For over the air the only soup bowl that is important is ATSC
MOST digital cable systems are QAM
Never heard of 8-VSB but guessing that is an odd-cable standard.
Hope this helps
The problem with reception in the rear is likely something I pick on all the time, Lowest bidder RG-59 cable.. This super high loss cable is not the best for anything... Quaility RG-59 might run the company a dollar or two more per RV but it does a much better job.. RG-6 is better still.
MOST (not all) Digital TV is UHF, where as in the old days they used not only UHF but two VHF bands.. The higher the frequency, the greater the loss in any coax cable... And what is more, with the switch to digital most stations not only moved UP in frequency, but DOWN in radiated power, Some way down (When I go to Digital modes on my radios I cut power to like 40%, and range .. Well it goes way up). It may well be the line loss is too great.. IS on my rig, I see the loss even on chan 3 (DVR output channel). I mean.. BAD.