How Digital Terrestrial TV Works – Satellite Technology – Digital Terrestrial TV in Spain
Terrestrial television is a mode of television broadcasting which does not involve satellite transmission or underground cables — typically using radio waves through transmitting and receiving antennas or aerials. The term is more common in Europe, while in the United States it is referred to as broadcast television or sometimes over-the-air television.
Terrestrial television broadcasting dates back to the very beginnings of television as a medium itself with the first long-distance public television broadcast from Washington, D.C., on April 7, 1927. The BBC began broadcasting television to the public in 1929, and had a regular schedule of programmes in 1930.
Terrestrial mean that the signals are transmitted from land based transmitters, usually masts on high ground so that their transmissions cover the larges possible area.
Analogue Terrestrial Television
In many countries, the analogue terrestrial televisions systems are being switched off, to make way for the digital terrestrial television systems.
Analogue televisions receive programming through radio frequencies that are transmitted by television stations. Each television station emits a specific frequency that corresponds to its designated channel number. Analogue televisions receive this continuous signal through their antennas. When viewers change channels on an analogue television, they are actually alternating which transmission their TV set receives.
Analogue televisions work best when they operate in close proximity to a television stations signal. The signals degrade over long distances, and buildings and objects can frequently interfere with the broadcast.
Digital Terrestrial Television (DTT / TDT)
Analogue TV broadcasting has served us well for over 70 years. However, in terms of the actual broadcasts – the production and distribution of programmes across the nation – analogue lost its exclusivity long ago and is fast reaching the end of its useful life.
Digital helps solve the scarce frequency problem by delivering a more efficient use of frequency band than the analogue method. The technique of digital compression allows a huge increase in capacity. More channels can be carried in digital format than in analogue across the same amount of frequency band.
Analogue takes up quite a lot of frequency band and cannot be efficiently compressed. Digital television uses compression technology that allows a greater number of digital channels to be transmitted in the same bandwidth required by an analogue channel.
Another advantage to digital is that it delivers a more consistent picture quality than analogue, and it does it with less signal level and through heavier interference than with the older method.
Common benefits offered on all digital television platforms include:
. Improved picture (e.g. no ghosting effects, true widescreen)
. Digital Quality sound
. More TV and new digital only radio channels
. Red button enhanced information services