4. Signal and transmission medium

Medium

Signal

Interface

Telephone line

analog signal

RJ11

Network cable

Digital signal

RJ45

The advantages of digital signal: strong anti-interference ability, long-distance transmission can also ensure the quality.

The maximum transmission distance of the network cable is 100 meters, and a repeater can be used to transmit it.

Network cable is also called twisted pair, twisted pair is divided into 7 types according to category, the larger the category number is, the better the quality is. Category 5 lines are used in 100m networks, super Category 5 lines are used in 1000m networks, and Category 6 wires are used in 10000m networks.

Twisted pair standard: EIA/TIA-568

Line sequence:

T568A: White green, green, white orange, blue, white blue, orange, white brown, brown

1 2 3 4 5 6 7 8

T568B: White orange, orange, white green, blue, white blue, green, white brown, brown

1 2 3 4 5 6 7 8

Note: 1236 is used for 10m data transmission, 4578 is used for 100m data transmission, and 8 wires are for compatible use.

The straight-through line is used to connect different devices, and the cross line is used to connect the same equipment.

Note: T568A+T568B is a cross line and T568B+T568B is a straight line.

Optical fiber is a network cable that uses optical transmission, which has high bandwidth, longer transmission distance and better quality.

Optical fiber classification:

V single-mode fiber: the transmission distance is thousands of meters, but the cost is high.

V multimode fiber: the transmission distance is 100m to 500m, and the cost is low.

Fiber interface:

V FC optical tail joint:

V SC optical tail joint:

V St type optical tail joint: