[linux-dvb] Lifeview LR306 clone does not receive ch 7.

Peter D. peter_s_d at fastmail.com.au
Mon Sep 18 06:38:05 CEST 2006

On Sunday 17 September 2006 16:18, Philip Shead wrote:
> Hartmut Hackmann wrote:
> > Hi,
> >
> > Peter D. wrote:
> >> On Friday 15 September 2006 06:16, Hartmut Hackmann wrote:
> >>> Hi, Peter
> >>>
> >>> Peter D. wrote:
> >>>> Hi,
> >>>>
> >>>> I have an MSI TV at nywhere A/D that mostly works when "saa7134
> >>>> card=94" is in /etc/modprobe.preload.  One of the interesting
> >>>> quirks is that it does not recognize digital channel 7.  (I
> >>>> think that that is transmitted on physical channel 6.)  It can
> >>>> find and display all of the other channels, digital and
> >>>> analogue, in the local area (Melbourne Australia).  Signal
> >>>> strength should be O.K. My other dvb-t card can receive all of
> >>>> the local channels, including ch 7.
> >>>>
> >>>> Any clues?
> >>>
 > >>> This can easily be a problem in your channels.conf file. There
> >>> are 2 possible causes:
> >>> - some onf the conding parameters like FEC or GI are wrong.
> >>> Some channel decoder ignore them, the driver for the tda10046
> >>> does not. - In some countries, the transmitters are +/- 167kHz
> >>> off the center frequencies. With the current driver, the
> >>> tda10046 can't lock with this offset,you need to correct the
> >>> center frequency.
> >>
> >> How do you determine what the correct center frequency is? 
> >> Trial and error edits to /etc/dvb/channels.conf-dvbt-australia? 
> >> Or do I just wait until the driver evolves to the standard of
> >> the driver for the Kworld with its cx8800?
> >
> > Try and error or search for appropriate information.
> > I will change the locking algorithm some time. But this is a
> > difficult change and definitely not be there within few days.
>   Well I'm bemused by this. I have had the same card in my desktop
> box (with no other pci card in it) and I had perfect service
> on all 5 channels (working off the same frequencies as Peter D).
> But today I pulled it out of that machine and stuck it in
> my mythbox (with a Visionplus branded Twinhan card (dvb-bt8xx)
> and a Kworld DVB-T card (using cx88-dvb)) and I am now
> suffering the exact same problem with Channel 7 being unable
> to tune. This machine has a much better antenna input (being
> a short better shielded cable from a wall socket v 3 cables
> strung together over 10m) and even skipping the passthrough
> on the kworld and putting the  antenna into the msi card by
> itself Channel 7 is not visible. 

So, when the signal goes from the wall socket to the Kworld DVB-T card 
in the first computer, out of the Kworld, across the room, into the 
MSI in a different computer it can tune to channel 7.  But when the 
signal goes directly from the wall socket to the MSI it can not tune 
to channel 7.  This is interesting.  

> On both machines I have a 
> very old version of kaxtv (0.23) (config file copied from one
> to the other) and on one the card could receive the missing
> channel but on other it does not work.

My other card is a Kworld V-Stream Xpert DTV DVB-T with Connexant 
chips and a Zarlink tuner.  

Something is interacting badly with something else.  It could be that 
each component behaves by itself but the system is unstable, or maybe 
one (or more) component is broken in such a way that a simple system 
can cope but a complex one can not.  

Maybe the signal strength is too strong.  I'll try attenuating it 

Maybe EMF from one card is interfering with the other.  I might try 
putting an insulated sheet of metal between the cards.  That could be 
rather nasty if I short things out.  

Other people are running multiple tuner cards, so I guess it is 
unlikely that one driver is interfering with the other - unless there 
is something really odd about the MSI. 

Peter D.
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