My parents get their HD service through Cogeco. Unfortunately, the cable company provides surprisingly few high def stations. Most of them are network TV stations with their time shifting counterparts. Overall though, Cogeco's HD service is pretty awful. For one, Global is not available in the Milton area for some unknown reason. There are some Global programs I'd love to see in HD. Rather than paying $10 to rent another box, I decided to go a different route. I just bought an HDTV when my old CRT set crapped out on me. It has an ATSC tuner built in. ATSC stands for "Advanced Television Standards Committee". The system is due to replace the current NTSC analogue colour TV standard that has been in place since the 1960s. ATSC is an all-digital format that uses MPEG-2 video streaming. It supports all resolutions from 480i SD broadcasts right up to full HD 1080p at 30 frames per second. In 2009, all American analogue over-the-air (OTA) TV stations will shut down. Canadian analogue stations except in the far north will shut down in 2011. This doesn't mean that OTA TV is going to go away, far from it.
Many people are now choosing to ditch expensive satellite and cable services and are bringing back the good ol' arial. The mast at the side of houses, once a staple in the 1950s and 60s, is making a come back of sorts. While analogue TV is going down in 2009/2011, TV stations will begin broadcasting it the digital ATSC standard in its place. Right now, there are plenty of ATSC stations already on the air, meaning you can legally watch HD shows without paying a cent for the service. I hardly expect it to ever replace satellite and cable but it's a great introduction to HD without requiring a huge investment or high monthly bills. Canadians are currently paying too much for HD.

For starters, you need either a HDTV with an ATSC tuner built in or a decoder box. Most newer HDTV models come with a digital tuner built in. Some don't but these are getting less common. By law, all new HDTVs sold in the United States must include an ATSC tuner. I'm unsure what Canada's policy is on this. When buying an HDTV, make sure it has a digital HD tuner built in. If you do have an older HDTV without an ATSC tuner, you can buy a digital converter box. These boxes can also be used with standard definition TVs to get digital SD programming. However, these boxes are nearly impossible to find in Canada right now, so you'll have to buy it in the US. Next you need an antenna. There are lots of options available. Indoor and outdoor. Outdoor gives the best reception while indoor can be hit and miss. A good indoor one is sold for $60 at The Source under it's Nextech brand. It includes a built in amplifier. They also sell one under the RCA brand which I'm told is also very good. For outdoor, you can use pretty much any standard UHF outdoor antenna. Antenna's Direct, a US company, sells in Canada through Tiger Direct and e-Outlet Canada. They're generally the recommended model for receiving HD over the air. Outdoor antennas can be mounted on a traditional mast or on a roof using a "J" type mount, the same used to mount satellite dishes. More height gives better reception regardless of whether the antenna is indoor or out. Another thing worth noting is that many UHF antennas are directional, meaning they have to be pointed at the TV transmitter. For Canadians living in the Greater Toronto Area, pointing it towards Toronto will get good reception from both Buffalo and Hamilton too. Indoor ones can be easily adjusted. If using an indoor antenna, get as much height as possible. Put it on the top floor of your house near an outside wall or window. Antennas can also be mounted in an attic but reception is lost compared to an outdoor one. Regardless of what antenna you use, weather can affect it. With Digital OTA, you'll either get a signal or you won't. There's no fuzz like with analogue. You may have to rescan the channels each time you adjust the antenna.
If you rent your home, check with your landlord to make sure you are allowed to set up an outdoor antenna. If you live in the United States, it is your legal right to mount a TV antenna on your roof, as stated by the FCC. This is because television is considered critical for delivering important information (ie weather warnings, informing the electorate) to citizens. I am unsure what the law is in Canada though.

So what kinds of stations can you get? Using my Nextech indoor antenna, I can pull in 14 digital TV stations. Reception with some is hit and miss. You'll generally get better UHF reception at night when it's clear or there are high level clouds. Here's a list of stations I get in Milton, ON.

4-1 WIBV: A CBS affiliate out of Buffalo NY. 1080i resolution. Reliable signal
5-1 CBLT: A CBC affiliate out of Toronto ON. 1080i, CBC surprisingly has tons of HD content. Very reliable signal. Airs blockbuster movies in HD on Sundays at 9pm. The network is now almost entirely in HD, older programming notwithstanding.
9-1: CFTO: A CTV affiliate out of Toronto ON. 1080i. Good signal.
7-1: WKBW: An ABC affiliate out of Buffalo NY. Reception is hit and miss. 720p resolution.
7-2: WNGS: Airs retro TV. A substation of WKBW. Standard def.
7-3: WCSN: Sports substation affiliated with WKBW. Standard def.
17-1: WNED: A PBS affiliate out of Buffalo NY. 720p HD resolution. Really difficult to receive.
17-2: WNED-SD: Airs PBS programming in standard definition
17-2: WNED-Th: Airs children's educational programming. Standard def
18-1: CHCH: Now known as E! Entertainment Television. Out of Hamilton ON. 1080i. Very reliable signal.
23-1: WNLO: A "The CW" affiliate out of Buffalo. Formally The Warner Brothers Network. Not much HD content. 1080i. Good signal.
25-1: CBLFT: Toronto ON based French language CBC station. 1080i. Signal weaker than it's English counterpart. Plenty of HD content.
36-1: CTS: Crossroads Television airs religious programming and is located in Burlington ON. 1080i. Good signal. Be awed by high def Jesus.
44-1: OMNI2: Airs multicultural programming, American sitcoms, and daytime talk. 1080i. Good signal. Not a lot of HD content at this time.

Remote Central offers a full list of digital TV stations you can get OTA in Toronto. You'll notice major stations like Global, CityTV, SunTV and OMNI1 missing from my list. Global, Sun, and City have surprisingly weak transmitters for their digital service. Surprisingly, all their analogue counterparts come in strong. Global has the weakest transmitter power of all Toronto OTA digital stations, which is odd considering it's a major network. You should be able to get these stations with a very powerful outdoor antenna or if you live near the CN Tower. The entire west GTA has the advantage of being almost equidistant between the three major TV transmitters in the area. In general, Canadian OTA HDTV is pretty poor at the moment though it will get better as 2011 approaches. The big problem is that Canadian OTA digital stations tend to have vary weak transmitter power compared to their American counterparts. This is why I can receive several American stations but not some closer Toronto based ones.

A couple final notes. You'll notice I mentioned ATSC supports up to 1080p but the majority of the channels only go up to 1080i. I don't know much about broadcasting but presumably this is because most HDTVs out there support 1080i out of the box. Secondly, you'll also notice sub-stations on some channels. Digital TV uses less bandwidth and therefore more than one station can be broadcast on the same frequency (channel) block. The problem with this is that it takes away bandwidth from the primary station. That's why you'll notice that the two channels I listed with sub-stations are only at 720p versus 1080i. 720p requires less bandwidth. One issue with sub-stations though is a TV station might have to further compress its HD station to accommodate the other SD ones. PBS is notably bad for this. I noticed compression artefacts with some of their HD shows on the main station. It can ruin the HD experience.