Signal Transmission Devices Review. Prt.2 Coaxial cables

Background interference is not the only trouble for the coaxial cable. In case of thunderhead, static discharges can appear in the shield or the center conductor. The difference of potentials between a metallic elements of transmission and receiving equipment and a cable armour comes up to a value of a few hundreds volts. Though this effect is short-run, it can disable the equipment, which costs a lot of money. To prevent this situation, it is necessary to implement the lightning guard systems. They are installed on transmitting and receiving cable sides and acts as a ground shunt for spurious pulses, which appear appear in the shield or the center conductor.

During the signal transmitting through the long mileage coaxial cable, amplitude-phase frequency distortions appear. The distortion level depends on the cable characteristic. Summary ohmic resistor of the center conductor and its shield makes the cable exit-signal amplitude decrease. This and the influencing of the capacitive component of coaxial cable leads to the substantial decrease of a signal on a high frequency. Besides, capacitance components of a cable impedance lead to the signal phase distortion at the cable output. As a result, the image definition and contrast are decrease, the color rendering is distorted and a color even can absolutely disappear. It is possible, that the signal will be distorted, because electromagnetic fields and noises can take an effect if a long mileage coaxial cable is used. It is impossible to do without extra equipment in this case. For example, the boosters, which compensate the signal losses and correct the amplitude-frequency and phase-frequency response characteristics.