Most readers know about the much-publicized transition to “digital” TV that took place earlier this year. At that time, some people mistakenly thought they’d need an HDTV in order to get broadcast cable. Now that the transition to digital is complete, people realize that’s not the case. But you might still be wondering: What exactly is the difference between digital TV and HDTV?

The difference is in quality of the signal. All TVs (from that old monster tube TV to your new 50-inch Panasonic LED) can receive a digital signal of at least one of three standards: 480p, 720p or 1080i.
Your older model television will receive the signal in 480p, which means 480 lines of resolution, scanned progressively.

The picture will be slightly better than a non-digital signal, but it’s not high-definition (HD) TV.

HDTV Signals: 720p and 1080i

The two HDTV signals are 720p and 1080i.

Why “i” and not “p?”? With 1080i resolution, rather than being scanned progressively, the lines are scanned in alternate fields of 540 lines each. The signal is then converted to 1080p for viewing on your big screen HDTV. Of the three digital TV standards, 1080i (or 1080p, by the time you are viewing it on your TV) is the most detailed. Most HD stations today are broadcast in 1080i.

When you start talking about larger screens (greater than 32 inches) you need that HDTV signal of either 720p or 1080i for enhanced picture quality. You can still view 480p resolution on a big screen HDTV, but it won’t look as good. That’s why you want to surf for the HD channels when you’re watching cable or DirectTV. When you’re comparing providers, you may want to make a list of your favorite channels and ask if they’re available in HD.

720p or 1080p: Which Should I Buy?

At JD Pro, we always recommend our customers buy a 1080p HDTV if they are considering screens larger than 32 inches. Especially with the growth in popularity of Blu-Ray, which displays in 1080p, and the small difference in price between 720p and 1080i, it just makes sense. Think of it as “future-proofing” your home theatre system.

More About HDTV Signals

You can hear JD Pro’s Jonathan Joyce discuss HDTV and more on Technical Tidbits with Debbie Mahler. Click here to listen to the streaming broadcast on demand.