[linux-dvb] Re: Signal monitoring with dvbtune -m

["Terry Lewis" <terry@kryogenic.co.uk>]

Oops, replied to author and not list, sorry :)

looks like you have added 167khz as opposed to 166666 hz

its freq = ((channel no)*8+306)+/-166666

> 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
>
>
>


Regards,
Terry Lewis