[linux-dvb] Re: Budget DVB-C tuning problems; dirty solution

[Torbjörn Jansson <torbjorn.jansson@mbox200.swipnet.se>]

I have done some more testing and it looks like I can tune in to ESPN
directly after a coold boot when the computer has been off for some time and
get a good picture.
But if I leave czap running for a minute or so, ber starts to slowly
increase untill I can't watch anything anymore, after that the channel is
always bad no matter what I do.
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> -----Original Message-----
> From: linux-dvb-bounce@linuxtv.org 
> [mailto:linux-dvb-bounce@linuxtv.org] On Behalf Of Torbjörn Jansson
> Sent: Saturday, February 07, 2004 7:48 PM
> To: linux-dvb@linuxtv.org
> Subject: [linux-dvb] Re: Budget DVB-C tuning problems; dirty solution
> 
> When I used czap to tune to ESPN I was surprised that I got a 
> good picture
> and a very low ber, on this computer I usualy get a very bad 
> picture and
> high ber.
> 
> So I left czap running for a few minutes and after a while 
> the ber jumped up
> and the picture went realy bad just as it usualy is.
> Czap said that the signal was locked all the time.
> 
> Is it posibel that it somehow locks on to the wrong signal or 
> something?
> 
> The only difference this time is that I had removed the dvb 
> card for a while
> before I tried.
> 
> > -----Original Message-----
> > From: linux-dvb-bounce@linuxtv.org 
> > [mailto:linux-dvb-bounce@linuxtv.org] On Behalf Of Antti Kaihola
> > Sent: Saturday, February 07, 2004 2:46 PM
> > To: linux-dvb@linuxtv.org
> > Subject: [linux-dvb] Re: Budget DVB-C tuning problems; 
> dirty solution
> > 
> > on 2004-02-07 at 12:57, I wrote:
> > > > The rule seems to be:
> > > > If I wait for more than 8 seconds after a successful tuning, the
> > > tuning will fail.
> > > > An immediate re-tuning attempt after a failed or 
> successful tuning
> > > will succeed.
> > 
> > 
> > OK, here's a dirty modification which makes the no-lock 
> > problem go away.
> > This is from someone who doesn't understand shit about the 
> driver and
> > has never seen any hardware specifications, but was just 
> poking around
> > in the dark... :)  I just hope it helps others figure out 
> > what the real
> > problem is.
> > 
> > 
> > In dvb_frontend.c function dvb_frontend_set_parameters(), 
> add an extra
> > call and a delay before the dvb_frontend_internal_ioctl call:
> > 
> > dvb_frontend_internal_ioctl (frontend, FE_SET_FRONTEND, 
> > param); /* wake
> > up! */
> > dvb_delay(100); /* clear your head before action */
> > err = dvb_frontend_internal_ioctl (frontend, 
> FE_SET_FRONTEND, param);
> > 
> > 
> > Somehow the extra ioctl call wakes the card up and properly 
> > prepares it
> > for the real action. I'm kind of simulating the
> > two-tunings-in-a-row-succeed phenomenon I've encountered before.
> > 
> > With this ugly fix dvbtune now works correctly, i.e. tunes 
> > successfully
> > also after a longer pause than 8 seconds.
> > 
> > I haven't experimented too much with the delay in between, I just
> > noticed that if I remove it, I still get some no-locks.
> > 



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