Thanks for the tip, GroundUrMast!
I do have an ATSC tuner built in and the setup is for antenna, not cable. I probably misused the term noise - what I have is picture breakup (not snow, like on an analog t.v.)...i.e. the picture (and the audio) cuts in and out and sometimes distorts. Sorry for the confusion. If you have any tips to cut this out, other than changing the antenna and directing as described on the forum (I've read the links below), I'd greatly appreciate it. Thanks again!
http://forum.tvfool.com/showthread.php?t=11
http://www.kyes.com/antenna/pointing/pointing.html