Am Freitag, den 01.05.2009, 20:52 -0400 schrieb Andy Walls: > On Sat, 2009-05-02 at 01:55 +0200, hermann pitton wrote: > > Guys, > > > > [snip] > > > > > > > > > > Do the circuit board traces in the FM1216ME_MK3 support the TDA9887 > > > > controlling the gain of the first stage? (I've never opened an > > > > equivalent NTSC tuner assembly to take a look.) > > > > > > "equivalent" NTSC tuners _do not_ exist at all. > > > > > > I don't forget all the time we spend to find out that some of them are > > > Intercarrier only! > > > > > > Also, the tda988x stuff is underneath the tuner PCB. > > > > > > I cut one off for those interested in line tracing ... > > > > still on the to do list ;) > > Thanks. I hope it doesn't cost you too many wasted Euros... Seven years later it is just trash and i hope to provide enough for everyone ;) Cheers, Hermann > > > > Without port2=0 you don't get any SECAM-L into the sound trap. > > > > > > It needs amplification from minus 40 dB AM for the first sound carrier, > > > and then of course you prefer the second with NICAM. > > > > > > > If not, then, if I understand things correctly, you need to set the > > > > first stage and second stage TOP settings so that they refer to about > > > > the same signal level before the IF SAW filter. > > > > > > > > > > > > I would think AGC TOP settings, for both stages of the tuner, are > > > > tuner-dependent and relatively constant once you figure out what they > > > > should be. > > > > > > > > Do you have a different understanding or insight? > > > > > > > > Regards, > > > > Andy > > > > Hartmut once offered to make contacts with colleagues at Philips Hamburg > > for such tuners and related tda9887 stuff. > > > > Unfortunately he is not active on the lists currently. > > > > If I see, how easily someone can get a patch to Andrew and disables all > > other SECAM stuff, again from Russia, I'm not convinced on anything from > > there. > > > > I seriously doubt that those tuners are meant for fumbling on TOP RF/IF > > settings from user space. > > The proper TOP settings should be a function of the input signal TV > standard (positive modulation vs. negative modulation vs. FM radio) and > the components in the tuner assembly (the IF filter for sure). Setting > TOP settings from user space only makes sense for laboratory > experimentation. > > > Linux is kind of funny in the way it breaks up the integrated assembly > of an analog tuner to be handled by separate drivers: preselector and > mixer/osc chip by tuner-simple; IF filter and IF demod by another module > like tda9887. Really the two chips should be set with coordinated > settings, taking into account the TV standard the tuner is being set to > demodulate and the properties of the IF filter and external components > to the IF demodulator. > > > The linux analog tuner drivers mostly appear to make some safe, default > settings, and don't attempt to get the best performance. I'm assuming > that is due to lack of data on the tuners and the tuners working well > enough. > > I'm glad to see Dmitri working at trying to improve analog performance. > > I wish I had the proper equpment to experiment wih NTSC tiners. If I > had a lab with a decent signal generator, oscilliscope, etc. I'd > probably have lots of fun playing around with these tuners. :) > > Regards, > Andy > > > > Cheers, > > Hermann > > -- To unsubscribe from this list: send the line "unsubscribe linux-media" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
