A communication system composed of microwave sending machines, receiving machines, heavenly feedback systems, multi -way reuse equipment and user terminal equipment.
Microwave communication system, using microwave communication has a large capacity, good quality, and can be passed to a long distance. Therefore, it is an important communication method for the National Communications Network, which is also commonly applied to various special communication networks.
Brief introduction
The use of microwave communication has a large capacity, good quality, and can be passed to a long distance. Therefore, it is an important means of communication of the National Communications Network. It is also generally suitable for various special communication networks. my country’s microwave communication is widely used in the frequency bands of L, S, C, and X, and the application of the K frequency band is still under development.
Due to the high frequency of microwaves and short wavelengths, the propagation characteristics of the air in the air are close to the light waves, that is, straight forward, and it is reflected or blocked when it is blocked. Therefore After visual distance, relay reposted.
Generally speaking, due to the impact of the surface of the earth and the loss of space transmission, every 50 kilometers, a relay station is required to extend the radio waves to extend. This communication method, also known as microwave relay or microwave relay communication long -distance microwave communication trunk lines, can be passed to thousands of kilometers after dozens of repeats, and can still maintain high communication quality.
Equipment
The equipment of microwave stations includes antenna, sending and receiving letters, modulators, multi -way reuse equipment, and power equipment, automatic control equipment, etc. In order to gather the radio waves into a beam and send it to the distance, the parabolic antenna is generally used, and its focusing effect can greatly increase the transmission distance. Multiple transceivers can be used together to use an antenna without interfering with each other. my country ’s current microwave systems can work in the same frequency band and six income and six rounds at the same time. Essence Multi -way reuse equipment has the division of simulation and numbers. Each sending and receiving meter of the simulation microwave system can work on the 60, 960, 1800, or 2700 channels, which can be used for microwave circuits of different capacity levels. Digital microwave system application digital reuse equipment is composed of one group with 30 re -use principles on time on time, which can form a secondary group 120, 3rd group 480, four groups 1920, and modify it on the transmitter through the digital modulator to the transmitter. , The Digital Small Capital Cross was originally made up. The latest microwave communication equipment, its digital series standards are completely consistent with the synchronous digital series (SDH) of optical fiber communication, called SDH microwave. This new microwave device eight beams on a circuit can convey more than 30,000 digital telephone circuits (2.4Gbit/s) at the same time.
System model
The source of the starting letter is a device that provides the original signal. The signal of the source output from the source is a digital signal after the modular conversion.
The channel code is to improve the reliability of digital signal transmission. Because noise and interference in the channels are inevitable, the number of digital signals transmitted can cause an error code. In order to automatically check and correct the wrong code element in the receiving end, the use of the channel encoder can add some additional code elements in the input digital series in accordance with certain rules, and form a new digital series. At the receiving end, check the receiving signal if there is an error code according to the regularity of the new digital code series.
The modulation is to modify the digital signal to the load frequency with a high frequency, so that it is suitable for wireless channel transmission. The functions of several boxes such as the cutting end and the channel decoding are the corresponding conversion of several boxes.