Well much has been addressed in the FCC merger filings.
They claim a joint venture satellite would not work because they currently use incompatible systems.
They have no plans yet for LIL HDTV. Problem is that HDTV takes up about 6-7 STD worth of space. If they update the Ku satellites to 8PSK (what dish uses now in new HDTV) they can get 2 HDTV stations per transponder, or 64 per satellite. Ku has a reuse factor with spots of about 5, so 3 satellites times 32 transponders times 5 reuse times 2 channels per transponder is 960 total capacity. This is not enough to carry the ~1400 stations in the US. So, even with all trying to do LIL they could not do it with the KU band.
Ka band has some possiblities. A Ka satellite could have 46 transponders, a reuse factor of 8 (tighter beams possible), 2 channels per beam would yield 736 locals per satellite. So, it would take 2 Ka orbital locations to have the capacity to handle all locals in HDTV.
This does not even address the problem of getting this much uplink capacity. Each of the 2 orbital slots would have to be composed of 4 satellites. 8 satellites might have enough power to up/down link all this.
It is not going to be easy no matter what. Overlaying local ads probably wont work unless the ads are in very low resolution... something advertisers probably will not like.
They claim a joint venture satellite would not work because they currently use incompatible systems.
They have no plans yet for LIL HDTV. Problem is that HDTV takes up about 6-7 STD worth of space. If they update the Ku satellites to 8PSK (what dish uses now in new HDTV) they can get 2 HDTV stations per transponder, or 64 per satellite. Ku has a reuse factor with spots of about 5, so 3 satellites times 32 transponders times 5 reuse times 2 channels per transponder is 960 total capacity. This is not enough to carry the ~1400 stations in the US. So, even with all trying to do LIL they could not do it with the KU band.
Ka band has some possiblities. A Ka satellite could have 46 transponders, a reuse factor of 8 (tighter beams possible), 2 channels per beam would yield 736 locals per satellite. So, it would take 2 Ka orbital locations to have the capacity to handle all locals in HDTV.
This does not even address the problem of getting this much uplink capacity. Each of the 2 orbital slots would have to be composed of 4 satellites. 8 satellites might have enough power to up/down link all this.
It is not going to be easy no matter what. Overlaying local ads probably wont work unless the ads are in very low resolution... something advertisers probably will not like.