[linux-dvb] Re: Frontend patch

[Ragnar Sundblad <ragge@nada.kth.se>]

--On den 17 mars 2003 07:32 +0100 Nils Ohlmeier <nils.ohlmeier@web.de> 
wrote:

> I have a very lousy signal here in Berlin. Most channels have a siganl
> level  of 4xxx in tzap (im still searching for the reason for this low
> signal).
This i a TT DVB-T card with an ALPS TDLB7 tuner and a SP8870
frontend, right?
If so, I think 4xxx is a pretty good signal level.

> But i also tried it with fixed values of 2 and 3 as third parameter for
> sp5659_set_tv_freq() (instead of the zero). And with a value of 3 i have
> a  stable picture and sound nearly immediately on every channel.
> The disadvantage seems to be that sometimes i get on switching only a
> black  screen without sound. Then i have to switch to a complete
> different  frequence, before a i can switch successful to the desired
> channel.
>
> As you notice i do not know what i'm doing here. It is more trial and
> error :)
As I have described earlier in this list I had simlar problems, and
played with both the PLL power and the PLL divider (to get faster
feedback to the PLL) and could improve the situation, but never got
it really good. It mostly seems to have been because I had a lousy
12V feed, I ended up replacing the power supply and moved a 12V fan
which was connected to the mother board to a separate connector.
If you want to get more info about playing with your tuner you
are welcome to contact me, but I'd first check the power supply.

I still have another interresting problem though, which I as far
as I know am the only one to have:
I need to run an older firmware in the SP8870 than any other
person I have spoken with, or I get serious disturbances,
shown as intermitten higher BER every 2-5 seconds with for
example tzap on one of four channels, and the same problem but
maybe only every 10 seconds and not as bad on another channel.
On the two last frequencies it doesn't matter which firmware I run.

$ ls -l /usr/lib/DVB/driver/frontends/
-rwxr-xr-x    1 root     root        19920 Oct  6  1999 Sc_main.mc
-rw-r--r--    1 root     root        20108 Jun  6  2001 Sc_main.mc.new
-rwxr-xr-x    1 root     root        19920 Oct  6  1999 Sc_main.mc.old

This is really annoying, I don't understand it at all.

/ragge




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