ABC and FOX should be 720p (720X1280) and CBS, NBC and PBS should be 1080i (1080X1920).
The Dish VIP line of receivers have a static output resolution that is settable in the menus anywhere from 480i to 1080i, Menu, 6, 7 on my 211; Menu, 6, 8 on my 722k.
Dish receivers do not pass native resolution through to the display.