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 _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
