Features of coaxial cable
Coaxial cable is characterized by good anti-interference ability, stable transmission data and low price. Coaxial cable is divided into: thick coaxial cable, which uses AUI interface and is mainly used for the construction of base trunk line; Thin coaxial cable, using BNC interface, is mainly used for network connection between computers.
Transmission characteristics of coaxial cable
1、The thinner the cable, the greater the attenuation coefficient: for example, the attenuation of the 75-7 cable at 1000 meters is approximately equal to the attenuation of the 75-5 cable at more than 600 meters, in other words, the actual effect of the 75-7 cable transmission at 1000 meters is approximately equal to the actual effect of the 75-5 cable transmission at more than 600 meters.
2、The longer the cable, the greater the attenuation: for example, the 75-5 cable 750 meters, the "dB" of 6M frequency attenuation is 75% of the "dB" of 100 meters attenuation, that is, 15 db; The attenuation at 200m (1000+1000) is 20+20=40db, and the calculation formula for other frequency points is the same. According to the above 1000 meter cable test statistical data, when calculating the attenuation of cables of different lengths, please remember that "the decibel number is the alkali addition relationship" or "the attenuation decibel number can be calculated according to the proportion of the length change", and then you can master it skillfully.
3、Frequency distortion characteristics: low frequency attenuation is reduced, and high frequency attenuation is large. The difference between high and low side frequency attenuation can be called "side frequency difference", which is a very key parameter. The longer the cable, the greater the "side frequency difference"; Fully understand and master this kind of "frequency distortion characteristics" of coaxial cable, which has very important meaning in engineering; It is the most important feature that affects the image quality, and it is also the most easily overlooked problem in engineering projects.
