Something like this may work:
http://www.google.com/products/catalog?q=atsc+tuner+box&cid=6201430135057719514&sa=title#ps-tech-specs
You could output via HDMI to your projector for video and output via toslink to your DD/5.1 receiver for the audio portion.
-Pedro
I am looking for a digital tuner that can receive hd digital signals from a roof top antenna and provide 1080i min output directly to my JVC RS2 hd projector. Does such equipment exist?
EJNLMN

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