Why is terrestrial digital television not working? Digital terrestrial television, how to adjust the antenna under different signal conditions.

The fact that digital television gives an image of better quality on screen than analog signalMany of our compatriots have already been able to make sure.

In order for your home to receive digital channels, you need:

Conventional decimeter antenna;

Reception room dVB prefix T2, or receiver;

TV tower transmitting a signal in DVB T2 format, within the range of antenna availability.

This function is called the device gamma factor, and a correction factor must be applied to obtain a linear response. The gamma correction required for the cathode tube is practically optimal for conceptual correction. For this reason, steps must be taken to evaluate the system in which correction factors are applied in the gamma correction device.

Plasma or LCD TVs?

Digital representations: and describe how to manipulate video signals with digital components of a standard digital system. In high-definition formats, the speed of sampling and data transmission will be higher. Even between the two types of devices there is an important competition.

So, you have it all installed, connected (except for the tower, of course) and even worked for some time, but suddenly the signal disappeared. What could be the reason and how to fix it on your own?

No signal from the TV tower

Sometimes the absence of a signal is explained by the simplest cause - at the moment the TV tower does not transmit it. For example, maintenance work is being carried out or equipment malfunctions were forced to suspend broadcasting and come to grips with repairs.

In stores, plasma screens look like LCD TVs, but the similarity stops TVs with a thin screen and home appliances. Plasma screens use a network of charged gas cells with accurate volt power that creates an image.

The image is created by applying electricity to the crystals. Each of the two technologies has strengths and weaknesses. However, both types display a very clear picture. However, plasma TVs have a slight advantage because they offer a more accurate black color. This means greater contrast in intense color scenes or movies.

Digital television is still quite a new direction, so the process of signal transmission is not established everywhere in the ideal form, there are failures and equipment breakdowns.

Bad reception conditions

In that case, if the signal is received on a weak antenna without an amplifier or with a low-power amplifier, or there are high-rise buildings or other interference-generating structures in the space between the antenna and the TV tower, the signal may periodically disappear if the weather conditions deteriorate.

In other words, during a rain, thick fog or snowfall there is a strong signal disturbance. In this case, the purchase of a more powerful antenna or the removal of an existing antenna to the greatest possible height can help, in order to ensure the direct visibility of the tower.

The nature of the liquid crystal technology leads to the fact that this contrast is weakening, since light leaks between the pixels. In addition, plasma screens have the best viewing angles. More specifically, even if you stay on the side of the TV, everything you can see in the image quality.

There are image maniacs who can say frankly that LCD monitors tend to make blurry images, especially in scenes with lots of movement or sports gear. And they have advantages over plasma monitors. For example, LCD televisions have a higher native resolution than plasma. A few pixels on the screen mean that the image is closer to reality. In addition, LCD displays are lighter and more ergonomic.

This is easy to do if you fix the antenna on the roof of the multi-storey building in which you live. If this is not possible, then you need to buy an antenna with a powerful amplifier.

Receiver failure

Inexpensive Chinese-made consoles from time to time can present such surprises - spontaneously disconnect from reception of the signal. In this case, the message “No signal” appears on the screen.

This means that after this time, the colors begin to fade, and the monitor just needs to be replaced, because there is no way to fix either of the two types of monitors. Modern plasma models no longer produce the effect of "burning" on the screen a few years ago.

The trouble is that if the image is too much displayed on the screen, it tends to keep that image, which is displayed behind the new image. Today's televisions have built-in screensavers to prevent the installation of these ghost images.

The simplest action is shutdown, and after a few seconds digital set-top boxes - Often returns the console in working condition.

Poor "firmware" receiver

This defect is most characteristic, again, for inexpensive Chinese technology. The only way out is to upgrade the processor of the console.

You can download the necessary firmware version from the manufacturer's website of the receiver, but at home and without certain skills, this is not so easy to do. Most likely, this will have to contact the workshop.

A 42-inch diagonal plasma monitor costs a lot today, but if you have money, you don’t want to choose one from the store. In any case, it is good to think before you go to the stores about how you use your TV, how long you use it and which programs. In addition to the technical characteristics, these things must also be taken into account.

The concept of a plasma display first appeared at the University of Illinois. The first displays were nothing more than bright spots created by laboratory experiments. Since then, technology has developed enough in the late 1960s to allow scientists to create geometric shapes, but development was moderated by the materials available at the time. The first screens were small, and the image was very bad. Only after technical progress in recent years have full-color plasma displays been made.

Spontaneous reset

Sometimes the technique presents such surprises as the failure of the channel settings. In order to restore the settings, you only need to start auto search, and all available channels will be restored in a few minutes.

Problems begin when autosearch could not find a single channel. In this case, you should repeat the search manually and make sure that even weak signals are missing, which are usually ignored by autosearch.

Plasma TVs are a new trend in video equipment. The main disadvantage is, of course, the price. Thus, the image has movement deformations, therefore the recommended viewing distance on such TVs is 3-4 meters for 42-inch screens and 4-5 meters for those that are 50-inch higher. Later models have reduced these problems, so the image can be viewed in good conditions, even from about 3 meters. Most televisions accept all video formats. Most plasma TVs can easily accept the first two systems.

To check the signal level, you need to find the “INFO” button on the remote and press it three times in a row - the screen should display information about the signal strength as a percentage of the required one. If the signal is really very weak, you will have to buy an amplifier or move the antenna higher.

Prefix Malfunction

The simplest and most obvious case is that the prefix has failed for some reason. This could be a power surge, a lightning strike to an antenna placed on the roof, etc.

Most likely, it does not give any messages at all on the screen, even if there is no signal. It may not even turn on. In this case, only contacting a repair shop or buying a new receiver will help.

Recently, a new type of video signal, called "video component". Devices that accept this type of signal can emit an excellent video signal to others. So, you need to check whether the plasma TV supports this signal. Most manufacturers offer speakers that can be attached separately from the TV.

In addition, many TVs allow you to "cooperate" with the classical audio system. Digital television already has two types of formats: standard analog definition and high resolution. Unlike other technologies, three main, red, blue and green colors are created in each pixel, which reduces the space. Loaded electrodes interact with small inert gas balloons that enter the plasma state. This process triggers ultraviolet rays that react with phosphorus pixels and produce light.

DVB-T2 digital terrestrial broadcasting is conducted in the television UHF band 470-862 MHz divided into 48 channels of 8 MHz (21-69 channels). That is why in the settings digital receiver or TV you need to choose 8 MHz, 7 MHz is for countries with a different broadcast standard where the channel width is already.

Also in the settings, select the channel number or the corresponding center frequency of the channel. Not to be confused with the carrier frequency of the image, this is for analog.

Unlike classical systems, where the image was “scanned” on the screen, all pixels are “lit” immediately. Without electrons, lights, or any polarization of light, the image is much clearer and brighter. What is a plasma on a plasma TV? Plasma is an electron-neutral, highly ionized substance consisting of ions, electrons and neutral particles. It contains approximately equal amount of free ions and electrons. Thus, plasma is a very good source of nutrition.

When a sufficient temperature is applied, the electrons are separated from their nucleus. In terms of quality, of course, yes. Plasma receivers behave perfectly, regardless of environmental conditions. Too bright light does not affect the image. When used to project images in presentations or video conferences, there is no need to turn off the lights in the room so that participants can see the photos in better conditions, but also record them. Another remarkable feature is the unusual viewing angle in good conditions, which is 160 °, which is the highest.

The UHF range has never been fully occupied by analog channels, so (and not only), free channels are used to transmit digital multiplexes. On one TV channel 8 MHz wide, you can transmit one analog channel or one digital multiplex With several digital channels. The fewer channels in the multiplex, the higher their quality

In addition, compared to similar displays, the weight of the plasma is significantly reduced. No other device can compete with them when it comes to dimensions, which simplifies customization anywhere. Some displays have a width of no more than 3, 5 inches. Unlike conventional televisions, they are not exposed to magnetic fields.

The main disadvantage of plasma TVs is durability. Size and price. The winner again is plasma. In terms of costs, both technologies have lower costs, which is reflected in the price paid by users. Digital television is a television in which television broadcasting is carried out by encoding images and sound in digital systemthe signal being binary code sequences without “resemblance” with the image taken over digital television, cable TV, satellite, Mobile or digital terrestrial television.

Independently install and configure the antenna for receiving digital television in principle, even easier than for analog, but you need to understand some simple things.

Indoor antennas only for reliable reception zones with a good location - high point, direct visibility to the transmitter. Indoor active antennas can slightly improve reception in the absence of a good location. In other cases, they will be just an element of the interior of the apartment.
For high-quality reception of digital television, it is necessary to use outdoor range UHF antennas. The antenna itself has a gain, the more elements in the antenna design (passive directors), the higher its gain. Two antennas of different designs will have a different signal level at the output at one receiving point.
At a greater distance from the transmitter, it would be more appropriate to use more powerful antennasthan active. Any passive antenna at any time, you can make it active by adding an antenna (mast) amplifier to it, and there you can choose from.
Those who wish to clarify more deeply on the choice of an antenna for digital television should read the following topics: “antenna wave channel”, “calculation of UHF antennas”
When choosing the antenna design, it is necessary to consider the distance from the transmitter, and when installing, the direction. Sometimes if it is not possible to install the antenna on a direct signal, you can try to receive the reflected one, with a reasonable approach the result will always be positive. For mountainous terrain, everything is much more complicated.
If you are in a zone where the transmitter is not yet running, you can try to receive a more distant signal. Here you need to experiment with more expensive antennas and amplifiers.
If the antenna has a gain, then the elements of the "wiring" is just the opposite weakening. All passive elements: cable, splitter, antenna sockets, connectors contribute their share of attenuation to the signal. In this case, you must remember that the signal received by the antenna will be larger than the signal delivered directly to the TV. To compensate for the attenuation, amplifiers are used, but here, too, you need to remember that the “many” signal is also bad, over-amplification will occur.
Spliter is a divider; the more parts we divide, the less each gets. If one apple is divided into three, each person’s losses will be 2/3 apples. Antenna sockets not only for beauty, but also for weakening the signal, too.
Any receiver, including DVB-T2 receiver has a sensitivity. Sensitivity is the signal level, from some minimum to some maximum value with which the receiver can work. All changes in signal level values that fall within this range. does not affect the quality of the picture on the TV screen (unlike analog TV). Anything less - weak signal (reception of all multiplex is impossible), all that is more, - overwork (again, the reception of the entire multiplex is impossible).
The signal level of multiplexes can be estimated approximately by neighboring or nearby analog channels. For each region has its own situation.

In fact, the right approach is to measure the signal level and calculate and / or monitor its attenuation.

Romania has 5 multiplexes at the national level, with the possibility of transferring not more than 70 television programs. The advantages of digital terrestrial television. Reception without subscription through the antenna in most parts of the country, including mobile reception, for most Romanian and prospective programs and for some foreign programs. Conditions for receiving digital television.

The existence of the signal also depends on the shielding, which may be caused by obstructions between the transmitter and the antenna reception. Technical regulation establishes the basic parameters and technical requirements for digital television, as well as technical requirements for the parameters of digital terrestrial television transmitters.

If, for example, to take the porch 16 etazhki, then there the main task is not in receiving the signal of digital television, and in its proper distribution of the house network. People encounter this problem only in miniature in private houses and apartments when connecting several TVs.