In the coming weeks, HDHomeRun hopes to have their CableCARD tuner ironed out and submitted to CableLabs for certification, which would give them enough of a head start to release a final product in time for the holidays. Unlike the version that was shown at CES earlier this year, the current prototype now sports four tuners instead of three, although one of those is for out of band data and isn't capable of recording HD. But hey, that still leaves you with three tuners to work with, plus a coax connector, USB port (for the Tuning Adapter, nothing else), and a single CableCARD slot to manage all three tuners. Despite the additional tuner, HDHomeRun still plans to sell the card for $249. 
 
That's a compelling price point for so many HD tuners on one device, but what are some of the technologies you should be looking for if you're in the market for an HD TV tuner for your PC right now? 
 

USB vs PCI vs PCI-E

The biggest question you need to ask yourself is where you plan on using your HD tuner. For mobile warriors always on the go, a USB tuner makes the most sense. You can try shopping for an ExpressCard tuner, but these tend to be hard to find, and unlike a USB tuner, you won't have the option of plugging it into a desktop or HTPC should you retire your notebook.
 
For stationary setups, a PCI-E or PCI tuner should be at the top of your list. For one, you won't have to avoid bumping into a permanently affixed USB flash drive jutting out from your case, but more importantly, internal tuner cards tend have more features and accessories (like a remote), though this isn't always the case. Less important is the choice between a standard PCI form factor and PCI-E. Even though a PCI Express interface offers far more bandwidth, this isn't the same as shopping for a gaming card where the faster slot automatically wins. Either type of port is sufficient for watching TV on your PC.
 

HDTV Resolutions

Not all high definition is created equal, so even though a tuner card may be billed as HD, it might not be up to snuff with your display Here are the different resolutions and types to choose from: 

• 1080p: 1920x1080, progressive scan
  
• 1080i: 1920x1080, interlaced
• 720p: 1280x720, progressive scan
  

 
Progressive scan means that all the lines of a frame are drawn in sequence, whereas interlaced scanning divides the horizontal lines into odd and even numbers and alternately refreshes them. Progressive scan typically results in smoother action with less flicker.
 

Software and Compatibility

Often times when shopping PC components, any software bundle ends being of little value and we've almost trained ourselves to overlook this part of the equation. But when buying a TV tuner card, the software makes all the difference in the world. It pays to do your research here and see what others have to say about the included software, such as whether or not it's easy to use and what features are included, like time-shifting (pausing live TV), scheduling (programming the tuner to record a specific show or time slot), and other DVR features.
 
Don't assume every HD tuner card works with Windows Media Center, either. Not all of them do, though there's good reason to invest in one that does. Windows Media Center supports a whole bunch of analog and digital TV signals, including ATSC, QAM, ISDB, DVB-T, and DVB-S. For more on what each of these are, see Microsoft's support page here.
 

QAM Decoding

There are two ways of receiving digital cable - either Over The Air (OTA) or through a cable receiver. A QAM (quadrature amplitude modulation) tuner allows you to receive unencrypted/unscrambled digital programming from your cable company without the need for a digital cable box, which means you're almost always limited to local broadcasts. Nevertheless, if you want to receive HD signals through cable, you'll need a tuner with QAM support.