信号与网络布线技术
Definition of signal :
Information,
data,
signal.
Signal is roughly divided into two categories: digital signal and analog signal. The
difference is that the
value of analog signal is not limited. The value of digital signal is specified as 1, 0. The
distribution of analog signals is continuous, and the distribution of continuous digital signals is dispersed.
The signal is distorted during the transmission process, which is specifically manifested as noise and signal strength attenuation.
Compared with analog signals, digital signals have the following advantages:
1. Strong anti-interference ability.
2. Long transmission distance and guaranteed quality
. Classification of network cables.
Network cables are generally called twisted-pair cables. There are 8 cores inside, which are twisted in pairs.
According to different link rates, they are classified into 1-7 categories.
1) Type 1 line: Mainly used to transmit voice (Type 1 standard is mainly used for telephone cables before the early 1980s), which is different from data transmission.
2) Type II line: The transmission frequency is 1MHZ, used for voice transmission and data transmission with a maximum transmission rate of 4Mbps. It is common in the old token network that uses the 4MBPS standard token transfer protocol.
3) Category three cable: refers to the cable currently specified in the ANSI and EIA/TIA568 standards. The transmission frequency of the cable is 16MHz. It is used for voice transmission and data transmission with a maximum transmission rate of 10Mbps. It is mainly used for 10BASE-T.
4) Four types of cables: The transmission frequency of this type of cable is 20MHz. It is used for voice transmission and data transmission with a maximum transmission rate of 16Mbps. It is mainly used for token-based local area networks and 10BASE-T/100BASE-T.
5) Category five cable: This type of cable has increased winding density, a high-quality insulating material, and a transmission rate of 100MHz. It is used for voice transmission and data transmission with a maximum transmission rate of 10Mbps. It is mainly used for 100BASE-T and 10BASE-T network. This is the most commonly used Ethernet cables.
6) Super Category 5 cable: Category 5 has low attenuation, less crosstalk, higher attenuation to crosstalk ratio (ACR) and signal-to-noise ratio (Structural Return Loss), smaller delay error, and very good performance. Greatly improved. Super Category 5 cable is mainly used for Gigabit Ethernet (1000Mbps).
7) Category 6 cable: The transmission frequency of this type of cable is 1MHz～250MHz, and the comprehensive attenuation crosstalk ratio (PS-ACR) of Category 6 wiring system should have a larger margin at 200MHz. It provides 2 times that of Category 5 bandwidth. The transmission performance of Category 6 cabling is much higher than that of the Super Category 5 standard, and is most suitable for applications with a transmission rate higher than 1Gbps. An important difference between Category 6 and Category 5 is: improved crosstalk and return loss performance. For a new generation of full-duplex high-speed network applications, excellent return loss performance is extremely important. The basic link model is cancelled in the six types of standards. The wiring standard adopts a star topology. The required wiring distance is: the length of the permanent link cannot exceed 90m, and the length of the channel cannot exceed 100m.
According to the different usage scenarios, it can be divided into twisted pair. It can be divided into unshielded twisted pair (UTP=UNSHILDED TWISTED PAIR) and shielded twisted pair (STP=SHIELDED TWISTED PAIR)
网线线序的分类和做法
网线有两种做法，一种是交叉线，一种是平行（直通）线交叉线的做法是：一头采用568A标准，一头采用568B标准平行（直通）线的做法是：两头同为568A标准或568B标准，（一般用到的都是568B平行（直通）线的做法）
568A标准：白绿 绿 白橙 蓝 白蓝 橙 白棕 棕
568B标准：白橙 橙 白绿 蓝 白蓝 绿 白棕 棕
网线的连接
直通线：两头都是568B标准。用于连接
PC(电脑)—————————— HUB(集线器)
PC(电脑)—————————— SWITCH(交换机)
PC(电脑)—————————— ROUTER(路由器)
HUB(集线器)———————— HUB(集线器)的级连口
SWITCH(交换机)—————— HUB(集线器)的级连口
SWITCH(交换机)—————— SWITCH(交换机)级连口
SWITCH(交换机)—————— ROUTER(路由器)
交叉线：一头是568A，另一头是568B。用来连接
PC(电脑)——————————PC(电脑)
HUB(集线器)————————HUB(集线器)
SWITCH(交换机)——————SWITCH(交换机)
ROUTER(路由器)——————ROUTER(路由器)
正反线：又叫Console，接口是典型的配置接口。使用Console线直接连接至计算机的串口，利用终端仿在本地配置路由器。 路由器的Console接口多为RJ-45接口，并标记有CONSOLE字样。
除此之外的还有用来远距传输的线缆，叫做光纤，因为工作模式分为单模和双模。
光纤的传输特点
传输带宽高
传输距离远
抗干扰能力强
|Characteristics of single-mode and dual-mode
| single | double |
|---|---|
| High speed and long distance | Low speed and short distance |
| high cost | low cost |
| Harder to terminate | Easy to terminate |
| Narrow core, need light source | The wide core is good for concentrating light, and the light source adopts laser |
| Very low dissipation and high efficiency | Dissipation and inefficiency |
Optical fiber interface
FC Round fiber optic connector with screw
ST snap-on circular fiber optic connector
SC Square fiber optic connector
LC Narrow body square fiber optic connector
MFRJ Transceiver integrated
Wireless transmission media Transmission media that
use electromagnetic waves as transmission media include:
radio waves, microwave infrared lasers radio waves
lower frequency RF signals in the frequency band of the computer free space (air and vacuum) propagation, the propagation loss is smaller, the greater the distance covered, the higher the frequency, the greater system capacity, the smaller the distance coverage
of radio wave propagation characteristics of
the waves Propagation
Sky wave propagation
Straight line propagation
Band: decimeter wave, centimeter wave, millimeter wave
Infrared and laser
Infrared: It is not interfered by radio waves, transmits at close distances, and is greatly interfered by sunlight, and cannot penetrate walls.
Laser: Long transmission distance, long delay, travel along a straight line, and cannot pass through obstacles.
Radio transmission methods: direct, reflection, refraction, penetrating diffraction, scattering . The device used by the
antenna
to radiate and receive phone calls is called an antenna, and generally has a vibrator. , The feeder network cover consists of three parts. The cover is used to protect the vibrator. The
shape is divided into directional antenna, microwave antenna and satellite antenna.