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

[Nigel Jewell]

Hi,

On 09/07/2011 20:32, Alex Butcher wrote:
>
> I'm surprised that your parameters for some of the other mplexes differ,
> given we're both receiving from the Mendip transmitter:
>

If I use dvbscan or dvbsnoop I can see 7 usable multiplexes from where 
we are:

794000000 FEC_2_3 QAM_64 TRANSMISSION_MODE_8K
738000000 FEC_2_3 QAM_64 TRANSMISSION_MODE_8K
802166670 FEC_2_3 QAM_64 TRANSMISSION_MODE_2K
802167000 FEC_2_3 QAM_64 TRANSMISSION_MODE_8K
754166670 FEC_3_4 QAM_16 TRANSMISSION_MODE_2K
754167000 FEC_2_3 QAM_64 TRANSMISSION_MODE_8K
842000000 FEC_2_3 QAM_64 TRANSMISSION_MODE_8K *

* As already discussed, this doesn't show.

Two of which carry the same channels another multiplex:

802166670 FEC_2_3 QAM_64 TRANSMISSION_MODE_2K same as
802167000 FEC_2_3 QAM_64 TRANSMISSION_MODE_8K

and

754166670 FEC_3_4 QAM_16 TRANSMISSION_MODE_2K same as
754167000 FEC_2_3 QAM_64 TRANSMISSION_MODE_8K

According to: 
http://stakeholders.ofcom.org.uk/binaries/broadcast/guidance/tech-guidance/West.pdf

"The centre frequency, Fc (in Megahertz) of the multiplex can be 
calculated using Fc=8n+306, where n is the UHF channel number.  A + or - 
following the channel number indicates that the frequency is offset by 
+0.167MHz or -0.167MHz with respect to the channel centre."

Which would make 802167000 and 754167000 correct, however I appreciate 
that the may be be rounding up to 0.167 for the document.

However, the same document also states:

"The post-switchover transmission mode for all multiplexes except BBC B 
is 64QAM modulation, coding rate 2/3, & 8K FFT."

Which would also make 802167000 and 754167000 correct.

However - this goes against what is documented on ukfree.tv.  As to 
which source to use and which multiplex parameters I guess it doesn't 
make a huge difference (in the short term).

> Still, if it 'ain't broke...

Absolutely.

Regards,
Nige.