What is Digital Television?

Digital TV has several advantages over analog TV, the most significant being that digital channels take up less bandwidth, and the bandwidth needs are continuously variable, at a corresponding reduction in image quality depending on the level of compression as well as the resolution of the transmitted image.

More channels and services

This means that digital broadcasters can provide more digital channels in the same space, provide high-definition television service, or provide other non-television services such as multimedia or interactivity. DTV also permits special services such as multiplexing (more than one program on the same channel), electronic program guides and additional languages (spoken or subtitled). The sale of non-television services may provide an additional revenue source.

Digital reception

Digital signals react differently to interference than analog signals. For example, common problems with analog television include ghosting of images, noise from weak signals, and many other potential problems which degrade the quality of the image and sound, although the program material may still be watchable. With digital television, the audio and video must be synchronized digitally, so reception of the digital signal must be very nearly complete; otherwise, neither audio nor video will be usable. Short of this complete failure, "blocky" video is seen when the digital signal experiences interference.

3D - How it works

Scenes are filmed using double cameras to emulate human stereoscopic sight although there is some compromise of resolution to enable distribution over existing HD networks. The TV receiver displays the left camera’s image on the odd-numbered lines of the screen and the right camera’s image on the even lines. A special polarised screen is needed.

The dual images are viewed using active shutter glasses so that the left eye sees only the left camera image and the right eye only the image from the right camera.

It is possible to take 2D images and reprocess them by adding additional data to create two separate images. This uses similar technology to the Blu-ray 3D disc.

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