The conversion is from analog (old over the air by antenna) signal to an (over the air, new) DIGITAL signal.....HD- High Definition is the next level up...this is a new signal received by satellite to a cable company or Satellite Service........Feb. 17,2009 is when the "analog" (old signal) goes away and everything goes to the digital signal (new).....Most new TVs already are digital...but if you have an older TV you will need an converter box to receive signal......New TVs are either Digital or High Def.....you can get the digital signal on both........as far as your antenna goes....if you have a Digital or HD TV, you should be able to use your present antenna without anything extra....but they do have digital antennas, if you feel you need one....If you are not sure, have the antenna tested for digital signal......( I knew all that tech training I received from working for Radio Shack would pay off someday....
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Okay, hope this helps.....this is how it was explained to us a couple of years ago when we bought our 17" digital TV.....HDTV is great and the picture is wonderful.....but digital TV is cheaper
and the picture is great too......