Ethereum LC
1. The network transceiver is the SC head< 2. The optical mole is LC
3. Optical transceiver is FC< 4. Cable TV is FC / APC
5. St is generally used in self-healing ring network<
knowledge extension:
optical fiber is a medium that transmits information from one end to the other. It is a glass or plastic fiber, which is used as a transmission medium for information< In general, the terms "optical fiber" and "optical cable" are confused. Most optical fibers must be covered with several layers of protective structure before use, and the coated cable is called "optical cable". The protective structure of the outer layer of optical fiber can prevent the surrounding environment from damaging the optical fiber, such as water, fire, electric shock, etc, It's just that there's no mesh shield. The center is the glass core of light propagation. In multimode fiber, the diameter of the core is 15mm ~ 50mm, which is roughly the same as the thickness of human hair. The diameter of single-mode fiber core is 8 mm ~ 10 mm. The core is surrounded by a layer of glass envelope with lower refractive index than the core to keep the fiber in the core. On the outside is a thin plastic jacket to protect the envelope. Optical fibers are usually bundled and protected by a shell. The core is usually made of quartz glass, which is a double concentric cylinder with small cross-sectional area. It is brittle and easy to break, so it needs a protective layer< Optical fiber is a kind of transmission medium, which can transmit telephone calls or computer data, just like common copper cables. The difference is that optical fiber transmits optical signals rather than electrical signals, Optical fiber has many unique advantages.
for example, broadband, low loss, shielding electromagnetic radiation, light weight, safety and privacy.
operation of optical fiber system
you may know that any communication transmission process includes coding → transmission → decoding. Of course, the transmission process of optical fiber system is roughly the same, The light is transmitted to the receiver at the other end through the optical fiber, and then the receiver decodes the signal and returns it to the original electronic signal output.
Application of optical fiber and cable
the application of optical fiber and cable can be divided into three types: professional use, general outdoor use and general indoor use, Radiation resistant optical cables for nuclear power plants, corrosion-resistant optical cables for chemical instry, etc, The scope of application is different.
Introction to various types of optical fiber interface
FC: round with thread (most used on distribution frame)
ST: snap on round
SC: snap on square (most used on router switch)
PC: grinding and polishing of microsphere surface
APC: grinding and polishing of microsphere surface at an angle of 8 degrees
MT-RJ
fiber mole: it generally supports hot swap,
GBIC (Giga bitrate interface converter): the fiber interface used is mostly SC or ST type
SFP: small package GBIC, and the fiber used is LC type
according to the outer sheath materials: PVC and LSZH
PVC are halogenated (chlorine) materials, which are flammable and proce harmful gases ring combustion, so they are not suitable for indoor use, but they have good mechanical properties; LSZH is a halogen-free material, non-toxic, flame retardant, but poor mechanical properties
No, most of the SFPs are LC optical ports. Interface types include SC / St / FC / LC, etc. The optical mole of SFPs is a small hot swap mole packaged in SFPs. At present, the highest speed can reach 10.3G, and the interface is LC. The optical mole of SFPs is mainly composed of lasers. The classification of SFPs can be divided into rate classification, wavelength classification and pattern classification
interface index of the optical mole:
1. Output optical power output optical power refers to the output optical power of the light source at the sending end of the optical mole, unit: DBM
2. Received optical power received optical power refers to the received optical power at the receiving end of the optical mole, unit: DBM
3. Receiving sensitivity receiving sensitivity refers to the minimum receiving optical power of the optical mole at a certain rate and bit error rate, unit: DBM. In general, the higher the rate is, the worse the sensitivity is, that is, the higher the minimum received optical power is, and the higher the requirements for the optical mole receiver devices are
Saturation optical power, also known as optical saturation, refers to the maximum input optical power when maintaining a certain bit error rate (10-10 ~ 10-12) at a certain transmission rate, unit: DBM
extended data:
components of the optical mole of the SFPs:
components of the optical mole of the SFPs include: laser: including transmitter Tosa and receiver Rosa circuit board IC, external accessories include: shell, base, pcba, pull ring, buckle, unlocking part and rubber plug, in addition, for the convenience of identification
generally, the color of the pull ring is used to identify the parameter type of the mole. For example, the black ring is multimode, and the wavelength is 850nm; Blue is a 1310nm mole; Yellow is a 1550nm mole; Purple is a mole with the wavelength of 1490nm
the relationship between SFF, SFP and GBIC optical mole:
SFP is the abbreviation of small form factor pluggables, that is, small package pluggable optical mole. SFF can be regarded as a pluggable version of SFF. Its electrical interface is 20pin gold finger, and its data signal interface is basically the same as SFF mole. The SFP mole also provides I2C control interface, which is compatible with optical interface diagnosis of sfp-8472 standard
SFF and SFP do not contain SerDes, but only provide a serial data interface. CDR and EDC are placed outside the mole, which makes small size and low power consumption possible. Due to the limitation of heat dissipation, SFF / SFP can only be used in ultra short distance, short distance and medium distance applications with 2.5Gbps and below
At present, the highest speed of SFPs can reach 10g, and most of them use LC interface. It can be simply understood as an upgraded version of GBIC. Compared with GBIC optical mole, the volume of SFP optical mole is reced by half, and the number of ports can be more than doubled on the same panel. In other functions, the function of the SFP mole is basically the same as that of the GBICWhether you are using single-mode or multi-mode optical fiber, you can use the equipment of optical fiber transceiver to convert it into RJ45 interface protocol. When purchasing, you should distinguish between single-mode and multi-mode
there should be, Taobao has many
1. Network card is a network component working in the link layer. It is the interface between the computer and the transmission medium in the LAN. It can not only realize the physical connection and electrical signal matching with the transmission medium in the LAN, but also involve the functions of frame sending and receiving, frame encapsulation and unpacking, medium access control, data encoding and decoding, data caching, etc
The optical fiber interface is LC, and the optical fiber is 50.0 multi-mode optical cable. According to the type of optical cable and the transmission distance, it is better to use optical cable above OM3; The device side needs an SFP + port
optical fiber jumper (also known as optical fiber connector) means that both ends of the optical cable are installed with connector plugs, which are used to realize the active connection of optical path; One end with a plug is called a pigtail
optical fiber patch cord / cable is similar to coaxial cable, except that there is no mesh shielding layer. The center is the glass core of light propagation. In multimode fiber, the core diameter is 50 μ m~65 μ m. It's about the same thickness as a person's hair. The diameter of single-mode fiber core is 8 μ m~10 μ m The core is surrounded by a layer of glass envelope with lower refractive index than the core to keep the fiber in the core. On the outside is a thin plastic jacket to protect the envelope
1. Is the channel the ordinary channel you usually watch? Is the channel dialed wrong. No, wipe the card. If it still doesn't work, call the local customer service and activate the card there
The service desk was not updated in time3. Turn off the power, take out the card and turn it on. Then shut down, insert the card, and then card the machine. If it doesn't work, please take it to the local cable TV service store for help
4. The smart card is overe, and the trouble is eliminated after payment; Digital TV set-top box has become an embedded computing device, which has a perfect real-time operating system, provides powerful CPU computing power, is used to coordinate and control the hardware facilities of the set-top box, and provides an easy-to-use graphical user interface (GUI)
set top box hardware
(1) network interface mole (NIM): the network interface mole completes channel demolation and channel decoding functions, and sends out transmission stream (TS) containing video, audio and other data information
(2) source data transport stream demultiplexer: transport stream generally contains multiple audio and video streams and some data information. Transport stream demultiplexer is used to distinguish different programs, extract corresponding audio and video streams and data streams, and send them to video decoder and corresponding analysis software
(3) conditional access mole: for pay TV, the conditional access mole also de scrambles the audio and video streams, and uses a smart card with the function of identifying users and memory to ensure the normal viewing of legitimate users
(4) video and audio decoder and post-processing: MPEG-2 decoder decompresses audio and video signals, restores analog audio and video signals through video encoder and audio D / a conversion, displays high-quality images on analog TV, and provides multi-channel stereo programs(5) embedded CPU and memory mole and interface circuit: embedded CPU is the heart of digital TV set-top box, it and memory mole are used to store and run the software system, and control each hardware mole. The interface circuit provides a wealth of external interfaces, including universal serial interface, USB, Ethernet interface and RS232, analog, digital video and audio interface, data interface, etc