What is digital TV? When we talk about digital television, we usually mean a digital television broadcasting. Digital TV broadcasting can be used in different platforms: cable, satellite or terrestrial. Each platform uses different transmission systems. How can we receive the digital signals? We need a digital receiver or integrated into a TV or a separate set-top box connected to the old TV.
But not one single standard for digital television broadcasting. For digital terrestrial television broadcasting There are four major and incompatible transmission (modulation) standards. For example in North America uses ATSC, China uses DMB-T, Japan and Brazil using ISDB-T and in Europe, Russia, India, Australia and many other countries use DVB-T. In addition, there are many codecs (algorithms) that can be used to compress audio and video: MPEG-2 and MPEG-4, the most commonly used compression standards for video. This means that you need a digital receiver compatible with standard transmission and codecs used in your country.
But this diversity of standards is nothing new. We had a similar situation in analog TV. The following parameters of analog television broadcasting can have different meanings:
* Number of lines
Velocity
* Channel bandwidth
* Video bandwidth
* Audio displacement
* Video modulation
* Audio modulation
* Color System
This means that you had a TV compatible with the standard used in your country to be able to watch TV. Nevertheless, almost all recent analog TV sets can receive and display the common standards used around the world. These analog standards were set many years ago, they have not changed and no new standard of analog television has been added. This meant a stable situation for decades.
Now the situation has changed. In the digital world is so easy to invent a new method or algorithm, better and more efficiently than the old one. A typical example is the standard transmission of DVB-T. It is the successor of DVB-T2, is incompatible with the old standard DVB-T, but also brings greater capacity, reliability and flexibility. MPEG-4 is also new and better method of compression compared to MPEG-2.
This means that digital technologies continue to evolve, and new, more and more difficult (incompatible) standards will come. The practical consequence of this rapid development is that you have plasma or LCD TV to display images and a separate set-Top-Box is compatible with the digital standards used in your country. Television is probably the last 7 years or more, while a set-Top-Box will have a much shorter life.
