On Saturday 21 February 2004 17:16, Johannes Stezenbach wrote: > Andrew de Quincey wrote: > > Just noticed another problem.. I've never been able to lock on to low > > symbol rate channels before... however, in diagnosing the other STV0299 > > problems, I disabled the FE_TIMEDOUT bit in dvb_frontend.c. > > > > Now, I'm able to lock on to low symbol rate signals... I've just managed > > it with a 4340000 symbol rate... getting a REALLY good signal from it, > > but it took about 10 seconds to tune (the current timeout is hardcoded to > > 2 seconds). The STV0299B docs say it needs a certain number of symbols > > before being able to get a lock... perhaps we need to have a timeout > > which is based on the symbol rate. Again, I can just hack my userspace > > app to ignore this bit, but IMO, it should be fixed in the driver. > > > > Opinions? If no one disagrees, I can sort something out.... > > The ves1893 data sheet has some formlas for calculating the > maximum sync time. Maybe some of them also apply to > other demods. 10 sec could happen if you have too much noise and > a worst case FEC, but I think the sync time depends only linearly > on the symbol rate.
Thanks, I'll give them a look. Hmm, I think I've tracked down one of the issues: stv0299_check_inversion(). This seems to not use the actual inversion value specifed in the frontend parameters... instead it just seems invert the inversion bit on every FE_SET_FRONTEND ioctl. This was causing my attempts to fail randomly. If I modify it to actually use the requested inversion, its getting more reliable (although not perfect yet). -- Info: To unsubscribe send a mail to [EMAIL PROTECTED] with "unsubscribe linux-dvb" as subject.
