ #576 Continuity counter error (total 7)
Dec 14 21:25:17 slemmehtpc tvheadend[18476]: TS: GET/256MHz/NRK1 HD: MPEG2AUDIO @ #640 Continuity counter error (total 7)
andersh
 
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Re: Linux drivers - bad signal level / quality

Postby cody » Mon Dec 21, 2015 3:59 pm

what about measure for 20-30 mins the errors with TransEdit?
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Re: Linux drivers - bad signal level / quality

Postby andersh » Mon Dec 21, 2015 4:53 pm

cody Wrote:what about measure for 20-30 mins the errors with TransEdit?

I don't know that TransEdit is, but Google indicates that this is something related to dvbviewer, which I don't use but believe is Windows only?
andersh
 
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Re: Linux drivers - bad signal level / quality

Postby andersh » Tue Jan 12, 2016 3:37 pm

After upgrading to the latest driver (151229) this problem got significantly worse, and I started to see continuity errors every minute or two.

Reverted back to the previous driver (151105) and am now back to seeing occasional continuity errors but there's at least 10-15 minutes between them.
andersh
 
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Re: Linux drivers - bad signal level / quality

Postby cody » Tue Jan 12, 2016 3:53 pm

andersh Wrote:After upgrading to the latest driver (151229) this problem got significantly worse, and I started to see continuity errors every minute or two.

Reverted back to the previous driver (151105) and am now back to seeing occasional continuity errors but there's at least 10-15 minutes between them.


there is no even single line of code difference for 6205 Linux driver between release v151105 and v151229, that's why my suggestion is still the same - instead believe the problem related to Linux, test your signal and computer in Windows with TransEdit. that will rule out a lot of things. i have no other ideas - 6205 is very popular in Linux, you're the only one that have complains. so, it has to be something isolated to your side - either signal, computer or your particular 6205 card. that's why i suggested even before test wth TransEdit in Windows - that way rule out software problem, because there is nothing in common between Windows and Linux on such test.
cody
 
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Re: Linux drivers - bad signal level / quality

Postby andersh » Tue Jan 12, 2016 9:39 pm

And how do I obtain TransEdit? As far as I can see that is only available for registered DVBviewer installations. It was not included in the DVBviewer demo installation.

As I pointed out in my initial post, this was working fine under Windows with MediaPortal. I am now on exactly the same hardware, but running Linux and TVHeadend.

I just did a test, booting the machine back up in Windows and see that MediaPortal reports Signal Level and Quality in the 90s and I have no discontinuities at all.
andersh
 
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