What are the outstanding advantages of optical fiber transmission
Bandwidth
The width of the frequency band represents the size of the transmission capacity. The higher the frequency of the carrier, the larger the frequency bandwidth over which the signal can be transmitted. In the VHF frequency band, the carrier frequency is 48.5MHz～300Mhz. The bandwidth is about 250MHz, which can only transmit 27 sets of TV sets and dozens of sets of FM broadcasts. The frequency of visible light reaches 100,000 GHz, which is more than one million times higher than the VHF frequency band. Although the frequency bandwidth is affected due to the different losses of optical fibers to different frequencies of light, the frequency bandwidth in the lowest loss region can also reach 30,000 GHz. The bandwidth of a single light source only accounts for a small part of it (the frequency band of multi-mode fiber is about several hundred megahertz, and a good single-mode fiber can reach more than 10 GHz). Using advanced coherent optical communication, 2,000 optical carriers can be arranged in the range of 30,000 GHz. , for wavelength division multiplexing, which can accommodate millions of channels.
low loss
In a system composed of coaxial cables, the best cable has a loss of more than 40dB per kilometer when transmitting 800MHz signals. In contrast, the loss of the optical fiber is much smaller. The loss per kilometer is less than 0.35dB when transmitting light of 1.31um. That's 100 million times less power loss than coaxial cable, allowing it to travel much farther.
In addition, there are two characteristics of optical fiber transmission loss,
One is to have the same loss in all cable TV channels, and it is not necessary to introduce an equalizer for equalization like a cable trunk;
The second is that its loss hardly changes with temperature, so there is no need to worry about fluctuations in mains level caused by changes in ambient temperature.
light weight
Because the optical fiber is very thin, the diameter of the single-mode optical fiber core wire is generally 4um ~ 10um, and the outer diameter is only 125um, plus the waterproof layer, reinforcing ribs, sheath, etc., the diameter of the optical fiber cable composed of 4 to 48 fibers is less than 13mm. It is much smaller than the standard coaxial cable's diameter of 47mm. In addition, the optical fiber is glass fiber and has a small specific gravity. It has the characteristics of small diameter and light weight, and it is very convenient to install.