Digital television DVB in Russia. All formats, coverage, pros, cons and how to connect for free. DVB digital television standards (DVB-T, DVB-T2, DVB-C, DVB-C2, DVB-S, DVB-S2)

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This is not a very common malfunction, and it cannot be called a malfunction, meaning when the quality of the received DVB T2 signal fluctuates. Most often this is due to the position of the cable from the antenna to the TV, reception conditions and a number of other reasons. Why this happens is simply incomprehensible to an inexperienced user in such matters, and he can explain this behavior of the tuner as a malfunction of the set-top box or antenna, but that is not the point. However, let's take things in order.

Causes

The intensity with which the dvb-t2 signal jumps depends on the height at which the cable has such a horizontal section and how long it is; if it is located close to the ground, then the influence of interference is minimal. It is clear that the longer such a section is, the more the useful signal will be suppressed. To avoid this, place the antenna close to the set-top box; using a high-quality cable also helps.

The digital TV signal also begins to jump when it is tilted, for example when it descends from the ridge of the roof to the wall. It is worth noting that there is a known case when, with an inclined cable, the receiver showed for quite a long time after tuning, and with the onset of summer and hot weather, the signal level began to change abruptly from 0 to 100, and the quality signal remained at 5%.

There have been cases in practice when, in urban conditions, with a nearby tower located, an active indoor antenna was used to receive the first and second multiplex. The signal arriving at the tuner was very large, which led to the protection being triggered and, as a result, the signal began to jump on the digital tuner.

There were also opposite cases when the signal was artificially lowered. This refers to obstacles in the form of buildings or trees. Moreover, if there is a tree between the antenna and the tower, the reception is excellent in winter, but in summer the foliage dampens the signal and jumps in its level also occur. In this case, it is enough to move the antenna. By the way, for this reason, the signal also fails on satellite TV; the installed dish was showing correctly for several years and suddenly glitches began to occur, the picture crumbles into squares. It turned out that the tree had grown over the years and began to block the dish from the satellite.

There are many nuances here and they can have an impact - weather, cable quality, tower location range (signal strength), so you need to understand each case when the signal starts to jump when receiving or configuring T2, and it doesn’t matter what World Vision console you have, Rolsen, etc..

Avoid twisting the wire into a coil, as well as long sections with horizontal and inclined cable positions; use in these cases.

To avoid interference, the cable must be placed away from power electrical wires and avoid crossing the cable with power lines, and when crossing, make it at a right angle.

Wire the TV cable in one piece; if breaks cannot be avoided, then use special connectors with reliable wire contact and shielding, and not twisted with electrical tape.

Reception of digital TV signal (DVB-T2) in extremely harsh conditions.
Due to the greyhound nature of Tricolor, I decided to “finish off” digital terrestrial TV at my dacha.
The first (winter) attempt ended in failure: it worked in cold weather, but at zero and above there was not enough signal. Reasons: in summer the absolute humidity is much higher than in winter, lowland near the river and nearby forest. Let me remind you that my directional relief to the repeater gives a completely “closed interval”, i.e. the signal should not pass through... A relief with a refractive ellipse is attached. A
I bought a highly sensitive receiver (-82dBm) and moved the antenna from the house away from the forest (to the summer kitchen). Now it’s 100 meters to the forest, but it was probably 20 meters (an acute angle towards the repeater).
I bought and connected/stretched 23-25 meters of RG-6U cable.
I installed an antenna lightning arrester at the receiver input. It would probably be necessary to install it at the output of the amplifier, but I won’t get around to it yet. And at the input, the antenna amplifier has a DC short circuit, so I think it is well protected.
Result, in general, positive (compared to what it was before): at 650 MHz the signal strength is 80%, and at 722 MHz - 48%. On both, “quality” is 100%, which I don’t believe. Of course, 48% is not enough, but it works. On the verge. When the receiver warms up and as the play progresses, there are signal interruptions... Moreover, the antenna had to be very accurately aligned in the direction.
I didn’t like it and decided to “finish off” further.
I installed a second amplifier in the house in front of the receiver (an ancient one, from an old antenna).
At the same time, I had to overcome the excitation of the amplifier and the too strong signal.
A strong signal won out over splitters, which is right for me, because I want to distribute DVB-T2 around the house.
Now both multiplexes have a signal level above 90%. And the quality... - see Note-3.
Liked.
Lightning protection:
I attached a meter-long thick aluminum lightning rod to the top of the antenna mast, and organized it through an aluminum-to-copper adapter With his lower part(and not from the bottom of the mast!) a copper descent to the grounding for which I bought and hammered a galvanized pipe 1.6 meters under the antenna. A steel cable was welded to the same grounding, to which an antenna cable was connected, running from the summer kitchen to the house. Copper to steel pipe - through stainless washers.
Note-1:
It is assumed that the TV (at least) and the rest are grounded, otherwise interference may form at the receiver input (up to 100-150 Volts), which, with a grounded antenna and a temporarily open antenna input, can (if they are connected) break through the mast antenna amplifier at the output. And this is not a theory, but a cruel truth of life.
Note-2:
It’s strange that my signal quality indicator is almost always 100%. I do not believe!

Update dated July 11, 2015:
Note to those who insist that reception does not deteriorate when it rains.
The other day we had a wild downpour. So during this, the signal at 722 MHz completely disintegrated, and was added to 650...
It’s clear, because My signal-to-noise ratio is borderline. And the antenna is not the longest-range...
I scratched my back, tore up an old antenna that was lying around, made 6 directors about 14.5 cm long (this is the length of the directors of the purchased part of the antenna), and screwed them to the main antenna. After this, the signal level, deliberately roughened to 50%, rose to 65% (compared to a purchased antenna). How many in decibels, of course, is unknown...
We're waiting, out of the rain!
Update dated July 21, 2015:
Result of antenna modification:
Today we had a very heavy downpour again, both of my Tricolors (I temporarily have two antennas pointing at 36E) went off for 5-10 minutes, and my CETV didn’t turn off for a second...
Here, by amplifying the antenna itself, I raised the signal-to-noise ratio and therefore the signal was no longer “on the edge” and the effect was no longer noticeable. However, the signal level during rainfall decreased from 91% to 72% (at the minimum point).

Now the antenna looks like this:

Addition to the antenna modification results:
There were heavy rains and thunderstorms. I noticed that at the moment of a distant lightning discharge the image is disrupted for 2-3 seconds...
Note-3:
I bought a slightly different receiver from the same company for a friend and was additionally convinced that the almost constant 100% signal quality on my receiver was a fiction. This new receiver “measures” more or less normally. The quality on it (from the same antenna-feeder system) is 60-70%. By the way, its software menu and controls are different.
Apparently, I will shake the manufacturer/representative to provide a software update, which is much better in terms of convenience.
Note-4:
Forum member about static electricity during snowfall from an antenna on the 27 MHz range (copper wire vertically):
Note-5:

Today, DVB-T2 can most likely be called the most advanced terrestrial digital television system in the world. In this article we will try to understand how the DVB-T2 standard managed to take a leading position in the global terrestrial digital television broadcasting market, as well as what advantages it has over its predecessor, the DVB-T standard.

What is DVB-T2?

The DVB-T2 standard is the most advanced digital terrestrial television (DTT) system in the world. It is characterized by greater stability, flexibility and at least 50% greater efficiency compared to all other DTT systems. This standard supports broadcasting in SD, HD, Ultra HD formats, mobile television broadcasting, as well as any combination of the above formats.

Origins

At one time, the DVB-T standard became the most widely used in the world. Since 1997, when it was officially approved as valid, more than 70 countries around the world have launched broadcasting DVB-T platforms, and today 70 countries around the world have already begun launching multiplexes in the DVB-T2 system or have officially approved this standard.

As European countries transition from analogue to digital broadcasting and the frequency spectrum shortage grows, the DVB concern outlined general commercial requirements for the developers of an updated version of the standard, which was supposed to ensure even more efficient use of the frequency resource. The DVB-T2 system was able to meet all these requirements without any problems, including increased capacity, reliability and the ability to continue to use existing antennas. The first version of the DVB-T2 standard was approved in 2009 (version EN 302 755), and in 2011 an improved version of the system appeared, which, in particular, includes a new substandard T2-Lite, designed for the needs of mobile broadcasting and TV reception. signal to portable devices.

How it works?

The DVB-T2 standard, like its predecessor, uses OFDM (orthogonal frequency division multiplexing) modulation with multiple subcarriers capable of transmitting a stable signal, and also has a large number of different modes, making this standard extremely flexible. The DVB-T2 system uses the same type of error correction coding that is used in the DVB-S2 and DVB-C2 systems: it is a combination of LDPC (Low Density Parity Check) and BCH (Bose-Chaudhury-Hocquengham code) coding types. ), providing high signal stability. At the same time, the system allows you to change the number of carriers, the size of guard intervals and pilot signals, making it possible to optimize the overhead for any specific transmitted channel.

The DVB-T2 system also uses additional new technologies, in particular:

The use of multiple physical layer channels allows for separate adjustment of the stability of each of the transmitted programs within the channel to adjust to the required reception conditions (for example, an indoor antenna or an external antenna). In addition, this function allows the receiver to save energy by decoding only a specific program from the multiplex, and not the entire transmitted package.
Alamouti coding, which is a transmitter diversity method. Allows you to improve the quality of coverage in small single-frequency networks.
Constellation Rotation feature provides reliability when using low order constellations.
Extended interval function, including bit, time, square and frequency intervals.
Future Extensibility Function (FEF) - allows future enhancements to the standard while maintaining compatibility.

As a result, a DVB-T2 system can offer much higher data rates than DVB-T and also provide greater signal stability. For comparison, the bottom two rows in the table show the maximum data rates at a fixed signal-to-noise ratio and the required signal-to-noise ratio at a fixed (usable) data rate.

T2-Lite

The T2-Lite subsystem was the first additional profile in the standard that was added due to the existence of the FEF principle. This profile was officially introduced in July 2011 to support mobile broadcasting and reception on portable devices, as well as reducing the costs of implementing these types of broadcasts. The new profile is a subsystem of the DVB-T2 standard using two additional LDPC encoding rates. By using only elements relevant to reception on mobile and portable devices in the subsystem, as well as limiting the data transfer rate to 4 Mbit/s per physical layer channel, the complexity of creating and implementing a new chipset was reduced by 50%. The use of FEF principles allows programs to be transmitted in the same frequency channel in T2-Lite and basic T2, even when the two profiles have different Fast Fourier transform (FFT) values or different guard intervals.

Conquering the market

As with DVB-T, the new standard was intended not only for transmitting programs to devices equipped with external or indoor antennas, but also for reception on PCs, laptops, car TVs, radios, smartphones, dongles, and other innovative receivers . In countries where DVB-T platforms were already in operation, the DVB-T and DVB-T2 standards usually continue to coexist for some time, and in those countries where there was no digital broadcasting as such, there is a unique opportunity to switch directly from analogue to digital broadcasting to the DVB-T2 standard, bypassing the DVB-T implementation stage.
Currently, there are a huge number of DVB-T2-compatible set-top boxes and televisions on sale on the world market, and prices have already dropped to $25 for the cheapest models. The price difference between DVB-T and DVB-T2 compatible TVs is no longer significant.
The first country to begin introducing digital broadcasting in the DVB-T2 standard was Great Britain, where DVB-T2 broadcasting was launched in March 2010 in parallel with existing DVB-T platforms. During 2010-2011, DVB-T2 platforms were launched in Italy, Sweden and Finland, and very soon in each of these countries broadcasting in this standard was organized at the national level.
In Ukraine, the launch of on-air digital broadcasting in the DVB-T2 format began in the fall of 2011. The construction of a network of on-air transmitters was carried out by the Zeonbud company. In January 2012, the air digit signal was encoded by the Irdeto Cloaked CA conditional access system. In this regard, the market for receiving equipment was limited, and as a result of tenders held in April and July 2012, two companies became the main suppliers of digital set-top boxes - Strong and Romsat.
However, in July of this year, the National Council for Television and Radio Broadcasting, in its new composition, turned the country’s digitalization process 180 degrees, obliging the provider of the national digital broadcasting network Zeonbud to disable signal encoding. Thus, the introduction of the DVB-T2 standard on the territory of Ukraine takes on a new color, and, most likely, in the near future the television market will be overflowing with digital television receivers at an affordable price, which will actually stimulate the population’s interest in the new type of television, and will also allow the country to fulfill its The deadline for commitments to switch to digital is July 17, 2015.
Note that paid DVB-T2 platforms have also been launched outside Europe. For example, in Zambia, Namibia, Nigeria, Kenya and Uganda, and in a number of other countries, the launch of broadcasting in this standard is expected in the very near future. Test broadcasts of this standard are currently being carried out in many parts of the world, and many countries are considering adopting DVB-T2 as a digital terrestrial broadcasting standard.