[mythtv-users] MtrhTv: Uk Mendip Transmitter issues

[John Pilkington]

On 04/07/10 18:29, Terry Barnaby wrote:
> Hi,
>
> I have been having quite a problem to get MythTv to work well after
> the Multiplex changes on the Mendip transmitter in April.
> Apart from issues where neighbouring transmitter multiplexes
> that are are found (from info from the Mendip transmitters
> info lists) and added to the list, which I have got around,
> the main issue is that I don't seem to be able to tune to
> channels from the "A" Multiplex.
>
> I have been playing around with dvbscan to check things out and
> to make sure by signal levels etc are about right. However
> I see a strange issue. If I give dvbscan the main "PSB1"
> multiplex to start with if finds the other multiplexes but
> gets some of the parameters wrong.
>
> The correct settings I believe are:
> T 794000000 8MHz 2/3 NONE QAM64 8k 1/32 NONE # PSB1
> T 738000000 8MHz 2/3 NONE QAM64 8k 1/32 NONE # PSB2
> T 802167000 8MHz 2/3 NONE QAM64 2k 1/32 NONE # A
> T 754167000 8MHz 3/4 NONE QAM16 2k 1/32 NONE # C
> T 778167000 8MHz 3/4 NONE QAM16 2k 1/32 NONE # D
>
> These work when you manualy set them for dvbscan.
>
> However if dvbscan scans from the main multiplex it returns:
> initial transponder 794000000 0 2 9 3 1 0 0
>>>> tune to:
> 794000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_2_3:FEC_AUTO:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_32:HIERARCHY_NONE
>
>>>> tune to:
> 738000000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_2_3:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_32:HIERARCHY_NONE
>
>>>> tune to:
> 802167000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_2_3:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_32:HIERARCHY_NONE
>
> WARNING: >>> tuning failed!!!
>>>> tune to:
> 754167000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_2_3:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_32:HIERARCHY_NONE
>
> WARNING: >>> tuning failed!!!
>>>> tune to:
> 778167000:INVERSION_AUTO:BANDWIDTH_8_MHZ:FEC_2_3:FEC_1_2:QAM_64:TRANSMISSION_MODE_8K:GUARD_INTERVAL_1_32:HIERARCHY_NONE
>
> WARNING: >>> tuning failed!!!
>
> It has got the settings wrong in the last three multiplexes.
>
> Is this a bug in dvbscan or is the transmitter sending out the wrong
> info ??
>
> If I create channels.conf by manually adding the channels from each
> multiplex
> in turn (setting the parameters correctly) I can tune into the channels
> with tzap ok. If I use tzap to tune in "Virgin1" which is in multiplex A
> I get a lock, a reasonable signal level, a reasonable SignalToNoise
> ratio, and a low bit error rate between 0 and 8.
>
> If I use these Multiplex values and enter them into Mythtv as its
> transponders and re-scan for channels, all works fine and I get all of
> the channels listed.
> However if I try and tune to "Virgin1" I get no-lock.
>
> My feeling is that MythTv is also getting the DVB parameters wrong.
> Is there a way I can get MythTv (frontend or backend) to list the DVB
> parameters it is using ?
>
> Cheers
>
>
> Terry
>
Hi again (from the4 dev list): Have you looked at the 'Edit Transports' 
page in the Channel Editor section of mythtvsetup?  Mine shows 'QAM 
Auto', coderates Auto, but if you're dissatisfied you can select 
specific values;  don't know if it works but maybe worth a shot.

There might also be a hardware link.  I have Freecom dvb-t stick from 
about 2006 that used to work but then failed to tune the BBC Four mux, I 
think because it can't pass the full transport stream to the demuxers. 
The hardware wiki - and maybe dmesg - might show if that was likely to 
be a problem for you.

John P