1. The cable is fine, the greater the attenuation, such as 75-7 cable 1000 meters of attenuation, and 75-5 cable more than 600 meters attenuation roughly 1000 meters, or 75-7 cable transmission effect and the 75-5 cable more than 600 meters cable transmission effect are roughly equal;

2. The longer the cable, the greater the attenuation, such as 75-5 cable 750 m, 6 m frequency attenuation "decibels," for 1000 meters attenuation "decibels" 75%, namely 15 db; 2000 meters (1000 + 1000) attenuation for twenty + and = and db, other each frequency point calculation methods. In accordance with the above 1000 meters cable test data, calculation of different length cable attenuation, please remember "decibels is alkaline relationship" or "attenuation decibels can be in accordance with the length change percentage relationship calculation", can use agile;

3. Frequency distortion characteristics: low frequency failure decreased, high frequency attenuation. High/low side frequency attenuation difference, can be called "side frequency difference", this is a very important parameter. The longer the cable, "side frequency difference" the Fully understand and grasp the coaxial cable "frequency distortion characteristic", this project has very important meaning; This is the most important influence the characteristics of image quality, but also the most easy to be ignored in engineering problems;