Why you have to retune the TV (if you still watch it) and how to do it

BarcelonaOn November 5th, the map of digital terrestrial television (DTT) will change both in Catalonia and the rest of the State. Here, TV3 will premiere, in trials, the broadcast in ultra-high definition (UHD, for its English acronym) on the second autonomous multiplex, a package of channels that share a frequency and which became empty with the closure of 8TV in 2023. It will be the second autonomous television station to broadcast in UHD, after the Galician TVG, which has been doing so since March 2025.

On the same day, one of the state DTT multiplexes will start broadcasting four channels in UHD: La 1, La 2, Antena 3, and Telecinco. La 1 already had one since 2024, but the others did not. The schedule is contained in a resolution from the Secretary of State for Telecommunications published in the Official State Gazette (BOE), which mentions a second RTVE channel without naming it, and everything indicates that it will be La 2.

Why is it necessary to retune?

A television only knows the channels it found the last time it searched for them. If a channel changes frequency or location, it will not know about it until a new search is performed, and on November 5th several will change: the group of channels moving to the new technology, Clan (which moves two days earlier), Atreseries, BeMad and DKiss, which are being redistributed, and La Séptima, a new high-definition channel.

Those who do not do so will continue to see most channels, because there is no blackout and the high-definition versions are maintained, but some may change position or disappear, and none will appear new. It is recommended to perform the search from eight in the morning on November 5th, not before. Subscribers to Movistar, Orange, Vodafone or Digi TV services do not need to do anything: the operator updates it.

What is UHD and what is noticeable about it?

UHD means 3,840 by 2,160 pixels, four times those of a Full HD screen, which has 1,920 by 1,080 (also called 1080p). Commercially it is called 4K, and in practice it is the same. On the other hand, in DTT high definition is not always Full HD: on many channels it is 720 lines, and that is why the jump can be more visible than the comparison between screens suggests.

However, the resolution depends on the bits that fit into the space of each channel. The new state multiplex has a capacity of about 33 megabits per second, which is distributed equally among four channels: about 8 each. 3Cat has explained to ARA that TV3 UHD will have between 9.5 and 10 for the entire service (video, audio, and data). With this compression, defects are noticed especially in sports and scenes with a lot of movement.

The content is also not always real 4K: the regulations allow UHD channels to broadcast programs produced in high definition and upscaled; TV3 has not specified how many it will do in native 4K. It can, however, improve color and contrast, thanks to high dynamic range (HDR), which La 1 and TV3 UHD broadcast in a format called HLG. And you might have to move the sofa, because the viewing distance matters: the further away, the harder it is to appreciate the difference between Full HD and UHD. On a 55-inch television, the ideal distance is between 1.67 meters, recommended by THX for watching movies, and 2.27 meters, recommended by the engineering association SMPTE for general use, such as news or series.

How to know if the television will receive it?

To watch UHD channels via antenna, three things are needed: a UHD screen, a DVB-T2 tuner (the second generation of the European DTT standard), and an HEVC decoder, also called H.265, the compression format used for broadcasting. Any modern television that is truly compatible has these built-in, and no additional device is needed. However, the fact that the box says "4K", "UHD", or "HDR" does not say anything about the tuner.

To find out, you must consult the manual, the technical specifications, or the manufacturer's website and look for "DVB-T2" and "HEVC" or "H.265". The 2025 state regulation requires brands to inform about this clearly, but it does not provide for any official logo. Televisions of 40 inches or more sold since March 2025 already carry a UHD tuner and decoder by legal obligation; for smaller ones, the obligation arrived one year later.

The consumer organization OCU proposes a test that is not conclusive: if the television already shows La 1 UHD, it follows that it has DVB-T2. But La 1 UHD is broadcast today with the previous system (DVB-T) and HEVC, so it only proves that the device understands HEVC. The first 4K models, which were born without DVB-T2, currently show La 1 UHD but will lose it on November 5th, although La 1 in high definition will continue to work. The reliable test will be to check, after the search, if the new UHD channels appear.

According to UHD Spain, the association that promotes this format, at the end of 2025 only 36.6% of the television stock was prepared to receive UHD via antenna.

Do you need to buy anything or call the antenna technician?

To continue watching TV, you don't need to buy anything. A television without DVB-T2 will continue to receive all channels in high definition. Only those who want to watch UHD on a 4K television that cannot receive it need a new device: an external receiver with DVB-T2, HEVC, and an HDMI output of 2,160 lines costs about 70 euros. There are some for 30 euros, but they usually only provide Full HD, so they are useful for receiving the new channels but not for watching them in 4K. It is advisable to be wary of those that have "4K" in the name but say 1080p in the specifications. With a high-definition television, a 4K receiver adds nothing.

The ministry assures that there is no need to change the antenna, touch the communal installation, or call any installer, and warns that no one should charge for "adapting it to 4K." The installers' association Fenitel adds a nuance: first you must rescan, and if channels are still missing in the whole building, consult the administrator, because the inspection of a collective installation is paid for by the community.

How do you rescan?

The automatic search, which in most brands erases the previous channel list, will leave them in an order that may need to be fixed later. In general, you need to go to the channel or installation menu, choose the automatic search and the Antenna source, but the menus change depending on the brand, year, and model, and the manufacturer's manual details the steps. If repeated channels appear after the search, it is recommended to keep the one with the best signal quality and delete the other.

With an external decoder, the process is the same from its installation menu. If it does not have HEVC it will not find the UHD channels, and if it does not have DVB-T2 it will not find those of the group that is changing either.

UHD arrives at TV3

According to 3Cat, TV3 UHD will broadcast using the usual standard (DVB-T) and HEVC, with HDR in HLG format and at between 9.5 and 10 megabits per second, and it will reach 99% of the population. In the Barcelona regions it will do so via radio channel 33, in those of Tarragona, Girona and the south of Lleida via 36, and in the north of Lleida via 40. This only matters to those who perform a manual search, because most televisions will find it with the automatic one.

Since it does not depend on DVB-T2, in principle any 4K television with HEVC should be able to see it, including those that will lose La 1 UHD on November 5th.

The channel occupies the second autonomous multiplex, which, according to the Government's note of October 13th, is distributed as follows: 50% for the CCMA, 25% for La 2Cat, a channel entirely in Catalan from RTVE Catalunya, and 25% for a private operator that will have to be awarded by tender by the Audiovisual Council of Catalonia.

The spectrum, a finite space

Behind all these changes there is a physical fact: the radio spectrum, the set of frequencies through which waves travel, is finite, and it must be shared by very different services. DTT currently occupies the band between 470 and 694 MHz. A few years ago it lost a part of it: the 800 MHz band went to 4G mobile phones, and the 700 MHz band to 5G, a transfer that forced the relocation of channels and the adaptation of community antennas in Spain.

The European Union reserved the remaining band for DTT at least until 2030, but the pressure continues. The European Commission notes a growing demand for this space, both from mobile operators and for public uses, such as emergencies and defense. The commitment to DVB-T2 and HEVC allows more information to be transmitted in the same space.

Who will win with the change

In fact, there are channels that can already be watched in 4K without an antenna. La 1 UHD can be viewed on Digi, Vodafone, and Orange set-top boxes, but not on Movistar Plus+, and the channels' applications (RTVE Play, Atresplayer, and Mediaset Infinity) broadcast live content mostly in high definition. Atresmedia has announced that La Sexta UHD will only be on Atresplayer and on platforms, but not on DTT.

A recent report by the consultancy Barlovento Comunicación shows who is reached by what: viewers over 55 years old watch 279 minutes of linear television every day, which is what is broadcast live, while those aged 18 to 44 watch only 62. In contrast, the latter spend 59 minutes on YouTube. A portion of the consumption that the report counts as internet takes place on the television: connected TV captures an average of 49 minutes per day among adults.

4K via antenna is therefore aimed mainly at an audience that watches a lot of linear television and likely has older devices. A second phase still remains, without a set date: all multiplexes will switch to DVB-T2 when, according to regulations, 95% of televisions support this system and 90% support UHD with HEVC, although the Spanish Government may bring the date forward. When that happens, devices that only have DVB-T will be left without DTT.