[mythtv-users] UK DVB-T Mendip Tuning Fails with Error: Wrong PMT

[Nigel Jewell]

Hi,

Alex - thanks again for your reply.  I've solved this issue.

On 06/07/2011 21:23, Alex Butcher wrote:
> On Wed, 6 Jul 2011, Nigel Jewell wrote:
>
>> Up until about 2 months ago I was able to receive all Freeview channels
>> on my MythTV box without any issues using a Hauppage Nova-T DVB card
>> from the Mendip transmitter, however at the end of May I noticed that
>> all channels on a single multiplex were failing to tune.
> ISTR that coincided with a change in the broadcasting parameters and/or
> frequencies. A quick Google can't confirm that, however.

I have a script that I run a few times a day that uses dvbscan to spot 
new channels and multiplexes (the tuning within MythTV has never worked 
for me as it seems to lock onto lower power transmitters from 
elsewhere).  It compares with what it finds with the channel and 
dtv_multiplex tables and emails me any differences.  That way I spot 
channel changes and multiplex changes quickly without having to go 
through the pain of scanning from within MythTV.  It has worked fine for 
years - you can guess where this is going

>> If I plug the aerial directly into my TV (which also has a Freeview
>> tuner) I receive all channels with good quality, so I can safely assume
>> that I should be able to pick it up.
>>
>> Using dvbscan as:
>>
>> /usr/bin/scandvb -u -vvv uk-Mendip
> The tuning files aren't being kept up-to-date, in my experience.

Agreed.  Based upon dvbscan and dvbsnoop I am using the following.  
Neither tool reported QAM16 or a 2k mode - and so whilst they may be 
listed on ukfree.tv, it isn't what the tools see.

# C54
T 738000000 8MHz 2/3 1/2 QAM64 8k 1/32 NONE
# C56+
T 754167000 8MHz 2/3 1/2 QAM64 8k 1/32 NONE
# C58
# .........................................
# C61
T 794000000 8MHz 2/3 1/2 QAM64 8k 1/32 NONE
# C62+
T 802167000 8MHz 2/3 1/2 QAM64 8k 1/32 NONE
# C67
T 842000000 8MHz 2/3 1/2 QAM64 8k 1/32 NONE

>> Any ideas?  I'm not sure where to begin with this as it could be a fault
>> of the signal, of the kernel drivers, or of MythTV ... or maybe my
>> channel configuration data ...
> You will need to adjust the contents of your dtv_multiplex table.

You're right, and it was the differences you had that pointed me in the 
right direction.  I had incorrect settings and transport id for C67.  I 
believe it was the transport id that was causing tuning to fail.

It wasn't picked up by my script because it appears that the DVB 
descriptor for that multiplex isn't broadcast with all of the setup 
information.

I now have the following multiplex entries:

mysql> select frequency, bandwidth, hp_code_rate, lp_code_rate, 
modulation, transmission_mode, guard_interval, hierarchy, transportid 
from dtv_multiplex order by frequency\G
*************************** 1. row ***************************
         frequency: 738000000
         bandwidth: 8
      hp_code_rate: 2/3
      lp_code_rate: 1/2
        modulation: qam_64
transmission_mode: 8
    guard_interval: 1/32
         hierarchy: n
       transportid: 8204
*************************** 2. row ***************************
         frequency: 754167000
         bandwidth: 8
      hp_code_rate: 2/3
      lp_code_rate: 1/2
        modulation: qam_64
transmission_mode: 8
    guard_interval: 1/32
         hierarchy: n
       transportid: 20544
*************************** 3. row ***************************
         frequency: 794000000
         bandwidth: 8
      hp_code_rate: 2/3
      lp_code_rate: 1/2
        modulation: qam_64
transmission_mode: 8
    guard_interval: 1/32
         hierarchy: n
       transportid: 4161
*************************** 4. row ***************************
         frequency: 802167000
         bandwidth: 8
      hp_code_rate: 2/3
      lp_code_rate: 1/2
        modulation: qam_64
transmission_mode: 8
    guard_interval: 1/32
         hierarchy: n
       transportid: 12294
*************************** 5. row ***************************
         frequency: 842000000
         bandwidth: 8
      hp_code_rate: 2/3
      lp_code_rate: 1/2
        modulation: qam_64
transmission_mode: 8
    guard_interval: 1/32
         hierarchy: n
       transportid: 16514
5 rows in set (0.00 sec)

Thanks again for your reply - your comments were very helpful.

Regards,
Nige.
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