Manu Abraham wrote: > Luc Brosens wrote: >> so I changed gnutv to only initialise the CAM after obtaining FE_HAS_LOCK >> apparantly, initialising the CAM is enough to loose the tuning lock, not to return afterwards >> so this is not a solution >> > > This won't help. The CPU on the CAM is running irrespective whether > you are trying to initialize it or not. In fact the CPU usage is much lower > at initialization time. > >> here's a run with femon monitoring the tuning status : >> >> I start of with the CAM in the slot, and try to gnutv-tune to BBC World (which is not scrambled, so need for the CAM) >> mythtv@silverstar:~/dvb-apps> femon -a 1 -H >> FE: ST STV0299 DVB-S (DVBS) >> status S | signal 63% | snr 49% | ber 14077 | unc 0 | >> status S | signal 79% | snr 51% | ber 13311 | unc 0 | >> status S | signal 69% | snr 50% | ber 13776 | unc 0 | >> status S | signal 31% | snr 49% | ber 13116 | unc 0 | >> status S | signal 54% | snr 49% | ber 13085 | unc 0 | >> status S | signal 75% | snr 49% | ber 13509 | unc 0 | >> status S | signal 80% | snr 50% | ber 13017 | unc 0 | >> status S | signal 21% | snr 41% | ber 0 | unc 0 | >> >> no FE_HAS_LOCK achievable, both signal levels and snr are too low >> so I pull out the CAM (and restart gnutv) >> the lock is immediate : >> >> status SCVYL | signal 80% | snr 84% | ber 0 | unc 0 | FE_HAS_LOCK >> status SCVYL | signal 79% | snr 84% | ber 0 | unc 0 | FE_HAS_LOCK >> status SCVYL | signal 79% | snr 84% | ber 0 | unc 0 | FE_HAS_LOCK >> status SCVYL | signal 78% | snr 84% | ber 0 | unc 0 | FE_HAS_LOCK >> >> signal is around 80%, snr a consistent 84% >> I re-insert the CAM, which is detected by gnutv, and the CAM is initialised >> tuning lock is lost at once : >> >> status S | signal 62% | snr 50% | ber 13585 | unc 0 | >> status S | signal 31% | snr 49% | ber 13498 | unc 0 | >> status S | signal 82% | snr 49% | ber 13540 | unc 0 | >> even though the signal level drops, it's probably the drop in snr that's causing trouble >> >> both cards have the same problem, so it doesn't appear that they're defective (or they both happen to have the same fault, which is unlikely) >> > > It looks to me that something is wrong with the frontend drivers (someplace) > which causes a phase distortions, alongwith that in that "tender" state the > digital noise from the CA module CPU's adds to it. The "tenderness" can be > possibly attributed to a wrong device setup. > > You might like to check with your windows installation whether you see the > same issue. Most likely, i guess not. If you see the same with windows 99% > chance is that that whatever you might do, digital noise is affecting your > demodulator and the tuner. > >> question time : >>> how much of a chance do I have of solving this if I somehow increase the signal strength ? would that increase the snr too ? (I could shorten the >> cables, even if it means relocating the PC) >>> without the CAM, I have a signal strength of 80%. Is that considered a good, strong signal ? (my settop box is happy with it) >>> I asked in a previous post if it's possible to capture scrambled to disk, and descramble later. This is what my settop box does. Is this even >> theoretically possible (sending data to the CAM from a file instead of from the tuner) ? Anybody know of a utility that supports this ? >> >> and now I'm off installing W2K on the damn thing, to see if that works ... >> >> Luc > > > Manu > > Manu, your guess is correct, under W2K no tuning problems. The scrambled channels tune in an instance, now and then there are some artifacts though. But tuning works ! so my hardware setup works, now how to find that 'tenderness' in the driver ? You think that the tuning-part of the drivers (that would be the STV0299-stuff wouldn't it ?) if somebody can set me off in the right direction, I'll get it solved the Windows TV-viewer that came with the cards reports a signal of 95%, even for scrambled channels : another indication that tuning could be done a bit better ? Luc _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
