So far, they don't seem to have the equipment to pass through the HD feed. So it's all upconverted SD for now. I have a call into KVOA on this very subject.
What I did find out in general from an Engineer at KTTU, is the following, regarding Bigalow stations:
CH13/4/18/11 are all on same digital tower. CH 4 has their analog tower there too. CH9 might build a new digital tower, but for now is planning to side mount their digital antenna on their analog tower if it holds the weight. They may have to build another tower. They will use a Solid State transmiter. However, their Oct 1st date won't be made. It's more going to be like the 1st of the year. They have their transmitter on the mountain, but it is not even installed yet. The University has their own tower for KUAS. The only real HD from the mountain so far.
FOX was to go live at same time as UPN, but still had some paperwork trouble with the FCC. They are expected to go live in a week. They should be using the 720p format.
UPN does not currently have any HD programming to pass thru to their HD signal, so it will be all upconverted SD for a while. Regarding Enterprise's 16:9 within a 4:3 within a HD 16:9 signal - this will stay the same, as all they do is pass thru what they get from the network feed. They will not expand this to full screen. Apparently, it is in 16:9 but not an HD program.
I asked why the upconverted UPN signal looked so much better than CBS or NBC upconverted material. He said they use different equipment and is probably better. He was also very pleased to hear that and was going to tell the other stations to get with it. You might notice that UPN is exceedingly sharp (almost HD like) compared to the fuzzy upconverted stuff on CBS/NBC.
He could not tell me why CBS has such a strange signal and dropouts. I leave that for someone who can get through to them to find out. Meantime, I'll wait to hear from KVOA.