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Terrestrial television

technology Maturity 9-11 Next article →

Terrestrial television is a way to send shows through the air. People often call this over-the-air or broadcast television.

Rabbit-ears dipole antenna with UHF loop 20090204
Rabbit-ears dipole antenna with UHF loop 20090204

It works by sending radio waves from a station on the ground. A TV receiver uses an antenna to catch these waves. This is different from cable or satellite TV. Satellite TV sends signals from space down to you. Cable TV carries signals through a physical wire. Internet TV uses a digital stream to reach your screen.

Antenna
Antenna

The way it works depends on radio waves. These waves travel in specific bands called VHF and UHF. The signals move in a straight line of sight. This means the signal usually stops at the visual horizon. Some signals can travel much further under special weather conditions. This is called tropospheric ducting. Stations use different frequencies to send their programs. In the Americas, these channels use specific ranges like 54 to 88 MHz. Some areas even use signal boosters to reach more homes.

This was the very first way to broadcast television. The BBC began its broadcasts in 1929. Many radio stations had experimental shows by 1930. However, those early pictures were not very good. They used mechanical scan technology which was quite limited. Television did not become popular until after World War II. This was because of new electronic scan technology. Early shows were only in black and white. People did not see color TV until the 1960s.

Different parts of the world used different rules. In the Americas, the NTSC standard was used for a long time. Japan also used this standard for its broadcasts. In Europe, many countries used a system called PAL. The UK switched off its old 405-line system in 1985. Many countries are now moving to digital terrestrial television. This is often called DTT. In the United States, the FCC set a deadline in 2009. This was the date to stop most analog signals.

Terrestrial television is still very important today. About 1.6 billion people use it around the world. Indonesia is a huge market with 250 million viewers. In the United States, about 14% of homes use an antenna. New systems like ATSC 3.0 are now starting to appear. This new way can show 4K UHD resolution. That means the picture is very sharp and clear. It also allows for better sound and mobile reception.

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File:Rabbit-ears dipole antenna with UHF loop 20090204.jpg
Rabbit-ears dipole antenna with UHF loop...
File:Antenna.jpg
Antenna.jpg
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