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What is the difference between shielded and unshielded jumpers?

There are many types of network cables. If you distinguish them according to the application scenario, you can divide them into outdoor and indoor network cables, shielded and unshielded network cables. Then, there will be many friends who will have doubts. What is the difference between shielded jumpers and unshielded jumpers? What is the role?

First, what is the difference between shielded jumpers and unshielded jumpers?

Shielded cable (shielded twisted pair), the outer layer of the shielded cable is wrapped in aluminum to reduce radiation but does not completely eliminate radiation. The price of the shielded cable is relatively high, and it is more difficult to install than the unshielded cable. Similar to coaxial cable, it must be equipped with a special connector that supports shielding and corresponding mounting technology. But it has a higher transmission rate and can reach 155Mbps within 100 meters. The price is relatively high and requires special connectors that support shielding and comparable mounting techniques, but at a higher transmission rate than the corresponding unshielded twisted pair.

The unshielded network cable is divided into 4 pairs by 8 differently colored wires. The effect of paired twisting is to minimize the influence of electromagnetic radiation and external electromagnetic interference. In the EIA/TIA-568 standard, twisted pairs are classified into three types: four types, four types, and five types of lines. The three most commonly used types in the network are the three types of lines and the five types of lines. Currently, there are more than six types.

Second, what is the role of shielded jumpers and unshielded jumpers?

The unshielded network cable is mainly used in the network without interference, so the shielded network cable is relatively used in an environment with interference. The unshielded network cable has no shielding layer. Its diameter is relatively small, and it is space-saving. It can be used in an environment without interference, which is not only convenient to use, but also saves space when wiring.

When indoors, our interference source is generally not very serious. The transmission speed of the unshielded network cable is actually faster than the shielded network cable. If the spatial structure of the wiring is close to the interference source of the air conditioner, the shielded network cable is used.

In terms of price, the price of the unshielded network cable is lower than the cost of the shielded network cable. Some people may ask, the transmission speed is obviously better than the unshielded network cable, why the price is low, but the price of the network cable is not completely determined by the transmission speed.

The shielded network cable exists in order to cope with the environment with interference sources, so its cost is relatively high, and it is also difficult to wire.

Therefore, the price of the unshielded network cable and the shielded network cable differs in this layer of shielding function, but not all shielded network cables are used in the electromagnetic environment. In fact, in the ordinary electromagnetic environment, we can use the unshielded network cable to deal with it. Normally, there will be no problem. According to the environment, the network cable can be used to make the wiring scheme better. Cost savings and easy wiring are the first priority.

In fact, the difference between a single shielded network cable and a double shielded network cable is that the double shielded network cable has a more shielding layer than the single shielded network cable. In fact, it can be seen from their names. And double-shielded cable transmission speed than a single shielded cable is slower.

Original Article Source http://www.qianjia.com/html/2019-04/10_332600.html

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What are the precautions for fiber jumper construction?

As we all know, the fiber jumper is used to make the jumper from the device to the fiber-optic wiring link. It has a thick protective layer, which is generally used for the connection between the optical transceiver and the terminal box. So you know how to make fiber jumpers? What are the precautions for fiber jumper construction?

How to make fiber jumpers

1 Steps for skipping content:

The first step: identify the light and the room, find the splitter.

Step 2: Identify the splitter number.

Step 3: Find the splitter port configured on the work order.

Step 4: Find the port of the cable core of the access user.

Step 5: Jump from the splitter port to the user cable port.

2 Basic knowledge and specifications of fiber jumper:

1) The fiber-optic operation must meet the principles of ODF frame, light communication, tidy inside the integrated box, beautiful wiring, easy operation, and less space.

2) The length of the jumper must be within the range of 500mm.

3) Jumpers of insufficient length shall not be used. It is not allowed to use flanges to connect two jumpers.

4) Each jumper should ensure that the radius of curvature is greater than 400mm.

5) General requirements for fiber removal:

1 For the fiber on the upper line, the cable should be off the outside of the ODF frame. Select the most suitable fiber column for the remaining fiber volume, and move the fiber upwards on the inside of the ODF frame. The horizontal edge is on the lower edge of the ODM and is perpendicular to the corresponding terminal.

2 One jumper is only allowed to go up once in the ODF frame (along the outside of the ODF frame), once on the side (along the inside of the ODF frame), and take a fiber column. It is forbidden to entangle, cross and hang between the multiple fiber columns. That is, there must be no filament winding on the upper edge of each disc.

3 The specific situation of the site should be stipulated after the initial preparation of the jumper.

4 All jumpers must be placed in the ODF frame. It is strictly forbidden to deploy outside the aircraft and fly the line.

5 The super long jump fiber for emergency use shall be hung on the inner fiber disc according to the rules, and shall not affect the future fiber jump.

3 Jumper type and length control

1) Select the corresponding fiber jumper (SC-SC, FC-FC, SC-FC) according to the flange head on the splitter and the splitter box.

2) The fiber jumper from the splitter to the user table, the length of the length is controlled within 50CM, and the pigtails of 1m, 2m, 2m5, 3m are generally selected.

3) The ONU and the fiber terminal jumper in the user terminal box generally use 50CM short pigtail.

4 Jumper label management and specification

1) All jumper labels must be labeled with the machine and no handwriting is allowed.

2) In the machine room, light communication, and corridor, the fiber-optic to the user’s leather cable must be attached to both ends of the fiber-optic cable.

3) The effect after completion is uniform specification length, according to the gap of the terminal position, the labels are not staggered.

4) The front side is the name of the light path, and the reverse side is the light path code and barcode, and the orientation is uniform.

5) The change text hangs down with the pigtails, naturally facing up.

5 Perform the necessary optical path test

After each fiber path jump is completed, it needs to be tested. The test steps are as follows:

1) Test the wavelength of the splitter at 1490 with an optical power meter, and the optical power should be less than -22dB.

2) The user end tests with the 1490 wavelength of the optical power meter. The receiving power should be less than -23dB, and the maximum sensitivity of the ONU is generally -24dB.

3) Use the ONU device to debug the Internet for the user.

4) If there is no light, you can judge whether the fiber is wrong by the visible light source (red light).

5) If there is no fiber but still no light, when the loss is large, the ONU can not work normally, and the cable maintenance department can be informed.

6 Resource Management

It is strictly forbidden to change the fiber order of the construction sheet without authorization. The optical path resources need to be changed during the loading and maintenance process. The relevant information of the optical path is recorded on the work order and timely reported to the resource department for updating.

What are the precautions for fiber jumper construction?

1 Types and uses of pigtails

According to the existing ODF shelf and device port standards, fiber jumpers can be classified into the following types:

(1) According to the interface type: the pigtail interface can be divided into three interfaces: FC, SC, and LC. The two ends are FC-FC, SC-SC, LC-LC, FC-SC, FC-LC, SC. -LC, a total of six types of fiber jumpers.

(2) According to the length of the interface: the pigtails are 1.5 meters, 2 meters, 3 meters, 5 meters, 10 meters, 15 meters, 20 meters. We usually use 3 meters, 5 meters, 10 meters, 15 meters, and 20 meters.

(3) Use: FC interface is used for ODF frame to connect remote core; SC interface is used for ODF frame (less) and equipment, such as OLT and ONU device interface in EPON, photoelectric converter interface, etc.; LC interface only Used on the interface of the device. Two of the three core interfaces are combined to achieve a physical connection between the ODF and the ODF shelf, between the ODF shelf to the device, and between the device and the device.

2 Preparations and precautions outside the field before fiber jumper:

Before the fiber jumper, it is generally based on the needs of the business, there will be a need for a fiber jumper. But for different needs, the equipment to be jumped is different, and the preparation work that needs to be done is different. Therefore, before the fiber jumper, there must be clear working ideas and clear work objectives. Otherwise, there will be cases where the jumper is not brought or not so that the work task cannot be completed on time, and the work target cannot be realized on time. , affecting the development of the company’s business. Therefore, preparation before the fiber jump is critical to the achievement of the work objectives. Preparations outside the site are generally outside the computer room, and the following preparations are required. Finally, there are matters needing attention.

1) Preparation work outside the field before fiber jumper:

1 Working ideas: What is the purpose of the jumper? What equipment is needed to jumper? What interface is the device? What type of fiber jumper do I need to use? Do I need to prepare an optical module? Do you need other tools? These are all things that need to be considered in advance.

2 Tool preparation: optical power meter (including test fiber jumper), red light pen, tube sleeve, label paper, oil pen, notepad, pliers, electric tape.

3 Material preparation: fiber jumper, optical module, the quantity, type or length of the corresponding material is determined according to requirements.

4 Disk information preparation: If the interconnection between different computer rooms, you need to know the information about the machine room and record it on the notebook.

2) Precautions before the field of fiber jumper:

1 If you need to bring a module, you should pay attention to the module type, distance, wavelength, and other parameters;

2 The core should pay attention to the type and length of the interface, and pay attention to whether it is necessary to cross the cabinet, how far apart the cabinet is, and whether it is necessary to walk the distribution frame.

3 Note that with spare modules and fiber jumpers, at least one spare module and one pair of corresponding jumpers must be prepared.

3 Preparations in the field before the fiber jumper

1 Untie the pigtail tape and unfold the two pigtails. After the whole fiber is unfolded, the same interface is put together. After straightening, the two fiber jumpers are bundled together with electric tape.

2 If you jump into the core of different computer rooms, you can first contact the colleagues in the remote computer room to test whether the pigtails can be used normally, whether the ODF shelf is faulty, and whether the cable light loss is normal; if it is the equipment in the machine room Connected, connected to relevant equipment, test whether the pigtail can be used normally;

3 Use Notepad to copy the serial number of the module to be used, the length and type of the core, to facilitate asset management.

4 Precautions in the field of fiber jumper

1 Jumping is divided into three cases: the same cabinet jumper, adjacent cabinet jumper, and cross-rack jumper. The difference is that the pigtails across the cabinet are protected by bushings when they cross the cabinet, and the patch panels are used for the patch panels.

2 When the pigtail is connected, connect one end of the core to the device, and the other end is routed from the left side facing the cabinet. The excess pigtails are wrapped in a circle (not folded into a straight line) and wrapped with electric tape. Well, connect the other end to the device or the ODF frame. The ODF frame enters the line from the left side hole of the ODF frame, and the flying line cannot appear.

After 3 good cores, label paper should be attached and labeled according to the naming requirements.

4 After the label is placed, the registration of the core of the ODF frame should be done. If the main core is jumped, the use of the core should be used (the local and the opposite information is written on the label paper). And use the notepad to record it.

5 Collect the protective caps of the module and pigtails and place them in the small box at the bottom of the cabinet for future use.

5 Finishing work after fiber jumper:

Before leaving the machine room:

1 Contact the relevant colleague to test whether the core is connected and whether the jump target has been completed;

2 After confirming that the fiber-hopping work is successfully completed, carry out on-site tool finishing, and clean the waste materials such as the pigtail packaging bag to keep the environment of the machine room clean and tidy;

3 Close the room lights, check again if something is in the machine room, and pay attention to lock the machine door when leaving.

The above is all the contents of the fiber jumper and the fiber jumper construction precautions. Of course, the fiber should not be excessively bent and looped during use, which will increase the attenuation of light during transmission. Be sure to protect the fiber connector with a protective sleeve after use. Dust and oil can damage the coupling of the fiber.

Original Article Source http://cabling.qianjia.com/html/2019-05/22_337862.html

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What is the video optical transceiver how to judge the performance index of the video optical transceiver

At present, multi-channel digital video optical transceivers on the market involve a wide variety of technical indicators. Most engineering companies and users lack the corresponding means to judge the rationality and authenticity of technical indicators, so it is easy to lose direction when selecting products. So, what is a video optical transceiver? How to judge the performance indicators of video optical transceivers?

What is a video optical transceiver?

The video optical transceiver is a device that converts one or more analog video signals into optical signals through optical fibers through various codes. Since the video signals are converted into optical signals, the two technologies of analog conversion and digital conversion are adopted. Therefore, video optical transceivers are divided into analog optical transceivers and digital optical transceivers. The principle of the optical transceiver is to modulate the signal onto the light and transmit the video through the optical fiber.

How to judge the performance index of video optical transceiver

1 Technical indicators considered

Multi-channel digital video optical transceivers can have a variety of functions, each type of function has corresponding technical indicators, such as video indicators, audio indicators, asynchronous data indicators, Ethernet indicators and so on. Specific technical indicators may require manufacturers to provide third-party test certificates. Conditional engineering companies should re-test according to the indicators provided by the manufacturers before purchasing equipment to verify the actual technical specifications of the equipment and the integrity of the manufacturers. Here we focus on the following two video indicators from an engineering perspective.

1.1 3dB video bandwidth is sufficient

Video bandwidth is a common problem. The video bandwidth is insufficient, the details of the monitor picture are not clear enough, the horizontal resolution is low, and even the color distortion or loss occurs. Because of the importance of video bandwidth to image quality, some unscrupulous vendors deliberately exaggerate the video bandwidth of their products to deceive customers.

A multi-channel digital video optical transceiver produced by a manufacturer claims that its video bandwidth is 8M, but its externally announced video sampling frequency is 12.5M. According to Nyquist’s law of sampling, to truly restore the signal, the sampling frequency should be at least twice the frequency of the signal.

In this way, the theoretical video bandwidth of this manufacturer’s optical transceiver may not exceed 6.25M in any case. Obviously, this is a lie that exaggerates performance to deceive customers, so that vendors without commercial reputation should not be considered for purchase. But not all customers can accurately identify the lie of the manufacturer. For the average engineer and user to observe the details of the image, the video bandwidth of the device can be roughly judged.

1.2 APL range is wide enough

APL, the average image level, is a measure of the average video brightness level and expressed as a percentage of the maximum white level. When APL is low, the image is dark, and when APL is high, the image is lit. Many engineers are not very concerned or not familiar with this indicator.

However, if there is a problem encountered in some projects: the video signal is transmitted through the optical transceiver, when there is a large area of ​​white in the picture (such as when the camera is illuminated by strong light), the picture on the monitor will horizontally jitter, then Engineers must be familiar. This is because the APL range of video optical transceivers produced by some manufacturers is too narrow. When there is a large area of ​​white in the image signal, the DC component in each line of image signals increases, and the APL will increase, causing the amplitude of the line sync signal to decrease. Or lost, the monitor cannot detect the line sync and the picture is shaken.

2 Reliability considerations

As a security monitoring project, the reliability of the equipment should be the first consideration. The reliability of the equipment must be considered by the equipment manufacturer when designing the product. However, some manufacturers may not be willing or do not know how to do this work for some reasons. The focus here is on the following issues from the engineering perspective.

2.1 Power supply is convenient, the power supply range is wide

The power supply is the primary consideration for ensuring the reliability of digital video optical transceivers. The power supply cannot be guaranteed to be reliable and reasonable. The reliability of digital video optical transceivers has become fishing in the water. The video optical transceiver with 220VAC power supply is convenient to take power and has high reliability. In the project, 220VAC power supply optical transceiver should be selected as much as possible. At present, the optical transceiver mainly has two power supply modes, one is a powerful external type, and the other is a powerful built-in type, that is, the power supply and the optical transceiver are integrated. From the perspective of engineering applications, the built-in power supply is not only easy to install, but also has high reliability. Therefore, most of the current multi-channel digital video optical transceivers are the built-in power supply.

Based on the domestic power grid situation, combined with the actual project site, you should choose a multi-channel digital video optical transceiver with a wide input power range. Generally, you should choose the optical transceiver that uses the switching power supply. Compared with linear power supply, switching power supply is not only efficient but also has a wide input voltage of switching power supply. It can basically guarantee normal operation in the range of 160VAC-265VAC, and its output voltage will not change with the input voltage, so it will not affect the optical transceiver. The working performance and technical indicators will not cause the optical transceiver to restart repeatedly due to the instability of the power grid, interrupting the transmission of monitoring video and audio signals.

2.2 High temperature and humidity adaptability

In some security monitoring projects, the working conditions of the optical transceiver are relatively harsh, the temperature variation range is wide, the air humidity is large, and some field monitoring points occasionally lose power. All of these require multi-channel digital video optical transceivers to have more considerations in terms of temperature range and allowable humidity to ensure stable operation in harsh environments and to meet security monitoring needs.

2.3 Grounding considerations

In the security monitoring project, ensuring the good grounding of the equipment is an important part of ensuring the reliability of the equipment. Good grounding is good for the equipment against the surge, anti-static and lightning strikes, which can significantly improve the reliability of the equipment. Therefore, when choosing an optical transceiver, pay special attention to the manufacturer’s grounding scheme, and thus the strength of the manufacturer. A good grounding should have the following considerations:

First, the power supply of the optical transceiver must be grounded. As an industrial grade product, for the safety of equipment and personnel, the multi-channel digital video optical transceiver should be connected to the three-eye power socket by the national standard 220VAC three-core power cord, and can not be connected to the power socket for the convenience of using a two-core power cord. Moreover, the ground wire of the power socket should be reliably connected to the earth during the project.

Secondly, the signal ground of the optical transceiver should be connected to the ground of the casing and the earth to provide a bleed circuit for the accumulated static charge to prevent static charge accumulation and damage the equipment. The signal ground of the optical transceiver is well connected to the ground of the casing and the earth, which can effectively prevent the damage caused by the induced lightning.

Finally, the RS485 data terminal of the multi-channel digital video optical transceiver should also be provided with a grounding wire to be connected to the ground terminal of the opposite device in the project to avoid damage to the data port due to the ground potential difference between the devices at both ends of the RS485 channel.

2.4 Port Protection

The video port, audio port and data port of the optical transceiver is extremely vulnerable parts. Static electricity, surge, and induced lightning strikes may cause damage to the port of the optical transceiver. Except that the project should be carefully operated in strict accordance with the construction requirements, the device itself is also The necessary port protection should be provided. When selecting an optical transceiver, special attention should be paid to the manufacturer’s port protection measures.

3 Practical considerations

Every manufacturer should provide users and engineers with mature products, not scientific prototypes, so it must have practical considerations. When selecting an optical transceiver, users and engineers can consider more from the practical point of view of the device. First, the practical problems of users and engineering companies are easy to judge; Second, it is hard to believe that manufacturers that cannot do practicality can do the reliability and technical indicators of optical transceivers. Here we focus on the practicality of optical transceivers from the following perspectives.

3.1 Appearance and reasonable structure

The multi-channel digital video optical transceiver has high technical content, and its appearance should be small and exquisite, beautiful and elegant, and the overall structure must meet the engineering installation requirements as much as possible. In general, the indoor multi-channel digital video optical transceiver is 19-inch wide to fit in a standard 19-inch cabinet. It should also take into account the need to place the optical transceiver on the desktop or wall in the project. In addition, multi-channel digital video optical transceivers must also have good thermal performance and electrical contact performance.

3.2 Rich interface and reasonable layout

In addition to requiring sufficient video interfaces, multi-channel digital video optical transceivers may require or may require other feature-rich interfaces, such as high-fidelity audio interfaces, ordinary telephone interfaces, asynchronous data interfaces, Ethernet interfaces, and digital interfaces. This requires that the selected multi-channel digital video optical transceiver must have the system upgrade capability, and will not completely replace the equipment due to network upgrade or system function change, thus protecting the user’s upfront investment.

There are many types of multi-channel digital video optical transceiver interfaces, and there are a number of mode setting dial switches. The user interface of all these elements should be laid out reasonably, and there is considerable operation space between the interfaces to facilitate engineering. Installation and repair. For example, the video interface is too dense. In actual applications, there will be an embarrassing situation in which one video connector must be removed and other normal video connectors must be unplugged.

3.3 The meaning of the indicator light is clear, which facilitates the opening and maintenance of the project.

In order to facilitate project opening and engineering maintenance, multi-channel digital video optical transceivers should be marked with clear-cut indicators. In addition to the power indicator, the transceiver of the multi-channel digital video optical transceiver must have a video indicator light to indicate whether the video channel has video signal input or output. The engineers and users are in the project opening phase and engineering maintenance phase. According to the indication of the video indicator, you can judge the situation during opening and maintenance, locate the fault point, and solve the problem that may occur as soon as possible.

In addition, for the audio and data sections, the corresponding indicator light should also be provided. The simple way is to refer to the practice of telecommunication equipment, provide synchronization indicator and loop indicator light, and engineers and equipment manufacturers can judge whether the equipment system is faulty or the interface part is faulty, so as to make a correct response.

For the Ethernet interface, the connection/activity indicator, full-duplex/half-duplex indicator, and the 10M/100M indicator should be provided in accordance with the general requirements of the data communication equipment.

The multi-channel digital video optical transceiver should also provide system indicators to indicate whether the sending device is normal and whether the receiving device is normal so that the engineering personnel can distinguish whether the device is faulty or the fiber link is faulty.

3.4 Video can be up and down, convenient networking

Some security monitoring projects, multiple optical fibers along the way to be transmitted to the central monitoring room; and some security monitoring projects, and the former is just the opposite, one or more video signals are transmitted to the receiving points along the fiber; There are also security monitoring projects, multi-channel video signals need to be transmitted a long distance, and several levels of relays may be used in the middle.

This requires multi-channel digital video optical transceivers to have video signal insertion and extraction functions and lossless relay functions (relaying signals directly at the transmission layer rather than relying on signals at the user interface layer, which will degrade the technical specifications of the video signal).

More powerful vendors have not only provided such products, but also provided products that cross-connect any video channel signals, any audio channel signals, and any data path signals, and have been put into practical use. If there is such a demand in the project, priority should be given to the use of such equipment, which not only reduces the point of failure, but also improves the reliability of the system, ensures technical specifications, reduces engineering costs, and saves user investment.

The above is what is the video optical transceiver and how to judge the performance of the video optical transceiver. In summary, the user can consider the technical indicators, reliability, and practicability of the device when selecting the device, according to the above method. Do more comparisons, according to the actual situation of the project to do the program, and finally will be able to find the most suitable multi-channel digital video optical transceiver. Shenzhen Electric

Original Article Source http://www.qianjia.com/html/2019-05/21_337707.html

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Precautions for using fiber jumpers

Precautions for using fiber jumpers

Across the fiber jumpers, optical module transceiver wavelength must be consistent, i.e. the fiber ends must be the same wavelengths of the light module, a simple distinction is the color of the light module to be consistent. In general, short-wavelength optical modules use multimode fiber (orange fiber), and long-wavelength optical modules use single-mode fiber (yellow fiber) to ensure data transmission accuracy.

Do not bend or wrap the fiber in use, which will increase the attenuation of light during transmission.

After the fiber jumper is used, the fiber connector must be protected with a protective cover. Dust and oil can damage the coupling of the fiber.

If the fiber connector is dirty, you can use a cotton swab to clean the alcohol, otherwise, it will affect the communication quality.

1. The fiber jumper ceramic ferrule and the ferrule end face must be wiped clean with alcohol and absorbent cotton before use.

2. The minimum bending radius of the fiber is less than 30mm when in use.

3. Protect the ferrule and the ferrule end face to prevent bumps and pollution, and bring the dust cap in time after disassembly.

4. Do not look directly at the fiber end face when the laser signal is transmitted.

5. In case of damage caused by man-made and other force majeure factors, the damaged fiber jumper should be replaced in time.

6. Read the instructions carefully before installation and install and debug under the guidance of the manufacturer or dealer.

7. If an abnormal situation occurs in the optical network or the system, the fault elimination method can be used to test one by one. You can do the continuity test when testing or troubleshooting the jumper. You can usually use the visible laser pointer to judge the entire fiber link. Or further, use the precision fiber insertion loss detector to test its various indicators. If the indicator is within the qualified range, the jumper indication is normal, otherwise, it is unqualified.

 

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What are the differences between fiber patch cords and copper wires?

What are the differences between optical fiber jumpers and copper wires? With the development of the times, optical fibers have gradually replaced copper wires as the mainstream connecting devices. Of course, there are always more controversies in the choice of optical fibers and copper wires, and even Many friends think that the delay of the fiber line is shorter than the delay of the copper wire. So, what are the differences between the fiber jumper and the copper wire?

What are the differences between fiber patch cords and copper wires?

1. What are the differences between fiber jumpers and copper wires?

Optical fiber and copper wire are two common data center transmission media, both of which have anti-interference and good confidentiality. So what is the difference between fiber and copper wire? The difference between the two is mainly reflected in the following four aspects:

1. Transmission distance

Generally speaking, the transmission distance of copper wire does not exceed 100m, and the maximum transmission distance of fiber can reach 100km (single mode fiber), which far exceeds the transmission distance of copper wire.

2. Transmission rate

At present, the maximum transmission rate of copper wire can reach 40Gbps (such as eight types of network cable, DAC passive copper cable), and the maximum transmission rate of optical fiber can reach 100Gbps (such as OM4 fiber jumper), far exceeding copper wire.

3. Maintenance management

The operation of the crystal head of the copper wire and the port connection of the device is very simple, and the operations of shear welding and equipment connection of the optical fiber are required to be high and the operation is complicated.

4. Price cost

In the case of the same length of fiber and copper wire, the price of fiber is generally 5-6 times the price of copper wire, and the price of fiber-optic plug-in equipment (such as fiber coupler) is much higher than that of copper wire. In terms of price cost, the price cost of fiber is much higher than the price of copper wire.

Second, how the delay of the fiber jumper and copper wire

1, fiber jumper

Because fiber is currently used more, let’s first look at the delay of the fiber.

Physical knowledge, the speed of light in a vacuum is 3 * 10 8 square meters/sec, the speed of light will be slower under air conditions. Therefore, when an optical signal propagates in a fiber link, there are five steps to wait: the electrical signal is converted into an optical signal to produce two; the optical signal is generated through the optical fiber, and the optical signal is converted into an electrical signal to produce two.

2, copper wire

The signal quality of copper wires is not as good as that of optical fibers. Especially in long-distance transmission, signals are easily interrupted by the surrounding environment. The longer the distance, the more severe the attenuation. Frequently caused by client loss, page faults, slow user opening, etc.

Third, the delay of fiber jumper and copper wire contrast

The difference in delay between fiber and copper wire theoretically means that the signal is transmitted faster in the copper wire, but under long-distance demand, the signal processing and repetition requirements are less, the fiber delay is lower, and the copper wire is susceptible to the outside. The interference, the loss is large, and the delay is also larger.

In fact, we don’t have to delay to describe the fiber and the network, which are described by distance and speed. Different distances and speed delays are different. For example, serializing a 150-byte packet on a 1.5 Mbps link requires 8 ms, while at 10 Gbps it only requires 1.2 us, and at high speeds, there is less latency.

For the difference between the fiber jumper and the copper wire, I would like to see that the friends here have already got a certain understanding of this. In fact, the difference in delay between the fiber jumper and the copper wire is affected by the speed and distance. In the choice of the fiber jumper and the copper wire, if the distance is short, we can choose the copper wire as the transmission medium, the cost. It will be much lower than the fiber jumper. On the contrary, if it is transmitted over long distances, we can choose the fiber as the transmission medium, and its performance will be more stable.

(This article is from the Internet, compiled and edited by thousands of hackers. If there is any infringement, please contact to delete.)

Original Article Sourcehttp://cabling.qianjia.com/html/2019-04/01_331517.html

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Common fault solving method for weak engineering optical fiber transceiver

Foreword:

Our commonly used fiber optic transceivers have 6 indicators, so what does each indicator mean? Do all the indicators light up to indicate that the fiber transceiver is working properly?

PWR: Lights up to indicate that the DC5V power supply is working properly.

FDX: Lights up to indicate that the fiber transmits data in full duplex mode;

FX 100: Lights up to indicate that the optical fiber transmission rate is 100Mbps;

TX 100: The light is on, indicating that the twisted pair transmission rate is 100 Mbps, and the light is off, indicating that the twisted pair transmission rate is 10 Mbps;

FX Link/Act: The long light indicates that the fiber link is connected correctly; the flashing light indicates that data is being transmitted in the fiber;

TX Link/Act: The long light indicates that the twisted pair link is connected. When the light is on, the data in the twisted pair is transmitted at 10/100M.

If the optical transceiver is working properly, the PWR power indicator must be steady on. The FX-LINK/ACT fiber link indicator and the TX-LINK/ACT network link indicator must be on or blinking. If the LINK/ACT indicator is off. Check whether the link is normal. The FDX working mode indicator, FX-100 fiber rate indicator and TX-100 network rate indicator are not on the fiber transceiver.

1. The function of the indicator light of the optical transceiver and the method for determining the fault

1. First, do you see if the indicator of the fiber transceiver or optical module and the twisted pair port indicator are on?

  • A. If the optical port (FX-LINK/ACT) indicator of the transceiver is not lit, please confirm whether the fiber link is correct cross-link, fiber-optic jack TX-RX; RX-TX.
  • B. If the optical port (FXFX-LINK/ACT) indicator of the A transceiver is on and the optical port (FXFX-LINK/ACT) indicator of the B transceiver is not lit, the fault is on the A transceiver side: one possibility is: The A transceiver (TX) optical transmission port is broken because the optical port (RX) of the B transceiver does not receive the optical signal; the other possibility is that the optical link of the A transceiver (TX) optical transmission port has Problem (the cable or fiber jumper may be broken).
  • C. The twisted pair (TXFX-LINK/ACT) indicator does not light. Please make sure that the twisted pair cable is faulty or connected incorrectly? Please use the continuity tester (although some transceivers’ twisted pair indicators must be on after the fiber link is connected).
  • D. Some transceivers have two RJ45 ports: (To HUB) indicates that the connection line connecting the switches is a straight-through line; (To Node) indicates that the connection line connecting the switches is a cross-line.
  • E. Some transceivers have an MPR switch on the side: the connection line connecting the switch is a straight-through mode; the DTE switch: the connection line connecting the switches is a cross-line mode.

2. Is the optical cable and fiber jumper broken?

  • A. The cable on/off detection: use laser flashlight, sunlight, illuminator to illuminate one end of the cable connector or coupler; see if there is visible light on the other end? If there is visible light, the cable is not broken.
  • B. Optical fiber connection continuity detection: use laser flashlight, sunlight, etc. to illuminate the fiber jumper; see if there is visible light on the other end? If there is visible light, the fiber jumper is not broken.

3. Is there a mistake in the half/full duplex mode?

Some transceivers have FDX switches on the side: full duplex; HDX switches: half duplex.

4, using optical power meter instrument detection

The luminous power of a fiber optic transceiver or optical module under normal conditions:

Multimode 2Km: between -10db and 18db;

Single mode 20 km: between -8 dB and 15 dB;

Single mode 60 km: between -5db and 12db;

If the luminous power of the optical transceiver is between -30db and 45db, then it can be judged that there is a problem with this transceiver.

Second, common faults and solutions

According to the daily maintenance and the problems that the users have summed up, I hope to bring some help to the maintenance staff, to determine the cause according to the fault phenomenon, to find the fault point, “the right medicine.”

1. What kind of connection is used when the transceiver RJ45 port is connected to other devices?

Cause: The RJ45 port of the transceiver is connected to the PC network card (DTE data terminal equipment) using a crossover twisted pair, and the HUB or SWITCH (DCE data communication equipment) uses parallel lines.

2. What is the reason why the TxLink light is not lit?

answer:

  • 1, wrong twisted pair
  • 2, the twisted pair crystal head is in poor contact with the equipment, or the quality of the twisted pair itself
  • 3, the device is not connected

3. What is the reason why the TxLink lamp does not flash but is always on after the fiber is normally connected?

the reason:

  • 1. The fault is generally caused by the transmission distance being too long;
  • 2, compatibility issues with the network card (connected to the PC)

4. What is the reason why the Fxlink light does not illuminate?

the reason:

  • 1. The fiber optic cable is connected incorrectly, and the correct connection method is TX-RX, RX-TX or fiber mode is wrong;
  • 2. The transmission distance is too long or the intermediate loss is too large, exceeding the nominal loss of the product. The solution is to take measures to reduce the intermediate loss or replace it with a transmission distance longer.
  • 3. The operating temperature of the fiber optic transceiver is too high.

5. What is the reason why the Fxlink light does not flash but is always bright after the fiber is connected normally?

Cause: The fault is generally caused by the transmission distance being too long or the intermediate loss is too large, exceeding the nominal loss of the product. The solution is to minimize the intermediate loss or replace it with a transceiver with a longer transmission distance.

6. What should I do if the five lights are all on or the indicator is normal but not transferable?

Reason: Generally, the power is turned off and restarted.

7. What is the ambient temperature of the transceiver?

Cause: The fiber optic module is greatly affected by the ambient temperature. Although it has its own built-in automatic gain circuit after the temperature exceeds a certain range, the optical power of the optical module is affected and decreased, which weakens the quality of the optical network signal and causes packet loss. The rate rises and even disconnects the optical link; (typical fiber optic modules can reach 70°C)

8. What is the compatibility with the external device protocol?

the reason:

Like the 10/100M switch, the 10/100M optical transceiver has a certain limit on the frame length, generally not exceeding 1522B or 1536B. When the switch connected at the central office supports some special protocols (such as Ciss ISL), The packet overhead is increased (the packet cost of the ISL of the Ciss is 30 Bytes), which is exceeded by the upper limit of the frame length of the optical transceiver. This indicates that the packet loss rate is high or not. In this case, the MTU of the terminal device needs to be adjusted. The overhead of the general IP packet is 18 bytes, and the MTU is 1500 bytes. Currently, the high-end communication equipment manufacturer has an internal network protocol, which generally adopts a separate packet method, which will increase the overhead of the IP packet. If the data is 1500 bytes, IP. After the packet, the size of the IP packet will exceed 18 and be discarded), so that the size of the packet transmitted on the line is satisfactory to the network device’s limitation on the frame length.

9. After the chassis has been working normally for a while, why is it that some cards are not working properly?

the reason:

Early chassis power supplies used relays. Insufficient power supply margin and large line loss are major problems. After the chassis works normally for a period of time, some cards may not work properly. When some cards are pulled out, the remaining cards work normally. After the long-term operation of the chassis, the connector oxidation causes a large joint loss. This power supply falls beyond the regulations. The required range may cause the chassis card to be abnormal. The power supply switching of the chassis is protected by a high-power Schottky diode to improve the form of the connector and reduce the power drop caused by the control circuit and the connector. At the same time, the power redundancy of the power supply is increased, which makes the backup power supply convenient and safe, and makes it more suitable for the long-term uninterrupted work.

10. What function does the link alarm provide on the transceiver?

Cause: The transceiver has a linked alarm function (linkless). When a certain fiber is dropped, it will be automatically fed back to the electrical port (that is, the indicator on the electrical port will also be extinguished). If the switch has network management, it will be reflected in the switch immediately. Network management software. Third, the fiber transceiver should pay attention to matters

1. Does the optical transceiver itself support full-duplex and half-duplex?

Some chips on the market can only use full-duplex environment at present, and can’t support half-duplex. If you receive another brand of the switch (SWITCH) or hub (HUB), and it uses half-duplex mode, it must be It can cause serious conflicts and packet loss.

2. Have you tested the connection with other fiber optic transceivers?

At present, there are more and more optical transceivers on the market. For example, if the compatibility of transceivers of different brands has not been tested beforehand, it will also result in packet loss, long transmission, 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. The biggest disadvantage of this method is that the transmission is unstable and packet loss and the best is to use the buffer circuit design, which is safe. 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 (not more than 50 °C), whether the fiber optic transceiver works normally is a factor worth considering when purchasing!

Original Article Sourcehttp://www.qianjia.com/html/2019-05/06_335742.html

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Familiar with 5G bearer requirements to grasp the optical module “pulse”

According to GSA statistics, as of the end of January 2019, 201 operators in 83 countries/regions tested, deployed or planned to deploy 5G. On April 3, South Korea’s three major operators and Verizon of the United States announced the opening of 5G commercial services for public users, and the 5G construction speeded up; on April 23, China Unicom announced the opening of 5G networks in 40 cities and officially released the 5G brand. It indicates that the domestic 5G construction is also accelerating.

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Figure 4G/5G networking solution comparison

5G construction, bearer first, but the global operators’ 5G bearer solutions are different. Especially after the introduction of the concept of the middle pass, compatibility is considered whether to use independent networking, and the bearer scheme is more varied: for example, China Mobile adopts a new SPN network, China Telecom prefers to adopt M-OTN network, and China Unicom adopts IPRAN as the main mode of the bearer. Korean carriers and US carriers that are the first to be commercialized also use different bearer solutions. As is known, the complex bearer scheme will increase the number of corresponding 5G optical modules. However, according to the needs of the three major operators in China, there are certain contexts to be found.

In terms of speed, after the introduction of the eCPRI protocol standard, the pre-transmission 25G rate has become the standard of various equipment manufacturers. As a result, the rate of the bearer network will be considered according to the convergence ratio of each layer, and the 50G rate is the most The choice of cost performance, according to the development of the predecessor, there may be a module demand of 100G or even 200G rate.

In terms of fiber utilization efficiency, considering the difficulty of fiber laying, there is always a problem of tight fiber resources in some areas. Therefore, the BiDi module and even the WDM-based color light module will become a powerful complement to the requirements of the load module. The combination of speed, single/dual fiber and color light has resulted in a wide variety of 5G optical modules. Fortunately, the package form of the current mainstream optical module is basically based on QSFP28. Otherwise, the market for carrying optical modules will be more confusing.

As mentioned above, the 50G rate is the most cost-effective option for the middle pass, but from a module perspective, the 25G laser is the most popular rate choice for the industry chain. What should be done if there is a difference between the two? PAM4 technology solves this problem in a timely manner. It can double the amount of information transmitted per unit time through the algorithm of the electrical layer DSP at the same laser rate. Therefore, 50G PAM4 is based on a single 25G laser, and 50G rate signal transmission is realized by the electrical layer PAM4 technology. At present, the 50G PAM4 QSFP28 module is a typical requirement of the China Mobile network in the China Mobile SPN system. Guangxun Technology is the earliest optical module manufacturer in China to invest in 50G PAM4 LR/ER development. It is also involved in the discussion and formulation of China Mobile’s previous related standards. It is currently one of the few to provide a full range of 50G PAM4 products (10km single/dual fiber), 40km single/dual fiber) optical module manufacturers.

In addition, WDM color light modules are gaining more and more attention in 5G bearer solutions. Because in the foreign markets such as Japan and South Korea, the 4G era has begun to lay the bearer network of WDM solutions, and the continued selection of WDM modules in the 5G era is natural. At the same time, because the domestic 5G uses high-frequency signals, the coverage of the base station is small, and the number of 5G base stations will double that of the 4G era, which poses a great challenge for fiber laying. In terms of cost, although the cost of a separate module for WDM color light solutions is high, the cost of the overall solution will be more competitive.

Original Article Source http://www.qianjia.com/html/2019-05/06_335620.html

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LC: The global AOC and EOM market will reach $1.09 billion in 2023

ICCSZ News (Compile: Nina) LightCounting’s newly released active optical cable (AOC) and embedded optical module (EOM) market analysis and forecast report pointed out that in the next five years (2019-2023), the size of both markets will grow steadily , although AOC will be a little less energetic than before.

LC said the price decline will offset the increase in AOC shipments. For example, the latest report predicts that global AOC shipments in 2022 will be raised by about 30% from the previous year’s forecast. However, due to lower prices and higher demand for single-channel AOCs, revenue forecasts for 2022 are down 18% from the previous year’s report. LC expects the global AOC market to grow from $280 million in 2018 to $547 million in 2023.

LC said that China and other data center operators often use single-channel active optical cable (AOC) to connect servers to the first-tier switches, so they raised their expectations for single-channel AOC requirements. At the same time, Chinese data center operators typically do not use AOC to connect switches, thereby curbing the potential demand for Ethernet four-channel AOCs typically used in such applications.

The report pointed out that the high-performance computing (HPC) and data center areas are rapidly adopting 100G AOC, and it is expected that the HPC field will begin to develop into the 200G AOC this year. However, the market research company did not see the same enthusiasm for adopting the 200G Ethernet AOC in the data center market.

Regarding the EOM market, LC analysts believe that the technology will enter a good growth track after a decade of bumps. In the latest report, LC’s shipments to EOM are expected to increase by about 20% from the previous year’s analysis, and revenues have increased by 29%. The report’s authors expect that growth in this market will accelerate by 2020, with revenue increasing from $136 million in 2018 to $543 million in 2023.

Original Article Source http://www.qianjia.com/html/2019-01/07_319218.html

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Fiber access equipment and usage diagram

As the demand for different kinds of information is also increasing, the accompanying ever-increasing demand for new services such as IP data, voice, and multimedia images has prompted the network environment of major network operators to become overwhelming. In the past, traditional metropolitan area networks and access networks, which mainly used to carry analog voices, have been unable to meet the requirements of a variety of new service transmission and processing in terms of capacity and interface types. As a result of the rapid advancement of social information, the technologies and equipment that provide new services for metropolitan area networks and access networks have rapidly developed. Among them, the development of MSTP (Multi-Service Transport Platform) and PON (Passive Optical Network) is the most representative. They are based on fiber-optic transmission technology and provide the best of various new service bearers on the metropolitan area network or access network. solution.

Fiber-optic cable access technology is the development direction of broadband networks in the future. Its development is also inseparable from the development and support of fiber access equipment, just like fish and water. Talking about the fiber access equipment has to mention its three generations of development experience: the first generation of large-scale PDH (fiber optic transceiver) equipment, including point-to-point and star-type office equipment, does not have aggregation function. All adopt PDH transmission protocol, and there is no optical interface specification. User services, such as E1 and data services, are multiplexed through the private PDH protocol and transmitted to the central office equipment via optical fibers. The central office equipment taps the PDH optical signal according to the proprietary protocol, and converts it into a PDH interface such as E1, and then connects to the metro backbone/aggregation device through the cable through the DDF distribution frame. Due to the limitations of the PDH protocol, various types of fiber access devices are quickly out of date.

The second generation In view of the defects of the first generation equipment, some PDH equipment manufacturers have developed a piece of second generation equipment, that is, adding an SDH (dense optical wave multiplexing) terminal card to the central office equipment. The private PDH protocol is still used between the central office and the remote device, and the aggregation function is provided at the central office to multiplex the original E1 signal through the SDH terminal card and provide a standard SDH interface. It mainly solves the interconnection problem and unified interface standard between the central office equipment and the metro backbone equipment.

The third generation is SDH pass-through equipment, including converged and non-converged types. Due to the wide coverage of the new services, the new generation of SDH pass-through devices can be automatically adapted to the SDH for transmission according to the SDH specification. The non-aggregated remote device can be directly connected to the metropolitan area network aggregation layer node through the SDH optical interface. There are fewer service interfaces on the aggregation layer network. The aggregation type is inserted into the SDH aggregation device at the central office to aggregate VC12 services from multiple directions to the uplink SDH interface, thus saving the number of STM-1 interface cards on the large-capacity backbone node device. It mainly solves the compatibility problem of each device and is convenient for future upgrade and maintenance.

With the development of fiber access equipment to date, due to the continuous updating of fiber access technologies and the increasing number of manufacturers joining, the categories of fiber access equipment are becoming more and more obvious, mainly in three categories:

(1) Optical fiber communication Continued text components (for communication and computer network terminal connections), such as fiber jumpers, fiber connectors (boxes).

(2) Optical fiber transceiver (for computer network data transmission), such as fiber optic box, fiber coupler and wiring box (rack).

(3) Optical cable engineering equipment, optical cable test instrument (for large-scale engineering), such as optical fiber fusion splicer, optical fiber loss test equipment.

For the first two categories, we can often understand and contact the fiber access equipment products. The following small series introduces two major types of equipment:

fiber optic communication and text fiber transceivers: the fiber jumper is without connection. The cable pair or cable unit of the unit is used to interface with various links on the distribution frame. Fiber optic patch cords are used for long-haul and local optical transmission networks, data transmission and private networks, and various test and automation systems.

　　Fiber optic connector (box)

fiber optic connector (box) is mainly used for the connection between fiber and fiber, fiber and device.

　　Fiber optic boxes

Fiber optic boxes are used to transmit digital and similar voice, video and data signals using fiber optic technology. Fiber optic boxes are available for direct or desktop installation. Particularly suitable for high-speed fiber transmission.

　　The product shown above is a 100Base-TX twisted pair 100Base-FX multi/single mode fiber optic repeater designed primarily for Fast Ethernet workgroup users who require a long distance, high speed, and wide bandwidth.

　　The product shown above is a 10/100M adaptive Fast Ethernet fiber optic transceiver. It can realize the conversion of two different transmission media of twisted pair and optical fiber and relays two different network segments of 10/100Base-Tx and 100Base-FX, which can meet the requirements of long-distance, high-speed and high-bandwidth Fast Ethernet working group users. need.

Fiber module card

　　The Gigabit series fiber-optic module card is used with the switch and uses fiber or Category 5 twisted-pair cable to expand the LAN range and expand the bandwidth. It is suitable for large and medium-sized LANs to expand bandwidth and expand their network coverage. The fiber optic module is fully compliant with the IEEE802.3z protocol and operates in the 850nm and 1300nm modes. It is also fully compliant with the IEEE802.3ab protocol. It is compatible with other devices with the same Gigabit protocol. Due to its small size, it is directly installed inside the switch and requires no additional space. Powered by the switch, it is easy to install and use, and can be used with a variety of switches.

Fiber

Coupler Fiber Coupler (Splitter) is a component that splits optical signals from one fiber into multiple fibers. It belongs to the field of optical passive components, in telecommunication networks, cable TV networks, and users. It is applied in the loop system and the regional network, and the largest item is used in the passive component of the fiber connector. The fiber coupler can be divided into a standard coupler (double branch, unit 1 × 2, that is, the optical signal is divided into two powers), a star/tree coupler, and a wavelength multiplexer (WDM, if the wavelength is high density, that is, the wavelength spacing is narrow, it belongs to DWDM), and the production method includes three types of sintering (Fuse), micro-optics (Micro-Optics), an optical waveguide (Wave Guide), while the production by sintering method is the majority (about 90). %).

ST coupler

　　FC coupler

Six-port SC coupler board

　　The above products are suitable for transfer between test equipment, local area network, fiber optic CATV and different types of signs.

Single and multimode fiber converter

single and multimode fiber transceivers are used for data communication between optical cables, allowing users to expand the scale of UTP networks using single mode or multimode fiber, and are widely used in Ethernet data communication to extend the transmission distance. The expansion and extension of the network are achieved through fiber optic links.

　　Optical transceiver

video multiplexer adopts the most advanced digital video, high-speed transmission technology of Gigabit fiber and all-digital uncompressed technology, so it can support any high-resolution motion and still image without distortion transmission; overcome the conventional analog frequency modulation and phase modulation. The amplitude modulation of the multi-channel signal of the amplitude modulation optical transceiver is severe, the interference is serious, the transmission quality is inferior, and the long-term working stability is poor. It can also provide multiple channels of video, audio, data, telephone voice, and Ethernet transmission on the optical fiber at the same time, which greatly saves the investment cost of the user equipment and improves the utilization of the optical cable. Widely used in security monitoring, highways, electronic police, automation, intelligent community, customs, electricity, water conservancy, petroleum, chemical, and many other fields.

　　The fiber distribution frame

fiber distribution equipment is designed for the fiber-optic communication equipment room. It consists of a fiber distribution unit and a cabinet or rack. The maximum wiring capacity of each unit is 24 fiber. The unit structure is 19-inch chassis, and the height is generally 9cm. In a standard cabinet or rack. Users can choose the number of units or unit specifications according to actual needs. It can be used as fiber distribution, and can also be used as a cable terminal box; it can be separately assembled into a fiber distribution frame, or it can be integrated with a digital distribution unit and an audio distribution unit in a cabinet/frame to form integrated wiring. frame. The device is flexible in configuration, easy to install and use, easy to maintain, and easy to manage. It is one of the indispensable devices for small and medium-sized fiber-optic communication equipment rooms to realize fiber-optic, fiber-optic, frit, and fiber-optic cable access. Applicable to the fiber termination point in the fiber access network, with the wiring and welding function of the optical cable, which can realize flexible jumper and storage of the optical fiber core.
The above equipment for the fiber access network greatly improves the data transmission and processing capability of the fiber access network, and can bring two advantages:

First, the problem of remote transmission of the access line is solved, and the fiber access network is provided. The coverage is broader. In this way, the number of transit nodes of the entire overlay network can be reduced, and the structure of the network is made simpler.

Second, it can meet the needs of users for a variety of new broadband services and can improve the quality of new business data. This solves the “bottleneck” problem of the traditional copper access network from the core technology and lays the foundation for the realization of the “fiber to the home” dream.

Therefore, the future fiber access network should become the main force of the Internet information highway.

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Talking about the testing and troubleshooting equipment of optical fiber network

In recent years, as people’s requirements for broadband speed are getting higher and higher because the performance of optical fiber is superior to that of copper cable, it is widely used in the backbone construction of broadband projects. At the same time, due to the increasing coverage of optical fibers, the detection of optical fiber faults is becoming more and more important. What methods can be used to eliminate the failure of optical components?

First of all, to eliminate the failure of optical components, it is necessary to pass the test, then what are the test and measurement equipment of the optical network? At present, the super six network cable manufacturers Weikang understand that there are mainly three kinds of instruments. They are optical loss test equipment (also known as an optical multimeter or optical power meter), fault locator (fault tracker), and fiber identifier.

1. Optical loss test equipment (combined by optical multimeter and optical power meter)

Optical power meter: Used to measure absolute optical power or relative loss of optical power through a length of the fiber. Optical Multimeter: Used to measure the optical power loss of a fiber link.

In order to measure the loss of a cable link, it is necessary to transmit calibrated steady light at one end and read the output power at the receiving end. These two devices constitute an optical loss tester. When combining a light source and a power meter into a set of instruments, it is often referred to as an optical loss tester (also known as an optical multimeter). When we measure the loss of a link, one person needs to operate the test light source at the transmitting end and the other person uses the optical power meter to measure at the receiving end so that only the loss value in one direction can be obtained.

Usually, we need to measure the loss in both directions (because there is a loss of the connection or it is due to the asymmetry of the transmission loss of the cable). At this point, the technicians must exchange equipment and conduct measurements in the other direction. However, what should they do when they are separated by more than a dozen floors or tens of kilometers? Obviously, if each of these two people has a light source and an optical power meter, then they can measure simultaneously on both sides. Today’s advanced cable test kits for certification testing are capable of two-way dual-wavelength testing, such as Fluke’s CertiFiber and DSP cable test series FTA cable test kits.

2, fiber fault locator (fault tracker)

Fault locators are mostly hand-held instruments for multimode and single-mode fiber systems. The OTDR (Optical Time Domain Reflectometry) technology is used to locate the fault of the fiber, and the test distance is mostly within 20 km. The instrument directly displays the distance to the point of failure by number. Suitable for: Wide Area Network (WAN), 20 km range communication systems, fiber to the roadside (FTTC), single mode and multimode fiber optic cable installation and maintenance, and military systems. In single-mode and multi-mode cable systems, fault locators are an excellent tool for locating faulty connectors and bad splices. The fault locator is easy to operate and can detect up to 7 multiple events with single button operation.

This device is based on the laser diode visible light (red light) source. When light is injected into the fiber, if there is a fiber failure, connector failure, excessive bending, poor welding quality, etc., the light emitted through the fiber can be on the fiber. The fault is visually located. The visual fault locator is transmitted in continuous wave (CW) or pulsed mode. Typical frequencies are 1 Hz or 2 Hz, but can also operate in the kHz range. Typical output power is 0dBm (1Mw) or less, the working distance is 2 to 5km, and supports all common connectors.

3, fiber recognizer

It is a very sensitive photodetector. When you bend a fiber, some of the light is radiated from the core. The light is detected by the fiber identifier, and the technician can identify the single fiber in the multi-core cable or the patch panel from other fibers based on the light. The fiber identifier can detect the state and direction of light without affecting transmission. In order to make this work easier, the test signal is usually modulated at the transmitting end to 270 Hz, 1000 Hz or 2000 Hz and injected into a specific fiber. Most fiber identifiers are used for single mode fiber optic cables operating at 1310 nm or 1550 nm. The best fiber identifiers are available to identify the direction and power of transmission in fiber optic cables and test cables online using technology.

In summary, the project that generally uses a large number of large-scale project equipment fiber optic is. To complete an optical loss measurement or to eliminate the failure of a fiber optic equipment, a calibrated light source, and a standard optical power meter are not available. Lack of.

Responsible Editor: DJ Editor

Original Article Source http://www.jifang360.com/news/2016120/n923777329.html