Digital television is not without reason grows. In analogous method broadcasting frequency band is simply divided between the channels. Detach each band (10 kHz radio), and were gang. Apart from the purely technical aspect of the difficulties identified adverse effects on human electromagnetic background. That's why the power of transmitters, including harmless Wi-Fi, strictly limit by law, punished with fines for disobedience. How to choose the antenna to the TV with the future.
Digital television
Roger Waters said the West broadcast 50 channels of rubbish, to be able to choose. Reminiscent of the current state of affairs. However, the Internet has replaced traditional methods of citizens in many ways. Think about it: today in the presence of a personal computer for free and allowed to talk with other countries. This is a revolution in the communication sector.
Antenna for the radio, many make their own. What about TV? According to the plans of the European Union, to 2015 godu digital broadcasting becomes 100%, ensuring the release of huge bandwidth for other uses. How this is possible. Antenna designers tortured with the manufacture of broadband devices. Listen to the radio lovers understand that the receiver "Ocean" has two receiving antennas:
- internal to the ferromagnetic core for VHF and HF;
- outer telescoping, swiveling to the side.
The inner core is wrapped coils, connecting them in a certain way, the user is tuned to the desired wave. Choosing the range had to adjust manually, changing the resonant circuit capacitance. TV - not yet the top difficulty. Equipment designed for narrow strips spaced away from each other, and assuming the presence of two or three frequencies do cheap and quality items for broadcast reception.
Along this path today and is digital TV. Moscow's first multiplex earned in 2010 (or in 2009), at the frequency of 559 MHz instead of 10 channels, not including three radio programs. Are broadcast for free on the territory of Russia, but at different frequencies 470 - 862 MHz. Used horizontal polarization, without protection by means of smart cards.
With an antenna for digital television, which will make even a schoolboy, the receiver scans the channels with high quality. For self-production will need information on the broadcast frequency in the region. For Moscow, it is 559.25 MHz, as already mentioned above.
Choose a digital TV antenna - in the capital for three multiplexes. And given the intention of Europe, we say with confidence: the broadcast method will gain momentum. Not all multiplexes are free, handy to have at home plate. Satellite broadcasting is a digital mode, the hosts from the physical channel watching a bunch of gear by moving the paraboloid at the point of the sky where the satellite hovers, and the receiver in charge of decoding the signal.
Digital broadcasting is similar, but entirely on the ground. Should not bother with a separate antenna selection. Room quarter-vibrator inserted into the receiver receives the signal perfectly. New plasma and LCD panel have been going on with native support for the standard, actively using data compression technology Mpeg technologies. However, a smart appliance, overtaking the PC, and the Internet can help to go and watch a film online. And no wonder why an old technique, all the features that overlap with modern digital technology.
Parameters selection of digital antenna TV
Choosing a TV antenna, good enough to take note of a couple of facts. Digital devices are different. Now, over the air, crawling dedicated frequency for all channels and one polarization. Here are two characteristics:
- Directional properties of the antenna.
- Ability active signal amplification.
Both factors improve the reception sensitivity due to increase. In the first case, the received signal is narrowed spatial sector, in the second - location next to the emitter amplifier are seeking opportunities to capture and detect inaudible broadcasting. The passive antenna is large attenuation in the connecting cable. Length directly included in the formula for calculating sensitivity of the system. Tip: do not leave on the floor of the bay unnecessary. cable cut off the excess.
To say on the choice of TV antenna will add:
- When visibility audio broadcasting points best fit Udo-Yagi antenna (e.g., REMO Saturn-Digital), referred to in the post-wave channel. It uses a traveling wave, amplifying on each director and reflector design give directional properties. The radiating antenna is supplied with an active vibrator, but in home systems is hardly present.
- A little on the characteristics of different phased array antenna, which resembles a square, dressed in plastic. Inside there are several molded metal pads included "in unison" for a narrow radiation pattern and increasing the amplitude of the signal.
- broadcast direction is unknown, or there is the effect of reflection of the beam from the walls of the surrounding houses, so that the bearing reception is constantly changing. Suitable antenna on the basis of a quarter of the vibrator. Directional properties of the unit are expressed much less. Today released two mobile devices with "mustache", rotate in different directions. To cover a range (40 - 870 MHz) add a square or circular frame.
The external antenna must be active, and better position the amplifier as possible next to the radiator. It is difficult to put into practice, but the process and will give the best result. For remote communities, where there is no multiplex, choose a satellite dish.
Satellite dishes for TV
Today, many satellite TV fans, there are not a billion free channels, but commercial - the sea. Fans of TV programs, choosing a satellite dish, you should pay attention to a number of options:
- A plate radiator has shifted from times truncated form without interfering reception quality. It appears two advantages, do not miss:
- In a typical plate azimuth and elevation angle to the satellite direction closed irradiator, and peak power is lost. If you move the radio wave receiving element, the most valuable land space is viewed by reflection of the law, at a glance.
- When the satellite is hanging high up above the horizon by shifting the focus of the illuminator angle of the paraboloid can be reduced. The argument is irrelevant for Russia - the satellites are hanging far above the equator, for China factor makes sense. Broadcast easier to catch, if the position of the satellite at the zenith point!
- The second feature is not constructive sophistication antenna, but rather is additive. waveguide piece with the resonator is placed on a special guide attached to the irradiator. The method aims at two satellites. Of course, the system gain decreases but can not re-adjust the antenna on the reception provider, broadcasting on different frequencies with different polarization.
- The toroidal satellite dish is a logical continuation of the previous case. It is provided with another reflector which changes in the opposite circular polarization (remember buying irradiator in the store), and the pile of feed elements arranged in a semicircle under basic paraboloid. Multifeed lossless allow broadcasting to take a huge number of satellites seen on the horizon. Option will appear through devices hanging at the same height, but different longitude over the equator.
Cable satellite antenna RK - 50 is considered standard, and feeds separately acquiring the additional equipment. To the device will have to buy the receiver decodes the signal and converts into a form understandable TV.
Paid channels require a special key card, which gives access to the encoded information. Without accessory commercial software - simply incomprehensible assemblage packages. Choosing an antenna to give, think about access. In the city people create an internet connection, where a dedicated server gives the key away from the settlements can not get a room.
