Antenna splitter helps to watch TV for several apartment subscribers. The network is laid in a special way. At least two varieties in terms of topology.
Splitters Avoid switching on the splitter in any other way than shown on the housing. As a rule, an intuitively clear piece of paper glued to the sidewall is drawn, describing the process of laying the net. Many have disassembled the splitter, grinning incredulously: each exit looks the same. Inside it is simply carried out the electrical connection of the central cores, shields of coaxial cables. Often additional details are missing.
Most people think that there is no difference where the signal comes from, where it goes. From the point of view of high-frequency waves brought by the ether, the splitter for the antenna is completely asymmetrical. Few had to see the equipment for assessing the state of high-voltage cables, the principle of operation exploits the parasitic effects that occur when the signal moves. We briefly describe the scheme.
Suppose, buried high-voltage cable. Count, lived, screen( braid, armor).The structure of the cables is different, each modification ultimately resembles a coaxial. There are current-carrying conductors protected outside by the screen. The equipment for testing high-voltage lines includes the elements:
- Tone generator. More often 50 Hz, since such is the voltage transmitted by the cables.
- High Voltage Transformer. The device aims to obtain high voltage, which is several times, orders of magnitude higher than the nominal.30 kV cables are checked with a 100 kV voltage.
Hazardous equipment based on vehicle chassis. Mounted inside the special kung. They even avoid powering up by opening the door.100 kV overtaken owner rubber gloves, boots. In addition to the above, we see other cable testing devices, mainly a generator. To understand why the antenna splitter cannot be turned backside down, let's make a clear picture of the reflection of the signal. Heterogeneity of the screen, conductive wires, couplings, connections are perceived by a moving wave obstacle.
Like an oncoming sea, reflected by a mole, electric current begins to flow back, sensing discontinuity. Cable testing exploits echo( reflected response).The highway receives a tonal impulse, which is partially returned, “hit” by heterogeneity. The screen shows a series of peaks. Conducting the experience several times, experts eliminate false tops. Each peak is formed by a clutch, a break, another non-uniformity. Moreover, the polarity of the voltage returned, the amplitude will allow to describe the nature of the obstacle that met the wave. Malfunctions are detected, elimination is a matter of technique.
Requirements High voltage is reflected in unsuccessful places of the network, the self-made splitter for the antenna leads a similar policy. Advanced soldering skills are not enough to make the product yourself. There are two factors, apart from mechanical solder joints, which the wave considers to be discontinuities:
- The multiplicity of the length of the wire to the wavelength;
- The magnitude of the impedance( impedance) of network sections for a television signal that are different in nature and appearance.
The first is clearly manifested at high frequencies. Anyone who tried to repair the microwave is aware that the magnetron antenna is located at a certain distance from the back wall of the waveguide, and protrudes to a predetermined length. Otherwise, some of the energy will be reflected back, moving incorrectly( extinguishing itself).In the microwave, the frequency used is 2.4 GHz, the stretch affects the upper range of satellite television. Inside the splitter for the antenna, the cable lengths, material, length, solder composition are selected based on the issues of minimum signal loss.
With regards to impedance, a radio amateur who has designed a satellite television antenna with his own hands knows: it’s not easy to reconcile resistance with a standard 50 or 75 Ohm cable. It is necessary to apply special designs, like the U-bend, to avoid the reflection of the signal, losses. A good splitter for satellite dish Tricolor has an impedance on all sides, equal to the resistance of the cables. By the way, it is appropriate to remind: the standard is the nominal 50 Ohm. Using other types of cable, the installer is very risky.
Attentive reader should notice one thing. Repeatedly mentioned: the length of the wires is a multiple of the wavelength, but the broadcast captures the widest range. It's time to discover the truth. The antenna splitter resistance to different frequencies is not the same; it is powerless to ensure perfect range matching. The housing says: attenuation is 3.5 dB.The maximum or minimum value is given, or the value is measured in the middle of the range.
Other options are allowed, ask the consultant. The purpose of the splitter is to provide an optimal scheme of power transmission range. Factory better homemade.
Splitters are so easy to solder on their own that craftsmen fill the market with low-quality products that do not meet the certificates of the state, forgotten to pass. Beware of fakes. Otherwise, the radio amateur, after reading the review, will exclaim: "My splitter for the antenna is better than the purchased one."It is time to notice: not all splitters are equivalent. On the working frequency range, we distinguish two families:
- Splitter for digital television with operating frequencies up to 1 GHz.
- Splitter for satellite antenna with a bandwidth of up to 2.5 GHz.
The latter can be equipped with a digital broadcast reception path, the first plate will be rejected. Similarity of the image may be present, solely due to the presence of code redundancy, other technical frills. It is appropriate to remind: digital technologies provide amazing opportunities, restoration of a spoiled signal. The image may be partially present, the damage will be visible in the form of multi-colored squares.
Additional features of antenna splitters
A splitter for a TV antenna will provide minimal loss( attenuation parameters).Each antenna is capable of producing a certain level of signal to the cable. The TV will recognize, amplify, show a certain minimum threshold. It turns out: a stronger signal, more likely to watch football without interference. If the antenna is passive( does not consume electrical energy), the wire to the TV is a source of incredible losses. Avoid folding the cable into a coil. Cut so that the length remains minimal. A positive effect on television reception.
There are active antennas. You will need to power up the external voltage source. Often used coaxial cable. An antenna splitter supporting the option is provided with special markings on the housing. Specified where, where the current flows. The splitter for the TV antenna cannot be switched in the direction opposite to that indicated. It guarantees the inoperability of the system.
splitter. Highlights are mentioned. Choose a splitter for the antenna with a minimum attenuation according to the broadcast range, preferring special models if the devices are powered with coaxial cable. Beware of buying handicraft devices, it is better to make a splitter with your own hands. Fortunately, parts are sold in specialty stores. Wait a while to expect unprecedented quality. It is foolish to buy a room antenna for 200 rubles with a splitter, paying a similar or large amount.
The signal is distributed around the apartment using two types of topologies:
- Herringbone. You will need special splitters for several outputs.
- Highway. From one route subscribers periodically branch off.
In the first case, it is difficult to do the wiring for the number of TVs more than four, the signal loss will be smaller. Concerns the last subscriber line.