Why does my local station only broadcasts primetime shows in HD and others shows in SD?
Lets says for example, channel-4 (NBC) can broadcast Heroes or Conan in HD, and Jeopardy, which although says 'Jeopardy HD' on the lower left, is shown only in 4:3 SD on the same digital channel. Why is that so? Also I notice that when the local station wants to show a weather alert map on the upper right, the picture changes from HD to regular definition [even when watching a primetime program]. Can somebody give me an explanation as to why this happens? Thank you.