In the era of analog monitoring, fiber optic transceivers are generally used in network communications. When the video surveillance system has begun to be networked, the optical transceiver has become an indispensable transmission product in the monitoring system. Today I have summarized common questions about fiber optic transceivers.
First, the fiber transceiver classification
A fiber optic transceiver, also called a photoelectric converter, is an Ethernet transmission medium conversion unit that interchanges short-distance twisted pair electrical signals with long-distance optical signals.
The difference in viewing angles makes people have different understandings of fiber optic transceivers:
For example, it is divided into single 10M, 100M optical transceivers, 10/100M adaptive optical transceivers and 1000M optical transceivers according to the transmission rate; it is divided into optical transceivers working at the physical layer and working at the data link layer according to the working mode. Fiber optic transceiver; if it is a structural point of view (desktop (stand-alone) fiber optic transceiver and rack-mount fiber optic transceiver; according to the access fiber, there are two types of multimode fiber transceivers and single-mode fiber transceivers Called the law.
There are also single fiber optic transceivers and dual fiber optic transceivers, built-in power fiber optic transceivers and external power fiber optic transceivers, as well as managed fiber optic transceivers and unmanaged fiber optic transceivers.
The fiber optic transceiver breaks the 100-meter limitation of the Ethernet cable in data transmission. It relies on a high-performance switch chip and a large-capacity cache to provide balanced traffic and isolation conflicts while realizing non-blocking transmission switching performance. Detection of errors and other functions to ensure high security and stability during data transmission.
Second, the scope of application
In essence, the optical transceiver only completes the data conversion between different media, and can realize the connection between two switches or computers within 0-120Km, but the actual application has more expansion.
1. Implement interconnection between switches.
2. Realize the interconnection between the switch and the computer.
3. Realize the interconnection between computers.
4. Transmission relay: When the actual transmission distance exceeds the nominal transmission distance of the transceiver, especially when the actual transmission distance exceeds 120Km, two transceivers are used to relay back-to-back or use light when the field conditions permit. The optical converter is a very cost-effective solution for relaying.
5. Single multimode conversion: When a single multimode fiber connection is required between networks, a single multimode converter can be used to connect, which solves the problem of single multimode fiber conversion.
6. Wavelength division multiplexing transmission: When the long-distance optical cable resources are insufficient, in order to improve the utilization rate of the optical cable and reduce the cost, the transceiver and the wavelength division multiplexer can be used together to allow two channels of information to be transmitted on the same pair of optical fibers.
Third, the use of precautions
We know that there are many different types of fiber optic transceivers, and most of the actual use is in the categories that are differentiated by fiber optic connectors: SC connector fiber optic transceivers and ST connector fiber optic transceivers.
When using a fiber optic transceiver to connect different devices, you must be aware of the different ports used.
1. Connection of optical transceiver to 100BASE-TX device (switch, hub): Confirm that the length of the twisted pair cable is no longer than 100 meters; connect one end of the twisted pair cable to the RJ-45 port of the optical transceiver (Uplink port) The other end is to the RJ-45 port (ordinary port) of the 100BASE-TX device (switch).
2. Connection of the optical transceiver to the 100BASE-TX device (network card): Confirm that the length of the twisted pair cable is no longer than 100 meters; connect one end of the twisted pair cable to the RJ-45 port of the fiber transceiver (100BASE-TX port) The other end is to the RJ-45 port of the network card.
3. Connection of the optical transceiver to 100BASE-FX: Make sure that the length of the optical fiber does not exceed the distance that the device can provide; one end of the optical fiber is connected to the SC/ST connector of the optical transceiver, and the other end is connected to the SC/ST connector of the 100BASE-FX device.
In addition, it is necessary to add that many users use optical transceivers as long as the length of the fiber can be used within the maximum distance that single mode fiber or multimode fiber can support. In fact, this is a misunderstanding. This kind of understanding is correct only when the connected devices are full-duplex devices. When there are half-duplex devices, the transmission distance of the optical fiber has a certain limit.
Fourth, the difference between ST, SC, FC, LC interface
Optical fiber connectors, that is, fiber connectors that are connected to optical modules, are also various and cannot be used interchangeably with each other. People who are not always in contact with fiber optics may mistake the fiber optic connectors of GBIC and SFP modules for the same type, but they are not. The SFP module is connected to the LC fiber connector, and the GBIC is connected to the SC fiber optic connector. The following is a detailed description of several commonly used fiber optic connectors in network engineering:
1 FC type fiber optic connector: The external reinforcement method is a metal sleeve, and the fastening method is a turnbuckle. Generally used on the ODF side (the most used on the patch panel)
2 SC type optical fiber connector: The connector that connects the GBIC optical module. Its outer casing is rectangular, and the fastening method is plug-and-pull type without rotating. (most used on router switches)
3 ST type optical fiber connector: commonly used in optical fiber distribution frame, the outer casing is round and the fastening method is screw buckle. (For 10Base-F connections, the connector is usually of the ST type. Commonly used for fiber distribution frames)
4 LC fiber optic connector: A connector that connects to an SFP module and is made with a convenient modular jack (RJ) latch mechanism. (used by routers)
5 MT-RJ: Transceiver integrated square fiber connector, one double fiber transceiver
Introduction to various fiber interface types (fiber connectors):
FC round with thread (most used on patch panels)
ST card type round
SC card type square (most used on router switches)
PC microsphere polishing
APC is at an angle of 8 degrees and is micro-spherical polished
MT-RJ square type, one double fiber transceiver
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Five, the principle of purchase
As a regional network connector device, the fiber transceiver is the main task of how to seamlessly connect the two parties. Therefore, we must consider the compatibility of its compatibility with the surrounding environment, and the stability and reliability of its own products. On the contrary: the price is lower, and it cannot be used!
1. Does it support full-duplex and half-duplex?
Some chips in the market can only use full-duplex environment at present, and can't support half-duplex. If you connect to other brands of switches (SWITCH) or hub (HUB), and it uses half-duplex mode, it will definitely cause Serious conflicts and packet loss.
2. Have you done connection testing with other fiber optic transceivers?
At present, there are more and more optical transceiver transceivers on the market. For example, if the compatibility of different brands of transceivers has not been tested beforehand, it will also result in packet loss, long transmission time, and rapid and slow.
3. Is there a safety device to prevent packet loss?
In order to reduce the cost, some manufacturers use the register data transmission mode when manufacturing the optical transceiver transceiver. The biggest disadvantage of this method is that the transmission is unstable and packet loss, and the ideal one is to adopt the buffer line design. It is safe to avoid data loss.
4, temperature adaptability?
When the fiber optic transceiver itself is used, it will generate high heat. When the temperature is too high (generally not as large as 85 °C), does the fiber optic transceiver work normally? What is the maximum allowable operating temperature? For a device that needs long-term operation, this is worthy of our attention!
5. Is there an IEEE802.3u standard?
If the optical transceiver meets the IEEE802.3 standard, the delay time is controlled at 46 bits. If it exceeds 46 bits, the distance transmitted by the optical transceiver will be shortened! ! !
6, after sales service
In order to make the after-sales service respond promptly and early, it is recommended that the customer choose a professional company with strong strength, high technical strength and good reputation.
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