[mythtv-users] multiple transmitters - same channel - DVB Australia
mythtv at cain.id.au
Wed Mar 19 04:41:15 UTC 2014
> I have been using Mythtv for some years, however, recently here in
> Sydney Australia they have been retuning the digital (DVB) transmit
> frequencies.So I took the opportunity to re-scan my channels.However, I
> am in range of a number a transmitters and in some instances they are
> carrying the same services but signal strength and quality varies
> between them.
> I allocated different channels for the different transmitters in order
> to compare the quality of my reception from each source.However, I
> believe myth is not tuning to each but defaulting to a particular
> transmitter, regardless of the channel selected.
> So I had a look at some of the tables in mythconverg to try to
> determine why that may be.When checking channelscan_channel and
> channelscan_dtv_multiplex it appears that the latest scan correctly
> identify the same channel information with multiple entries for each
> frequency.I also checked dtv_multiplex, however, this table did not
> have all the available frequencies listed.It would seem that where
> transportid and networkid are identical for two different frequencies
> then only one of the frequencies is shown.
> So my questions are;
> Can mythtv show the same channel (2 channels with identical
> transportid, networkid and serviceid)but on different frequencies?
> If not how can you choose which transmitter between multiples
> transmitting the same channels?
I'd like to re-clarify the statement above as it may be confusing.
I have 2 sources of the same channel. (Same technology - DVB - same tuner -
Here in Sydney I can receive the ABC1 channel from the Gore Hill transmitter
on a frequency of 226500000, it has a transportid of 545 and a networked of
4112. During the myth-scan I assign this as channel 2 with it being
automatically assigned a callsign of ABC1.
An identical transmission is also broadcasts ABC1 from the South-West Sydney
transmitter on a frequency of 620500000, it also has a transportid of 545
and a networked of 4112. During the myth-scan I assign this as channel 200
with it being automatically assigned a callsign of ABC1.
Both channel 2 and channel 200 can be selected and displayed by mythtv,
however, it appears to always set the tuner to 620500000 regardless of which
channel I choose.
When you check the database dtv_multiplex table there is no entry for
(I'm guessing the myth channel scanner sets the frequency to the last
scanned frequency where two channels have identical transportids?)
This is not a real problem if both channels are truly the same. However,
although the content is the same, the reception quality is not. Hence I
would like to be able to check both to see which is best and then select one
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