[linux-dvb] Re: Twinhan DST / TS204 and signal quality questions

["Werner Johansson" <wj@yodel.net>]

----- Original Message ----- 
From: "Jukka Tastula" <jukka.tastula@kotinet.com>
To: <linux-dvb@linuxtv.org>
Sent: Sunday, August 15, 2004 2:57 PM
Subject: [linux-dvb] Re: Twinhan DST / TS204 and signal quality questions


> The ber/unc values can apparently be completely bogus and the signal and
> snr values are card specific. Some cards report and work with low values,
> some start giving errors at high numbers. Some cards (like my nebula)
> don't report any numbers at all. None of this has anything to do with how
> well the card actually performs. Just look at the picture to determine
> that: if it's perfect then you don't really care if it says 0.

Yes, exactly.. Well, I have glitches in the picture and audio from these
cards, and it's the same issues in several machines (even tried them one by
one in a W*****s box), same quality metering and same image issues from time
to time. There are no more than 2-3 glitches per minute though, but somehow
the STBs aren't affected. Having the tuner inside a PC chassis surely
doesn't help it, but isn't it supposed to be sufficiently shielded by the
metal box it sits in, or is this perhaps caused by power supply noise?

At least the TER card seems to give somewhat realistic values for signal
quality and snr as I get really low values (and eventually unlocked
frontend) when disconnecting the antenna. Similar behavior has been noted on
the SAT cards, even though the signal strength stays around the same values
whether or not an LNB is connected for some strange reason.

> From your dmesg output first thing I think might be worth trying is
turning
> off acpi irq routing and trying to give each card it's very own irq to
> abuse, not share them.

I will do some further digging into this, even though it doesn't seem to
corrupt packets on the bus itself. I can run two mplayers from the two cards
sharing IRQ 12 without problems except for the bad TS packets, but that's
the same issues I get with only one card in the box (and same on both Linux
and W*****s), which makes me believe that (for once) the ACPI stuff cannot
be blamed for this..

Regards,
Werner