The Difference Between Analog and Digital Television

What is digital television? When we talk about digital television we usually mean digital television broadcasting. Digital television broadcasting can use different platforms: cable, satellite or terrestrial. Each platform uses different transmission system. How can we receive digital signals? We need a digital receiver, either integrated in the TV set or a stand alone set-top-box connected to the old TV set.

But there is not one single standard for digital television broadcasting. For terrestrial digital television broadcasting there are four major and incompatible transmission (modulation) standards. For example North America uses ATSC, China uses DMB-T, Japan and Brazil use ISDB-T while Europe, Russia, India, Australia and many other countries use DVB-T. In addition to this there are many codecs (algorithms) that can be used to compress audio and video: MPEG-2 and MPEG-4 are the most commonly used compression standards for video. This means that you need a digital receiver compatible with the transmission standard and codecs used in your country.

But this variety of standards is nothing new. We had similar situation in analog television. The following parameters in analog television broadcasting can have different values:

• Number of lines
• Frame rate
• Channel bandwidth
• Video bandwidth
• Audio offset
• Video modulation
• Audio Modulation
• Color system

This means that you had to have a TV set compatible with the standard used in your country to be able to watch TV. However, almost all recent analog TV sets are able to receive and display common standards used worldwide. These analog standards were defined many years ago, they were not modified and no new standard for analog television was added. This meant a stable situation for decades.

Now this has changed. In the digital world it is so easy to invent a new method or algorithm, better and more efficient comparing to the old one. A typical example is the transmission standard DVB-T. It has a successor DVB-T2 which is incompatible with the old DVB-T standard but brings more capacity, robustness and flexibility. MPEG-4 is also a newer and better compression method comparing to MPEG-2.

This means that digital technology will continue to develop and new, better and more complex (incompatible) standards will come. A practical consequence of this rapid development is that you will have plasma or LCD TV set to display picture and a separate set-top-box compatible with digital standards used in your country. The TV set will probably last 7 years or more, while the set-top-box will have much shorter life.

If you are interested in implementation of digital terrestrial television you can check the website of Igor Funa where you can get many practical examples of DVB-T broadcasting in many countries and you can also examine a DVB-T multiplex transport stream analysis in real-time.