The Sony KP46WT510 does not have a built-in ATSC tuner and cannot pick up over-the-airwaves (OTA) HDTV broadcasts on its own. If you wish to receive OTA HDTV broadcasts you will need to purchase a separate ATSC tuner.
ATSC tuners such as the RCA ATSC11 and the Samsung SIR-T165 can "decode" all 18 ATSC Digital TV formats, including the 6 HDTV formats, and convert them to the "native" format of your TV set, whatever its type. They can even output the signal in 480i format for viewing on a standard definition TV set. You connect your antenna to the tuner and connect the tuner to the TV set.
If you go to the Samsung and RCA web sites, the owner's manuals for these tuners are available for download as PDF files. While these tuners are readily available in the USA, they are hard to find in Canada at the moment. However, in another thread on this forum the phone number of the RCA distributer in Mississauga is listed in a response to a question that I asked in December.
As far as true HDTV sets are concerned, at the present time Sony only produces 3 HDTV models with built-in ATSC tuners: KDP-51WS550, KDP-57WS550 and KDP-65WS550. However none of these models is yet available in Canada.