OK, here's the whole story: There are many things that make the difference of what actual quality and resolution you see on the screen. If ANY ONE of those things is not present, you will be seeing less than real HD (1080P/1080I).
1) The cameras and studio gear MUST all be HD. Not all of them are, and often not for some lower-priced productions or college sports events.
2) The station must be using their HD transmitter, and be using all HD equipment. Often they'll transmit SD if it's a rebroadcast, or if there are flaws in the photography which would be made worse by HD, etc
3) The microwave uplink and downlink for the broadcast from the live remote (games, etc), must all be HD.
4) The cable or dish provider must be receiving and distributing in HD, and often there's a hiccup there.
5) Your cable or dish service must be in HD, and you must select the CORRECT CHANNEL to get the HD version. Many people don't know that on Dishnet, for instance, there are several sets of the same channels, with different channel numbers for different types of reception.
6) Your TV must be connected correctly! Most I saw when I was still in the TV repair business, were NOT. Only HDMI and DVI can give 1080I. Component R-Y, B,Y, SVHS, and regular RCA video jacks can't.
7) Your satellite or CATV box AND the TV must be set to the correct settings. If the box is sending out SD, the TV will show SD not HD, and if the TV is set to some aspect ratios, it will automatically go SD. That varies by brand, but most all TVs must be manually configured to HDTV and to the correct aspect ratio.
Now it should be clear why there's so much hassle with HDTV... When there was just regular TV, if you got a picture at all, you were already getting it best. No ifs ands or buts.
Charles