and I thought I was the culprit lol. Last night after writing for almost , who knows how long , I tried to post my long reply and then bang , the whole thread had disapear and I could not find it anywhere!. I copied it before posting (it has happened to me before that after taking too much time writing I lost the connection somehow so now I tend to copy and paste before) to the wordpad so I will post it when ever I get home and have the time.
Smith P, not necessarilly , by using hierarchical modulation they could attain this, the european DVB-T (equivalent of the american ATSC) could use it to send 2 kind of services an HD version for most receivers and the SD version for mobile TV users or DVB-T receivers in very poor reception conditions. Their standard can use 3 modulations , QPSK, 16QAM and 64QAM as I recall. Of course it could not be a combination of QPSK and 8PSK but rather BPSK (only 2 symbols therefore 1 bit ) as the high priority service and 8PSK (8 symbols , 3 bits)as the low priority service for a total of 8 symbols, 3 bits that is 8PSK. The first bit would always be the BPSK service and will always be embeded at the begining of the 8PSK signal. So from every XYZ in the 8PSK constellation X belongs to the BPSK service , low quality , lower bitrate of course and XYZ are the 3 bits of the 8PSK higer bitrate lower priority service. In European OTA case they could use 64QAM that has 6 bits (2 power of 6 equals 64) as low priority HDTV service and QPSK with 2 bits SD version service for mobile TV for instance. It is always a compromise and it will be better to use only 1 kind but heck at least someone inside a mini van could watch their favorite major US network while they travel , actually major European network since the american ATSC standard does not have the capability to do this. sporry FCC, lol.
this is all theoretically and has been patented (google shows a Direct TV patent about this) and the 8PSK constellation has to be mapped hirearchically (becomes a non-uniform 8PSK constellation) accordingly and I beleive there is no equipment nor a TV provider implementing this , at least not yet. Maybe DVB-S2 will evolve in the future to implement this and finally be backwards compatible with QPSK receivers therefore legacy receivers will not have to be upgraded , for now that is not the case and not only Dish Network but also Bell TV here in Canada have upgraded their receivers accordingly.
DN will not do this anyways probably and even European TV stations might not implement it OTA either at least not in the near future (the narrower the gap between symbols the higher the errors on the low priority 8PSK service , HDTV probably) . Of course , technology will evolve as bandwith will always be scarce and more efficiency is needed.
In other words for now if Lyngsat shows a TP as QPSK MPEG 4 HD service it is QPSK and if it says 8PSK turbo FEC or turbo coded it is 8PSK turbo and as such you need a capable receiver. do not expect to watch an 8PSK TP with a HD QPSK receiver , not for now at least. That is why I insisted on getting the now not so new 9242 Bell receiver that is MPEG 4 and 8PSK compatible instead of the 9200 (only MPEG 2 although it was 8PSK compatible) that the Bell Store CSR wanted to sell me. Although , recently bell has upgraded for free the old 6100 receiver that is not 8PSK capable but who knows in the future , just in case , lol. Bell is supposed to start 8PSK service soon if it has not started yet , they have been testing for several months now. And guess what the result will always be .... the same crappy picture quality than before as they will add more HD channels on the already very narrow satellite bandwith.
