Digital television or simply DTV is the transmission of both video and audio by digitally processed using multiplexed signal. Digital television is the contrast to the channel separated signal which is used by analog television. The main difference between analog and digital television is that digital television is able to support multiple programs that are in the same channel bandwidth. This is the first innovation of great significance since the introduction of color television back in the 1950s. Currently, several areas of the world are in different phases of implementing and adapting digital broadcasting standards.
Digital Television Broadcasting Standards
There are different digital television broadcasting standards including DVB or Digital Video Broadcasting, STSC or Advanced Television System Committee, ISDB or Integrated Service Digital Broadcasting, DTMB OR Digital Terrestrial Multimedia Broadcasting and DMB Digital Multimedia Broadcasting. The difference between these standards is in different frequency-division which they use. For instance, DVB uses orthogonal frequency-division which supports hierarchical transmission. This standard is currently adopted in New Zealand, Singapore, Australia and Europe. On the other hand, ATCS standard uses eight-level sideband which is adopted in six countries Canada, United States, South Korea, Honduras, Mexico and the Dominican Republic.
History of Digital Television
Roots of digital television are closely related to the introduction of inexpensive but high-performance desktop computers. However, the digital television didn’t become a realistic possibility until the 1990s. The Japanese standard MUSE which is based on an analog system was, in fact, the front-runner technical concepts among more than twenty-three other technical concepts. Later that same year, and American electronics company General Instruments demonstrated the practicability of digital TV signal. This was a giant breakthrough, and digitally based standard could be developed.
The FCC introduced some critical decisions in March 1990, since it was clear that digital standards were feasible. They declared that new standard must be more than analog signal and also be able to provide HDTC signal with a better resolution of already existing television images. They also dedicated that new standard must be capable of being simulcast on various channels. The new analog television standard also allowed the new digital television to be entirely based on newly developed design principles. Adopted by the FCC, the new television standard didn’t require a single standard for lines of resolution, scanning formats, and aspect ratios.
Digital television is capable of supporting a wide range of different picture formats that are defined by the broadcast systems which are a combination of aspect ratio and size. Also, with DTT or digital terrestrial television, the range od available formats can be broadly divided into HDTV or high definition TV and SDTc of standard-definition television. There are several HDTV formats including progressive scan mode 1280×720 or interlaced video mode 1920×1080. Each of these formats uses a 16:9 ratio. Some televisions also can receive and HD resolution 1920×1080 known as 1080p. Due to analog channel capacity issues, HDTV cannot be transmitted over analog television.
Standard definition television may also use several formats. For instance, NTSC standard countries can deliver a signal in ratio 4:3 using resolution 640×480. On the other hand, PAL can deliver 768×576 in the same ratio.
Timeline of Transition
Some countries completed their transition to digital television including Netherlands, Finland, Andorra, Germany Switzerland, Denmark, Belgium, Latvia, Spain and majority of the European countries. The first country which moved to digital broadcasting was Netherlands in 2006. Following countries were Finland which ceased analog transmission in 2007 and Andorra completely switching off analog signal also in 2007.
When it comes to the African countries which terminated analog signals these are Algeria, Mauritius, Gabon, Morocco, Namibia, Kenya, Ghana, Tanzania, and Rwanda. The first country to do so was Namibia which adopted digital television standard in 2014 on thirteenth of September. American continent countries including Mexico, Bermuda, United States and Canada also terminated analog signal and first to so was Mexico in 2000. Asian countries like Japan, Saudi Arabia, Israel, South Korea, Qatar and Taiwan terminated analog terrestrial transmissions as well.