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Thread: [SOLVED] One channel won't work in MythTV

  1. #1
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    Sep 2005
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    [SOLVED] One channel won't work in MythTV

    Hardy x86_32, Fusion HDTV Pro tuner card, onboard intel graphics chip

    Am in Brisbane Australia.

    All channels except channel 7 work fine in MythTV.
    Using vlc 0.8.6h channel 7 (all including HD) work.

    Myth doesn't appear to be getting a channel lock on any of the channel 7 signals.

    Nothing obvious in the log, signal strength on all the other channels appears fine and like I said channel 7 works fine in vlc.

    I have gone into the backend and deleted and rescanned all the channels already twice and imported the working channels.conf that use vlc uses - everything except channel 7 in myth is fine.

    Nothing obvious in the logs (frontend or backend).

    Any ideas?

  2. #2
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    Feb 2008
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    Re: One channel won't work in MythTV

    Well that's weird What part of Brisbane? I'm in Camp Hill (southside) and get Seven/Seven HD fine.

    When trying to view the channel do a Ctrl-F7 (or is it Alt-F7 ?) this brings up the signal strength box. Check the strength and BE (Bit Error) values.


    One thing - what case and Power supply do you have? I had a Antec NSK2480 with the built in Earthwatts 380W PSU - it was interfering badly with Channel Seven. Once I replaced the PSU reception was much better.

  3. #3
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    Re: One channel won't work in MythTV

    Looks like you were right about the interference - deleted all the transports and that took the channels with them and rescanned and am getting a signal strength of 1% or 2 % on Seven HD - most HD channels I get 60+%.

    I will open the case and vacuum it out and see if that helps.

    Thanks

    BTW - am in Runcorn

  4. #4
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    Re: One channel won't work in MythTV

    I presume Seven SD is only 1-2% as well.

  5. #5
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    Re: One channel won't work in MythTV

    Hi,

    Only 1-2% signal quality, I'm suprised you get anything. On my system with 2 DVB-C cards I get problems when the signal strength is under about 45%.

    Try using tzap to tune to one of your bad channels and see what ber/unc (bit rate error/uncorrected block rate).

    Have a look here http://www.mythtv.org/wiki/index.php/Tzap

    Regards
    Ian Dobson
    Walking on water and writing software to specification is easy if they're frozen.

    My corner of the internet http://www.planet-ian.com

  6. #6
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    Re: One channel won't work in MythTV

    ian@tqft:~/.tzap$ tzap "7 HD Digital"
    using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
    tuning to 177500000 Hz
    video pid 0x0441, audio pid 0x0000
    status 00 | signal 0000 | snr 0000 | ber 00000000 | unc 00000000 |
    status 1e | signal 0000 | snr ffff | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 00a0 | snr ffff | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr ffff | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr fcfc | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr f4f4 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr e4e4 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr f1f1 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr f4f4 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr f6f6 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr fcfc | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr eeee | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr f2f2 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr f2f2 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr f6f6 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr fdfd | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr fefe | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr fcfc | ber 00000000 | unc 00000000 | FE_HAS_LOCK



    ian@tqft:~/.tzap$ tzap "7 Digital"
    using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
    tuning to 177500000 Hz
    video pid 0x0401, audio pid 0x0402
    status 00 | signal 0000 | snr 0000 | ber 00000000 | unc 00000000 |
    status 1e | signal 0000 | snr f6f6 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr f4f4 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr eded | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 01fc | snr f0f0 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr f2f2 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr fafa | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr f9f9 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr f2f2 | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal 0000 | snr f5f5 | ber 00000000 | unc 00000000 | FE_HAS_LOCK


    When opening Myth front end - watch tv and switching to 7 Digital or 7 HD only get a partial lock or no lock at at all.

    Reading the link about tzap - it notes the snr should be steady and I notice the data above indicates it isn't, whereas TEN HD has a steady signal to noise ratio


    ian@tqft:~/.tzap$ tzap "TEN HD"
    using '/dev/dvb/adapter0/frontend0' and '/dev/dvb/adapter0/demux0'
    tuning to 219500000 Hz
    video pid 0x0202, audio pid 0x0000
    status 00 | signal 0178 | snr 0000 | ber 00000000 | unc 00000000 |
    status 1e | signal 9fdc | snr ffff | ber 00000000 | unc 00000000 | FE_HAS_LOCK
    status 1e | signal a000 | snr ffff | ber 00000000 | unc 00000000 | FE_HAS_LOCK


    Options? Vacuum the inside of the machine? Is there a way to reduce the sensitivity of myth to the snr as vlc plays 7 HD fine?

  7. #7
    Join Date
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    Re: One channel won't work in MythTV

    Hi,

    Could you try increasing the tuning timouts in mythtv-setup. That might help abit. It looks as if mythtv isn't calculating the signal strength correctly.

    Regards
    Ian Dobson
    Walking on water and writing software to specification is easy if they're frozen.

    My corner of the internet http://www.planet-ian.com

  8. #8
    Join Date
    Feb 2008
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    124

    Re: One channel won't work in MythTV

    What's your aerial - rooftop? is it split between many devices?

  9. #9
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    Re: One channel won't work in MythTV

    Thanks all - increasing the timeout in the backend seemed to have done the trick.

    A bit slower changing channels in myth but sucj is life.

    When I change to any 7 - it shows 0% signal but gets a lock and plays fine now.

    On the aerial split - just one split. When the guy installed the antenna about 3 months ago he checked the readings - about 80dB here in the study at the wall outlet. We are halfway up the side of a hill and have a reasonably clear line of sight over the houses between us and the TV broadcast towers.

  10. #10
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    Re: One channel won't work in MythTV

    Quote Originally Posted by tqft View Post
    Thanks all - increasing the timeout in the backend seemed to have done the trick.

    A bit slower changing channels in myth but sucj is life.

    When I change to any 7 - it shows 0% signal but gets a lock and plays fine now.
    Weird but good Glad things worked out.

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