[mythtv-users] MtrhTv: Uk Mendip Transmitter issues

Terry Barnaby terry1 at beam.ltd.uk
Sun Jul 4 17:29:57 UTC 2010


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:
>>> tune to:
>>> tune to:
WARNING: >>> tuning failed!!!
>>> tune to:
WARNING: >>> tuning failed!!!
>>> tune to:
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 ?



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