[mythtv-users] known issues related to DVB-T in Australia (was: Channel tuning broken in 0.24)

[Vincent McIntyre]

On 6/6/12, Igor Cicimov <icicimov at gmail.com> wrote:

>
> Please don't take this as attack on myth I never had any intention doing
> that and I never will. I love myth and a problem tuning couple of channels
> will not stop me using this great product. There are lots of awesome stuff
> one can do with myth and it comes for free! My thread literally started
> with the question "Does anyone know about any changes in MythTV or cx88-dvb
> kernel driver that might affect the tuning of this card". I was not
> winging, accusing or complaining I simply asked for other peoples
> experience. And from couple of threads I've been following came out that
> people in general have tuning problems with Leadtek WinFast DTV2000 H (my
> is revision J).
>
> Just for the record, editing the frequencies in the dtv_multiplex table ie
> adding 125KHz to the transport, didn't make any difference for me. The
> channels that have tuned fine are still tuning fine and the ones that
> didn't still suck. This channels like GO and GEM can't acquire a proper
> lock, come up with horrible picture for a second and lock the
> frontend completely.
>

In my area these chanels are in the same multiplex as channel 9 (i.e.
'good' channels) so should be at the same carrier frequency. Are there
other misbehaving channels?
FWIW this is from my channels.conf (scanned with w_scan, July 2011).

% grep Nine channels.conf
NINE DIGITAL(Nine
Network):191625000:INVERSION_AUTO:BANDWIDTH_7_MHZ:FEC_3_4:FEC_NONE:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:519:720:1057
GEM(Nine Network):191625000:INVERSION_AUTO:BANDWIDTH_7_MHZ:FEC_3_4:FEC_NONE:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:512:0:1058
GO!(Nine Network):191625000:INVERSION_AUTO:BANDWIDTH_7_MHZ:FEC_3_4:FEC_NONE:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_16:HIERARCHY_NONE:517:700:1059


It may be worth asking about this on the linux-media list as there
were some changes specifically to do with tuning in Australia in the
last couple of years that affected my cards (which use
tuners-xc2028.c), eg [1]. There may still be issues with other
drivers.
You can look at the history of the driver yourself at [2] - in fact a
quick squiz shows explicit mention of something that looks like it
could be your card.

You may need to be prepared to run tests with w_scan etc and build the
latest drivers to get this fixed. And precise hardware ids, see lspci
etc below. Adventure calls!

For the record - I think my tuners are working ok now (myth 0.24-fixes
and ubuntu lucid) but in the past I have had to create a channels.conf
and import it. I'll try some tests when I upgrade to 0.25.

% lspci -kv
04:00.0 Multimedia video controller: Conexant Systems, Inc. CX23885
PCI Video and Audio Decoder (rev 02)
        Subsystem: DViCO Corporation Device db78
        Flags: bus master, fast devsel, latency 0, IRQ 19
        Memory at 90000000 (64-bit, non-prefetchable) [size=2M]
        Capabilities: [40] Express Endpoint, MSI 00
        Capabilities: [80] Power Management version 2
        Capabilities: [90] Vital Product Data <?>
        Capabilities: [a0] Message Signalled Interrupts: Mask- 64bit+
Queue=0/0 Enable-
        Capabilities: [100] Advanced Error Reporting <?>
        Capabilities: [200] Virtual Channel <?>
        Kernel driver in use: cx23885
        Kernel modules: cx23885

% modinfo cx23885|grep version
srcversion:     8B372C18D81D94481D3C03E
vermagic:       2.6.32-41-generic SMP mod_unload modversions 586

(Dvico FusionHDTV, rev 2 I think)

% lsusb
Bus 003 Device 003: ID 0fe9:db78 DVICO FusionHDTV DVB-T Dual Digital 4
(ZL10353+xc2028/xc3028) (initialized)
Bus 003 Device 002: ID 0fe9:db78 DVICO FusionHDTV DVB-T Dual Digital 4
(ZL10353+xc2028/xc3028) (initialized)

(One PCI card with two USB tuners, also happens to use cx23885)

Cheers
Vince

[1] http://git.linuxtv.org/media_tree.git/commit/7f2199c03b4946f1b79514b3411e3dbf130a6bba
[2] http://git.linuxtv.org/media_tree.git/history/HEAD:/drivers/media/video/cx88