A, the formation and solution of electromagnetic radiation interference during the signal transmission
For video interference, mainly from the interference mode to explore; audio signal because of the large wavelength, communication building shielding function is more obvious, compared to the radiation mode interference can be ignored.
b, the transmission line eliminates the external electromagnetic interference principle
If the cable is buried underground, or the use of lead-skin cable, balanced symmetrical cable, etc. can better overcome this interference.
Coaxial cable is shielded against electromagnetic interference. The coaxial cable is composed of an outer conductor and an inner conductor, and an insulating material is used as filler material between the inner and outer conductors. The outer conductor is usually woven from the copper wire, which has a good shielding effect on the external electromagnetic interference. The inner conductor is under the strict protection of the outer conductor, so the coaxial cable has good anti-interference ability.
Cable shielding layer for the lower frequency of the signal its shielding effect is worse, due to this reason the introduction of interference signals are carrier phones, radio signals and so on. They cause horizontal stripes to interfere in the image.
C, strong electromagnetic radiation on the line of interference and elimination
The transmission line has the ability to resist the external electromagnetic interference and can transmit the signal effectively. However, when the source of interference is too strong, the image signal will be disturbed. These strong electromagnetic interference mainly has the following two kinds:
1 Nearby have strong electromagnetic radiation source.
2 The line design is improper, the strong electric line to the transmission line interference.
Strong electromagnetic radiation source through the high-power radio or electromagnetic radiation of electrical equipment produced. The interference caused by strong electromagnetic radiation in the image is the network ripple interference. For this kind of interference, the following methods can be used to eliminate interference.
1 as far as possible to avoid the source of interference, system equipment and line with the radiation source to leave a certain distance.
2 Select the shielded cable with good performance. The braiding density of the outer shielding network of the coaxial cable directly affects the anti-interference performance of the cables, the greater the weaving density, the stronger the anti-interference ability.
3 Increase anti-interference equipment.