At present, in the construction process of the public b […]
At present, in the construction process of the public broadcasting system system engineering, people often follow the form of "speaker cable" used in the home audio system to select the transmission system of the broadcasting system. In fact, there are certain misunderstandings.
In order to distinguish the positive and negative polarity of the "speaker wire" used in the home audio system, a transparent plastic wrapped copper wire is dyed into two colors of gold and silver. Learn the Hong Kong name in the market, commonly known as "gold and silver wire". The specifications of the "gold and silver wire" are based on the number of copper wires wrapped inside, and the classification is not very standardized.
"Speaker cable" is mainly used in home audio systems. Generally, the length is only 3-5 meters. Therefore, you should try to choose a "speaker cable" with a bit thicker and better material to improve the signal Transmission rate and reduce transmission loss.
If the "speaker cable" is used in the public broadcasting system, due to the long laying line, the project cost determines that it is impossible to choose high-grade "speaker cable", and only low-grade "speaker cable" can be used. The quality of this type of "speaker cable" is relatively poor, and most of them are manufactured by some small factories using relatively backward production processes, and users cannot refer to national standards for identification and acceptance.
Low-grade "speaker cables" are generally parallel lines, that is, two copper wires wrapped in transparent plastic and arranged in parallel. The principle of electromagnetics tells us that there is parasitic capacitance between any two parallel wires, and the existence of parasitic capacitance between wires will cause high frequency components in the transmission signal to be bypassed. The longer the wire, the greater the influence of the parasitic capacitance between wires. . Therefore, it is not suitable to use parallel lines for long-distance transmission of broadcast signals, otherwise it is easy to cause unclear treble and dullness.
Scientists have found that the twisted pair method can effectively overcome the influence of the parasitic capacitance between the wires, so the twisted pair method is widely used in computer network cables and high-end audio cables. With the popularization of twisted pair cable manufacturing technology, more and more transmission cables have adopted the twisted pair method. Therefore, the public broadcast system should also use twisted-pair cable for long-distance transmission and broadcast signals.
Wrap a layer of plastic jacket on the outer layer of the twisted-pair broadcasting cable, which can further protect the internal twisted-pair wire, and can avoid the trough, the bridge, the cut, and the short-circuit of the internal core wire in the construction project. This is the twisted pair Sheath broadcasting cable. Therefore, we recommend the use of twisted-pair sheathed broadcast cables for public broadcast systems.
In addition, on the basis of the twisted pair sheathed broadcast cable, there is also a twisted pair sheathed transmission cable with shielding layer. For large-scale public broadcasting systems, we recommend using shielded twisted-pair sheathed transmission cables. Due to the shielding effect of the shielding net, this kind of cable can effectively prevent the radiation influence of the broadcast cable on other cables laid in the same pipe (same trunking), and can strengthen the cable's anti-stretch function, especially suitable for the interior of weak current shafts in high-rise buildings Laying and outdoor long-distance laying.
In summary, during the construction of the broadcasting system project, we must not only select good equipment, but also select suitable cables to match it, so as to achieve better broadcasting effects.