>On Thu, May 25, 2006, christophpfister@xxxxxxxxxxx wrote: >> >On Thu, May 25, 2006, christophpfister@xxxxxxxxxxx wrote: >> >> >On Tue, May 23, 2006, christophpfister@xxxxxxxxxxx wrote: > >your quoting is broken :-( > >> >- hierarchical modulation: one DVB-S and one DVB-S2 signal are >> > combined via a hierarchical mapper; the DVB-S2 signal >> > is _SIS_ (note that the hierarchical mapper is located *after* >> > PL header insertion); a DVB-S receiver will only see the >> > DVB-S stream; a DVB-S2 receiver will see the DVB-S2 stream, >> > however to do so it needs to be set in a special BC mode >> > (because of the "asymmetric 8PSK constellation"); >> > again our API would use DVBFE_DELSYS_DVBS vs. DVBFE_DELSYS_DVBS2 >> > to select HP vs. LP stream, but also needs the obc_mode flag. >> >> That's not quite correct. While a DVB-S device receives only the HP stream, >> a DVB-S2 device receives *both* streams. >> So the most used mode is MIS. The stream_id is used in this case to select >> either the lp or the hp stream. > >I'm looking at EN 302 307 figure F.1. It shows that the HP stream >is a DVB-S stream of I/Q-bits (outer & inner coding, not yet >spectrum shaped and modulated) according to EN 300 421, thus it >cannot have a stream_id. Yes. > >Please explain why you think hierarchical BC mode uses >MIS and stream_ids to select HP/LP. It contradicts >my understanding of the standard. Let's try this way: 1. What SISMIS is used in the hierarchical modulation for the DVB-S2 stream? -> if SISMIS == SIS then there is no problem -> if SISMIS == MIS then there is a problem (see 2.) I think this question isn't answered clearly by the standards. As long as we don't know the correct answer we can't dicuss further on that. (Well Manu and I suppose that SISMIS == MIS) 2. How does the demod filter? Does it exact matching or intelligent matching? -> intelligent matching means that if we use SIS we get the whole stream -> exact matching means that we have to use MIS and the correct stream_id, otherwise we don't receive anything Both would be possible (because HP and LP are already distinguished by different modcods), but again: We don't know. So my suggestion is: Please leave that out in the current api as long as we don't have a working testing environment. > >The frame structure of DVB-S2 is totally different than >DVB-S, so a DVB-S2 demodulator will not be able to demodulate >a DVB-S stream. E.g. STB0899 contains two completely >seperate demodulators for DVB-S and DVB-S2 mode. > >Thus I think one uses DVBFE_DELSYS_DVBS vs. DVBFE_DELSYS_DVBS2 >to select the HP or LP stream. Yes, it contains two demods. We can use DVBFE_DELSYS_DVBS to access the HP stream, but I think it's possible with an appropriate modcod too (just speculation from my side - please let us freeze it here according to my suggestion above). > > >> >> >- NBC-BS == "normative broadcast mode"? >> >> >> >> Yes. >> > >> >After sleeping it over, I think NBC-BS and >> >"normative broadcast mode" are not equivalent. >> >DVB-S2 NBC-BS has mandatory and optional parts >> >(EN 302 307 table 1), and "normative broadcast mode" >> >means "the mandatory parts of NBC-BS only". >> > >> >I.e. MIS is optional and thus nor part of >> >"normative broadcast mode". Thus what EN 300 468 >> >means to say is: "If you only use the mandatory parts >> >of NBC-BS you don't need the S2 descriptor". >> >> NBC-BS doesn't need the S2 descriptor (as explained earlier). >> But still NBC-BS == "normative broadcast mode", e.g. because the backward >> compatible mode isn't the same as normative broadcast mode. > >It really a bummer that EN 300 468 uses the term >"normative broadcast mode" without defining it, >but I am now convinced that "normative broadcast mode (NBC-BS)" >means "those parts of NBC-BS which are mandatory", >i.e. "normative broadcast mode" means a subset of NBC-BS. > >Look at EN 302 307 table 1. > >E.g. MIS is NBC-BS, but not part of "normative broadcast mode" >since MIS is an *optional* feature of NBC-BS. > > >Johannes Manu explained that ... Christoph _______________________________________________ linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
