[linux-dvb] typhoon usb dvb-t card low signal

Bertrand Marquis bertrand.marquis at gmail.com
Sat Feb 25 12:34:00 CET 2006

Hi Patrick

Sorry for the last two messages, mistake in the address

Le Samedi 25 Février 2006 12:05, vous avez écrit :
> Hi Bertrand,
> On Sat, 25 Feb 2006, Bertrand Marquis wrote:
> > I am trying to make a Typhoon dvb-t usb to work under linux.
> >
> > When i plug the card, the kernel detects it correctly as a typhoon card,
> > load the firmware i downloaded in linuxtv and then the led is on. I am
> > then able to look for channels using scandvb and i can found all channels
> > available in my area.
> Very good.
> > The problem is that i have a really low signal:
> Actually the signal strength should give a value of the Signal power
> before any tuner/LNA/AGC of the board. A lot of boards currently supported
> don't give that value or it cannot be calculation due to the lack of
> floating point operations at kernel level.
> Furthermore your board has everyhting "hidden" in a firmware and the value
> you read from it is "pre-calculated". From the information we have we just
> assumed that it is a percent value, but we might be wrong.
> However, in DVB the signal strength is not so important. If BER and UNC is
> zero everything is OK and you will not have any bad video or something.
> I would not recommend this device and using its signal strength to find
> a good position for the antenna.
> > Under windows the typhoon application says that i have a signal of about
> > 95% and the same for the snr and then i can look television without
> > problems.
> >
> > But under linux i can see practically nothing and kaffeine says that my
> > signal is only 20%.
> And there is no TV visible?

i can see part of the images from time to time but then the player (mplayer, 
xine or kaffeine) give an error saying that i have a lack of resources.

Here is the output of mplayer:
           **** Your system is too SLOW to play this!  ****

Possible reasons, problems, workarounds:
- Most common: broken/buggy _audio_ driver
  - Try -ao sdl or use the OSS emulation of ALSA.
  - Experiment with different values for -autosync, 30 is a good start.
- Slow video output
  - Try a different -vo driver (-vo help for a list) or try -framedrop!
- Slow CPU
  - Don't try to play a big DVD/DivX on a slow CPU! Try some of the lavdopts,
    e.g. -vfm ffmpeg -lavdopts lowres=1:fast:skiploopfilter=all.
- Broken file
  - Try various combinations of -nobps -ni -forceidx -mc 0.
- Slow media (NFS/SMB mounts, DVD, VCD etc)
  - Try -cache 8192.
- Are you using -cache to play a non-interleaved AVI file?
  - Try -nocache.
Read DOCS/HTML/en/video.html for tuning/speedup tips.
If none of this helps you, read DOCS/HTML/en/bugreports.html.

In fact it seems like i have only part of the image and due to this the player 
is not able to decode the video.

There are only noises from time to time 
for the sound and every 10 seconds xine is redoing buffering to end saying 
that i have an error messaying that there are too much dropped frame. My 
processor is only between 10 and 20% use.

> > Does anyone has this problem and knows how to solve it ?
> What is the problem?
> regards,
> Patrick.
> --
>    Mail: patrick.boettcher at desy.de
>    WWW:  http://www.wi-bw.tfh-wildau.de/~pboettch/


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