[mythtv-users] Can't tune after UK switchover

John Pilkington J.Pilk at tesco.net
Thu Jul 14 11:01:53 UTC 2011


On 14/07/11 11:33, David Watkins wrote:
> On 14 July 2011 10:50, john legion<johnlegion6 at gmail.com>  wrote:
>> Hi All,
>>
>> I am in Edinburgh and previous to the digital switchover I was able to see
>> two transmitters, Blackhill and Craigkelly.
>> Subsequent to the switchover I can no longer get  Mythtv to lock onto any
>> channel on either transmitter.
>>
>> When I retuned I could see most multiplexes on both of the transmitters but
>> not all.
>> I have tried tuning using full scan in Myth, scan of existing transports,
>> scan of existing transports where I had manually edited the transports to
>> only include the few I would need and also by importing channels.conf .
>>
>> All of these methods according to Mythtv have found>100 channels and so
>> everything seems good but when I go into the frontend then I can't watch
>> live TV because the channel never gets past partial lock, even though the
>> signal strength is ~75% .
>>
>> Also , no matter what I do I can't see any EIT data on any channel .
>>
>> With the ariel connected directly to my TV I can see all channels and EIT
>> data. I can also play tv through Xine on the backend server so I guess that
>> the ariel and card are working, it just seems to be some issue with Mythtv.
>>
>> Is anyone else seeing the same or does anyone have any suggestions ?
>
> I'm only guessing but:
>
> 1) Are you using an aerial amplifier or amplified splitter?  Digital
> signal strength may have increased significantly following switchover
> and it's possible you're saturating the capture card input.  I live
> quite close the Crystal Palace transmitter and have to use an
> attenuator with one of my capture cards.
>
> 2) It's also possible that, if the digital multiplexes have changed
> frequency,  your antenna is no longer suitable.  As I understand it,
> DVB multiplexes can use channel frequencies within the analog TV
> channel range, in which case an old 'analog'  antenna will work fine,
> or use frequencies outside that range, in which case it may not work
> so well.
>
> 3) It's also possible that, now the broadcast power has been
> increased, your two transmitters are interfering with each other and
> you need a more directional antenna.
>
> I'd hope for option 1 if I were you!
>
> Good Luck.

There have been several similar threads on this list as different 
regions have entered switchover.  The first thing to do is to delete all 
your existing digital channels - which requires a high level of trust 
but really is important.  Then you ought to decide which transmitter you 
want to use and enter just one of its mux frequencies into the transport 
editor, tick the 'search for other muxes' box and try a tuned scan. 
With luck this might populate 4 other transports - or 5 if you have 
dvb-t2.  If you don't get the luck try a few more searches on 
gossamer-threads!

Cheers,

John P




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