We explain what digital television is and its characteristics. In addition, its operation and what is analog television.
What is digital television?
It is known as Digital Television or DTV (for its acronym in English: Digital TVVision) to a set of new audiovisual transmission and reception technologies that uses digital signals instead of traditional analog from the television.
This means that while ordinary television is transmitted by radio waves in the VHF and UHF bands, or failing that by coaxial cables with an analog signal, digital television uses binary signals that allow feedback between consumers and producers, giving rise to a whole new range of interactive television experiences and allowing the transmission of several signals on the same channel.
Is about a television revolution that began towards the beginning of the 21st century, through the international adoption of different DTV standards in the different continents of the planet, as the countries and companies that provide this type of service took a step forward towards overcoming analog.
There are several types of digital television, which are:
- Open (broadcast or free). It is broadcast through frequencies of 700 Hz of the radioelectric spectrum, freely to all televisions compatible with digital television or equipped with a specialized decoder.
- By cable. Identical to traditional cable television, except that the signal transmitted over the coaxial cable is digital.
- IPTV. The Television Protocol allows the transmission of digital television over the copper twisted pair used in the telephone line, just like ADSL.
- Satellite The one whose digital signal is sent via satellite to each of the antennas located in buildings and homes, just like ordinary satellite television.
Characteristics of digital television
Digital television presents a series of interesting innovations compared to traditional television, such as:
- Accepts various formats. Television can be transmitted in different resolutions, from 480, 576, 720 or 1080 pixels, both progressive and interlaced, as well as in HD (High Definition). Which represents a very substantial image improvement.
- It allows simultaneous transmissions. The transmission bandwidth can be subdivided to transmit different programming on various devices, in what is called technology multiplex.
- Allows interactivity. Digital television allows the sending of information from the home to the station and not only its reception, thus turning the device into an interactive experience. This occurs through both public and private text messages.
- It has different standards. Each one adapted for a specific geographical area, such as ISDB-TB, DVB-T2 / H or ATSC.
How does digital television work?
Digital Television, in its numerous presentations, operates based on the use of the radioelectric spectrum or the physical means of connection to transmit much more information than was done analogically, through image and sound encoding mechanisms that maximize the quality and speed of reception.
Thus, the available bandwidth is used to transmit numerous packets of compressed information, rather than one uncompressed signal occupying it all. A stream of up to 20 Mb can contain 4 or 5 different programs, in a single transmission channel, without counting on the retransmission of information, which would go from the device to the operator.
For it the only addition to ordinary televisions necessary is a cable box, which interprets and decompresses the data packets and recovers the signal directly to the display apparatus.
Analog television
Analog or traditional television, unlike DTV, does not use binary coding but analog, that is, similar to electrical, highly susceptible to noise from the environment and that sabotages the clarity of the transmission, especially in open radio signals (UHF and VHF).