Wiring structure of coaxial cable
In the computer network wiring system, there are three different construction methods for the thick and thin cables of the coaxial cable, namely the thin cable structure, the thick cable structure and the thick / thin cable mixed structure.
1. Thin cable structure
1) Hardware configuration
(1) Network interface adapter: Each node in the network needs an Ethernet card, a portable adapter or a PCMCIA card that provides a BNC interface.
(2), BNC-T type connector: each node on the thin cable Ethernet is connected to the network through a T-type connector, and its two horizontal plugs are used to connect two thin cables, and the vertical socket Connect to the BNC connector on the network interface adapter.
(3) Cable system: The cable system used to connect the thin cable Ethernet includes:
Thin cable (RG-58 A / U): a thin coaxial cable with a diameter of 5 mm and a characteristic impedance of 50 ohms.
· BNC connector plugs: installed at both ends of the thin cable segment.
· BNC barrel connector: used to connect two thin cables.
· BNC terminal matchers: BNC 50 ohm terminal matchers are installed at both ends of the trunk section to prevent the reflection of electronic signals. The terminal matchers at both ends of the trunk cable must have a ground.
(4) Repeater: For Ethernet using thin cables, the length of each trunk section cannot exceed 185 meters, and two trunk sections can be connected with repeaters to expand the length of the trunk cable. Up to four repeaters can be used in each Ethernet to connect five trunk line cables.
2) Technical parameters · Maximum trunk length: 185 meters.
· Maximum network trunk cable length: 925 meters.
· Maximum number of nodes supported by each trunk segment: 30.
· Minimum distance between BNC-T connectors: 0.5 meters.
3) Features · Easy to install.
· Low cost.
· Strong anti-interference ability of the network.
· Network maintenance and expansion are more difficult.
· There are many breakpoints in the cable system, which affects the reliability of the network system.
2. Thick cable structure
1) Hardware configuration A thick cable Ethernet requires a series of hardware equipment, including:
(1), network interface adapter: each node in the network needs an Ethernet card, portable adapter or PCMCIA card that provides an AUI interface.
(2) Transceiver: Each node on the thick cable Ethernet is connected to the network through an external transceiver installed on the trunk cable. When connecting a thick cable Ethernet, the user can choose any standard Ethernet (IEEE802.3) type external transceiver.
(3), transceiver cable: used to connect the node and external transceiver, usually called AUI cable.
(4) Cable system: The cable system connecting the thick cable Ethernet includes:
Thick cable (RG-11 A / U): a thick coaxial cable with a diameter of 10 mm and a characteristic impedance of 50 ohms, with a mark every 2.5 meters.
· N-series connector plugs: installed at both ends of the thick cable section.
· N-series barrel connector: used to connect two thick cables.
· N-series terminal matchers: N-series 50 ohm terminal matchers are installed at both ends of the trunk cable section to prevent the reflection of electronic signals. The terminal matchers at both ends of the trunk cable section must have a ground.
(5) Repeater: For the Ethernet using thick cable, the length of each trunk section does not exceed 500 meters, you can use a repeater to connect two trunk sections to expand the length of the trunk cable. Up to four repeaters can be used in each Ethernet to connect five-segment trunk cable.
2) Technical parameters · Maximum trunk length: 500 meters.
· Maximum network trunk cable length: 2500 meters.
· Maximum number of nodes supported by each trunk segment: 100.
· Minimum distance between transceivers: 2.5 meters.
· Maximum length of transceiver cable: 50 meters.
3) Features · High reliability and strong anti-interference ability of the network.
· With a large geographic coverage, the longest distance can reach 2500 meters.
· Network installation, maintenance and expansion are difficult.
· High cost.
3. Mixed thick / thin cable structure
1) Hardware configuration When setting up a thick / thin hybrid cable Ethernet, in addition to using the same hardware as thick and thin cable Ethernet, you must also provide connection hardware between thick and thin cables. Connected hardware includes:
· N-series socket to BNC socket connector.
· N-series plug to BNC socket connector.
2) Technical parameters · Maximum trunk length: greater than 185 meters and less than 500 meters.
· Maximum network trunk cable length: greater than 925 meters and less than 2500 meters.
In order to reduce the cost of the system, thin cables should be used as much as possible while ensuring the maximum length that a mixed trunk line can reach. You can use the following formula to calculate the maximum length of thin cable that can be used in a mixed trunk section t =
(500-L) / 3.28, where: L is the length of the trunk section to be constructed, and t is the maximum length of thin cable that can be used. For example, to construct a 400-meter trunk section, the maximum length of thin cable that can be used is: (500-
400) / 3.28 = 30 (m).
3) Features · Reasonable cost.
· Strong anti-interference ability of the network.
· The system is complex.
· Network maintenance and expansion are more difficult.
Increased the number of breakpoints in the cable system, affecting the reliability of the network
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