A high frequency signal must be conveyed and diffused using suitable rules and equipment. In the system design, the cables placed in the riser column must ensure uniformity of signal between the farthest and closest socket to the roof.
Remember that it is always BETTER "NOT TO LOSE" the signal THAT AMPLIFYING !!!.
Better is the cable's quality, less will be the the equalization interventions in the switchboard.
Normally in the antenna-switchboard stretch are used PVC cables . This thermoplastic tends to degrade when subjected to atmospheric agents, moreover it is not completely impermeable if it is laid in areas where can occur water stagnation . For this connection it is advisable to use our INTSAT series cables whose advantages are:
1) polyethylene sheath (resistant to UV rays)
2) great mechanical strength that makes them more tolerant to being trampled
3) the addition of a layer in "petrol jelly" applied under the sheath, together with the characteristics of the polyethylene itself, guarantee them an absolute water resistance for a plant that will challenge time.
TRUNK CABLES - for descent columns
In presence of multiple columns, the signal should be subdivided using splitters. These components have the function of dividing the signal into equal parts, originating a low loss and a maintaining of impedance accorded. The attenuation of these devices varies according to the number of outputs: generally it goes from 4 dB for 2 outputs, to 8 dB for four outputs.
It is important to remember that this equipment does not offer a good separation and should not be used for derivation on final utility.
Before coming to the sockets, the signal must be diveded and SEPARATED from the column, so that any interference or disturbance generated in a utility does not propagate in the system. The device responsible for this function is the SHUNT, which has a very high separation between output and column (> 30 dB).
Unfortunately, the signal is subject to a significant attenuation (about 18 dB).
1) DISTRIBUTION INPUT
3) TRUNK CABLE
6) DROP DERIVATION CABLE
7) TERMINATION RESISTANCE
YOU SHOULD GUARANTEE THE SAME QUALITY 365 DAYS PER YEAR / 24 HOURS PER DAY.
TO GET THIS YOU SHOULD USE LOW ATTENUATION CABLES WITH HIGH SCREENING.
This device is made to be connected in cascade: at each passage it has an attenuation of about 1.5 dB.
CLOSING LOAD at 75 Ohm
Warning: it is very important to close column with the LOAD (75 Ohm), otherwise the whole distribution will not be accorded with the switchboard and it will occur reflected waves, signal drops or distortions. Absolutely avoid to connect the socket to the passing terminal of the shunt. Someone, sometimes, use this practise to recover (quickly) the lost signal due to some failure in the system (old cables, small switchboard, broken antenna, etc.). If it is true that in this socket the signal will be greater, it is even more true that the whole system will be compromised.
YOU MUST NOT TO CONNECT TWO CABLES IN THE SAME TERMINAL!
With digital signals is also necessary to shield the entire system from any interference generated by electrical equipment inside or in the nearby of the house. The standard EN 50117, for cables, has introduced the "classes" (B, A, A +, A ++), which identify shielding efficiency.
The impedence tolerance was also restricted, and the use of the return band of some Broadcast companies has introduced a further measure ever used before: the transfer impedance.
QPSK Costellation. All symbols are at the center with a wide safety margin.
Very disturbed signal, symbols outside their quadrant can not be decoded.
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