How much difference between SD and HD

We depend on the NATL BROADCAST System from the local towns to give us the High Def TV signals when camping. Even when we are connected at the campground CABLE HOOKUPs we still watch the local BROADCAST TV stations using our OTA BATWING setup from the local towns that are transmitted in High Def HDTV mode. Once you start watching TV in High Def mode its hard for us to go back to the standard mode.

I'm hearing some campgrounds are just now converting over to digital HDTV signals feeding the trailers.

Roy Ken