[linux-dvb] Signal monitoring with dvbtune -m

[Tony Houghton <h@realh.co.uk>]

I've got a Hauppauge Nova-T card and I'm having reception problems with
the channels on a particular frequency (530167000Hz from Rowridge: ITV,
C4 etc). I get these sort of figures from
dvbtune -f 530167000 -m

Signal=52428, Verror=6160, SNR=65278dB, BlockErrors=0, (S|L|C|V|SY|)

The Verror fluctuates, 6160 is somewhere in the middle.  Despite it not
reporting any block errors the picture has obvious MPEG artefacts
constantly and it's quite unwatchable. The picture immediately starts
lagging badly behind the sound, then the sound disappears after about a
minute - except with vdr-xine, xine has usually crashed by then.

Other channels - at least the ones I care enough about to have checked
so far - seem OK. For 489833330Hz (BBC etc) Verror is around 50, for
556433330Hz (Channel 5 etc) it's around 1200. The other figures are the
same for all 3 frequencies and don't fluctuate.

I saw a mesasge in the archives which said that you should be able to
maintain a stable picture with Verror below 10000 and that these
figures:

Signal=13107, Verror=14191, SNR=47802dB, BlockErrors=0, (S|L|C|V|SY|)

should be "good" with some artefacts every few minutes with changing
atmospheric conditions. Assuming low Verror and high Signal and SNR are
good, my worst figures are better than that, but it's unwatchable.

If I ran dvbtune -m and kept an eye on the figures while I moved the
aerial would that be a good way to improve reception in case it isn't
aligned properly?

-- 
TH * http://www.realh.co.uk