HDTV What's All The (Signal to) Noise About? - The Signals

Discussions of HDTV focus mostly on the receiver, which is natural since that's the most visible part. But that receiver has to have something to receive.

HDTV sets display 1080 lines of pixels (small, colored rectangles composing the screen), about twice the traditional number. And the screens themselves typically have a 16:9 aspect ratio rather than the standard 4:3. That means, even though the dimensions of the sets vary, the ratio of width to height is always 16 to 9 vs 4 to 3 for standard sets.

Behind the scenes, so to speak, other technology is at work.

Traditional TV signals were broadcast in analog fashion. Avoiding some complicated physics, that just means the radio waves composing TV signals are wiggled (modulated) in different ways. Those modulations make variations that the set's electronics can process into moving images that look like people, horses, etc. No variation, no moving image.

Digital signals, by contrast, make those changes by varying the pattern of 1's and 0's that form every kind of digital source (DVDs, TV, MP3, etc).

Whether the signal is delivered over the air via satellite transmitters and receivers, via cable or even into your PC or TV via DVD player or over the Internet the basic idea is the same. Make a changing pattern of 1's and 0's and translate that into a series of moving images to create the illusion of real people riding real horses.

There are several advantages (and a few hurdles) to using that method.

One advantage just hinted at is the ability to transmit movies to PCs. That's becoming ever more popular since, among other things, it enables people to see more kinds of content on their PC - such as movies from a library on a pay-per-view basis. People aged 16-24 throughout the world now spend more time on a PC than they do watching TV.

Another is the ability to deliver not just better quality images, but vastly better sound. Though it's long been possible to hook up your TV to your stereo, the sound broadcast wasn't always worth the effort. Now Dolby Digital 5.1 sound is commonly broadcast along with standard HDTV video signals, making the investment in a full home entertainment center much more attractive.

Digital broadcasts will, in the long run, lower broadcasters costs. Currently, they're supporting two different technologies. That eats into revenue that could be used elsewhere. Converting to digital-only broadcasts (currently scheduled for 2009) enables them to invest more in programming content and other things consumers want.

Digital broadcasts make it much more feasible to eliminate different kinds of interference. Though with cable and DVD many of the older problems with TV are history, such as snowy or rolling pictures, digital broadcasts eliminate even more sources of trouble.

And, of course, last but not least, high-definition digital broadcasts allow sending signals with much more 'information', feeding those HDTV sets that can display those impressive pictures of people riding horses.

<<<Articles     HDTV     Technology>>>