1. Transmission cables, wear galvanized iron pipes, take galvanized iron wire troughs, and bury underground wiring, etc., to give transmission cables a shielding environment for electromagnetic interference. This is the most basic and most effective way to prevent interference from "intrusion", including substations. Safe transmission in ultra-high pressure environments is effective. The disadvantage is that the cost is high, the overhead wiring cannot be used, and the construction is more troublesome;
2. Double-insulated and double-shielded anti-interference coaxial cable is a new achievement of anti-interference technology with its own intellectual property rights. Its principle is basically the same as that of the iron pipe. , the inner shielding layer is the actual signal ground of the coaxial transmission circuit, the interference generates induced electromotive force on the outer shielding layer, and the interference is shielded by connecting to the "earth", and the inner and outer shielding layers are insulated to insulate the interference induced electromotive force from the video signal transmission circuit, effectively preventing the The "invasion" of interference. The advantage is that the wiring is simple and convenient, and the cost is low. When it is impossible to accurately judge whether there will be interference, it is basically possible to achieve "anti-interference blind wiring";
"Avoid": Avoid interference, choose another "path", and change the source signal transmission mode. The technologies that belong to this category include: optical cable transmission (analog and digital modulation and demodulation technology), radio frequency, microwave, digital conversion, etc. All kinds of transmission methods belong to the "information modulation and transformation" method, or "frequency division method", which can effectively avoid the direct interference in the 0-6M frequency range in the source signal transmission; this method is very effective in anti-interference. At present, there are also some products that do not want to introduce the principle, such as the method of using coding and moving the signal frequency band up, and so on, probably also belong to this category of products. Using the "avoidance" technology, two issues should also be considered in the project: one is the increase of cost and complexity, and the other is the reduction of transformation loss, distortion and signal-to-noise ratio. One contradiction should not cover up the other.
