What is Digital Terrestrial Television and how it works

For years, analogue terrestrial television has always been the most widespread form of television in the world, receivable through normal antennas. In the last twenty years, especially since 2003, however, is the so-called digital terrestrial, or DTT, to play the lion's share, and to be imposed as the international standard for television broadcasting.

And if it is true that technological progress can not and should not stop, even the digital channels are marching hard towards a further evolution, aimed at improving even more all the advantages found with the transition to this mode. In this guide, we are going to understand what digital terrestrial television is and how it works, its peculiar characteristics and what will change once the new DVB-T2 will be introduced all over Italy.

What is digital terrestrial TV

By definition, digital terrestrial television is digital television that adopts a terrestrial transmission system of the digital signal. To make it simpler, DTT implies the use of a numerical transmission system, that is, a mode that is not affected by interference, lowering of signal levels or disturbances and that, above all, allows to multiply the number of available channels. All this is done using an instrument called a decoder, which allows the signal to be conveyed in an optimal way. From an exquisitely technical point of view, in fact, television is information enclosed in an electrical signal: for this reason, it can be represented in analogue or digital form, for two significantly different technologies and with specific features.

Consequently, in the comparison between analogue and digital transmission of television channels are valid the same general considerations found in the comparison between analogue and digital technology, with all the consequences of the case. It seems obvious that analogue signals are more subject to sudden disturbances, almost always due to the fact that the receiver is not able to distinguish a disturbed signal variation from a normal information content. On the other hand, the digital is by its very nature immune to disturbances of various kinds, as long as they are minor. After a certain threshold of "noise" in normal transmission, however, even the DTT is completely indecipherable to the human eye.

All the advantages of DTT

As already mentioned, digital terrestrial TV has a number of advantages over analog transmission. The main one lies in the possibility of multiplying the number of channels that can be transmitted through the same frequencies previously used in analogue. This translates into more channels visible to viewers, thanks to data compression techniques that allow you to occupy only about 1/5 of the bandwidth used for the transmission of an analog channel, while maintaining the same quality.

In fact, this goes even better, due to the ability of this technology to convey video and audio content with 16:9 format and quality very similar to DVD and Blu-ray Disc. In some cases, there is the possibility of high-definition transmission, and that of transmitting multiple audio, for example in multiple languages. On the same frequency it is also possible to broadcast simultaneously both HD channels and channels optimized for the smaller screens of smartphones and tablets.

In addition to the improvement of spectral efficiency and greater flexibility, the interactivity of DTT should not be underestimated in the analysis of the strengths of digital broadcasting. Interactivity that is guaranteed by the presence of various additional data in addition to the simple television transmission, such as the EPG, or a special electronic TV guide that allows you to know which program is on air at that precise moment and which will be the next one. All within reach of the remote control, which acts as a real "pilot".

Not only that, among the features of note is also that it provides a transmission in isofrequency for digital terrestrial, which was impossible to do for the previous television transmissions of analog type. This specific technique involves sending the same signal on the same frequency simultaneously from several synchronized transmitting sites. Consequently, several antennas with partially overlapping areas of coverage transmit the same signal always on the same frequency, provided they are used on a rather large territory.

DVB-T2: the new digital terrestrial

In the name of that technological progress we were talking about, by June 30, 2022 here in Italy the new transmission signal of digital terrestrial will come into force throughout the country. You will also understand that this translates into the need for our televisions to be compatible in time with the new standard, which will be introduced after we witnessed in 2012 what is defined as the switch off of analogue television in favor of DTT. The objective, with DVB-T2 (Digital Video Broadcasting - Second Generation Terrestrial), is to further improve signal quality and free up space for 5G telephone frequencies, bringing transmissions up to 8K high definition.

Among the advantages of the new standard there are, in addition to the predisposition for ultra high definition, the possibility of transmitting a "cleaner" signal and allowing a greater distance between the antenna that receives the signal and the receiver that transmits it on the screen. DVB-T2 also supports MiMo, multiple input-multiple output, systems that allow the device to handle multiple streams of data input and output, just like the latest smartphones.

The next standard will be fully operational in just over a year, but several intermediate stages are planned to ensure a painless transition and as "smooth" as possible.

The first phase to make the new digital terrestrial operational will start on September 1, 2021 and will see the beginning of the encoding of the MPEG-4 code, and the consequent abandonment of the MPEG-2 standard. This phase will not have any obvious repercussions on HD televisions, considering that even DVB-T HD TVs have the capacity to decode this type of signal.

This is different for older televisions that do not have HD technology, i.e. high definition. The government has planned a launch from the regions of northern Italy, until reaching those in the south by June 2022. The second phase will have a higher impact and will be activated throughout the country between June 21 and 30, 2022 to ensure the switch off of the DVB-T signal in favor of DVB-T2 with H.265 or HEVC encoding. or HEVC.

DevB-T2 compatible and bonus TVs

By the set date, all TV networks will switch to the new frequencies, and since there is no scheduled switchover period from one signal to the other, everyone will need to equip themselves in time with DVB-T2 compatible TVs or a decoder. Fortunately, the televisions currently on the market are all compatible with the frequencies of the new digital terrestrial. It's no coincidence that since 2016, all major manufacturers have gone to comply with this new type of signal, with the same retailers, both physical and online, that from the following year are in fact obliged to sell only TVs equipped with DVB-T2.

Naturally, all those who bought a TV before this period and who have no intention of buying a new one any time soon can easily resolve the situation by opting for a compatible decoder, investing only a few tens of euros. The functioning is identical to that of the previous decoders: if before they transformed the signal from analogue to digital, now they transform the DVB-T signal to the new DVB-T2.

To know for sure if our TV set is compatible with MPEG-4 encoding, all we need to do is go to high definition channels, those in HD, to be clear, and scroll them from 501 onwards. If these channels are not displayed correctly or only error messages are returned, then our TV is not compatible with this encoding, and most likely it will not be compatible with the DVB-T2 signal either. For a safer check, we can then look in the main menu for Digital Tuning.

If the different options include the words DVB-T2 HEVC/H265, then the TV is compatible. Recently, another way to understand the compatibility of our device has been developed. There are in fact two test channels, namely RAI's channel 100 and Mediaset's channel 200: if by selecting them, the words "test HEVC MAIN10" are displayed, then it means that our TV supports the new digital terrestrial or DVB-T2.

Not everyone knows this, but the Italian government has allocated funds to buy a new TV, facilitating the transition to the next TV broadcasting standard. Those who have an ISEE income of less than 20 thousand euros per year can therefore request a bonus of 50 euros to buy a new TV set or, alternatively, a decoder designed for the DVB-T2 signal. This bonus is then disbursed directly in the form of a discount at the checkout by the retailer, obviously after the customer has shown the application to the administrative entities in charge. The application can be easily downloaded from the site of the Ministry of Economic Development.